Seasonal water relations in native and reconstructed mine soils : implications for ponderosa pine
establishment
by Karin Marie Jennings
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Soils
Montana State University
© Copyright by Karin Marie Jennings (1998)
Abstract:
Reclamation at the Rosebud Mine in Colstrip, Montana is generally considered to be successful based
on the establishment and high productivity of cool season grasses. However, survival of ponderosa pine
in pine reclamation sites varies between zero and 80 percent, with overall pine survival only 20 to 25
percent. Ponderosa pine frequently die shortly after planting, generally during the first two years.
Competition with grasses for limited soil water is believed to reduce pine survival during this period.
This thesis focuses on available soil water and competition for available soil water among plant species
at the Rosebud Mine. Seasonal soil water status and soil physical and hydrologic properties of six
native sites and six reclamation sites are quantified and compared. Secondary objectives were to
evaluate whether a more suitable substrate for establishment and survival of ponderosa pine could be
created, and if so, to recommend one or more soil profiles. Soil water was measured in the field during
parts of the 1996 and 1997 growing seasons with a neutron moisture meter (NMM). Field descriptions
of soil profiles and site characteristics were completed. Soil water retention was characterized using a
pressure plate apparatus. The ERHYM-It computer simulation model was modified and used to
extrapolate beyond the measured seasonal soil water data, using the measured soil physical and
hydrologic properties in combination with 34 years of climate data from Colstrip, Montana.
Differences in soil physical and hydrologic properties were measured between native and reclamation
sites, including higher mean soil bulk density (greater than 1.4 g cm-3) for reclamation sites, which is
consistent with the effects of reconstruction practices and the sandier soils. Reclamation sites contained
more soil water, especially early in the growing season, than native sites. Despite lower plant available
water holding capacity, reclamation sites experienced greater soil water depletion, with more than
twice as much as native sites. Grass productivity appeared to be greater on reclamation sites, perhaps
related to greater measured soil water contents. Based on the results of this study and relevant
literature, several strategies are suggested to create more favorable conditions for survival of ponderosa
pines. Establishment and productivity of grasses immediately surrounding ponderosa pine seedlings
should be reduced to decrease competition for limited soil water. A soil profile which promotes deeper
storage of soil water is generally expected to favor pines rather than grasses. Continued management to
control grasses is recommended even for apparently established saplings, especially during periods of
lower than average precipitation. Planting ponderosa pine into soil conditions better suited to the
production of cool season grasses may hot be the best use of available resources. Adjustment of final
bond release criteria may be reasonable, in some instances, to allow species that support an approved
post-mine land use to take precedent. SEASONAL WATER RELATIONS
IN NATIVE AND RECONSTRUCTED MINE SOILS:
IMPLICATIONS FOR PONDEROSA PINE ESTABLISHMENT
by
Karin Marie Jennings
A thesis submitted in partial fulfillment
o f the requirements for the degree
of
Master o f Science
>
Soils
MONTANA STATE UNTVERSITY-BOZEMAN
Bozeman, Montana
May 1998
CVV447
APPROVAL
o f a thesis submitted by
Karin Marie Jennings
This thesis has been read by each member o f the thesis committee and has been
found to be satisfactory regarding content, English usage, format, citations, bibliographic
style, and consistency, and is ready for submission to the College o f Graduate Studies.
sr-/9~?x
Jon M. Wraith
Committee Chair
Date
Approved for the Department o f Plant, Soil and Environmental Science
Jeff Jacobsen
Interim Department Head
?) i Lih r
Date
Approved for the College o f Graduate Studies
Joseph J Fedock
Graduate Dean
Date
iii
STATEMENT OF PERM ISSION TO USE
In presenting this thesis in partial fulfillment o f the requirements for a master’s
degree at Montana State University-Bozeman, I agree that the Library shall make it
available to borrowers under rules o f the Library.
I f I have indicated my intention to copyright this thesis by including a copyright
notice page, copying is allowable only for scholarly purposes, consistent with “fair use” as
prescribed in the U.S. Copyright Law. Requests for permission for extended quotation
from or reproduction o f this thesis in whole or in parts may be granted only by the
copyright holder.
Signature
Date
ACKNOWLEDGMENTS
I would like to acknowledge the assistance o f my committee members. Dr. Jon
Wraith, Dr. Paul Hook, Dr. Tom Keck and Dr. Roger Sheley, for their technical support and
guidance. Special thanks to my major advisor, Dr. Jon Wraith, whose general good nature
and availability to answer questions was greatly appreciated.
I would also like to
acknowledge Dr. Bhabani Das for his assistance with laboratory methods, Mike Mullin for
assistance with some especially ugly field work, Greg Millhollin for providing information
about the Rosebud Mine and their reclamation practices, and my husband, Stuart Jennings,
for his love and encouragement throughout this adventure. Thank you.
V
TABLE OF CONTENTS
Page
1. IN TRO D U CTIO N......................
I
2. LITERATURE REVIEW .................................................................................................
4
vo t"
Land Reclamation at the Rosebud Mine...................... ...........
Previous Research on Pondero$a Pine at the Rosebud Mine
Distribution o f Ponderosa Pine on Western Landscapes . . .
Site Characteristics .........
8
Root Distribution o f Ponderosa Pine ........................................................................... 9
Soil Physical Properties and Soil W a t e r ................................................................... 12
Competition Between Pondetosa Pine and Grass
for Below Ground R esources............................................................................. 16
3. O B JE C T IV ES....................
21
4. MATERIALS AND M E T H O D S ....................................................................................
23
Field Measurement Sites . . . ......................................... .........................................
Neutron Moisture M eter Cahbration and Bulk
Density M easurem ents........................................................................................
Soil W ater Retention and Plant Available W a te r......................................................
Computer Simulation Modeling o f Long Term
Seasonal Soil W ater Status ...............................................................................
Recommendations for Soil Profile Design ................................i .............................
23
5. RESULTS AND DISCUSSION ....................................................................................
41
Field Measurement Sites .................
Neutron Moisture M eter CaUbration and Bulk
Density M easurem ents........................................................................................
Soil W ater Retention and Plant Available W a te r......................................................
Soil W ater S ta tu s.....................
Computer Simulation Modeling o f Long Term
Seasonal Soil W ater Status ......................... ............... ...............
Model Sensitivity A nalysis............................. ...........- .......... ........................
RunoflT Curve Number ...........................
Soil Initial A bstraction...........................
Effective P rec ip ita tio n ...............................................................................
41
28
30
32
40
43
48
52
70
70
70
71
72
vi
Transpiration C oefficien t........................................................................... 72
Root Depth D istributions......... ........................................................
73
Model Simulation Results ................................................................................. 74
Model I n p u t................................................................................................. 74
Model Output ............................................................................................. 77
Recommendations for Soil Profile Design ...................................................... 106
6. SUMMARY AND CONCLUSIONS ...........................................................................
109
7. LITERATURE C IT E D ..............................................................................
APPENDICES ......................................................................................................................
114
121
Appendix A— Site Description Forms ........................................................................ 122
Appendix B—Model Predicted Soil W ater
Contents During the Growing Season o f
'
Selected Years, for Native and Reclamation
Sites (Figures I SE through I SE) ..................................................................
147
Appendix C—Model Predicted Soil
W ater Status by Wetness Class
• (Tables 14A though 1 4 F ).................................................................................... 156
vii
LIST OF TABLES
Table
Page
1.
Summary o f site characteristics ........................................................................
26
2.
Soil order and soil series designation
for each study s i t e ...............................................................................................
27
Summary o f dominant grass species o f
Native and reclamation site s ...............................................................................
44
4.
Site groupings for neutron moisture meter calibration ........... ......................
45
5.
Mean profile (0 to 90 cm) soil bulk density
for each study s i t e ..................................................
46
Laboratory measured plant available water holding
capacity (PAWHC) for native and reclamation s ite s ......................................
49
Percent effective overwinter precipitation during
October I, 1996 to April I, 1997 for each
Site, calculated from neutron moisture
meter and daily precipitation d a ta ......................................................................
54
Selected site characteristics used in
Computer simulation modeling ........................................................................
74
Computer simulation modeling site input
File values for native sites .................................. ...............................................
75
Computer simulation modeling site input
File values for reclamation s i t e s .................................................... ....................
76
IOA Soil water retention results used in native site
Input files obtained by fitting measured water
retention data to van Genuchten’s (1980) equation ......................................
78
I OB. Soil water retention results used in reclamation
Site input files obtained by fitting measured water
retention data to van Genuchten’s (1980) equation ......................................
79
3.
6.
7.
8.
9A.
9B.
viii
11. Correlation o f measured and model predicted
soil water contents for 1996 and 1997 .............................................................
12.
81
Summary o f thickness, field capacity water
content and wilting point water content
based on pressure plate measurements
for each soil layer modeled ...............................................................................
87
13. 34-year precipitation summary for Colsttip, MT
weather station (no. 1 9 0 5 ).................................................................................
88
14A-F. Model predicted 34 year mean (standard
error) number o f days per month within
each soil wetness c la s s ........................... ............................................. Appendix C
X
ix
LIST OF FIGURES
Figure
Page
1.
Field study site location map, Colstrip, Montana ...........................................
24
2.
Example o f differences in grass productivity on
native and reclamation sites, May 1 1 ,1997 ...................................................
42
3.
Mean measured soil bulk density by d e p t h ......................................................
47
4.
Pressure plate results: measured depth equivalent
plant available soil water holding capacity by depth
for each s i t e .............................................................
50
Distribution o f 1996 and 1997 overwinter and
growing season precipitation,Colstrip, M o n ta n a ............................................
53
Mean field-measured soil water content for
all native and reclamation s ite s ...........................................................................
56
Mean incremental soil water depletion o f near
surface soil horizons (0 to 70 cm) ....................................................................
57
8A. Soil profile (0 to 90 cm) starting w ater content
based on 1996 neutron moisture meter measurements ..................................
59
SB. Soil profile (0 to 90 cm) starting water content
based on 1997 neutron moisture meter measurements ..................................
60
9A. Soil profile (0 to 90 cm) starting plant available
water based on 1996 neutron moisture meter
measurements as a percent o f plant available
water bolding capacity . . . ; ...............................................................................
62
9B. Soil profile (0 to 90 cm) starting plant available
water based on 1997 neutron moisture meter
measurements as a percent o f plant available
water holding cap acity ........................................................................................
63
5.
6.
7.
X
I GA.
Comparison o f soil profile (0 to 90 cm) water
depletion from native and reclamation sites based
on 1996 neutron moisture meter m easurem ents.............................................
65
Comparison o f soil profile (0 to 90 cm) water
depletion from native and reclamation sites based
on 1997 neutron moisture meter m easurem ents....................................
66
Comparison o f soil profile (0 to 90 cm) water
depletion from vegetated and non-vegetated
reclamation sites based on 1996 neutron
moisture meter measurements ...........................................................................
68
Comparison o f soil profile (0 to 90 cm) water
depletion from vegetated and non-vegetated
reclamation sites based on 1997 neutron
moisture meter measurements ..........................................................................
69
Measured and model predicted soil water content
o f native sites during 1996 to 1997 NM M
measurement p e rio d .............................................................................
82
Measured and model predicted soil water content
o f reclamation sites during 1996 to 1997
NMM measurement period ...............................................................................
83
13. Daily precipitation recorded at the
Colstrip, MT weather station (no. 1905) during
1996 and 1997 NM M measurement p e rio d s....................................................
85
14. Distribution of monthly precipitation for
selected years, and mean daily precipitation
o f 34-year re c o rd ........................................................................................
89
I OB.
I I A.
I IB.
12A.
12B.
15A. Model predicted soil water contents during
the growing season o f selected years, for
native site 493D-A with pine r o o ts ......................................................................90
15B. Model predicted soil water contents during
the growing season o f selected years, for
native site 493D-A with grass r o o t s ...............................
v
•
91
Xl
I SC. Model predicted soil water contents during
the growing season o f selected years, for
reclamation site 4901-C with pine r o o t s .........
................................................92
15D. Model predicted soil water contents during
the growing season o f selected years, for
reclamation site 4901-C with grass r o o t s ...........................................................93
I SE-L. Model predicted soil water contents during
the growing season o f selected years for
native and reclamation sites ..................................................................Appendix B
16 A. Relative root depth distribution o f pine and
grass for native site input v alu es........................................................................
96
16B. Relative root depth distribution o f pine and
grass for reclamation site input values .............................................................
97
17A. Model predicted mean monthly number
o f days soil water content was equal to
or greater than a given matric potential
during the growing season (34-year record):
native site 121E-C with pine or grass roots......................................................... 99
17B. Model predicted mean monthly number
o f days soil water content was equal to
or greater than a given matric potential
during the growing season (34-year record):
native site 183E-C with pine or grass r o o ts ..................................................... 100
17C. Model predicted mean monthly number
o f days soil water content was equal to
or greater than a given matric potential
during the growing season (34-year record):
native site 493D-A with pine or grass roots.................................... ................. 101
I TB. Model predicted mean monthly number
o f days soil water content was equal to or
greater than a given matric potential during
the growing season (34-year record): reclamation
site 4888-A with pine or grass roots................................................................... 102
Xll
I TE. Model predicted mean monthly number
o f days soil water content was equal to or
greater than a given matric potential during
the growing season (34-year record): reclamation
site 3915-C with pine or grass roots................................................................... 103
17F. Model predicted mean monthly number
o f days soil water content was equal to or
greater than a given matric potential during
the growing season (34-year record): reclamation
site 4901-C with pine or grass roots................................................................... 104
xiii
ABSTRACT
Reclamation at the Rosebud Mine in Colstrip, Montana is generally considered to be
successful based on the establishment and high productivity o f cool season grasses. However,
survival o f ponderosa pine in pine reclamation sites varies between zero and 80 percent, with
overall pine survival only 20 to 25 percent. Ponderosa pine frequently die shortly after
planting, generally during the first two years. Competition with grasses for limited soil water
is believed to reduce pine survival during this period. This thesis focuses on available soil
w ater and competition for available soil water among plant species at the Rosebud Mine.
Seasonal soil water status and soil physical and hydrologic properties o f six native sites and
six reclamation sites are quantified and compared. Secondary objectives were to evaluate
whether a more suitable substrate for establishment and survival o f ponderosa pine could be
created, and if so, to recommend one or more soil profiles. Soil water was measured in the
field during parts o f the 1996 and 1997 growing seasons with a neutron moisture meter
(NMM). Field descriptions o f soil profiles and site characteristics were completed. Soil
w ater retention was characterized using a pressure plate apparatus. The ERHYM-H
com puter simulation model was modified and used to extrapolate beyond the measured
seasonal soil water data, using the measured soil physical and hydrologic properties in
combination with 34 years o f climate data from Colstrip, Montana. Differences in soil
physical and hydrologic properties were measured between native and reclamation sites,
including higher mean soil bulk density (greater than 1.4 g cm'3) for reclamation sites, which
is consistent with the effects o f reconstruction practices and the sandier soils. Reclamation
sites contained more soil water, especially early in the growing season, than native sites.
Despite lower plant available water holding capacity, reclamation sites experienced greater
soil water depletion, with more than twice as much as native sites. Grass productivity
appeared to be greater on reclamation sites, perhaps related to greater measured soil water
contents. Based on the results o f this study and relevant literature, several strategies are
suggested to create more favorable conditions for survival o f ponderosa pines. Establishment
and productivity o f grasses immediately surrounding ponderosa pine seedlings should be
reduced to decrease competition for limited soil water. A soil profile which promotes deeper
storage o f soil water is generally expected to favor pines rather than grasses. Continued
management to control grasses is recommended even for apparently established saplings,
especially during periods o f lower than average precipitation. Planting ponderosa pine into
soil conditions better suited to the production o f cool season grasses may hot be the best use
o f available resources. Adjustment o f final bond release criteria may be reasonable, in some
instances, to allow species that support an approved post-mine land use to take precedent.
I
CHAPTER I
INTRODUCTION
Regulations governing coal mining in the United States require that mined lands be
“reclaimed”, or revegetated to a condition as productive or more productive than pre-mine
conditions.
Federal regulations require the establishment o f “diverse, effective, and
permanent vegetative cover o f the same seasonal variety native to the area, or species that
support the approved post mining land use” (Section 515.19 SMCRA, 1977). Montana
revegetation regulations require that productivity, cover and diversity be similar to the native
vegetation (Coenenberg,
1982).
The Rosebud Coal Mine, operated by W estern Energy Company, is located near
Colstrip, located in the eastern Montana ponderosa pine savanna vegetation type (Payne,
1973). Native vegetation surrounding the mine is a mosaic o f mixed prairie grassland and
pine woodland with Idealized areas o f riparian vegetation. Native landscape is characterized
by sandstone ridges and rolling prairies. Sandstone ridges are frequently capped by hard,
erosion-resistant porcelanite (heat-fused shale and clay from the ro o f and floor o f burned out
coal seams) and are dominated by ponderosa pine (Firmsponderosa Laws. var. scopulorum)
trees.
2
Since 1968, Western Energy Company has disturbed about 4,300 hectares (10,500
acres) o f land mining coal at the Rosebud Mine (Montana Power Company, 1995). About
1,750 hectares (4,200 acres) have been revegetated. The majority o f mined lands at the
Rosebud Mine will be returned to “multipurpose native vegetation”, including areas o f
ponderosa pine. Most o f the mined land was native rangeland, providing forage for livestock
and wildlife (Coenenberg, 1982). Although final bond release has not yet been sought for any
o f the reclamation sites where ponderosa pine establishment is required, reclamation at the
Rosebud Mine has generally been considered successful based on the establishment and high
production o f cool season grasses and forbs (Keck et al., 1993).
Amaximum o f 920 permitted hectares (2,272 acres) o f ponderosa pine habitat may be
disturbed by the Rosebud Mine (Martin, 1990). While reestablishment o f ponderosa pine is
occurring in a few areas o f the mine, mortality is high. Pine survival varies between zero and
80 percent at sites planted with ponderosa pine.
The overall average survival rate o f
ponderosa pine on sites requiring pine is approximately 20 to 25% (personal communication:
Pete Martin, Western Energy Company, 1997). High mortality has resulted in five tree
densities far below the 40 trees per hectare (100 trees per acre) expected to be required for
final, phase HI bond release on most sites (Martin, 1990).
Y oung pine trees in reclamation areas frequently die during the first two years after
planting (Martin, 1990; Richardson, 1981). It is during this time when competition for limited
resources, primarily soil water, is high and most detrimental (Larson and Schubert, 1969).
However, trees may also die when eight to ten years old and thought to be established.
3
Establishing woody species is generally difficult in arid climates. Competition with
grasses for limited soil water is believed to limit survival o f ponderosa pine seedlings
(Baumbauer and Blake, 1984; Larson and Schubert, 1969; Potter and Green, 1964;
Richardson, 1981). Competition decreases when the pines reach sapling stage, apparently due
to differences in the spatial distribution o f pine and grass root systems (Lee and Lauenroth,
1994; Potter and Green, 1964). Despite competition with grasses, native stands o f ponderosa
pine are expanding away from sandstone/pprcelanite outcrops as individual pines successfully
establish, survive and reproduce in areas o f deeper soil that are dominated by grasses.
The Rosebud Mine has experienced continued difficulty with establishment o f ponderosa
pines in reclamation areas. Poor pine establishment is a great concern to operators o f the
Rosebud Mine for several reasons, including repercussions for the overall success o f the
reclamation program, economic effects because o f the expense o f repeated plantings, and
possible difficulty in obtaining final bond release for a potentially large area o f the mine. The
problem o f ponderosa pine establishment at the Rosebud Mine is the subject o f this thesis.
4
CHAPTER 2
LITERATURE REVIEW
Land Reclamation at the Rosebud Mine
One o f the fundamental objectives in land reclamation is the rapid establishment o f
vegetative cover to stabilize surface soils. Another objective is that this cover be diverse,
effective, permanent, and similar to the pre-mine community or a different, but approved post­
mining land use. To achieve these general goals. Western Energy Company currently applies
a two-phase seeding sequence at the Rosebud Mine, as outlined by Coenenberg (1982) and
summarized in the following paragraphs.
The first step in reclamation is redistribution o f the salvaged soil materials, which are
primarily stripped and directly hauled to recontoured spoil areas (reclamation sites) or
occasionally stockpiled in separate topsoil or subsoil storage areas. Replacement o f soil in
a reclamation site occurs either as “ single-lift” or “ double-lift” . Single-lift refers to the
placement o f one layer of topsoil over spoil material (replaced geologic material from below
the soil resource and above the coal seam). In contrast, double-lift refers to two layers,
subsoil then topsoil, placed over spoil material. The replaced soil materials are then chisel
plowed to reduce compaction, break up soil clods, and prepare the surface for seeding.
5
The next step is seeding. Four main seed mixes are used for reclamation at the Rosebud
Mine: upland, supplemental, conifer and lowland. “Upland” contains primarily cool-season
grasses and forbs.
“ Supplemental” contains primarily warm-season grasses and forbs.
“Conifer” is also comprised o f warm-season grasses and forbs, although a slightly different
mixture than the supplemental mix. The conifer mix is only seeded in areas planned for
ponderosa pine. Rocky Mountain juniper and/or skunkbush sumac. “Lowland” contains
perennial grass species adapted to more mesic environments. Seeding is followed by planting
o f shrub or tree species on designated reclamation sites.
Seeding occurs in multiple phases depending on the community desired for the site.
Efforts are made to seed and plant during early spring when natural moisture is most
dependable (April to June) or late fall when seeds or plants are considered dormant.
“Upland” and “supplemental” seed mixes are seeded at the same time.
“Conifer” and
“lowland” seed mixes are seeded alone. Sites with slopes near the maximum (20 percent) are
mulched with native grass hay, which helps to temporarily protect the surface from erosion.
Ponderosa pine and Rocky Mountain juniper are planted as tubeling or bare root stock with
a Vermeer tree spade. These seedlings are propagated by a contracted nursery from locally
collected seeds.
Various strategies for establishment o f ponderosa pine have been tested by W estern
Energy Company. These include: planting o f bare root and containerized stock in single-lift
and double-lift soils; planting in areas with different seed mixes, in both newly seeded areas
and locations where herbaceous vegetation was already established; chemical spraying to
reduce competition from grass and forb species; protection from mammal depredation with
6
plastic tubing; and protection from moisture loss due to excess radiation with shade cards and
“Terra-Mats” (Martin, 1990). Despite these strategies mortality o f young trees remains high.
M artin (1990) summarized Western Energy Company’s preferred strategy for the
establishment o f ponderosa pine in reclamation areas as “planting 1-0 containerized pine
seedlings grown from locally gathered seeds, with a treeplanter..., into shallow soil (or
subsoil) newly seeded with the “conifer” seed mix, followed by an application o f simazine
(herbicide) the following spring and cattle grazing tw o to three years after planting.” The
numbers “ 1-0” indicate the age o f the seedling in years since germination, then the number
o f times the seedling has been transplanted. In this case, the seedlings are one year old and
have never been previously transplanted.
Previous Research on Ponderosa Pine at the Rosebud Mine
Establishment o f ponderosa pine at the Rosebud Mine was evaluated between 1979 and
1987 by personnel o f the University o f M ontana’s School o f Forestry (Martin, 1990). This
research, performed at the Rosebud Mine, focused on the following topics:
o
ponderosa pine ecology, including native stand structure and regeneration (Richardson,
1981)
o
summer climatic influences (Vance and Running, 1985)
o
establishment and early growth o f seedlings on mine soil (Danielson, 1986)
o
effect o f grass control on ponderosa pine seedlings (Baumbauer and Blake, 1984)
0
root distribution and shodtroot characteristics on mine soil (Thamams, 1987b), and
observations o f root egression o f container stock (Thamams and Blake, 1984)
7
6
heritability o f drought resistance (Riley, 1984)
o
effects o f seed stratification (Woods and Blake, 1981)
°
local genetic variation (Woods, 1982; Woods et al., 1983) and the application o f genetic
analysis to select seed for reclamation (Woods et al., 1984).
According to Martin (1990), the most important discoveries from this research include
the occurrence o f inherited drought resistance in ponderosa pines o f the Colstrip area (Riley,
1984), the ability to identify specific pine trees with superior survival qualities (Woods, 1982),
and the documentation o f extensive root development unimpeded by planting technique,
materials used or reconstructed minesoils (Thamarus, 1987b).
Distribution o f Ponderosa Pine on Western Landscapes
Throughout the western United States ponderosa pine grows under a wide variety o f
ecological conditions (Schubert, 1974). However, in southeastern M ontana and in N orth
Dakota, ponderosa pine occurs almost exclusively on the top o f knolls or exposed sandstone
or porcelanite (Potter and Green, 1964). These landscape features are interrupted by valleys
o f deeper, finer textured soils.
Although sandstone or porcelanite outcrops are the primary locations o f ponderosa pine,
pine are slowly encroaching into areas o f deeper soil, away from outcrops in locations with
a constant nearby seed source (Potter and Green, 1964; Richardson, 1981). Historically,
periodic fires probably confined the pines to outcrops. Among other factors, the relatively
recent practice o f fire suppression may contribute to the observed encroachment and apparent
shift in the position o f ponderosa pine on the landscape.
8
Site Characteristics
Ponderosa pine in the Colstrip area are mostly found on coarse textured soils or rocky
substrates. The majority o f ponderosa pine trees on native sites at the Rosebud Mine grow
in areas w ith 50% or more rock in the substrate (Stout, 1980). Blake and Running (1986)
also stated that most native pine stands are found on coarse textured soils, ofteii with large
rock fragments. Richardson (1981) found native ponderosa pine near Colstrip to be “largely
associated with Entisols and to a lesser extent Aridisols” (Aridisols in this area have since
been reclassified as Inceptisols). Entisols and Inceptisols are generally weakly developed,
rocky or skeletal and often erosive. Potter and Green (1964) observed that a sandy soil, with
deeper and more rapid penetration o f rainfall, favors the establishment o f pine Seedlings over
that in heavier silts and clays.
In a study at the Rosebud Mine, Stark (1985) found no significant soil texture
differences between reclamation areas and undisturbed forest soils. Stark found that percent
clay o f replaced topsoil and subsoil in reclamation areas was highly variable, averaging 28%
clay, 44% sand and 28% silt. Native forest areas averaged 25% clay, 40% sand and 35% silt.
In comparison. Keck and Wraith (1996) found reconstructed soils at the Rosebud Mine to
have lower mean percent clay, ranging from 23 to 25 percent. Topsoil, subsoil and spoil
horizons had mean clay contents o f 23%, 24% and 25%, respectively. These clay contents
are most similar to the percent clay o f native soil found by Stark (1985). Differences in
results for percent clay o f reconstructed soils may relate to the area sampled, number o f
samples taken and method o f analysis. Keck and Wraith (1996) analyzed 174 samples from
9
a 30 hectare (75 acre) portion o f Area E o f the Rosebud Mine, whereas Stark (1985) took
240 samples from the much wider, and unspecified, “Colstrip area.” In summary, the overall
range o f textures in reconstructed soils at the Rosebud Mine is not different than in native
soils from which they were constructed, though there are abrupt textural changes between
horizons in reconstructed soils compared to native soils (Keck, 1993).
Root Distribution o f Ponderosa Pine
The distribution o f ponderosa pine roots varies with substrate. Cox (1959) compared
the distribution o f 51- to 78-year old ponderosa pine tree roots growing in three soil types
having different textures. H e found the greatest number o f roots in a medium-textured (silt
and clay loam) soil and the smallest number in a fine-textured (clayey) soil. Over 70% o f the
measured roots were in the upper 61 cm (24 in) o f soil for all textures. In all soils, roots
penetrated at least 1.2 m (4 ft) deep, which was the extent of excavation. A larger component
o f understory vegetation present at a site resulted in lower density o f pine roots within the Ahorizon(Cox, 1959).
Studies o f 30- to 70-year old ponderosa pine tree roots on native sites near the Rosebud
Mine also indicated that the majority o f fine and lateral roots are located within the upper 46
cm (18 in) o f the substrate (Stout, 1980). He further observed that roots tend to grow deeper
where the substrate is fractured rock or coarse to medium textured soils. Curtis (1964) also
observed many roots o f a 60 year old pine in the central Idaho area within cracks and crevices
in the bedrock or hardpan. Zwieniecki and Newton (1994) found at least one quarter to one
10
third o f the total root length o f 12 year old ponderosa pine roots located within the
metasedimentary rock layer in southwest Oregon.
P o tter and Green (1964) observed differences in the distribution o f ponderosa pine
(predominantly 20 to 50 years old) roots on sandstone or porcelanite outcrops and downslope
areas in southwestern North Dakota. Pine roots on outcrops were confined to the horizontal
and vertical cracks in the platy porcelanite, extending to great depths (observed to 7.6 m [25
ft] below the surface). On downslope positions, where the amount o f fine soil material
increased, root systems were more extensive and widespread but not as deep. Even further
from the outcrops the depth o f fine soil exceeded the depth o f penetration o f moisture. This
resulted in a permanently dry subsoil lacking roots. Fibrous grass roots dominated the top
20 cm (8 in) o f soil in these areas.
Thamarus (1987b) excavated six-year-old pine seedlings from reclamation areas at the
Rosebud Mine and found most fine roots, laterals, and mycorrhizal associations were within
the topsoil, which varied in depth from 20 to 30 cm. Lateral roots were observed to extend
up to one meter from seedling stems. Taproots o f the seedlings had grown through the
subsoil into the spoil to depths greater than one meter (39 in). Based on measurements o f
several thousand 1-0 and 2-0 ponderosa pine seedlings obtained from nurseries, the average
extent (depth) o f the root system before transplanting was 22.5 cm (9 in) and 27.7 cm (I I in),
respectively (McDonald and Fiddler, 1989). Therefore, during a six year period the roots o f
ponderosa pine seedlings may extend more than 70 cm (28 in) in length, depending on
conditions.
11
Comparison o f root distribution o f one to three year old ponderosa pine seedlings in soils
derived from metamorphic and limestone (sedimentary) parent materials indicated deeper root
penetration on the coarser textured metamorphic soil (van Haverbeke, 1963). Average
penetration for one, two and three year old seedlings on metamoiphic soil was 29 cm, 3 1 cm
and 34 cm, respectively. Average root penetration for seedlings on the limestone soil was 26
cm for all three ages. Van Haverbeke (1963) attributed much o f the difference in rooting
depth in the two soils to a denser subsoil (no soil bulk density provided) and more abundant
grass cover for the limestone soil
Soil texture and bulk density have been shown to affect root growth arid development
o f pine seedlings. In soils with high percentages o f silt and clay lateral and vertical root
development as well as growth o f pine seedlings was restricted (Potter and Green, 1964; van
Haverbeke, 1963). Seedling growth at the Rosebud Mine was observed to be most rapid on
soils with greater than 50% sand, haying a compacted horizon at 60 cm (24 in) depth (Stark,
1985). Increased soil bulk density (1.12 g cm"3 compared with 0.80 g cm"3 within the upper
30 cm [12 in] o f soil) reduced young ponderosa pine stand volume and reduced annual shoot
grow th by 43% in two year old seedlings and 13% in 15 year old trees (Helms, 1983).
Thamarus (1987b) observed that soil layer interfaces and localized areas o f soil compaction
in reclamation areas at the Rosebud Mine did not impede growth or development o f pine
seedling roots. This review indicates substantial pine root plasticity and the importance o f soil
structure and density.
12
Soil Physical Properties and Soil Water
It is well documented that plant available soil water is a primary factor limiting the
establishment and growth o f ponderosa pine in many locations (Heidmann and King, 1992;
McDonald and Fiddler, 1989; Richardson, 198.1; Riegel et al., 1992; Running and Danielson,
1984; Schubert, 1974; Shainsky and Radosevich, 1986; Stark, 1982, 1985). Competition for
soil w ater is apparently most detrimental when ponderosa pine trees are young and an
extensive root system has not developed. The highest tree mortality typically occurs during
the first one to two years after planting (Larson and Schubert, 1969; Martin, 1990;
Richardson, 1981; van Haverbeke, 1963).
One of the more important variables related to the distribution o f soil water, in addition
to texture, is soil structure. The original structure o f disturbed soil, which had generally
developed over hundreds or thousands o f years, may be altered or destroyed (Schafer et al.,
1979).
Disturbance o f soil structure can affect aeration and soil water retention and
movement and therefore plant growth. Potter et al. (1988) stated that soil structural units and
the associated interaggregate pore spaces are among the most important soil properties
disrupted during mining and reclamation because o f their importance for root penetration and
growth.
Soil bulk density is closely related to soil structure, texture, porosity, aeration and water­
holding capacity. Bulk density can indicate the relative degree p f soil compaction, the
resulting changes in ability o f a soil to transmit water and gases to plant roots, and the ability
o f roots to penetrate the soil. In natural soils, bulk density generally increases with depth as
13
organic matter content, root and biotic activity, and porosity decrease (Sutton, 1991). A soil
may naturally possess high bulk density, depending on the soil texture (e.g., bulk density o f
sand is about 1.6 g cm'3) and particle arrangement. Presence o f rocks and sand in soil favors
high bulk densities, whereas the content o f fine fractions favors relatively low bulk density and
high total porosity. Reconstructed soils generally have an artificially higher bulk density than
the native soil material because o f compaction due to the size and weight o f equipment used
for soil salvage and redistribution. Reconstructed soils also generally lack large pore spaces,
such as those between peds.
The bulk densities o f native soils o f the Colstrip area are not well characterized. Stark
(1985) reports a native soil bulk density o f 1.03 g cm"3, but this value seems too low for the
types o f weakly developed, often rocky soils (Entisols and Inceptisols), around Colstrip.
M ean bulk density for reconstructed topsoil, subsoil, and spoil materials in Area E o f the
Rosebud Mine has been reported as 1.54, 1.67 and 1.79 g cm'3, respectively (Keck and
Wraith, 1996). Also at the Rosebud Mine, Keck (1993) determined that bulk density o f spoil
material in Area A ranged from 1.6 to 1.95 g cm"3 after reclamation was complete.
At a given soil texture, higher soil bulk density generally results in lower soil water
holding capacity and also lower plant available water. Penn et al. (1987) measured soil water
content and matric potential on a restored mine and an undisturbed site.
They found
significantly lower plant available water in both topsoil and subsoil layers on the reclaimed site
compared to the undisturbed site. They attributed this result to the loss o f soil structure,
specifically the reduced volume o f mesopores, and suggested that drought is more likely to
occur on the reclaimed than undisturbed site. Sharma and Carter (1993) observed that matrix
14
and preferential water flow rates o f pre-mine compacted soils and post-mine reclaimed soils
were about one to two orders o f magnitude lower than those o f undisturbed pre-mine soils.
In addition, they noted that the redistribution o f soil and spoil materials results in discontinuity
o f pores at soil layer interfaces.
Saturated hydraulic conductivity (Ks) is a measure o f water flow rate in soil under watersaturated conditions, and is strongly influenced by pore size distribution and pore continuity.
Mean Ks was determined to be 25 to 50 percent less for reconstructed soils than for native
soils at the Rosebud Mine (Hepfher et al., 1996). Saturated hydraulic conductivity decreased
with soil depth in reconstructed soils. Hepfher et al. (1996) stated that decreased Ks was
likely due to higher measured bulk density in these lower layers. Measured Ks at the
Glenharold Mine in N orth Dakota indicated similar results, with Ks o f the reconstructed
topsoil material 25 percent lower than that o f the undisturbed A horizon. Saturated hydraulic
conductivity o f the reconstructed subsoil materials was less than 10 percent that o f an
undisturbed B horizon (Potter et al., 1988).
Reconstructed topsoil and subsoil layers at the Rosebud Mine had a narrower pore size
distribution than native soils (Hepfher et al., 1996). The narrower pore size distribution
V
indicates lack o f structural development in the reclaimed sites, and was consistent with bulk
density measurements. Furthermore, the mean effective water transmitting pore size was
greater for native than reclaimed topsoil layers (Hepfher et al., 1996). Potter et al. (1988)
likewise found significant differences in pore volume distribution between undisturbed and
reconstructed soils, with the greatest difference observed in pores having radii >15 pm, and
most evident at lower profile depths.
15
The effects on soil water of variable topsoil and subsoil thicknesses over spoil materials
have been studied in reclaimed mine lands. Other factors being equal, thicker topsoil and
subsoil replacement depths will store more water than shallower replacement depths (Power
et al., 1981; Stark and Redente, 1985). However, Schroeder (1995) found no significant
difference in soil water content between native and reclaimed sites in N orth Dakota, even
though native sites had uneven depths and reclaimed sites had uniform depths o f topsoil and
subsoil replaced. The amount of water in a given soil was site specific, depending on climate,
soil textural and structural attributes, and reclamation practices.
Topography is another important factor that influences soil water content. Wollenhaupt
and Richardson (1982) found that concave slopes accumulated more soil water than convex
sites. Greater Soil water was also found at downslope positions (Schroeder, 1995). Greater
plant-available soil water holding capacity was measured at top and middle slope positions
in native soils in the Colstrip area than for the bottom slope position (Hepfiier et al., 1996),
based on the “m” parameter o f the van Genuchten (1980) soil w ater retention model. The
“m” parameter is related to the width o f the pore size distribution, and potentially to soil
structural development. Although this result might appear to be counter to expectations, it
was hypothesized that the result o f erosive deposition o f soil particles from up slope positions
cduld fill in larger pore spaces in bottom slope positions. This results in narrower pore size
distribution which influences soil water retention and availability to plants.
Rock materials can also influence water availability. Numerous studies have concluded
that various types o f underlying weathered rock are an important source o f plant-available
water for ponderosa pine and other species when surface soils are dry (Arkley, 1981; Jones
16
and Graham, 1993; Stark, 1983; Wang et al.„ 1995; Zwieniecki and Newton, 1994). Wang
et al. (1995) determined that bedrock and dispersed rock fragments o f slightly
metamorphosed sandstone, siltstone, and shale provided an important storage reservoir.
B edrock in their study held 71 to 80% o f all w ater stored at >-2.0 M pa (-20 bar) matric
potential between the surface and 3.0 m depth.
Competition Between Ponderosa Pine and Grass for Below Ground Resources
Cofnpetitive success is often determined by early resource capture and the capacity o f
a species to maintain productivity in a competitive environment (Shainsky and Radosevich,
1986). W ater is required for most plant physiological processes. Soil water is one o f the
most frequent controls o f plant growth and community structure, especially in arid or semiarid environments (Coffin and Lauenroth, 1991).
Soil water has been repeatedly identified as a primary factor limiting the establishment
and growth of ponderosa pine (Richardson, 1981; Riegel et al., 1995; Running and Danielson,
1984; Schubert, 1974; Shainsky and Radosevich, 1986; Stark, 1982, 1985). Competition for
available soil water is most critical during the first one to two years after planting (Larson and
Schubert, 1969; Martin, 1990; Richardson, 1981; van Haverbeke, 1963). During this period
the root systems o f pine seedlings are not well developed, and most photosynthate produced
is used for taproot growth and extension (Richardson, 1981). Significant development o f
lateral roots generally does not occur until the vertical roots reach a zone o f available soil
water (McDonald and Fiddler, 1989). Usually, this is not until the second or third growing
season, when lateral roots may double or triple in length (van Haverbeke, 1963).
17
Limited root growth o f ponderosa pine was observed where interspecific competition,
especially from grasses, was heavy (vanHaverbeke, 1963). Interspecific competition was also
attributed to a decrease in secondary lateral roots within the top 46 cm (18 in) (Curtis, 1964).
Baumbauer and Blake (1984) observed significantly greater seedling growth rates after
competing vegetation, primarily grasses, was removed by chemical application at the Rosebud
Mine. This observation has been supported by many others (McDonald and Fiddler, 1989;
Riegel et al., 1992; Riegel et al., 1995; Sands and Nambiar, 1984). Potter and Green (1964)
noted that once ponderosa pines reached the sapling stage interspecific competition with
grasses was significantly reduced.
The shifr in competitive advantage from grasses to pines near the sapling stage is largely
attributed to greater development o f root systems by this stage. The extensively branching
root systems o f woody plants, including ponderosa pine, allows nearly exclusive access to the
deeper soil layers compared to grasses (Lee and Lauenroth, 1994). The intensive root
systems o f grasses are more adapted to exploiting resources concentrated in smaller volumes
nearer the soil surface.
A comparison o f the spatial distribution o f grass roots and roots o f woody species
provides an explanation for the dominance o f grass in the shortgrass steppe ecosystem.
Limited and variable water availability in this ecosystem and the concentration o f precipitation
in the summer lead to the majority o f water remaining in upper soil horizons (Lee and
Lauenroth, 1994). W oody plants in semiarid regions are favored by conditions that promote
storage o f water deep in the soil. Grasses are generally favored by water being available
mainly in upper soil layers during the growing season.
18
Soil depth pan affect inter- and intraspecific competition. For example, Sheley and
Larson (1995) observed that unrestricted soil depth permitted resource partitioning between
species, with intraspecific competition having the most significant influence on each species.
Yellow starthistle (Centcmrea solstitialis L.) had an advantage over cheatgrass (Bromus
tectorum L.) in deep soils because its taproot morphology enabled continued resource uptake
When adequate deep moisture was available and surface soils had dried. However, under
conditions o f restricted soil depth, interspecific competition was more significant. Apparently
the relatively shallow, fibrous rooting system o f cheatgrass was better suited for resource
capture in shallow soil.
In addition to spatial partitioning o f resources, temporal partitioning is also an important
aspect o f inter-plant competition. Zwieniecki and Newton (1994) noted temporal and spatial
differences in root function o f conifers. Shallow roots absorbed water only during the wet
season. After the surface soil dried to the wilting point, the deeper roots became the main
source o f water and nutrients. Cool season and warm season grasses are known to have
different periods o f growth, which result in different levels o f competition between ponderosa
pine and each grass type (Larson and Shubert, 1969). Western Energy Company is taking
advantage o f this strategy by seeding warm season grasses before cool season grasses to
encourage successful establishment o f the warm season grasses, and also by only seeding a
variety o f warm season grasses and forbs into areas to be planted with ponderosa pine
(Coenenberg, 1982; Martin, 1990).
Despite the well-documented interspecific competition between ponderosa pine and
grasses, native stands o f ponderosa pine are successfully moving into areas o f deeper soils
19
dominated by grasses, away from the sandstone/porcelanite outcrops in the Colstrip area
(Potter and Green, 1964; Richardson, 1981). Although many situational distinctions exist
between pines locally expanding from areas o f high pine density onto deep soils and planting
pines in reclamation sites, the above observations suggest a potential for establishment o f
ponderosa pine in reclamation areas at the Rosebud Mine. However, pine mortality continues
to be high and if it continues will be detrimental to the overall success o f reclamation efforts.
Specifically a problem exists in obtaining final bond release for acreage designated for
ponderosa pine establishment. What factors may allow the expansion o f native stands o f
ponderosa pine, yet still restrict the establishment o f ponderosa pine in similarly deep
reconstructed minesoils?
According to Archer (1989), “quantitative and historical assessments suggest that
woody-plant abundance has increased substantially in arid and semiarid grasslands over the
last 50 to 300 years in many parts o f the world.” Partial explanations for the conversion o f
savannas to woodlands within the past century are fire suppression, overgrazing, and climatic
changes, which have interacted in complex ways (Archer, 1989). The expansion o f native
ponderosa pine stands is greatly enabled by the presence o f mature trees which provide a
nearby and constant seed source, a canopy for shading, and other benefits to seedlings,
including root/mycorrhizal interactions (Richardson, 1981). Nearby trees may also improve
the nutrient conditions in their immediate surroundings, providing more suitable conditions
for the establishment o f ponderosa pine seedlings (Skarpe, 1992).
The balance between grasses and woody vegetation may be regulated by the ratio o f
topsoil to subsoil wetness (Archer, 1989). Factors reducing the ratios o f topsoil to subsoil
20
water could cause savannas to develop into woodlands (i.e., reducing topsoil wetness an d /o r.
increasing subsoil wetness). Climatic influences which could increase topsoil/subsoil water
ratio include an increase in annual rainfall, shifts from small, frequent precipitation events to
large, infrequent events, and/or a shift toward increased winter precipitation (Archer, 1989).
In addition, grazing limits the ability o f grasses to competitively exclude the invasion and
establishment o f woody vegetation by decreasing the transpiring leaf area and root initiation
and extension o f grasses, which subsequently decreases their ability to take up water. Grazing
o f grasses may therefore enhance percolation o f water to the subsoil (Archer, 1989; Skarpe,
1992), increasing the availability o f soil water for the more extensive pine roots. Grazing can
also increase surface soil wetness, enhancing woody seedling establishment and growth
(Skarpe, 1992).
21
CHAPTERS
OBJECTIVES
At the Rosebud Mine, a maximum o f 920 permitted hectares (2,272 acres) o f pine
habitat may eventually be disturbed (Martin, 1990). Western Energy Company is required
by federal and state laws to reestablish ponderosa pine over some portion o f this disturbed
area. Much effort has gone toward pine establishment, yet mortality rates continue to be high,
resulting in tree densities far below the 40 trees per hectare (100 trees per acre) expected to
be required for final (phase HI) bond release (Martin, 1990). A variety o f factors appear to
affect the successful establishment o f pines, including: I) available soil water and competition
for available soil water among plant species; 2) site suitability (slope, aspect, soil physical and
chemical characteristics, etc.); 3) handling o f seedlings; 4) planting technique and timing; and
5) animal and insect predation. This study is focused on the first, and to lesser extent, the
second factors listed.
The objectives o f the study were to: I) quantify and compare soil physical and
hydrologic properties o f selected reclamation and native sites at the Rosebud Mine; 2)
compare seasonal soil water status in reconstructed soil profiles to that o f selected native sites
supporting ponderosa pines; 3) evaluate whether a more suitable soil substrate for ponderosa
pine tree establishment might be reasonably constructed (i.e., considering economics and the
22
current regulatory laws),
I f the outcome o f this objective is positive, one or more
reconstructed soil profiles having' physical and hydrologic properties potentially more
conducive to the establishment and survival o f ponderosa pines will be recommended, using
materials and resources reasonably available to the Rosebud Mine.
I hypothesized that seasonal soil water status and soil physical and hydrologic properties
are different for reconstructed mine soil and native soil. Furthermore, my intentions were to
provide suggestions for at least one reconstructed soil profile that could be reasonably
implemented at the Rosebud Mine to improve establishment and survival o f ponderosa pines.
23
CHAPTER 4
MATERIALS AND METHODS
Field Measurement Sites
Native and reclamation sites were selected based on pre- and post-mine soil surveys, air
photograph's, and mine planning maps. Native and reclamation sites were located within or
immediately outside Areas A, B and C o f the Rosebud Mine (Figure I). The objectives o f site
selection were to: I) encompass a range o f soil textures present in the area both naturally and
following mining and reclamation; 2) include some reclamation sites in which pine
establishment appears successful; 3) select reclamation sites that were greater than three years
old; and 4) select sites with reasonable access. A total o f 12 sites were selected; 6 in native
areas, and 6 in reclamation areas. The term ‘native’ as used here means undisturbed by
mining activities.
All o f the native sites supported ponderosa pine trees. Half o f the
reclamation sites supported ponderosa pine regeneration.
Numerical references given native sites are those o f the soil map units identified in the
Rosebud Soil Survey for these sites (Soil Survey Staff, draft manuscript), followed by a letter
designation for the area o f the mine it is located in or adjacent to, then a direction to
differentiate sites within similar soil series. For reclamation sites, references are those used
Figure I . Field study sites located at Colstrip, Montana.
25
by the Rosebud Mine to identify specific fields, similarly followed by a letter designation for
the area o f the mine in which it is located. The Rosebud Mine’s numbering system tracks
when and where reclamation occurred. The first digit indicates the quarter-year and the
second and third digits indicate the year o f reclamation.
The fourth digit sequentially
identifies all the fields reclaimed during that quarter.
The native sites were purposely not located on sandstone/porcelanite outcrops because
o f the difficulty o f installing neutron access tubes in this rock substrate and the lack o f a
comparable substrate in reclamation areas, both currently and in the future. Sampling native
sites focused on substrates supporting ponderosa pines that were more similar to substrates
that are and could potentially be reconstructed following mining.
Soil and landscape features at each site Were characterized through direct sampling
following the standard soil profile description and classification process used by the USDA
Natural Resource Conservation Service (NRCS). Observations o f soil properties included
horizon thickness, color, texture, structure, soil consistence (workability), lime (calcium
carbonate), root and pOre distributions, rock fragments, and soil pH. Profile descriptions
were accomplished by excavating one 90 cm soil pit at each site, and using a bucket auger to
sample an additional 90 cm to a total depth o f 180 cm where possible. Soils were classified
to the subgroup level based on criteria in Keys to Soil Taxonomy (Soil Survey Staff, 1994).
Landscape was characterized by identifying the dominant plant species at each site,
determining canopy coverage classes by species from ocular estimates, and measurement o f
slope steepness and slope direction (aspect).
Table I summarizes some o f the main characteristics o f the selected sites. Table 2
Table I. Summary o f site characteristics.
Site Name/
Reference
Number
Site Type
Location
Dominant Land Use
Year
Reclaimed
Pine Trees
Present
Dominant Soil Texture
o f Profile
(weighted average)
%Hard Coarse
Fragments
(70-90 cm)
121E-C(s)
Native
Area C
Pine Woodland
N/A
Yes
Loam
15
121E-C(n)
Native
N: of Area C
Pine Woodland
N/A
Yes
gravely Loam
30
183E-C(s)
Native
Area C
Pine Woodland
N/A
Yes
Loam/Silt Loam
20
I83E-C(n)
Native
N. of Area C
Pine Woodland
N/A
Yes
Silt Loam
2
493D-A(e)
Native
Area A
.Rangeland/Open
Pine Woodland
N/A
Yes
Clay Loam/
Silty Clay Loam
trace
493I>-A(w)
Native
Area A
Rangeland/Open
Pine Woodland
N/A
Yes
Silty Clay/Soft
Sandy Shale
trace
4888-A
Reclamation
Area A
Pine Reclamation/
Rangeland
1988
Yes
Silty Clay Loam/
Sandy Clay Loam
28
4822-B
Reclamation
Area B
Reclamation
Rangeland
1982
No
Sandy Clay Loam
30
2856-B
Reclamation
AreaB
Reclamation
Rangeland
1985
No
Sandy Clay Loamvaried: SL, LS1SCL1
SiCL
40
4881-C
Reclamation
Area C
Reclamation
Rangeland
1988
No
Loam
40
4901-C
Reclamation
Area C
Pine Reclamation/
Rmigeland
1990
Yes
Clay Loam/
Sandy Loam
30
3915-C
Reclamation
Area C
Pine Reclamation/
Rangeland
1991
Yes
Loam/Sandy Loam
20
27
presents the soil classification for profiles sampled to the family level. Appendix A provides
site description forms with riiore specific information for each site, including landscape and
vegetation information and detailed soil descriptions.
Table 2. Soil order and family designation for each study site.
Site Reference
Soil Order
Family Designation
Native Sites
12IE-C (s)
Inceptisol
fine loamy, mixed, frigid Aridic Ustochrept
121E-C (n)
Inceptisol
fine loamy, mixed, fiigid Aridic Ustochrept
183E-C (s)
Inceptisol
fine loamy, mixed, frigid Aridic Ustochrept
183E-C (n)
Inceptisol
fine loamy, mixed, Aridic Ustochrept
493D-A (e)
Inceptisol
fine, montmorillonitic, fiigid Aridic Ustochept
493D-A (w)
Entisol
fine, montmorillonitic (calc.), fiigid, shallow Aridic
Ustorthent
4888-A
Entisol
fine loamy, mixed (calc.), fiigid Aridic Ustorthent
4822-B
Mollisol
fine loamy, mixed Aridic Haploboroll
2856-B
Mollisol
fine loamy, mixed Aridic Haploboroll
4881-C
Entisol
fine loamy, mixed (calc.), fiigid Aridic Ustorthent
4901-C
Entisol
fine loamy, mixed (calc.), frigid Aridic Ustorthent
3915-C
Entisol
coarse loamy, mixed (calc.), fiigid Aridic Ustorthent
Reclamation Sites
Based on qualitative descriptions, the most distinct site characteristic is land use (Table
I). All native sites selected have ponderosa pine trees present and are considered woodlands
or open woodlands. None are grazed by cattle, but they do experience grazing by deer, elk
and antelope. Reclamation sites are all classified as rangeland, with those sites havitig
28
ponderosa pine trees present classified additionally as pine reclamation. All reclamation sites
experience periodic grazing by cattle, with grazing leases overseen by Western Energy
Company.
Neutron Moisture M eter Calibration and Bulk Density Measurements
Following site selection, twb neutron moisture meter access tubes were established at
each site to measure seasonal soil water status. Access tubes were installed May 14 and 15,
1996 to a depth o f tw o meters, wherever possible.
Shallower installation depths, were
sometimes required because o f hard bedrock material. Five-cm (2 in) diameter, thin-walled
polyvinyl chloride (PVC) pipe was used for access tubing. Soil water content was measured
in the field using a neutron moisture meter (NMM) (CPN Model 503DR), every 20 cm (8 in)
to a depth o f up to 2 m (6.5 ft). Neutron count ratios were taken at tw o week intervals
(except for one three week interval) during May 15 through September 12,1996, and at three
week intervals during M arch 30 through May 1 1 ,1997.
A total of 12 NMM access tubes were installed in the six native sites and 12 tubes in the
six reclamation sites, with two tubes ‘paired’ a few meters apart at each site. Within each o f
the six reclamation sites, soil water status was also assessed without live vegetation. To
accomplish this, two additional access tubes were installed at each reclamation site followed
by repeated spraying with Roundup® (Glycophosphate, N-[phosphonomethyl] glycine) to
remove live vegetation within an approximate 1.5 m radius o f the access tubes. The purpose
was to determine the seasonal soil water status in reconstructed soil profiles without the
influence o f established vegetation, primarily grasses.
29
The neutron moisture meter was calibrated by collecting soil samples for gravimetric
analysis o f volumetric water content. NMM count ratios were measured at depths o f 20, 40,
60, and 80 cm just prior to collecting soil samples at the same depths adjacent to the access
tubes. Measured soil water content was then related to the field count ratio collected by the
NM M to derive the tube-specific calibration. Soil samples were collected June 24 and 25,
1996 for calibration at the.“wet” end, and again September 12 to 14, 1996 for calibration at
the “dry” end o f the soil water content range.
Soil samples were collected by pressing or carefully pounding an aluminum ring o f
known volume (152 cm3) into the soil. The ring was carefully removed to obtain the soil
sample. It was occasionally necessary to chisel away soil surrounding the ring in order to
remove the ring with an intact core. Soil cores were placed in labeled plastic Ziplock® bags,
stored in a cooler containing ice and weighed within 12 hours. W et soil mass was obtained
with a Sartorius B3100P balance, The soil was later oven-dried for at least 24 hours at 105°
C, and dry soil mass obtained from the same samples. Volumetric water content (6) was
calculated as the volume o f water per bulk volume o f soil. Volume o f water was obtained as
mass of moist soil minus mass o f oven-dry soil, divided by density o f water. Soil bulk density
was calculated as the ratio o f the mass o f oven-dry soil to its bulk volume, which assumes a
core having dimensions equal to the sampling ring.
Calibration o f the NM M to each soil material was accomplished by linear regression o f
measured volumetric soil water content against field measured count ratios. The coefficient
o f determination (r2) was used as the goodness o f fit criterion. In order to obtain optimal
palibratipn, readings and samples were separated into eight groups based on soil horizon
30
(topsoil and subsoil, and spoil if frorii reclamation sites) then soil texture class where
appropriate. The resulting Hnear caUbrations were used to convert NM M count ratios
measured during 1996 and 1997 to 0.
Field soil water contents measured by NM M were compared based on soil horizons,
textures, depths, and sites.
The characteristics o f seasonal soil water status that were
compared include total soil profile water content, and soil water depletion at each site. Soil
water status over time was determined by comparing soil water changes between each NMM
reading (incremental soil w ater depletion). Comparison o f beginning and ending soil water
content for each NMM measurement interval (May 15 to September 12, 1996 and March 30
to May 1 1 ,1997) provided cumulative soil water depletion for each site. The purpose o f the
above comparisons was to determine if relationships exist between seasonal soil water content
and soil physical properties or site characteristics, with particular emphasis on differences
between native and reclaimed sites.
Soil W ater Retention and Plant Available W ater
Soil cores collected in June and September, 1996 for caHbration o f the neutron moisture
meter were also used for laboratory measurement o f soil water retention. W ater retention at
one-third bar and 15 bar pressure was measured using a pressure plate apparatus. Disturbed
samples were repacked to initial soil bulk density, as described by KJute (1986). Each soil
sample was individually sieved through a 2 mm screen to remove coarse fragments and
repacked to the initial bulk density (previously measured from the field core samples) by
pressing a specific mass o f soil into rigid 7.3 cm (2.9 in) inside diameter PVC segments (rings)
31
to attain a standard volume o f 23 cm3, with a sample height o f I cm. By packing a variable
mass o f soil into a consistent volume, the previously measured bulk densities were replicated
and all samples had uniform dimensions, To obtain a representative soil sample, soil was
redistributed and sampled using the cone method prior to weighing and packing.
Repacked soil within the rings was saturated with 3 pM calcium sulfate (CaSO4) solution
on the pressure plate for at least 24 hours. Paired samples for each o f four depths at each site
were prepared for 15 bar soil w ater measurements (total o f 72 samples). Four samples o f
each depth for each site were prepared for one-third bar measurements (total o f 144 samples).
A greater number o f samples were analyzed for the one-third bar pressure because retention
results at this low pressure are sensitive to differences in soil pore size distribution. It was
recognized that any original soil structure was destroyed by sampling, crushing and sieving
dried samples. Thus, samples at one-third bar are expected to be different (wetter) than for
the field condition. Fifteen bar samples were allowed to equilibrate at the applied pressure
for I days. One-third bar samples equilibrated for 2 to 3 days.
These relatively short
equilibration times were possible because the sample height was only I cm (Klute, 1986).
Plant-available soil water holding capacity was calculated for each soil horizon at each
site based on soil w ater retention data, by taking the difference between measured volumetric
soil water contents at one-third bar and 15 bar pressures. The value obtained was corrected
for percent coarse fragments and converted to equivalent depth o f water based on the soil
horizon depth (Marshall et al., 1996). Percent coarse fragments and horizon depths were
obtained from soil profile descriptions for each site.
32
Computer Simulation Modeling o f Long Term Seasonal Soil W ater Status
Computer simulation modeling was used to extrapolate beyond the measured seasonal
soil water data using the measured soil physical and hydrologic properties in combination with
34 years o f climate data from Colstrip, MT. The intent o f the model exercise was to: I)
estimate seasonal soil water within the soil profile relative to the anticipated location and
demands o f ponderosa pine root systems relative to grass root systems; and 2) determine
whether a more suitable soil substrate might be reasonably created that would promote a more
favorable time- and depth-dependent soil water status for pines. Finally, if the outcome o f
Objective tw o were positive, to recommend one or more reconstructed soil profile designs.
The computer simulation model used was an upgraded version o f Ekalaka Rangeland
Hydrology and Yield Model (ERHYM), known as ERHYM-II (Wight, 1987). TheERHYMII model was selected because it is a fairly simplified “tipping bucket” soil water model, based
on the water balance equation and thus requires minimal input data. Conceptually, with a
“tipping bucket” model, soil water is redistributed from one soil layer to the next when the
water content o f a particular soil layer exceeds its plant available water holding capacity. In
this manner, any soil water in excess o f field capacity (one-third bar pressure) is redistributed,
or “tipped”, to the adjacent and lower soil layer(s). Or “bucket(s)” .
Some salient
characteristics o f a “tipping bucket” model include: I) it does not allow upward flow o f soil
water; and 2) water additions, depletions and redistributions are instantaneous (daily time
step) rather than gradual, as would actually occur in the field.
The ERHYM-II model was developed specifically for application to rangeland
33
environments. It incorporates a rangeland crop coefficient curve that was developed using
lysimeter data from a mixed prairie range site in southeastern Montana (Wight, 1987). Weltz
and Blackburn’s (1993) analysis o f the ERHYM-II model on south Texas rangelands
determined that the model has the potential to simulate the annual water balance o f semiarid
rangeland plant communities where runoff and deep drainage are limited components o f the
water balance.
ERHYM -II is a climatically-driven water balance model that functions on the plant
community level (Weltz and Blackburn, 1993).
Components o f the water balance are
associated with changes in precipitation, evaporation, transpiration, runoff and soil water
routing, occurring on a daily time-step basis.
A primary advantage o f a “tipping bucket” model is limited input information
requirements, or more specifically, that required input data is limited in scope and generally
readily available. This was critical to application to the Rosebud Mine, where only basic
climatic and soil hydrologic data are available, ruling out use o f more complex, mechanistic
models. Disadvantages o f a “tipping bucket” model are associated with its assumptions and
simplifications, and therefore the caution required in applying resulting interpretations to the
natural system.
The ERHYM-II model code was modified for input o f actual climate data instead o f
using the model’s ability to generate stochastic climate data. Thirty-four years (January 1964
through May 1997) o f climate data from the Colstrip weather station were acquired from
Climatedata Summary o f the Day, Western, a computerized database (National Climatic Data
34
Center, 1997) and via electronic mail from the Western Regional Climate Center in Reno,
NY.
Climate data from the Colstrip station included daily maximum and minimum air
temperatures and daily precipitation totals. Pan evaporation data were obtained for the
Yellowtail Dam weather station, located approximately 75 miles southwest o f Colstrip. This
is one o f the closest weather stations collecting this information and was considered most
ecologically similar to the Colstrip station. Daily maximum and minimum temperature records
were also collected from the Yellowtail Dam weather station and compared to daily
temperature records from the Colstrip station to confirm the applicability o f Yellowtail Dam
evaporation data to the Colstrip area.
Climate data were reformatted for use as input files to the ERHYM-II model. Where
daily temperature data were missing from the climate record, a value was provided by
averaging the temperature o f the preceding and following days. I f greater than 2 days in a
row were missing (for example no records were available for the entire year o f 1975), daily
temperatures from a year determined to have average temperature closest to the year with
missing data was substituted. Data were substituted in whole or part depending on the
number o f days missing. For air temperature, values from 1970 were substituted for missing
information in 1973 and 1974; 1977 data were substituted for missing data for years 1975,
1980 and 1981; and 1995 data were substituted for missing data during 1997.
A similar method was used for substitution o f missing precipitation data, however, only
for years or periods missing several days in a row.
For precipitation data, 1970 was
35
substituted for 1973 and 1974; and 1995 was substituted for 1997, in whole or in part. The
34-year average was substituted entirely for 1975 (which had no climatic record).
The root water uptake algorithms in ERHYM-II were modified from the original version
in an attempt to more closely simulate what is known about water uptake by plant root
systems. Plant available water is defined in ERHYM-II as soil water held between 1/3 (field
capacity) and 15 bar (permanent wilting point) tensions. The model was altered such that soil
water was considered to be freely available to plants above 60 percent (0.6) plant available
water, but water availability decreased linearly below this point until zero at the permanent
wilting point. This concept follows that o f Doorenbos and Kassam (1979) and is commonly
used in computer simulation models.
A second modification was to constrain the proportional amount o f daily transpirational
demand met from a given soil layer based on the proportional root system density in that
layer. A natural growth function, y = l-exp(-bx), was incorporated into the model. In this
equation, “y” is proportional daily transpirational water that a given layer could provide, and
“x” is the proportional root density in that layer (ROOTF variable in ERHYMrII). A value
o f 5 for “b” was selected as providing reasonable constraints to soil water uptake. This
modification prevented an unreasonably large amount o f water being removed from a soil
layer having very few roots present. The constraint on water uptake is small until relative
root density decreases to about 0.4 or less, and increases in severity as ROOTF approaches
zero. Simulation models based on more deterministic principles generally calculate depthdependent root water uptake as proportional to its availability (i.e., soil water potential) and
36
the root density at that location. Hence, we surmised this to be an appropriate modification
for our purposes.
A final modification to ERHYM-II was to allow multiple iterations within the soil water
uptake module. The algorithm cycled through the four soil depths, in order from top to
bottom , until either daily transpirational demand had been met or no plant available water
remained in soil layers haying roots present. Calculations in this algorithm were constrained
by the modifications noted above.
Three native sites and three reclamation sites were selected for computer simulation
modeling. Sites were selected to encompass the range o f measured profile water holding
capacity and plant available water holding capacity. The range o f dominant soil texture was
represented.
Site-specific information regarding soil properties and soil water content were organized
into the input format for the model. Site specific information collected or measured during
field and laboratory investigations, and used in the ERHYM-H model for each soil horizon,
included horizon thickness, bulk density, percent rock fragments, soil w ater content at field
capacity, and soil water content at wilting point. Because the model required mass (kg/kg)
soil w ater content, volumetric measurements were converted to mass equivalents using
measured soil bulk density (Marshall et al., 1996). Horizon thickness for each o f four soil
layers was input as measured during profile description. The only exception was that the top
layer could not exceed 30.5 cm in the model and was therefore divided and entered as two
equal soil layers if greater than this limit.
37
Site specific input data that were derived or estimated included air-dry soil water content
and a runoff curve number (RCN)- The amount o f w ater below permanent wilting point, but
above air-dry water content which can be evaporated from the upper soil layer, was estimated
from Table 4 o f the ERHYM-II model description and user guide (Wight, 1987). This is
based on measured water content at -15 bar and the soil.texture o f the top 30 cm (12 in) o f
each site.
Site specific runoff curve numbers were derived using NRCS methodology
(Chapter 2 o f the Engineering Field Manual), which takes into account the soil hydrologic
group. Cultural practice, and vegetation cover and condition. The soil hydrologic group for
each site was determined based on field descriptions and criteria in the National Soil Survey
Interpretations Handbook (Soil Survey Staff, 1992).
Due to its structure, the model could not simulate two different root systems at one time.
In order to predict seasonal soil water distribution with pine and grass roots on the same site
the model was run twice for each site with the same soil and climatic input values, changing
only the relative root density within each soil horizon (ROOTF value).
This allowed
comparison but did not simulate competition. Another important consideration is that the
model was unable to reasonably simulate potential temporal differences in pine and grass root
‘activity’. Temporal niche separation may be a critical aspect o f below ground interactions
o f these plants.
Relative root density with depth for tw o year old pine seedlings was estimated from
studies in the literature that were conducted at the Rosebud Mine (Richardson, 1981;
Thamarus, 1987a and b) and North Dakota (van Haverbeke, 1963). Relative root depth
density for grasses was estimated from root abundance recorded during profile description
38
work using the specific native and reclamation sites selected for modeling. The ROOTF input
values for each soil layer at a site were dependent on the characteristics o f each root system
(pine or grass) and the horizon thicknesses specific to the native or reconstructed soils being
modeled.
Several input and output modifications were made to the model. Input parameters
CROPCO, TRANCO, STRGRO and ENDGRO were disengaged. An evaporation pan
coefficient was applied to the climate input data, which made a crop coefficient (CROPCO)
unnecessary.
Evaporation pan coefficient for the Yellowtail Dam weather station was
estimated to be 0.55, based on photographs o f the immediate surroundings o f the weather
Station (Jensen, 1973). The transpiration coefficient (TRANCO) was modified as an input
variable in order to test its affect on model results. Similarly, decimal fractions to estimate
effective Overwinter precipitation (that portion o f total ovenyinter precipitation that remained
in the soil by April I) was set Up as a model variable to test model sensitivity to its estimated
(
value.
1
The model was altered to accept climate input files including daily precipitation, potential
evaporation, and total overwinter precipitation in addition to daily maximum and minimum
temperatures. Overwinter precipitation was added to climate input files because simulations
were only conducted during the growing seasons (April I through September 30) for 34
years. The model is not designed or suitable for use during winter months in Montana.
Four new lines were added at the end o f each site input file to provide measured and/or
predicted water retention data for matric potentials o f 0, -1/3, -I, -2, -5 and -15 bar [Q ^0 _1/3
-i,-2 ,-sand-isbar)] f°r each o f the four soil layers. Measured water retention data were O ^ 173
39
-is bar), using the pressure plate apparatus. W ater retention data at B0jf0j _1( .2 amj _5 baf) were
predicted using nonlinear optimisation (Wraith and Or, 1998) o f the parametric model
developed by van Genuchten (1980), The purpose o f adding this information to the input files
was to more clearly define model-predicted seasonal soil water status between field capacity
and wilting point, by providing soil wetness classes to summarize model output. Monthly
summaries o f the total number o f days within each soil water retention class, as predicted by
the model over the 34-year simulation period, were added as output.
Several assumptions were made regarding model input information. Climate data
recorded at the Colstrip weather station was assumed to be the same for all field sites. The
value used for FURCAP (surface water storage capacity) was input as zero because it was
assumed to be taken into account in the runoff curve number. SIA (soil initial abstraction
coefficient for runoff curve number) was input for all sites as 0.2 in (0.5 c m ), as suggested
by the ERHYM-H user manual (Wight, 1987) and based on model sensitivity analyses. Input
values which relate to the seasonal relative plant growth curve were selected based on
obtaining a shape with dates o f “green-up” and senescence that corresponded with qualitative
observations from staff at the Rosebud Mine (personal communication: Greg Millhollin,
Western Energy Company) and those during 1996 and 1997 field work.
Model sensitivity analyses were performed for the following model parameters: runoff
curve number (RCN), soil initial abstraction (SIA), effective overwinter precipitation,
transpiration coefficient (TRANCO), and relative root depth distribution (ROOTF). Model
runs for the sensitivity analysis were conducted using selected site input files and changing
only one input value at a time for each o f these parameters, then comparing the results to
40
determine how Sensitive the model was to a particular input. This was used to help determine
the most reasonable values to input in some cases.
Each native and reclamation site Was also simulated separately for only 1996 and 1997,
corresponding to field NM M measurement periods. Running these years separately allowed
the model simulation to begin with measured 0, rather than the predicted 0 resulting from the
previous 32 or 33 year simulations. The purpose o f simulating 1996 and 1997 separately was
to evaluate agreement o f model-predicted and field measured soil w ater contents. Because
NMM measurement depths were different from modeled soil horizons, the NMM measured
0 for each soil layer was conformed to the modeled soil layer thicknesses by c|epth-weighted
average to allow Comparison o f measured and predicted 0 for each site.
Recommendations for Soil Profile Design
The ERHYM-II computer simulation model used to extrapolate beyond the field
measured data was determined to be unsuitable for evaluating the potential seasonal soil water
status o f various “designed” soil profiles. Therefore, recommendations for creation o f soil
profiles at the Rosebud Mine are based on information obtained from literature and on
observations from the 1996 and 1997 field studies.
41
CHAPTERS
RESULTS AND DISCUSSION
Field Measurement Sites
The most distinct soil physical characteristic differences between native and reclamation
sites were soil texture and percent hard coarse fragments o f the lower horizons (70 to 90 cm
depth). O f the sites investigated, native soils were, in general, finer textured with greater
percent silt than reconstructed soils (refer to “Dominant Soil Texture o f Profile” in Table I).
Reconstructed soils overall tended to be more coarse textured than the native soils sampled.
In addition, reconstructed soils had greater percent hard coarse fragments in the. lower
horizons than native soils (refer to “Percent Coarse Fragments” in Table I). Another
difference observed between native and reconstructed soils was the abrupt textural changes
frequently encountered between soil horizons (topsoil, subsoil and spoil) in reclamation sites
(see site description forms in Appendix A).
Although not quantified, reclamation sites had substantially greater grass biomass
production than native sites (Figure 2). The most common dominant grass species in native
sites is bluebunch wheatgrass (Elymus spicatus (Pursh) Gould), followed by green
needlegrass (Stipa viridula Trin.) and little bluestem (Andropogon scoparius Michx.), as
42
Native site 493D-A(w)
(top photo)
Reclamation site 3915-C
(bottom photo)
Figure 2. Example o f differences in grass productivity on native and reclamation sites.
May 11, 1997.
43
indicated on the site description forms in Appendix A and summarized in Table 3. Prairie
sandreed (Calamovilfa longifolia (Hook.) Scribn.) is the most common dominant grass
species in reclamation sites, followed by bluebunch wheatgrass and thickspike wheatgra?s
(Elyrtms lanceolatus (Schribn. & Smith) Gould). Bluebunch wheatgrass is a cool-season,
native, perennial range grass which is valuable for forage. Prairie sandreed is a warm-season,
native perennial o f little value for forage, but is strongly rhizomatous making it useful for
erosion control. Table 3 summarizes some characteristics o f the other dominant grass species,
as provided by Lovell (1992).
Neutron Moisture M eter Calibration and Bulk Density Measurements
Neutron moisture meter (NMM) calibration results are presented in Table 4, which also
outlines the site numbers, soil horizon(s) and dominant soil texture(s) that were grouped
together as having similar calibration relationships. R2 values obtained from NMM calibration
for the sites sampled range from 0.61 to 0.94, with a mean value o f 0,85±0.04. The highest
possible r2 value is 1.0, indicating 1:1 correlation o f measured and predicted values. R2 values
from calibration o f reconstructed subsoil horizon readings were all below the mean r2. All
other site/horizon/soil texture groups were above mean. The low r2 values which were
obtained for reconstructed subsoil likely result from the variety o f soil textures present in
these horizons within and between reclamation sites. The measured data collected were
considered insufficient to do reliable location-specific calibrations for each site.
Table 3. Summary o f dominant grass species o f native and reclamation sites.
Native Sites
Dominant Grass Species
Common
Name
Latin Name
Type
m e­
e ts)
121Ec #
183EC (S )
183EC(n)
X
X
X
X
bluebunch
wheatgrass
E ly m u s
s p ic a tu s
C, N, P
prairie
sandreed
C a la m o v ilfa
lo n g ifo lia
W, N, P
green
needlegrass
S tip a
v ir id u la
C,N,P
little
bluestem
A ndropogon
s c o p a r iu s
W,N,P
thickspike
wheatgrass
E ly m u s
la n c e o la tu s
C,N,P
crested
wheatgrass
A gropyron
c r is ta tu m
QkP
sideoat
grama
B o u te lo u a
c u r tip e n d u la
W,N,P
cheatgrass
B ro m u s
te c to r u m
C,I,A
Reclamation Sites
493DA(e)
493DA(w)
4888A
X
X
X
4822B
2856B
X
4901C
3915C
X
X
X
X
X
4881C
X
X
X
X
X
X
X
X
X
X
X
X
Type: A=annual, C=cool season, I=Introductd, N=native, P=perennial, W=warm season (Lovell, 1992).
Dominant grass species based cm ranking from Site Description Forms located in Appendix A.
This table includes only those grass species ranked as dominant on more than one site.______________
X
X
X
45
Table 4. Site groupings for neutron moisture meter calibration.
Site Type
Site Number(s)
Horizon
Dominant Soil
Texture(s)
Linear
Regression
I2 Value
Native
121E-C(s), 183E-C(s), 493D-A(e)
Topsoil
CL, SiL, L
0.89
Native
121E-C(s), 493D-A(e)
Subsoil
SiCL, SiL
0.89
Native
183E-C(s)
Subsoil
L
0.94
Reclamation
4888-A, 4822-B, 2856-B. 4881-C,
4901-C, 3915-C
Topsoil
fSCL, fSL, SiCL,
L
0.89
Reclamation
4822-B, 4881-C, 4901-C ,3915-C
Subsoil
L/SCL, SL, CL, L
0.82
Reclamation
2856-B
Subsoil
LfS, fSCL
0.61
Reclamation
4888-A
Subsoil
SiCL
0.84
Reclamation
4888-A, 4822-B, 2856-B, 4881-C,
4901-C, 3915-C
Spoil
SL, SiCL, grSCL,
SL
0.94
Statistics: range 0.61 to 0.94; mean 0.85; std. error mean 0.04.
The mean measured soil profile bulk density for each site is presented in Table 5. Mean
profile soil bulk density o f native sites is lower than reclamation sites, with native sites having
a range o f 1.15 g cm"3 to 1.37 g cm"3 and reclamation sites ranging from 1.45 g cm"3 to 1.61
g cm"3. Thus, mean profile soil bulk density for all native soil horizons was less than 1.4 g
cm"3, whereas mean profile soil bulk density for all reconstructed soil horizons was greater
than 1.4 g cm"3 Increased soil bulk density is expected to constrain root growth and reduce
shoot growth in pines (Helms, 1983; Potter and Green, 1964, van Haverbeke, 1963).
46
Table 5. Mean profile (0 to 90 cm) soil bulk density for each study site.
Native Sites
Mean Soil Bulk Density (g/cm3)
121E-C(s)
1.15
183E-C(s)
1.16
493D-A(e)
1.37
Reclamation Sites
4888-A
1.49
4822-B
1.45
2856-B
1.45
4881-C
1.55
4901-C
1.61
3915-C
1.61
Statistics: Native Sites mean 1.23, std. dev. 0.10; Reclamation Sites mean 1.53, std. dev. 0.07.
Figure 3 illustrates mean measured soil bulk density by depth for native and reclamation
sites. Mean soil bulk density o f native sites 121E-C(s) and 183E-C(s) were similar to one
another at all depths and consistently lower than that measured for site 493D-A(e). Mean
bulk density for reclamation sites in Area C (4881-C, 4 9 0 1-C and 3915-C) is higher than the
other reclamation sites sampled in Areas A and B (4888-A, 4822-B and 2856-B) at all depths
except 0 to 30 cm, where 4822-B has higher bulk density than 4881-C. For most reclamation
sites, soil bulk density increases with depth. However, soil bulk density decreases consistently
with depth for 4822-B. Sites 4 9 0 1-C and 3915-C increase in bulk density to 70 cm depth,
then decrease.
The higher soil bulk densities measured for reconstructed soils are consistent with
expectations because o f soil disturbance, reconstruction and use o f heavy equipment that is
47
Figure 3. Mean measured soil bulk density by depth.
Native Sites
S
I
1.2
t
1.0
C
0)
1'4
Q 0.8
m 0.6
I
0.4
0.0
0-30
30-50
50-70
70-90
Soil Depth (cm)
Q 121 E-C(S)
■ 183E-C(s)
D 493D-A(e)
Reclamation Sites
i
C
1.0
<D
Q 0.8
m 0.6
I
0.4
0.0
Soil Depth (cm)
□ 4888-A
■ 4822-B
□ 2856-B
D 4881-C * 4 9 0 1 -C
[]3915-C
48
required to move large quantities o f earthen material, The higher bulk densities observed in
Area C sites (4881-C, 4901-C, 3915-C) are apparently unrelated to soil texture.
The
dominant soil textures o f these sites are finer (tending toward clay loam, loam, or sandy loam)
than at the other reclamation sites sampled in Areas A and B (predominantly sandy clay
loam). The relatively higher bulk density measured for. native site 493DrA(e) is somewhat
surprising given the finer textured soil (clay loam/silty clay loam) o f that site compared with
the other native sites sampled (loam and silt loam).
Soil W ater Retention and Plant Available Water
Plant available water holding capacity (PAWHC) is conventionally calculated as the
difference between field capacity and wilting point.
On a volume water content basis
(expressed as percent), mean plant available w ater for native and reconstructed soils was
determined to be very similar; 16±0.00 percent for native sites and 15±0.01 percent for
reclamation sites (Table 6). The range o f PAWHC for native soils was narrower than for
reconstructed soils; 15 to 20 percent for native compared with 9 to 19 percent for
reconstructed soils.
Plant available water holding capacity by soil depth, in terms o f equivalent depth o f
water, for native and reconstructed soils is presented in Figure 4. The greatest PAWHC
occurs in the 0 to 30 cm soil depth for native sites, with a mean o f 4.7±0.15 cm. All other soil
depths within native sites have less PAWHC, ranging from 3.1±0.32 cm to 3.4=1=0.28 cm.
However, it should be noted that Figure 4 compares PAWHC within 30 cm soil depth for the
0 to 30 cm range (consistent with NM M calculations) with 20 cm depth increment for all
49
Table 6. Laboratory measured plant available water holding capacity (PAWHC) for native and
reclamation sites.
Native Sites
Mean
Measured Water
Retention (0)
Reclamation Sites
Plant
Available
Water
Mean
Measured Water
Retention (0)
Plant
Available
Water
Depth (cm)
SiteID
1/3 Bar
15 Bar
0
SiteID
1/3 Bar
15 Bar
0
0-30
121E-C(s)
0.29
0.12
0.17
4888-A
0.34
0.16
0.17
30-50
0.29
0.12
0.17
0.37
0.18
0.19
50-70
0.29
0.13
0.16
0.33
0.16
0.17
70-90
0.29
0.13
0.16
0.26
0.09
0.17
0.28
0.12
0.15
0.25
0.13
0.12
30-50
0.27
0.12
0.15
0.23
0.11
0.12
50-70
0.34
0.14
0.20
0.22
0.10
0.12
70-90
0.32
0.13
0.19
0.18
0.08
0.10
0.31
0.16
0.15
0.18
0.09
0.09
30-50
0.31
0.15
0.16
0.20
0.09
0.10
50-70
0.29
0.14
0.15
0.23
0.11
0.12
70-90
0.31
0.15
0.16
0.27
0.13
0.15
0.27
0.12
0.15
30-50
0.30
0.13
0.17
50-70
0.27
0.11
0.16
70-90
0.30
0.15
0.15
0.32
0.14
0.18
30-50
0.31
0.14
0.18
50-70
0.30
0.13
0.17
70-90
0.25
0.11
0.14
0.30
0.15
0.14
30-50
0.31
0:15
0.16
50-70
0.24
0.10
0.14
70-90
0.21
0:07
0.14
0-30
0-30
0-30
0-30
0-30
183E-C(s)
493D-A(e)
4822-B
2856-B
4881-C
4901-C
3915-C
.
Native Sites: PAWHC mean 0.16±0.00 (0.15-0.20); 1/3 bar mean 0.30±0.01, (0.27-0.34); 15 bar mean 0 .14±0.00,
(0.12-0.16).
1
Reclamation Sites: PAWHC ihean 0.15±0.01 (0.09-0.19); 1/3 bar mean 0.27±0.01, (0.18-0.37); 15 bar mean
0.12±0.01, (0:07-0.18).
50
Figure 4.
Pressure plate results: measured depth equivalent plant available soil
water holding capacity by depth for each site.
Native Sites
0-30
30-50
50-70
70-90
Soil Depth (cm)
Q121E-C(s)
HlSSE-C(S)
□493D-A(e)
Reclamation Sites
0-30
30-50
50-70
70-90
Soil Depth (cm)
□ 4888-A
■ 4822-B
D2856-B
□4881-C
■ 4901-C
0 3915-C
51
other depths. Scaling the mean PAWHC o f the top horizon o f native sites to 20 cm o f soil
results in 3.1 cm water. Mean PAWHC is, therefore, fairly uniform throughout the profile
for native sites.
Pressure plate results for reclamation sites also indicate the greatest PAWHC within the
0 to 30 cm soil depth (for 30 cm o f soil). The average depth equivalent PAWHC at this depth
(4.3±0.40 cm) was similar to that for native soils (4.7±0.15 cm). Scaling the mean PAWHC
to 20 cm soil depth results in 2.8 cm water for reclamation site surface layers. Below 70 cm,
the mean PAWHC o f reclamation sites decreases significantly to 1.9±0.14 cm, which is 1.2
cm per 20 cm soil less than measured for the same depth in native sites. The lower PAWHC
o f the 70 to 90 cm soil depth o f reclamation sites is related to spoil material, which is
encountered at approximately 75 cm in most o f the reclamation sites, and has greater
percentage o f coarse fragments and higher soil bulk density than other horizons.
The sum o f the mean measured depth equivalent PAWHC over soil depths provides the
mean PAWHC for the profile (0 to 90 cm). For native sites, the mean PAWHC for the
profile was calculated as 14.4±1.5 cm, compared to 12.0±0.4 cm for reclamation sites.
Native sites thus had 2.4 cm (20 percent) greater mean plant available water storage capacity
within the upper 90 cm soil profile. The range o f measured plant available water holding
capacity for native sites was 13.8 to 15.3 cm; and 9.0 to 14.3 cm for reclamation sites.
Lower plant available water holding capacity in reclamation sites is consistent with
measured soil bulk density. Generally, greater soil bulk density results in lower PAWHC, for
a given soil texture, due to decreased total pore space and smaller range o f pore sizes.
52
Soil W ater Status
Neutron moisture meter (NMM) measurements were taken during parts o f the growing
seasons in 1996 and 1997. Therefore, comparison o f the early growing season measurements
(March 30 through May 11, 1997) with the later growing season measurements (May 15
through September 12, 1996) must be done with the knowledge that each set o f NM M
readings will likely be different because o f different preceding climatic conditions.
Figure 5 presents the distributions o f overwinter and growing season precipitation for
1996 and 1997. Monthly precipitation for 1997 only extends through May because NM M
field measurement's only occurred to that time. Total overwinter precipitation (October 1995
through March 1996) preceding the 1996 growing season was 10.95 cm, compared to 12.90
cm for October 1996 through March 1997. 1996 had total overwinter precipitation nearly
identical to the 34-year average, whereas 1997 had above-average total overwinter
precipitation (difference o f 1.92 cm; 34 year mean is 10.98±0.69 cm). Figure 5 indicates the
distribution o f total monthly overwinter precipitation during each year was slightly different,
w ith a greater amount o f the 1997 overwinter precipitation occurring October through
December, whereas 1996 overwinter precipitation had greater monthly fluctuations. Also o f
interest is the difference between March and April precipitation patterns for 1996 and 1997.
Effective overwinter precipitation was estimated based on field measured soil water
contents (NMM readings) and corresponding precipitation records from the Colstrip weather
station for the period during which soil water measurements Were taken, Effective overwinter
prCCjill^lfoifWas calculated as the measured gain in depth equivalent soil water content (cm)
53
Figure 5. Distribution o f 1996 and 1997 overwinter and growing season precipitation,
________ Colstrip, Montana.
10
E
8 -
CL
4 --
2
Overwinter:
October - March
- -
Growing Season:
April - September
—
OCT
NOV
DEC
JAN
FEB
MAR APRIL MAY JUNE JULY AUG SEPT
Month
■
1996
- W
-
1997
between September 12, 1996 and March 30, 1997 NMM readings, divided by the total
overwinter precipitation (cm) from October 1996 through March 1997 measured at the
Colstrip station. Overwinter precipitation was determined to be 21 percent more effective for
reclamation sites than native sites, with 61 percent (0.61±0.031) mean effective precipitation
calculated for reclamation sites and 40 percent (0.40±0.049) mean effective precipitation for
native sites. The calculated effective overwinter precipitation for each site is presented in
Table 7. Note the variability shown between all sites, especially for native sites, which had
54
a standard error o f 4.87 percent, compared to 3.07 percent standard error for reclamation
sites.
Table 7. Percent effective overwinter precipitation during October I, 1996 to April I,
1997 for each site, calculated from neutron moisture meter and daily
precipitation data.
Site Reference
Site Type
Effective Precipitation (%)
121E-C(s)
Native
43.8
121E-C(n)
Native
61.2
183E-C(s)
Native
26.6
183E-C(n)
Native
36.1
493D-A(w)
Native
41.7
493D-A(e)
Native
32.8
4888-A
Reclamation
69.5
4822-B
Reclamation
62.4
2856-B
Reclamation
55.8
4881-C
Reclamation
61.7
4901-C
Reclamation
66.1
3915-C
Reclamation
48.6
Statistics for Native Sites: mean=40.4%, std. error mean=4.87%, n = ll.
Statistics for Reclamation Sites: mean=60.7%, std. error mean=3.07%, n=10.
Many o f the comparisons among native and reclamation sites assume the same amount
o f precipitation occurred over the entire area encompassing all sites sampled.
This
assumption is a questionable but necessary simplification, given a lack o f location-specific
climatic information. Differences related to calculated effective precipitation at a given site
may be from any, or a combination o f the following: I) differences in actual precipitation
55
which fell at a given Ideation; 2) site-specific infiltration differences, potentially caused by
topography, surface conditions or soil properties; 3) precipitation interception and
evaporation before reaching the soil; 4) site-specific differences in evaporative influences and
evaporative loss; and 5) temporal and spatial differences in vegetation in ternis o f soil water
use during October through March, i:e., conifers generally transpire during this period
whereas grasses and forbs do not.
The most obvious difference between native and
reclamation sites which may influence the amount o f effective precipitation is the presence o f
the tree canopy over native sites, even though native sites consist o f open woods rather than
dense forest.
Figure 6 presents mean measured soil water content for native and reclamation sites for
the 1996 and 1997 NMM measurement periods. Measurements indicate reclamation sites had
greater mean volumetric soil water content than native sites for all sample dates prior to midJuly both years, which is likely related to greater effective precipitation for reclamation sites.
The greatest differences in mean measured soil water content o f native and reclamation sites
occurred between the middle o f May (May 15) through beginning o f July (July 2), 1996.
During this period reclamation sites had up to 0.05 cm3 cm"3 ( 5 percent) greater measured
volumetric soil water content (6) than native sites. This result further implicates differences
in effective precipitation between native and reclamation sites, because the greater measured
soil water content on reclamation sites during this period correspond to the high amount o f
total precipitation that occurred during May, 1996. Furthermore, mean measured 6 o f
reclamation sites was less than native sites toward the end o f the 1996 growing season, yet
began the 1997 growing season with greater mean measured 0 than native sites.
56
Figure 6.
Mean field-measured profile soil water content for all native and
reclamation sites.
0.24
0.22
0.18
0.16
0.14
0.12
0.10
0.08 - —
-
5/15 5/29 6/19
7/2
7/16 7/30 8/14 9/12
3/30 4/20 5/11
NMM Sample Date
— A --N a tiv e Sites
- * -
Reclamation Sites
Mean incremental soil water depletion of near surface horizons (0 to 70 cm) is presented
in Figure 7 for native and reclamation sites. Incremental soil water depletion was calculated
as the change in measured soil water content between each consecutive NMM reading during
1996 and 1997, multiplied by the corresponding soil depth.
The results presented for
incremental depletion indicate the greatest depletion in both native and reclamation sites
occurred from the 0 to 30 cm soil depth during the period May 29 to June 19, 1996,
corresponding to a period of active plant growth, and therefore plant water uptake. Negative
depletion, or an increase in soil water content, was measured during May 15 to May 29, 1996
and March 30 to April 20, 1997 in all near surface soil horizons (0 to 70 cm) for both native
57
Figure 7. Mean incremental soil water depletion o f near surface soil horizons
(0 to 70 cm).
Native Sites
I 0-30 cm I
I 30-50 cm
Reclamation Sites
c
0
is
1
c
$
z
50-70 cm
58
and reclamation sites. These periods correspond to increased precipitation (Figure 5), which
occurred relatively early in the growing season before significant plant growth.
Depletion from near surface horizons was consistently greater from reclamation sites
than native sites. The differences in incremental depletion were greater for reclamation sites
during May 29 through July 16, 1996, which corresponds to the period where reclamation
sites had greater mean measured 0 than native sites (Figure 6). However, greater incremental
depletion from reclamation sites also occurred during July 16 through September 12,1996,
even though mean measured 0 o f reclamation sites was less than native sites for this same
period (Figure 6).
Starting profile (0 to 90 cm) depth equivalent o f water, or the depth equivalent o f water
at the beginning o f each NMM measurement period (May 15,1996 and March 30, 1997) for
native and reclamation sites is presented in Figures 8A and SB. M ean measured profile
starting water on May 15, 1996 was measured as 14.4±1.4 cm for native sites and 18.4±0.9
cm for reclamation sites (Figure 8A). On March 30, 1997 mean profile starting water was
measured as 15.5±1.3 cm for native sites and 17.6±0,9 cm for reclamation sites (Figure SB).
Reclamation sites began the 1996 NMM measurement period with an average o f 4.0 cm m ore
mean soil water than native sites, and the 1997 NM M measurement period with 2.1 cm more
mean soil water than native sites. Greater variability in starting water content is observed for
native sites during both measurement periods. This result may be related to greater variability
of native sites, including topography and site specific differences in water use and interception
o f precipitation.
59
Figure 8A. Soil profile (0 to 90 cm) starting water content based on 1996 neutron
moisture meter measurements.
Native Sites
May 15, 1996
30 -I--------------------------------------------------------------
mean: 14.4 cm
sem: 1.4 cm
1 Z Z E -C (S )
1 8 3 E -C (s )
1 2 2 E -C (n )
J
1 8 3 E -C (n )
J
4 9 3 D -A (e )
4 9 3 D -A ( w )
Reclamation Sites
May 15, 1996
I 4888-A
m
4822-B
J 2856-B
4881-C
|22] 4901-C
3915-C
60
Figure SB. Soil profile (0 to 90 cm) starting water content based on 1997 neutron
moisture meter measurements.
Native Sites
March 30, 1997
30
E
mean: 15.5 cm
sem: 1.3 cm
r 25
I
O 20
L
0)
1 10
3
cr
LU
f0)
5
Q
0
1 2 2 E -C (S )
1 2 2 E -C (n )
]
1 8 3 E -C (s )
J
1 8 3 E -C (n )
4 9 3 D -A (e )
4 9 3 D -A (w )
Reclamation Sites
March 30, 1997
I 4888-A [ H
4822-B
2856-B
4881-C |
4901-C
3915-C
61
Variability in starting water content is more evident when calculated as a percent o f plant
available water holding capacity. Figures 9A and 9B present the relationship between field
measured profile (0 to 90 cm) starting water content and laboratory measured profile (0 to
90 cm) plant available water holding capacity for native and reclamation sites. As depicted,
there is significant variability among native sites compared to reclamation sites. Among native
sites, one or both NM M access tubes within several sites was calculated as starting the
growing season without plant available water in the prqfile (negative plant available water)
for both the May 15, 1996 and March 30, 1997 measurements. Note that these results are
/
calculated using measured water content averaged over the entire (0 to 90 cm) soil profile,
thus any plant available water at specific depths is not represented in the mean value.
Calculated starting soil water content as a percentage o f plant available water indicated
that all NM M access tubes in both native and reclamation sites had less than 70 percent o f
potential (maximum) plant available water when NM M measurements were initiated each
year. However, reclamation sites began each NM M measurement period for each year with
more than twice the mean percent plant available water than native sites. Reclamation sites
were calculated to have 36.8±4.1 mean percent plant available water on May 15, 1996,
compared to 15.3±7.0 mean percent for native sites (Figure 9A). On March 30, 1997,
reclamation sites were calculated to begin the NMM measurement period with 47.2±4.6 mean
percent plant available water compared to 21.8±7.0 mean percent for native sites (Figure 9B).
Total soil water depletion during the growing season was calculated as the sum (over
depths) of the difference between measured beginning and ending soil w ater content for each
NMM measurement period (May 15 to September 12,1996 and March 30 to May 1 1 ,1997),
62
Figure 9A.
Soil profile (0 to 90 cm) starting plant available water based on 1996
neutron moisture meter measurements as a percent of plant available
water holding capacity.
Native Sites
May 15, 1996
mean: 15.3%
sem: 7.0%
1 2 2 E -C (s) m
1 2 2 E -C (n )
0
1 8 3 E -C (s)
I 1 8 3 E -C (n )
4 9 3 D -A (e )
1 j
4 9 3 D -A ( w )
Reclamation Sites
May 15, 1996
100
80
£
I
60
0)
jQ 40
ro
I
20
C
JS
Cl
0
-20
J 4888-A [
] 4822-B
[
j
2856-B
4881-C |2 2 ] 4801-C
3915-C
63
Figure 9B.
Soil profile (0 to 90 cm) starting plant available water based on 1997
neutron moisture meter measurements as a percent of plant available
water holding capacity.
Native Sites
March 30, 1997
100
mean: 21.8%
sem: 7.0%
80
-20
1 Z Z E -C (S )
1 Z Z E -C (n )
___
1 8 3 E -C (s)
J
1 8 3 E -C (n ) |
| 4 9 3 D -A (e )
4 9 3 D -A (w )
Reclamation Sites
March 30, 1997
100
mean: 47.2%
sem: 4.6%
80
SE
-20
I 4888-A
4822-B
| 2856-B
4881-C I
| 4901-C
■' 3915-C
64
multiplied by corresponding NM M measurement depth increments. Negative depletion
indicates net gain o f soil water (profile redharge). Soil water depletion from native and
reclamation sites for each period is presented in Figures IOA and I OB. Results indicate
greater depletion from reclamation sites compared to native sites during 1996.
Mean
measured depletion from reclamation sites is more than twice the depletion from native sites,
with 10.8±0.46 cm mean depletion calculated from reclamation sites and 5.0±0.51 cm mean
depletion calculated from native sites between May 15 and September 12, 1996.
Native and reclamation sites were calculated as having similar soil water recharge during
the M arch 30 to May 11, 1997 measurement period. Native sites were calculated to have
-1.6±0.53 cm mean soil water depletion, compared to -1.5±0.37 cm mean soil water depletion
for reclamation sites (Figure I OB). Negative depletion (soil water gain) was calculated for
all native sites except 121E-C(s) and all reclamation sites except 3915-C. Negative depletion
during this measurement period is not surprising as it is early in the growing season,
corresponding to a period o f high measured precipitation and relatively little plant water
up tak e.
The greater soil water depletion from reclamation sites during the 1996 measurement
period is consistent with reclamation sites having more total and more plant available soil
w ater to use. Reclamation sites started the 1996 growing season with greater 0 and were
measured throughout much o f the growing Season as having greater 0 than native sites.
Higher depletion was also expected from reclamation sites given the greater grass and forb
vegetative production compared with native sites.
65
Figure I GA.
Comparison o f soil profile (0 to 90 cm) water depletion from native and
reclamation sites based on 1996 neutron moisture meter measurements.
Native Sites
May 15 through September 12, 1996
I
121 E -C (S )
| 2 2 | 1 2 1 E - C ( Ii)
I
1M E -C (S )
2
2
1 8 3 E -C (n )
4 9 3 D -A ( w )
4 9 3 D -A ( e )
Reclamation Sites - Vegetated
May 15 through September 12, 1996
16
14
12
I
10
c
0 8
JD
CL
0)
Q
6
4
1
2
o
0
(/)
-2
-4
-6
] 4888-A U
4822-B j^jj] 2856-B
0
4881-C
4901-C
3915-C
66
Figure I OB.
Comparison o f soil profile (0 to 90 cm) water depletion from native and
reclamation sites based on 1997 neutron moisture meter measurements.
Native Sites
March 30 through May 11,1997
16
14
12
mean: -1.6 cm
sem: 0.53 cm
I 10
0 8
I e
?
4
1
2
1S 0
V)
-2
__
-4
-6
I
121 E-C(S)
|2 2 ]
121E -C (n)
I
1 8 3 E -C (s)
H U j
183E-C (n)
I
493D -A (w )
493D -A(e)
Reclamation Sites - Vegetated
March 30 through May 11, 1997
16
14
12
H 10
I
8
I
2
o
0
q.
mean: -1.5 cm
sem: 0.37 cm
a> 6
a 4
V)
-2
EH fiW 5U
-4
-6 ---------------------------------------------------- 1---------------------------------------------------J 4888-A J | 4822-B -
2856-B
0
4881-C
4901-C
3915-C
67
Comparison o f profile depletion for reclamation sites with and without vegetation is
presented in Figures I lA and I IB. NMM measurements from areas where vegetation had
been killed within an approximate 1.5 m radius around the access tube showed less mean
profile depletion than from areas within the same sites with vegetation, as expected. Later
in the growing Season (May 15 to September 12, 1996), significantly higher depletion from
vegetated reclamation sites than non-vegetated sites was observed; 10.8±0.46 cm mean
depletion for vegetated compared to 2.6±0.97 cm mean depletion for non-vegetated (Figure
11 A). Early season measurements (March 30 to May 11, 1997) indicated slightly less soil
w ater depletion from Vegetated reclamation sites than non-vegetated reclamation sites;
-1.5±0.37 cm from vegetated reclamation sites compared to -0.9±0.32 cm mean profile
depletion from non-vegetated reclamation sites.
This result is likely related to greater
evaporation from sprayed plots, especially during sunny and/or windy conditions, as a result
o f lower surface cover.
\
68
Figure 11 A. Comparison o f soil profile (0 to 90 cm) water depletion from vegetated
and non-vegetated reclamation sites based on 1996 neutron moisture
meter measurements.
Reclamation Sites - Vegetated
May 15 through September 12, 1996
16
14
12
E 10
O
C
O 8
a>
6
|
Q
OT
4
2
0
-2
-4
-6
^ 4888-A U
4822-B
2856-B
4881-C
4901-C |___ 3915-C
Reclamation Sites - Non-Vegetated
May 15 through September 12,1996
mean: 2.6 cm
sem: 0.97 cm
4888-A
4822-B
2856-B
4881-C
4901-C
3915-C
69
Figure I IB. Comparison o f soil profile (0 to 90 cm) water depletion from vegetated
and non-vegetated reclamation sites based on 1997 neutron moisture
meter measurements.
Reclamation Sites - Vegetated
March 30 through May 11,1997
mean: -1.5 cm
sem: 0.37 cm
4888-A
4822-B
2856-B
4881-c [ J eoi-c Qaeis-C
Reclamation Sites - Non-Vegetated
March 30 through May 11,1997
16
14
mean: -0.9 cm
sem: 0.32 cm
12
I 10
C
0 8
JD
0) 6
Q.
Q
1
4
2
0
y/jm
-2
-4
-6
4888-A I H
4822-B
I
2856-B | % | 4881-C
4901-C
391S-C
70
Computer Simulation Modeling o f Long Term Seasonal Soil W ater Status
Model Sensitivity Analyses
R unoff Curve Number. The runoff curve number (RCN) represents a site specific
relationship between rainfall and runoff, based on soil type, land use and management
practices, and takes into account previous precipitation and therefore antecedent soil moisture
(Wight, 1987).
Several 34-year model runs were conducted using the native pine 3 (NP3) and native
pine 5 (NP5) input files, altering only the runoff curve number. The RCN predicted by the
NRCS methodology was 89 for NP3 and 60 for NP5. The RCN predicted using Table I o f
the ERHYM-E model description and user guide (Wight, 1987) was 75 for NP3 and 65 for
NP5. The model proved to be quite sensitive to differences in RCN, with a higher RCN value
resulting in greater predicted runoff, as expected.
For NP3, model sensitivity analysis runs were conducted using RCN o f 89, 85, 80 and
75, with 15, 13, 9 and 5 the corresponding average number o f predicted runoff events per
year. For site NP5, simulations were conducted using RCN o f 65 and 60, with 2 and I
average predicted runoff events per year, respectively. All RCN sensitivity simulations were
conducted using a soil initial abstraction value o f 0.2 in, which is discussed below.
Runoffcurve number also affected the simulated distribution o f plant available soil water
in the profile. For NP3, a higher RCN (89 compared to 80), which produced more runoff
events, resulted in soil layer I having less soil water, a 34-year mean o f 6 more days per
growing season within water retention class Och^ 15 bar) and 8 less days per growing season
71
within water retention class 0(h>_2bar)- A similar result occurred for soil layer 2, but RCN had
little to no affect on soil layers 3 and 4.
For NP5, the varied RCN resulted in no noticeable affect on the distribution o f predicted
soil water in the profile. This result is likely due to the small affect RCN had on runoff for
this site.
The RCN generated by the NRCS methodology was used for each site instead o f the
m ore simplified approach o f ERHYM-II. The NRCS method is more site specific and
produced more reasonable numbers o f predicted runoff events based on expectations for arid
rangeland sites in eastern Montana and on observations o f the number o f runoff events
observed at the Rosebud Mine (personal communication: Greg Millhollin, Western Energy
Company).
Soil Initial Abstraction.
The model was tested by varying only the Soil Initial
Abstraction (SIA) value during several different 34-year runs. SIA is an estimate o f surface
soil water detention before runoff begins, including water retained in surface depressions and
intercepted by vegetation. The NRCS methodology produces a different SIA value for each
RCN, with a lower RCN having a higher SIA value. For example, site NP5 was determined
to have a RCN o f 60 and an SIA o f 1.33 in, based on NRCS criteria. Running the model
using these values resulted in no predicted runoff. The model description (Wight, 1987)
recommends using an SIA value o f 0.20 in. R unoff was predicted for site NP5 when using
RCN of 60 and SlA of 0.2 in, with an average o f I runoff event per year, as discussed above.
SIA predicted from the NRCS methodology were 0.25 in for several other sites. Based
72
on results from the SlA sensitivity analysis and the similarity o f the SIA for several other sites,
a value o f 0.2 in was used for all native and reclamation sites modeled, regardless o f the RCN
value used.
Effective Precipitation.
The model was modified to allow input o f an effective
precipitation coefficient (0 to 1.0) for each site. This value was used to scale total October
through March precipitation to that amount estimated to remain in the soil as o f April I, the
beginning o f each annual simulation period. A range o f effective precipitation values from 0.2
to 0.6 were input for 34-year runs on sites NP3 and NP5. The model output was not sensitive
to these values. Output from various effective precipitation inputs did not have any effect on
the number o f runoff events or seasonal distribution o f plant available water in the profile.
The effective precipitation based on calculated soil water balance during the winter o f 19961997 were thus used for all model runs. For native sites an effective precipitation o f 0.4 (40
percent) was used. For reclamation sites an effective precipitation o f 0.6 (60 percent) was
used.
Transpiration Coefficient. A transpiration coefficient is an estimate o f the fraction o f
total potential evapotranspiration attributed to plant water uptake, or transpiration. The
model output was only slightly sensitive to changes in the transpiration coefficient
(TRANCO). Comparison o f TRANCO o f 0.9,0.8 and 0.6 for NP3 and NP5 showed slightly
more runoff with a lower TRANCO value. TRANCO also affected soil water distribution
throughout the profile, with a higher TRANCO resulting in soil layfer I having greater water
content, soil layer 2 having less water content and no changes to soil layers 3 and 4.
73
Presumably this result is from relatively less direct evaporative water loss from the upper soil
layer (layer I) associated with the higher TRANCO value. The different TRANCO resulted
in imperceptible differences in the ratio o f predicted actual transpiration to predicted potential
transpiration. Based on the sensitivity analysis and a review o f relevant literature (e.g., Ham
et al., 1990), a TRANCO o f 0.7 was used for native sites and 0.8 for reclamation sites.
Root Depth Distributions. The ERHYM-II model appears to be very sensitive to root
depth distribution. This observation is supported by Weltz and Blackburn (1993), who stated
that accurate estimates o f root density as a function o f depth are critical to estimate
transpiration using ERHYM-II. Results from the sensitivity analysis indicated that soil water
distribution was highly correlated to the relative proportion o f roots present in each soil
horizon, with lower soil water content in a given horizon resulting from greater proportion
o f roots present. This result was true even after the addition to the model o f a relative soil
water availability curve.
The model was modified to input the fractional root distribution for each soil layer,
which gum to 1.0 for the soil profile, rather than relativize the proportion o f roots in each soil
layer to the top horizon, which is normally entered as 1.0 (Wight, 1987). Sensitivity analyses
for root depth distribution before modification resulted in significantly more soil water being
removed from the top horizon. Weltz and Blackburn (1993) provided a good description o f
the original root density function: “root density is a means o f restricting water uptake from
each soil layer. Soil water extraction through transpiration proceeds one layer at a time,
beginning with the surface layer. Ifthe surface layer cannot supply the full potential ET, then
74
the model extracts water from the second layer, and so on, until the full potential ET has been
satisfied or until all soil layers have been sampled.”
Model Simulation Results
Model Input. Table 8 presents the dominant soil textures and w ater holding capacities
represented by the three native and three reclamation sites selected for computer simulations.
Site-specific input values are presented in Tables 9A (native sites) and 9B (reclamation sites),
which also identify the contents o f each input fine. The Only differences in input values
between “pine” and “grass” model runs for each site were the descriptive comment (line I)
and relative root distribution (ROOTF) for each soil layer (line 11), which is dependent on
characteristics o f each root system and the horizon thicknesses for each site. Therefore, lines
I and 11 are the only input lines listed for model runs with grass roots in Tables 9A and 9B.
Table 8. Selected site characteristics used in computer simulation modeling.
Site Type
Site Reference
Number
Profile Water
Holding
Capacity (cm)
ProfilePlant
Available Water
(cm)
Dominant Soil
Texture*
Native
12IE-C
29.8
15.9
L
Native
183E-C
30.7
17.1
L/SiL
Native
493D-A
29.6
.15.4
CL/SiCL
Reclamation
4888-A
29.6
15.8
SiCL/SCL
Reclamation
4901-C
26.4
14.9
CL/SL
Reclamation
3915-C
24.9
9.2
L/SL
^Dominant soil texture is weighted average of approx. 100 cm depth soil profile.
75
Table 9A. C om puter sim ulation m odeling site input file values fo r native sites.
N ative Sites
Line #
I
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
12 IE-C
NatPine.5
U ,3
64,97,91,273
4,14,0
30.5,15,36,18
1.12,1.10,1.19,1.20
0,0,0,0
0.16,0.17,0.14,0.11
0.26,0.27,0.25,0.24
0.11,0.11,0.11,0.10
0.75,0.15,0.1,0
74,201,0.7,6,0
1,0.14,1,60,0.2
I
21.4,31.2,35.0,45.3,54.3,64.3
70.8,69.4,58.5,47.0,33.4,23.7
0.26,0.12,0.12,0.11,0.11
0.27,0.15,0.13,0.12,0.11
0.25,0.14,0.12,0.11,0.11
0.24,0.14,0.13,0.12,0.10
NatPine.6
1,1,3
64,97,91,273
4,1.3,0
25.5,25.5,23,26
1.12,1.09,1.22,1.20
0,0,0,0
0.16,0.11,0.19,0.08
0.25,0.25,0.28,0.27
0.11,0.11,0.12,0.11
0.63,0.33,0.05,0
74,201,0.7,6,0
1,0.12,1,60,0.2
I
21.4,31.2,35.0,45.3,54.3,64.3
70.8,69.4,58.5,47.0,33.4,23.7
0.25,0.12,0.12,0.11,0.11
0.25,0.15,0.13,0.12,0.11
0.28,0.14,0.12,0.11,0.12
0.27,0.14,0.13,0.12,0.11
0.16,0.18,0.16,0.14
0.17,0.23,0.22,0.22
0.11,0.11,0.10,0.11
0.75,0.21,0.04,0
74,201,0.7,6,0
1,0.15,1,89,0.2
I
21.4,31.2,35.0,45.3,54.3,64.3
70.8,69.4,58.5,47.0,33.4,23.7
0.17,0.13,0.12,0.11,0.11
0.23,0.17,0.14,0.12,0.11
0.22,0.15,0.13,0.11,0.10
0.22,0.16,0.14,0.12,0.11
I
11
NatGrss. 5
0.66,0.06,0.14,0.06
NatGrss.6
0.64,0.1,0.1,0.08
NatGrss. 3
0.66,0.1,0.06,0.1
183E-C
493D-A
NatPine.3
1,1,3
64,97,91,273
4,23,0
30.5,25,14,30
1.37,1.37,1.37,1.39
o,o,o,o
Line Contents and Explanation:
1
2
3
4*
COMMENT - alphanumeric characters.
PRTOPT, DAYOPT, LOPT - input/output options.
STARTY, ENDYj STRDAYj ENDDAY.
SLARESj AIRDRYj FURCAP: AIRDRY (cm) based on texture of top 12 inches (site description work
average if mixed texture) and Table 4 of model (converted to cm from in); FURCAP assumed 0.
5*
THK in cm of each horizon (if SURFACE LAYER >12 in (30.5 cm) split into separate, equal horizons);
total depths for each site (cm) are : 100, 100, 100.
6*
BDENST used average BD from June/Sept, samples for each soil layer from pressure plate work.
7*
ROCKF only if >5% - made sure to correlate with horizon listed in line 5, some split because > 30.5 cm.
8*
INITSM - beginning soil water per horizon - used 3/30/97 NMM readings converted to gravimetric soil
water content from volumetric soil water content.
9*
MHC - gravimetric water content at field capacity - volumetric measurements converted to gravimetric.
10* UNASM - gravimetric water content at wilting point.
11 * ROOTF - varies for each run based root type and soil horizon depths (THK input).
12
STRRGC, PSCDAYj CSHAPEj DSHAPEj RGCMIN - values related to Relative Growth Curve.
13* DACREJCS,LWJCN2JSIA: DACRE - assume I; CS-slope of site from desc. work; LW-assume I;
CN2-input calc, values based on SCS package and field work; SIA-SCS Initial Abstraction (la).
14
TEMOPT - entered I for daily temp read from input file. SOLOPTj XLATj STWF disengaged.
15
Ave. Mthly Temps: January to June.
16
Ave. Mthly Temps: July to December.
17-20* Measured and Predicted (using Van Genuchten's (1980) eq.) soil water retention data for each layer
(on separate lines), at matric potentials of 0, 0 .3 ,1 ,2 ,5 , 10 bars.
* Denotes input lines containing values which may differ among sites.
76
Table 9B. Computer simulation modeling site input file values for reclamation sites.
Reclamation Sites
Line ft
4888-A
3915-C
4901-C
I
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
RecPine.4
1,1,3
64,97,91273
4 2 1 ,0
18,4320,18
1.44,1.49,1.49,1.54
0,0.05,0.05,0.25
0.18,0.19,0.17,0.12
0.24,0.25,0.22,0.17
0.11,0.12,0.11,0.06
0.5,0.49,0.01,0
74201,0.7,6,0
1,0.08,1,85,0.2
I
21.4,31.225.0,45.3,54.3,64.3
70.8,69.4,58.5,47.0,33.423.7
0.17,0.13,0.12,0.11,0.11
0.23,0.16,0.14,0.12,0.11
0.22,0.15,0.13,0.11,0.10
0.22,0.15,0.13,0.12,0.11
0.15,0.12,0.11,0.09
0.19,0.19,0.14,0.13
0.10,0.09,0.06,0.04
0.63,0.28,0.1,0
74201,0.7,6,0
1,0.09,1,74,02
I
21.421.2,35.0,45.3,54.3,64.3
70.8,69.4,58.5,47.0,33.423.7
0.17,0.13,0.12,0.11,0.11
0.23,0.15,0.13,0.12,0.11
0.22,0.14,0.12,0.11,0.10
0.22,0.15,0.13,0.12,0.11
RecPine.8
U 2
64,97,91273
4,1.7,0
182424,34
1.59,1.63,1.64,1.57
0,0,0,03
0.14,0.13,0.11,0.10
0.20,0.19,0.18,0.16
0.09,0.08,0.08,0.07
0.5,0.4,0.1,0
74201,0.7,6,0
1,0.17,1,74,0.2
I
21.4,31.2,35.0,45.3,54.3,64.3
70.8,69.4,58.5,47.0,33.423.7
0.17,0.13,0.12,0.11,0.11
023,0.16,0.14,0.12,0.11
0.22,0.15,0.12,0.11,0.10
0.22,0.15,0.13,0.12,0.11
I
11
RecGrss.4
0.75,0.24,0.01,0
RecGrss.7
0.83,0.11,0.06,0
RecGrss.8
0.75,0.19,0.06,0
RecPine.7
U ,3
64,97,91273
4,1.3,0
2320,3324
1.55,1.67,1.69,1.54
0,0,0,0
Line Contents and Explanation:
1
2
3
4*
COMMENT - alphanumeric characters.
PRTOPT, DAYOPT, LOPT - input/output options.
STARTY, ENDY, STRDAY, ENDDAY.
SLARES, AIRDRY, FURCAP: AIRDRY (cm) based on texture of top 12 inches (site description work
average if mixed texture) and Table 4 of model (converted to cm from in); FURCAP assumed 0.
5*
THK in cm of each horizon (if SURFACE LAYER >12 in (30.5 cm) split into separate, equal horizons);
total depths for each site (cm) are : 10 0 ,10 0 ,100.
6*
BDENST used average BD from June/Sept, samples for each soil layer from pressure plate work.
7* ROCKF only if >5% - made sure to correlate with horizon listed in line 5, some split because >30.5 cm.
8* INTTSM - beginning soil water per horizon - used 3/30/97 NMM readings converted to gravimetric soil
water content from volumetric soil water content.
9*
MHC - gravimetric water content at field capacity - volumetric measurements converted to gravimetric.
10*
UNASM - gravimetric water content at wilting point.
11 * ROOTF - varies for each run based root type and soil horizon depths (THK input).
12
STRRGC, PSCDAY, CSHAPE, DSHAPE, RGCMIN - values related to Relative Growth Curve.
13*
DACRE,CS,LW,CN2,SIA DACRE - assume I; CS-slope of site from desc. work; LW-assume I;
CN2-input calc, values based on SCS package and field work; SIA-SCS Initial Abstraction (la).
14
TEMOPT - entered I for daily temp read from input file. SOLOPT, XLAT, STWF disengaged.
15
Ave. Mthly Temps: January to June.
16
Ave. Mthly Temps: July to December.
17-20* Measured and Predicted (using Van Genuchten's (1980) eq.) soil water retention data for each layer
(on separate lines), at matric potentials of 0 ,0 .3 ,1 ,2 ,5 ,1 0 bars.
* Denotes input lines containing values which may djfTer among sites.___________________________________
77
The fitted soil water retention (volumetric water content) values for each soil layer using
the van Genuchten (1980) model are presented in Tables IOA and 10B, along with the
coefficients o f determination (r2) obtained by nonlinear least squares optimization (Wraith and
Or, 1998). Coefficients o f determination ranged from 0.91 to 1.00, with some native sites
having the poorest fits. The mean r2 obtained for all soil layers and sites was 0.98.
Model Output. Single partial-year model runs for 1996 and 1997 were conducted for
each site with either pine or grass roots in order to compare predicted seasonal 0 with NM M
measurements. The ERHYM-II model did not allow simultaneous modeling o f two root
systems. Therefore results from each run with either pine or grass roots depict the predicted
0 from a solitary unit area root system.
Correlation coefficients were determined from these model runs for the following
comparisons: I) measured and predicted 0 as modeled with pine roots; 2) measured and
predicted 0 as modeled with grass roots; and 3) predicted 0 modeled with pine and modeled
with grass roots. The correlation coefficients for each comparison set are presented in Table
11. N o correlation could be made for soil layer 4 o f most sites because one or both data
arrays did not show variance.
Differences were expected for predicted 0 with pine or grass root systems. However,
these differences were not strongly observed from single year model output for 1996 and
1997. Correlation results showed little difference between predicted 0 based on the root
system modeled on a given site. Differences between predicted 0 with pine or grass roots
were most evident for soil layer 2. Differences were not observed for soil layer I, which had
78
Table I GA. Soil water retention results used in native site input files obtained by fitting
__________ measured water retention data to van Genuchten's (1980) equation.______
________________________Soil Water Content (cmA3/cmA3)______________________
12 IE-C
h (bar)*
0
1/3
I
2
5
15
183E-C
h (bar)*
0
1/3
I
2
5
15
493D-A
h (bar)*
0
1/3
I
2
5
15
Layer I
Layer 2
Layer 3
Layer 4
Measured Predicted Measured Predicted Measured Predicted Measured Predicted
0.55
0.55
0.56
0.56
0.54
0.54
0.54
0.54
0.26
0.16
0.27
0.22
0.25
0.20
0.24
0.20
0.12
0.15
0.14
0.14
0.12
0.13
0.12
0.13
0.11
0.12
0.11
0.12
0.11
0.11
0.11
0.11
0.11
0.10
0.10
0.11
rA2:
0.91
rA2:
0.97
rA2:
0.97
rA2:
0.98
Layer I
Layer 2
Layer 3
Layer 4
Measured Predicted Measured Predicted Measured Predicted Measured Predicted
0.55
0.55
0.56
0.56
0.53
0.53
0.54
0.54
0.25
0.16
0.25
0.22
0.28
0.20
0.27
0.20
0.12
0.15
0.14
0.14
0.12
0.13
0.12
0.13
0.11
0.12
0.11
0.12
0.11
0.11
0.11
0.11
0.12
0.11
0.10
0.11
rA2:
0.93
rA2:
0.99
rA2:
0.92
rA2:
0.95
Layer I
Layer 2
Layer 3
Layer 4
Measured Predicted Measured Predicted Measured Predicted Measured Predicted
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.17
0.17
0.23
0.23
0.22
0.22
0.22
0.22
0.13
0.17
0.15
0.16
0.12
0.14
0.13
0.14
0.11
0.12
0.11
0.12
0.11
0.11
0.11
0.11
0.1
0.11
0.10
0.11
rA2:
1.00
rA2:
1.00
rA2:
1.00
rA2:
1.00
♦Column heading 'h' indicates soil water matric pressure.
79
Table I OB. Soil water retention results used in reclamation site input files obtained by
fitting measured water retention data to van Genuchten's (1980) equation.
Soil Water Content (cmA3/cmA3)
4888-A
h (bar)*
0
1/3
I
2
5
15
3915-C
h (bar)*
0
1/3
I
2
5
15
4901-C
h (bar)*
0
1/3
I
2
5
15
Layer I
Layer 2
Layer 3
Layer 4
Measured Predicted Measured Predicted Measured Predicted Measured Predicted
0.48
0.48
0.47
0.47
0.47
0.47
0.46
0.46
0.17
0.17
0.23
0.22
0.22
0.21
0.22
0.21
0.13
0.16
0.15
0.15
0.12
0.14
0.13
0.13
0.11
0.12
0.11
0.12
0.11
0.11
0.11
0.11
0.10
0.10
0.11
0.11
rA2:
1.00
rA2:
1.00
rA2:
1.00
rA2:
1.00
Layer I
Layer 2
Layer 3
Layer 4
Measured Predicted Measured Predicted Measured Predicted Measured Predicted
0.46
0.46
0.43
0.43
0.43
0.43
0.46
0.46
0.17
0.16
0.23
0.21
0.22
0.20
0.22
0.21
0.13
0.15
0.14
0.15
0.12
0.13
0.12
0.13
0.11
0.12
0.11
0.12
0.11
0.11
0.11
0.11
0.10
0.10
0.11
0.11
rA2:
1.00
rA2:
0.99
rA2:
0.99
rA2:
1.00
Layer I
Layer 2
Layer 3
Layer 4
Measured Predicted Measured Predicted Measured Predicted Measured Predicted
0.45
0.45
0.44
0.44
0.44
0.44
0.46
0.46
0.17
0.16
0.23
0.21
0.22
0.20
0.22
0.21
0.13
0.16
0.15
0.15
0.12
0.14
0.12
0.13
0.12
0.11
0.11
0.12
0.11
0.11
0.11
0.11
0.10
0.10
0.11
0.11
rA2:
1.00
rA2:
0.99
rA2:
0.99
rA2:
1.00
*Column heading 'h' indicates soil water matric pressure.
80
Table 11. Correlation o f measured and model predicted soil water contents for 1996
and 1997.
Comparison of Model Predicted with Pine Roots and Model Predicted with Grass Roots
Site
Site Type
Profile
Soil Layer I
Soil Layer 2
Soil Layer 3
Soil Layer 4
12IE-C
Native
0.98
1.00
0.96
0.99
*
183E-C
Native
0.99
1.00
0.94
0.97
*
493D-A
Native
0.97
1.00
0.95
0.99
*
4888-A
Reclamation
0.99
0.99
1.00
1.00
*
3915-C
Reclamation
0.98
1.00
0.97
0.98
*
4901-C
Reclamation
0.98
0.99
0.97
1.00
*
Mean
0.98
1.00
0.97
0.99
*
Comparison o f Measured and Model Predicted with Pine Roots
Site
Site Type
Profile
Soil Layer I
Soil Layer 2
Soil Layer 3
Soil Layer 4
12IE-C
Native
0.64
0.87
0.59
0.63
*
183 E-C
Native
0.13
0.81
0.58
0.47
*
493D-A
Native
0.79
0.73
0.77
0.72
*
4888-A
Reclamation
0.41
0.75
0.68
0.95
*
3915-C
Reclamation
0.65
0.73
0.83
0.52
*
4901-C
Reclamation
0.72
0.74
0.75
0.63
*
Mean
0.64
0.74
0.76
0.70
*
Comparison o f Measured and Model Predicted with Grass Roots
Site
Site Type
Profile
Soil Layer I
Soil Layer 2
Soil Layer 3
Soil Layer 4
12IE-C
Native
0.70
0.87
0.77
0.57
0.52
183E-C
Native
0.16
0.81
0.41
0.33
*
493D-A
Native
0.80
0.74
0.91
0.60
0.09
4888-A
Reclamation
0.39
0.72
0.72
0.95
*
3915-C
Reclamation
0.67
0.70
0.85
0.65
*
490I-C
Reclamation
0.73
0.71
0.80
0.67
*
Mean
0.65
0.72
0.82
0.72
0.20
*No correlation coefficient can be determined because one or both data arrays show no variance.
81
the highest correlation values o f all soil layers, with mean correlation coefficient o f 1.00.
Comparison o f field measured and model predicted 0 throughout portions o f the 1996
and 1997 growing seasons for each site are presented in Figures 12A (native sites) and 12B
(reclamation sites). Field measured 0 was conformed through depth-weighted averaging to
the same soil layer thicknesses used for modeling each native and reclamation site. Although
daily output was obtained from the model, output presented in Figures 12A and 12B was
plotted only for the same dates NM M measurements were taken to facilitate visual
comparison between measured and predicted 0.
The comparison of measured and predicted 0 during the 1996-1997 growing season, as
illustrated in Figures 12A and 12B, only model results for pine roots because predicted 0 for
each site with either pine or grass roots are similar, as previously discussed (Table 11).
Difierences between measured and predicted 0 were expected and were observed. Predicted
0 with pine or grass roots did not correlate well with measured values, based on correlation
coefficients determined for each soil layer and for the soil profile (excluding soil layer 4)
(Table 11) and on graphical comparisons (Figures 12A and 12B). Qualitative differences
betw een measured and predicted 0 for all sites are:
I) greater variation in predicted 0
between soil layers at the end o f the growing season than for measured; and 2) significant
decline in predicted 0 compared to measured during May 29 through June 19,1996 and April
20 through May 11, 1997 (Figures 12A and 12B). Based on these graphs, predicted 0
appears to be more sensitive to precipitation events than was observed from field
measurements. Field measured seasonal changes in 0 are much more gradual than for
predicted.
82
Figure 12 A. Measured and model predicted soil water content of native sites
during1996 to 1997 NMM measurement period. Predicted data
are shown for measured dates only.
N a tiv e S i te 1 2 1 E - C
ro 0 .1 5
5 /1 5
5 /2 9
6 /1 9
7 /2
7 /1 6
L a y e rl
□
7 /3 0
8 /1 4
9 /1 2
N M M R e a d in g D a te
L ay e r 2
▼
L ay e r 3
A
L ay e r 4
F Y ed c te d
L ay e r I --------- L ay e r 2 ------------L ay e r 3
L ay e r 4
N a tiv e S i te 1 8 3 E - C
to 0 .1 5
5 /1 5
5 /2 9
6 /1 9
7 /2
7 /1 6
L ay er 1
□
7 /3 0
8 /1 4
9 /1 2
N M M R e a d in g D a te
L ay e r 2
L ay er 3
A
L ay er 4
L ay e r 3 ---------
L ay er 4
F Y ed c te d
L ay er 1 --------- L ay e r 2
—
-
N a t i v e S i t e 4 9 3 D -A
E
0 .3
0 .0 .2 5
m---- ^---- .
i
5 /1 5
5 /2 9
M e a su re d
P re d ic te d
6 /1 9
7 /2
L ayer I
3 /3 0
7 /1 6
7 /3 0
8 /1 4
9 /1 2
N M M R e a d in g D a te
a
L ayer 2
L ayer 3
L a y e r 1 ---------L a y e r 2 ------------L a y e r s
A
Layer 4
Layer 4
4 /2 0
5 /1 1
83
Figure 12B. Measured and m odel predicted soil water content o f reclamation
sites during1996 to 1997 N M M measurement period. Predicted
data are shown for measured dates only.
R e c l a m a t i o n S i te 4 8 8 8 - A
5 /1 5
5 /2 9
6 /1 9
7 /2
7 /1 6
L ay e r I
7 /3 0
8 /1 4
9 /1 2
N M M R e a d in g D a te
□
L ay er 2
▼
L ay e r 3
A
L ay e r 4
L a y e r l ---------L ay er 2 ------------L ay e r 3 ----------
L ay er 4
P re d ic te d
R e c l a m a t i o n S i te 3 9 1 5 - C
0 .3 5
15 0 . 1 5
5 /1 5
5 /2 9
712
6 /1 9
Meastred
■
7 /1 6
L ay e r 1
□
7 /3 0
8 /1 4
9 /1 2
N M M R e a d in g D a te
A
L ay e r 4
L a y e r ! ---------L a y e r 2 ------------L a y e r3 ----------
L ay e r 2
▼
L ay e r 3
- L a y e r4
P r e d c te d
R e c la m a tio n S ite 4 9 0 1 -C
0 .3 5
E
0 .3
J i 0 .1 5
;r.S_~ ~ ■
5 /1 5
5 /2 9
M e a su re d
P re d ic te d
6 /1 9
7 /2
L ayer 1
7 /1 6
7 /3 0
8 /1 4
9 /1 2
N M M R e a d in g D a te
□
L ayer 2
▼
L ayer 3
L a y e r 1 ---------L a y e r 2 ------------L a y e r 3
3 /3 0
A
L ayer 4
L ayer 4
4 /2 0
5 /1 1
84
These differences between measured and predicted 0 are likely related to the simplifying
nature o f the model used (daily time-step, “tipping bucket” format) and its assumptions
related to processes o f soil water redistribution and root water uptake. Other significant
influences may include differences in actual versus measured or estimated model input values
such as root depth distribution, soil horizon thickness, and plant available soil water holding
capacity. Furthermore, site specific climatic conditions may actually be quite variable, but
were assumed for modeling exercises to be uniform throughout the entire area (as represented
by the weather station at Colstrip), with the exception o f rather modest differences in effective
overwinter precipitation between native and reclamation sites. The transpiration coefficients
were also different between native and reclamation sites, reflecting the different vegetative
characteristics. However, the model was determined to not be very sensitive to differences
in effective overwinter precipitation or transpiration coefficient,
. To relate measured and predicted 0 with precipitation events, daily precipitation records
corresponding to the 1996 and 1997 measurement periods are presented in Figure 13. The
sharp decline in predicted 0 for all sites between May 29 and June 19, 1996 (Figures 12A and
12B) corresponds with a period having little precipitation (Figure 13). A relatively large
precipitation event occurred on June 22, which is after the NMM measurements were taken
on June 19,1996. Precipitation occurred between April 20 and May 11, 1997, but in modest
amounts.
As depicted in Figures 12A and 12B, measured 0 o f conformed soil layers is more
variable early in the growing season, reaching the highest water content at the NM M
measurement on May 29,1996, then drying to more uniform water content throughout the
85
Figure 13.
Daily precipitation recorded at the Colstrip, MT weather station (no. 1905)
during 1996 and 1997 NMM measurement periods.
August
September
Month
profile by the end o f the growing season. This pattern is most prominent for native sites
121E-C and 183E-C and reclamation sites 3915-C and 4901-C. The measured 9 near the end
of the growing season for each site is believed to correspond with a field-apparent lower limit
o f soil water availability, or wilting point.
By the end o f the growing season, conformed measured 9 for native sites was well
below laboratory measured wilting point (9(h=.15 bar)) for all horizons o f sites 121E-C and
183E-C and all horizons except soil layer 4 of site 493D-A. Measured 9 for reclamation sites
were below laboratory measured wilting point for all horizons except soil layer 4. These
results are logical for the surface soil layer, as a result o f direct evaporative soil drying.
However, they are also likely an artifact o f independent or combined errors in field measured
86
soil water content (likely related to NM M calibration) or laboratory measured wilting point
water content. Laboratory measured field capacity ( Q ^ v3 bar)) and wilting point (6(ll=_15bar))
w ater contents for each modeled soil layer for each site are summarized and presented in
Table 12.
To simplify the substantial volume of model results from the 34-year simulations at each
o f six sites, three years were selected for graphical representation. The selected years were
1978, 1979, and the 34-year mean. 1978 represents an above-average year, and 1979 a
below-average precipitation year for the 34-year period o f record, as presented in Table 13.
Figure 14 graphically presents monthly precipitation for each o f these years, and plots
the distribution o f mean daily precipitation during the 34 year period. The general pattern o f
precipitation at Colstrip, MT is for most o f the yearly precipitation to occur during the
growing season, with greatest amounts during May and June, and late August through
October.
Examples o f the predicted seasonal soil water distributions for native and reclamation
sites during each o f the selected years are presented in Figures 15 A through 15D. Results for
native site 493D-A are presented in Figures 15A and I SB, and reclamation site 4901-C are
presented in Figures 15C and 15D. Results for all other modeled sites are presented in
Figures I SE through I SE, located in Appendix B. These figures present predicted soil water
distribution for model runs with either pine or grass root distributions for each selected year.
Comparison o f predicted 0 between years 1978, 1979, and 33-year mean indicates the
influence o f precipitation on soil water distribution throughout the growing season. Model
results indicate predicted 0 o f soil layer I is very responsive to precipitation events.
87
Table 12. Summary o f thickness, field capacity water content and wilting point water
content based on pressure plate measurements for each soil layer modeled.
Site Reference
Site Type
Soil Layer
Thickness (cm)
Field Capacity
(cm3/cm3)
121E-C (5)
183E-C (6)
493DrA (3)
4888-A (4)
3915-C (7)
4 9 0 1-C (8)
Native
Native
Native
Reclamation
Reclamation
Reclamation
Wilting Point
(cnrVcm3)
I
30.5
0.29
0.12
2
15
0.29
0.12
3
36
0.29
0.13
4
18
0.29
0.13
i
25.5
0.28
0.12
2
25.5
0.27
0.12
3
23
0.34
0.14
4
26
0.32
0.13
I
30.5
0.31
0.16
2
25
0.31
0.15
3
14
0.29
0.14
4
30
0.31
0.15
i
18
0.34
0.16
2
43
0.37
, 0.18
3
20
0.33
0.16
4
18
0.26
0.09
j
23
0.3
0.15
2
20
0.31
0.15
3
33
0.24
0.1
4
24
0.21
0.07
1
18
0.32
0.14
2
24
0.31
0.14
3
24
0.3
0.13
4
34
0.25
0.11
88
Table 13. 34-year precipitation summary for Colstrip, MT weather station (no. 1905).
Year o f
Record
Total
(Jam-Dec)
(cm)
Overwinter
(Oct-March)
(cm)
Growing Season
(April-Sept)
(cm)
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1976
1977
46.91
36.42
32.99
43.66
50.39
44.70
39.55
48.74
42.06
33.44
47.12
32.66
40.82
12.90
6.99
13.51
11.94
10.72
14.45
15.39
22.73
11.63
9.29
10.22
10.41
35.03
28.57
20.85
31.19
37.59
33.81
26.72
21.01
29.36
24.33
30.93
24.59
26.77
1978
1979
56.18
14.83
12.78
8.74
45.57
10.19
1980
32.21
6.10
1981
47.53
11.38
1982
39.85
16.61
1983
27.53
7.54
1984
28.09
7.57
1985
30.56
8.94
1986
35.89
8.03
8.86
1987
36.32
1988
4.34
20.52
37.36
10.54
1989
1990
28.27
7.95
38.79
7.16
1991
35.89
6.91
1992
1993
40.34
9.63
12.78
1994
38.15
1995
37.13
17.22
10.95
1996
36.42
18.24
12.90
1997
Statistics:
Mean (std. error mean)
37.55 (1.47)
10.98 (0.69)
33
32
n
56.18
22.73
Max
14.83
4.34
Min
Notes:
1) Model results from bold years were graphed for each site;
2) * Denotes April through May data only.
19.63
36.61
24.92
20.55
21.51
21.79
28.85
28.70
14.10
24.99
22.10
31.04
27.20
31.06
20.37
27.23
20.52
13.94*
26.49 (1.21)
32
45.57
10.19
89
Figure 14. Distribution o f monthly precipitation for selected years, and mean daily
precipitation o f 34-year record.
Distribution of Monthly Precipitation
Colstrip, Montana
Growing Season:
April - September
JAN
FEB
MAR APRIL MAY JUNE JULY AUG SEPT OCT
NOV
DEC
Month
■
mean —v — 1978
1979
Mean Daily Precipitation (1964-1997)
Colstrip, Montana
0.5 —
E
o
0 U.4
1
2 0.3
CL
i
O 0.2
-
-------
c
$
■■■ V . ’ f V . V . A x .
■
0.1
0
30
60
90
120
150
180 210
Day of Year
240
270
300
330
360
90
Figure 15A. Model predicted soil water contents during the growing season
of selected years, for native site 493D-A with pine roots.
A v e ra g e P re c ip ita tio n
0.2
0.1
0 .0 5
180
D ay O fY e ar
L ay e r I ---------- L ay er 2 --------- L ay e r 3
L ay e r 4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
1 0 .2 5
0.2
5 0.1
0 .0 5
180
D ay O fY e ar
L a y e r 1 ---------- L a y e r 2 ---------
Layer 3
L ayer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
§ 0 .2 5
0.2
I
0.1
0 .0 5
180
D ay o fY e a r
Layer I ------- Layer 2 ------ Layer 3
Layer 4
91
Figure I SB. Model predicted soil water contents during the growing season
of selected years, for native site 493D-A with grass roots.
A v e ra g e P re c ip ita tio n
0 .2 5
0.2
§ 0 .1 5
I
0.1
0 .0 5
180
D ay of Y ear
L a y e r 1 ----------
L ayer 2
---------
L ayer 3
Layer 4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
0.1
0 .0 5
180
D ay o fY e a r
L a y e r 1 ---------- L a y e r 2
---------
Layer 3
Layer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
0.2
0 .1 5
005
180
D ay of Y ear
Layer 1 ------- Layer 2 ------
Layer 3
Layer 4
92
Figure I SC. Model predicted soil water contents during the growing season
of selected years, for reclamation site 4901-C with pine roots.
A v e ra g e P re c ip ita tio n
0 .3
0.2
0 .1 5
0.1
0 .0 5
180
D ay of Y ear
L ay er I
L ay e r 2 ---------
L ay er 3
L ay er 4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
0 .3
§ 0 .2 5
0.2
§
0.1
180
D ay of Y ear
L ayer I
L a y e r 2 ---------
L ayer 3
L ayer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
0 .3
0.2
0 .1 5
§
0.1
0 05
180
D ay o fY e a r
Layer 1
Layer 2 -------
Layer 3
Layer 4
93
Figure 15D. Model predicted soil water contents during the growing season
of selected years, for reclamation site 4901-C with grass roots.
A v e r a g e P re c ip ita tio n
03
"
0 .0 5
180
D a y o fY e a r
----------
L ay er 1 — —
L ay er 2 -----------L ay er 3
Layer 4
1 9 7 9 - A b o v e A v e r a g e P re c ip ita tio n
I 0 .2 5
0 .0 5
180
D ay of Y ear
----------
L a y e r 1 ----------- L a y e r 2 ---------
L a y e rs
Layer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
0 .0 5
180
D ay o fY e a r
Layer I -------- Layer 2 ------
Layer 3
Layer 4
94
represented by the sharp increases and decreases in 0. Graphs for 1978, an above-average
precipitation year, show slightly greater overall fluctuations in predicted water content than
for 1979 or average conditions, including increased soil water content near the end o f the
growing season which corresponds to above average monthly precipitation during September
o f that year.
1979, a below-average precipitation year, followed 1978 in the 34-year
simulation sequence, and the influence o f the high precipitation during 1978 is evident in the
relatively high 0 predicted early in the growing season. Note that layer 4 was wetted to field
capacity during 1978, and remained so during 1979 because there were no roots in the layer
to extract water.
Comparison o f results for a given site with different root systems under otherwise
identical site conditions (Figures 15A through 15D; remainder o f set located in Appendix B),
indicates that predicted 0 is strongly influenced by root distribution. A greater proportional
root distribution for a given soil layer resulted in lower predicted 0 due to increased plant
water uptake. This decrease is simulated by the model to occur earlier in the growing season
and/or over shorter periods o f time, and primarily affects soil layers 2 and 3.
Results for pine and grass root systems for selected years with contrasting precipitation
indicated that root system-specific differences in predicted 0 occur most strongly during a
below average precipitation year. Seasonal and overall differences in predicted 0 between the
two root systems were most evident in 1979 for soil layers 2 ,3 and 4 o f native sites and layers
2 and 3 o f reclamation sites. Overall, the general degree o f difference in predicted 0 between
pine or grass roots was directly related to the degree o f difference in the proportional root
distribution in each soil layer o f a given site. N ote that the model does not consider
95
differences in actual root densities, but only proportional depth differences within a given site,
as the total roots in each profile is specified as 1.0.
Figures 16A and 16B illustrate the relative proportion o f pine or grass roots which
correspond to the different soil layer thicknesses used as model input for each site. For native
sites, soil layer I contains slightly greater relative root distribution for pine compared to grass.
Soil layer 2 o f native sites are shown to contain more than twice the proportion o f pine than
grass roots.
However, soil layers 3 and 4 o f native sites contain greater relative root
distribution for grass. For reclamation sites, soil layer I contains greater proportional
distribution o f grass roots, soil layers 2 and 3 contain more pine roots, and soil layer 4
contains no roots (grass or pine).
Although input values for pine and grass roots are different for soil layer I for both
native and reclamation sites, differences in predicted 6 were not observed in this soil layer.
This result occurred for all selected years (mean, 1978 or 1979) for each site, even during the
below average precipitation year (1979) where more dramatic differences in 0 in deeper soil
layers were predicted. The model does not appear to be sensitive to proportionately small
plant-specific differences in root distribution compared to the relatively high overall
proportion o f roots in these modeled horizons. Furthermore, this result may be related to the
way the model simulates plant water uptake. Available soil water is withdrawn first from
layer I at each time step, then from successively deeper layers, until transpirational demand
is met. H ence a large proportion o f roots in layer I results in most available water being
depleted. This also explains the exaggerated simulated fluctuations in 0 for layer I compared
to field measurements (Figures 12A and 12B). For the deeper soil layers, 2, 3 and 4, model
96
Figure 16 A. Relative root depth distribution o f pine and grass for native site
input values.
Pine Roots
a>
60
Estimated Proportion of Total Roots
C5 121E-C
B IS S E -C
□ 493D-A
Grass Roots
Estimated Proportion of Total Roots
0 1 2 1 E-C
CS183E-C
D 493D-A
97
Figure 16B. Relative root depth distribution o f pine and grass for reclamation
site input values.
Pine Roots
Estimated Proportion of Total Roots
□ 4888-A
S 3915-C
■ 4901-C
Grass Roots
Estimated Proportion of Total Roots
■ 4888-A
0 3915-C
Q 4901-C
98
predicted soil water conditions with either pine or grass roots were directly related to the
comparative proportion o f roots specified in each layer.
To categorize differences in predicted soil water status among sites and vegetation, the
mean number o f days per month with 0 within specified soil wetness classes were calculated
and are graphically presented in Figures 17A through 17F. The mean values were calculated
based on all 34 years as simulated by the model. Tables 14A through 14F in Appendix C
present this data for each site in numerical format, along with the corresponding standard
errors.
The most obvious differences in predicted seasonal soil water status between pine and
grass roots occur in soil layers 2 and 4. Differences in mean seasonal distribution o f soil
water for pine or grass roots within all other soil layers are minor (Figures 17A through 17F).
For native and reclamation sites, model results predict soil water in layer 2 to be held within
similar wetness classes whether pine or grass roots are present, but within the more plant
available wetness classes for slightly greater mean number o f days per month with grass roots
compared to pine. HoWever- more plant available water is predicted in soil layer 4 with pine
roots than grass roots with no pine roots being present, as expected. Similarly, no differences
are predicted between grass and pine roots for soil layer 4 if neither root system was input as
present (Figures I TE and 17F).
Comparison o f the predicted seasonal distribution o f soil w ater between native and
reclamation sites indicates soil layer I o f native sites displays soil water held at lower tensions
than reclamation sites, based on the mean number o f days within each wetness class. This
condition is especially predicted early in the growing season (April through June) and for
99
Figure 17 A. Model predicted cumulative mean monthly number o f days soil water content was equal to
or greater than a given matric potential during the growing season (34-year record):
native site 12 IE-C with pine or grass roots.
P in e R o o ts : S oil L a y e r I
P in e R o o ts : S o il L a y e r 2
IM QbM Qb
D 1*'5 E3"
P in e R o o ts : S oil L a y e r 3
I ^
J
April
M ay
June
Ju ly
P in e R o o ts : S oil L a y e r 4
A ugust
Sept
M onth
I
h—1/3
i:
April
I
h—1/3
17
M ay
June
Ju ly
A ugust
S e p t.
H D m E3h
h>-1
G r a s s R o o ts : S o il L a y e r 2
G r a s s R o o ts : S o il L a y e r 1
April
J u ly
M onth
Q m Qb
h>-1
June
A ugust
S e p t.
O o
I
A pril
M ay
June
M onth
J u ly
I
A ugust
S e p t.
M onth
Im CM CM 5
I
G r a s s R o o ts : S o il L a y e r 3
1/3
| bM CM C l"
h>-1
G r a s s R o o ts : S oil L a y e r 4
I
L
S7
April
M ay
June
J u ly
A ugust
S ept
o0
April
M ay
June
M onth
M CM CM*
J u ly
A ugust
M onth
3□
h>-1
1 0
h»-2
Q
h>-5
h x l5
S e p t.
100
Figure 17B. Model predicted cumulative mean monthly number o f days soil water content was equal to
or greater than a given matric potential during the growing season (34-year record):
native site 183E-C with pine or grass roots.
P in e R o o ts : S o il L a y e r 1
P in e R o o ts . S o il L a y e r 2
A ugust
M onth
0 j j b—1/3 |
| b»-1
0 0
h>-2
I
I h>-5
0 0
h—1/3 Q
P in e R o o ts : S o il L a y e r 3
h>-1
0 0
A ugust
h —1/3 Q
h>-1
h>-2
□
h»-2
A ugust
■
h>-5
EHm
Eg
G r a s s R o o ts : S o il L a y e r 2
h>-2
□
h>-5
[ J h . »
[ _ j "-•»
G r a s s R o o ts : S o il L a y e r 4
G r a s s R o o ts : S o il L a y e r 3
0 0
[T ^
M onth
I "-2
h—1/3 [ ~ ] h>-1
h>-5
S e p t.
G r a s s R o o ts : S o il L a y e r 1
J
Q
P in e R o o ts : S o il L a y e r 4
M onth
J j
Sept
M onth
Q
h x is
0 0
h=-i/3 Q
hxi
0 0
h>-2
Q
h>-5
Q
h x is
S e p t.
101
Figure 17C.
Model predicted cumulative mean monthly number o f days soil water content was equal to
or greater than a given matric potential during the growing season (34-year record):
native site 493-A with pine or grass roots.
P in e R o o ts : S o il L a y e r 1
I h — 1/3
h »-1
0 0
t P -2
12]
h >-5
P in e R o o ts : S o il L a y e r 2
I
[ 2 ] h >-15
h — 1/3
P in e R o o ts : S o il L a y e r 3
P in e R o o ts : S o il L a y e r 4
I '
April
M ay
June
Ju ly
A ugust
S e p t.
M o n th
I h — 1/3
i:
April
M ay
June
J u ly
A ugust
S e p t.
M onth
D m E 3n
h »-1
□ ^5 Q h*-15
h >-1
I
h — 1/3
G r a s s R o o ts : S o il L a y e r 1
h >-1
I h--2 Q to-5 EHIh
G r a s s R o o ts : S o il L a y e r 2
I
I 7
April
M ay
Jm e
J u ly
I
A ugust
S e p t.
M onth
I h = - 1/3
h >-1
IM Qh-S Qhx15
G r a s s R o o ts : S oil L a y e r 4
G r a s s R o o ts : S o il L a y e r 3
I
I
I 7
$7
April
M ay
Jm e
Ju ly
A ugust
Sept
April
M ay
June
M onth
I h — 1 /3 Q
h^ 1
H
1^2
2 ]
J u ly
A ugust
M onth
h^ 5
Q
h^ 15
I
h = - 1/3
h »-1
Qhx5 Qhx15
S e p t.
102
Figure 17D. Model predicted cumulative mean monthly number o f days soil water content was equal to
or greater than a given matric potential during the growing season (34-year record):
reclamation site 4888-A with pine or grass roots.
P in e R o o ts : S o il L a y e r 2
P in e R o o ts : S o il L a y e r I
A ugust
Sept
M onth
A ugust
M onth
g IfV3Q If-. g|h»-2 Qif-s Q
P in e R o o ts : S o il L a y e r 3
P in e R o o ts : S o il L a y e r 4
A ugust
A ugust
M o n th
g
IfV
3Q
If-'
g
f-2
I II f - S Q
g --2 [_in>* [_j
G r a s s R o o ts : S oil L a y e r I
G r a s s R o o ts : S o li L a y e r 2
A ugust
M onth
S e p t.
M onth
g IfVJ Q If.' J|h».2 Qif-s Q
G r a s s R o o ts : S o il L a y e r 3
J h=-1Z3Q h>-1 J l h>-2 [2] h>-5
G r a s s R o o ts : S o il L a y e r 4
A ugust
A ugust
M o n th
M onth
J| h=-1Z3|2] h>-1 J| h>-2 Q
Q
^h=-Ia Qif-I J | If-2 Qif-S Q
S e p t.
103
Figure 17E. Model predicted cumulative mean monthly number o f days soil water content was equal to
or greater than a given matric potential during the growing season (34-year record):
__ reclamation site 3915-C with pine or grass roots.
P in e R o o ts : S o il L a y e r I
P in e R o o ts : S oil L a y e r 2
A ugust
H n-I D
0
h*-1
Hm D
n*-5
S e p t.
D
H n-iaD h=-I H n=-: D m D
P in e R o o ts . S o il L a y e r 3
P in e R o o ts : S oil L a y e r 4
A ugust
H n=-ioD
it- 1
H
k- 2
S e p t.
Dm D
G r a s s R o o ts : S o il L a y e r 1
G r a s s R o o ts : S oil L a y e r 2
M onth
H
n=-V3 Q
h>-l
n> j
Q
M
H
[x ]
G r a s s R o o ts : S o il L a y e r 3
h = - i/3
122|
u
h>-2
[22]
h>-s
G r a s s R o o ts : S oil L a y e r 4
A ugust
S e p t.
A ugust
M onth
h=-i/3[2]h>"1
[22]
H h>'2 D h>"5 [Vi
g h = -1 /3 Q h > -1
g
h>-2
I
|h > - 5
S e p t.
104
Figure 17F. Model predicted cumulative mean monthly number o f days soil water content was equal to
or greater than a given matric potential during the growing season (34-year record):
reclamation site 4 9 0 1-C with pine or grass roots.
P in e R o o ts : S oil L a y e r I
Lu
April
M ay
$
JL
June
[3] h>*1 H
Ju ly
P in e R o o ts . S o il L a y e r 2
A ugust
S e p t.
M onth
h>-2
1/3
Q r^"5 E3h
h>-1
I h=-
P in e R o o ts : S o il L a y e r 3
1
7
M ay
P in e R o o ts : S o il L a y e r 4
17
Jfl I Jl
April
I"-2 C M D h
June
Ju ly
A ugust
S e p t.
April
M ay
June
M onth
I
h=-1/3
h>-1
I
J u ly
h>-2 [ Ih>-5 [-Xj h>-15
1/3
h>-1
I h=-
G r a s s R o o ts : S o il L a y e r 1
I
"
2
A ugust
h=-1/3 Q
h>-1
h>-2
S e p t.
G r a s s R o o ts : S o il L a y e r 2
A ugust
M onth
0
A ugust
M o n th
□
M o n th
hs^ 5
d
E U h^ 15
h=-1/3 Q
G r a s s R o o ts : S o il L a y e r 3
h>-1
J |h > - 2
[]h > -5
[~~~] h>-15
G r a s s R o o ts : S o il L a y e r 4
a.
>
A ugust
S e p t.
2
April
M ay
Jm e
J u ly
A ugust
M onth
J | h=-1Z3[2 ]
h>*1 H h>'2 □ ^>-5
I h=-1Z3
h>-1
I
2
□ n>-« Q h
S e p t.
105
native sites 121E-C and 183E-C, which both had coarser textured soil than native site 493DA.
In summary, results indicated differences between predicted and measured 0, based on
correlation coefficients and graphical comparisons. Predicted 0 appeared to be more sensitive
to changes in precipitation than was observed from field measurements. This sensitivity to
precipitation inputs was most evident for soil layer I, but also seen in layers 2 and 3. Some
differences are expected due to frequency o f measured 0 versus predicted 0 (daily time step).
Others probably derive from the simplified nature o f the model.
The ERHYM-II model did not allow simultaneous modeling o f two different root
systems, therefore soil water status was predicted by the model from separate simulations
with either pine seedling roots or grass roots. Comparison o f predicted 0 for a given site with
pine or grass roots indicated little difference, based on correlation coefficients (Table 11) and
graphical summaries (Figures 12A and 12B).
Predicted 0 was strongly influenced by
differences in proportional root depth distributions, with greater root distribution for a given
soil layer resulting in lower predicted 0 because o f increased plant water uptake. Differences
in predicted 0 related to root depth distribution were most evident in the non-surface soil
layers and during years with below average precipitation. Predicted 0 o f the surface soil layer
was most responsive to precipitation events, regardless o f the proportional root distribution
input values. This is not surprising for the tipping bucket model.
106
Recommendations for Soil Profile Design
Competition between ppnderosa pine seedlings and herbaceous vegetation (primarily
grasses) for limited soil water resources has been implicated as a primary cause in reducing
the establishment and growth o f ponderosa pine in many regions. Establishment o f woody
species is generally difficult in arid areas similar to Colstrip, Montana. Therefore, competition
for soil water is likely one o f the main causes o f ponderosa pine seedling mortality on
reclamation sites at the Rosebud Mine.
Ponderosa pine seedling mortality related to
competition with grasses is not limited to reclamation areas, in which soils are removed,
transported and reconstructed, but has been observed in reforestation studies throughout the
western United States.
Recommendations for site selection, soil profile creation or modification and
management strategies to improve the establishment o f ponderosa pine are made based on
results o f the 1996 and 1997 field studies at the Rosebud Mine, and review o f relevant
literature.
One such strategy is simply to select reclamation sites for ponderosa pine
establishment which have soil physical characteristics that promote storage o f soil water
deeper in the soil profile.
This may involve coarse textured topsoil and subsoil lifts,
particularly at the surface, which promote deeper penetration o f precipitation and thus
encourage root growth and extension to soil depths below those occupied by the highest
densities o f fibrous roots.
A more intensive approach is to reconstruct specific soil profiles for ponderosa pine
reclamation sites and/or make specific modifications during or immediately following soil
reconstruction. Suggested reconstruction techniques are to: I) specifically reconstruct soil
107
profiles with sandy, coarser textured, lower water holding capacity topsoil and subsoil to
increase penetration o f precipitation into deeper, finer textured spoil and reduce grass
establishment; 2) minimize soil compaction and resulting high bulk density by all reasonable
techniques possible, recognizing the types o f heavy equipment that are necessary to transport
and redistribute such large quantities o f earthen material at an active mine. Working moist
soil is particularly conducive to compaction; 3) use a ripper to create a series o f vertical
channels set horizontally along the contour o f sites to capture, retain and increase surface
w ater infiltration directly to subsoil, regardless o f the surface soil physical properties, then
transplant pine seedlings adjacent to these troughs; 4) use a power auger or similar instrument
to remove a core o f soil roughly 30 cm in diameter and 100 cm deep, backfill the hole with
finer textured, loam soil and transplant one pine seedling into each resulting “tree hole” . The
intent o f such a “tree hole” is to give the seedling a competitive advantage over grasses
growing in the adjacent soil when the seedling is most susceptible to competition. FertiUzer
and/or water may be added only to the tree microsites if desired or deemed necessary.
EquaUy and perhaps more important than site selection or reconstruction and
preparation, is to also implement effective management strategies to control competition for
soil water. This is especially important during early phases o f pine establishment. However,
it is also important after trees are apparently established, particularly during years having
lower than average precipitation, as was iUustrated by simulated w ater contents for model
year 1979 (Figures 15A through 15L). Although the extensively branching roots o f the pine
trees may be well below the surface soil by this time, during low precipitation years the weU
established and frequently dense grass community on reclamation sites may utilize all added
108
water before it percolates to substantial depths. Over a period o f several low precipitation
years, this competition would likely be detrimental to survival o f the ponderosa pine trees.
Recommended management strategies to control and reduce grass immediately
surrounding ponderosa pine seedlings or trees, some o f which are currently employed by the
Rosebud Mine, include the following: I) seeding grass after transplanting pine seedlings when
and where possible, while avoiding excessive soil erosion; 2) controlling grass establishment
surrounding pine seedlings or trees by periodic application o f herbicide; 3) periodic manual
cutting o f grass immediately surrounding ponderosa pine seedlings or trees with a lawmriower
or ‘weed-eater’; and 4) general grazing by cattle to reduce grasses.
These recommendations for soil profile design and management practices to improve the
establishment o f ponderosa pine are intended as guidelines. They have been made without
discussions with or input from Western Energy or staff from the Rosebud Mine or regulatory
agencies. Feasibility o f proposed solutions will depend also on economics and the relative
importance o f ponderosa pine establishment to overall mine operations. Planting ponderosa
pine into soil conditions better suited to the production o f cool season grasses may not be the
best use o f available resources. Adjustment o f final bond release criteria may be reasonable,
in some instances, to allow species that support an approved post-mine land use to take
precedent.
109
CHAPTER 6
SUMMARY AND CONCLUSIONS
Differences in soil physical and hydrologic properties were measured between native and
reclamation sites at the Rosebud Mine near Colstrip, Montana. Native soils were generally
finer textured, with greater percent silt, whereas reclamation sites generally had coarser
texture due to greater percent sand. Mean soil bulk density o f native sites was lower than
reclamation sites, which is consistent with the effects o f reconstruction practices and the
sandier soils observed in the reclamation sites. M ean bulk density for all native site horizons
was less than 1.4 g cm'3, whereas mean bulk density for all reclamation site horizons was
greater than 1.4 g cm'3. Increased soil bulk density is expected to constrain root growth and
reduce shoot growth in pines.
Calculations based on laboratory pressure plate measurements indicated native sites had
2.4 cm greater mean profile plant available water holding capacity than reclamation sites.
Mean plant available water holding capacity was fairly uniform throughout the soil profile for
native sites. Reclamation sites showed a significant decrease in mean plant available water
holding capacity within the 70 to 90 cm depth, which does not correspond to a noticeable
change in bulk density for this measurement horizon. This observation is likely related to
spoil material, which is generally encountered at approximately 75 cm depth.
Reclamation sites were measured to have greater mean 0 than native sites during much
o f the most active growing season. During the 1996 growing season up to 5 percent greater
no
mean 0 waS measured for reclamation sites at the end o f May. Reclamation sites began the
1996 and 1997 NM M measurement periods with greater mean measured profile 0 than native
sites; 4.0 cm more water at the beginning o f the 1996 measurement period and 2.1 cm more
water at the beginning o f the 1997 measurement period. These differences in mean measured
starting 0 and mean measured 0 throughout much o f the growing season are thought to be
at least partly related to differences in effective overwinter precipitation between native and
reclamation sites. Reclamation sites were measured to have 21 percent greater mean effective
precipitation than native sites. This may be related to the established tree canopy present in
and around sampling areas o f native sites, perhaps with greater interception o f precipitation,
including potentially less snow retention, and potential transpiration by conifers during
October through March.
Reclamation sites also began each measurement period with more than twice the mean
percent plant available water o f native sites. Greater soil water depletion occurred during the
1996 measurement period than for 1997, which was expected because the 1996 measurements
covered a longer time interval and were later in the growing season when precipitation was
lower and evaporational demands were higher.
M ore than twice the mean soil water
depletion occurred on reclamation sites than for native sites during 1996, which is probably
directly related to their having started this period with more than twice the mean percent plant
available water. Early season (1997) mean depletion for native and reclamation sites was
similar, having negative, mean soil water depletion (soil water recharge) as a result o f high
rainfall combined with lower early season plant growth.
The substantially greater grass productivity observed on reclamation sites is likely
Il l
directly related to the greater amount o f soil water measured for reclamation sites. Although
more w ater was measured for reclamation sites at the beginning o f and throughout most o f
each growing season, not all that soil water was calculated to be plant available. Site specific
information regarding the spatial distributions o f grass and ponderosa pine seedling roots
would have allowed more informed speculations related to competition for soil water.
The EKHYM-II computer simulation model used to extend the measured seasonal soil
water data with 34 years o f climate records from Colstrip, Montana was considered to be
inadequate to address potential competition between ponderosa pine seedlings and grasses
for limited soil water. However, some useful results regarding predicted seasonal soil water
status were obtained from the model.
The most significant observation from the computer simulation modeling exercise was
the predicted effects o f precipitation on soil water content, most evident during periods of low
precipitation. This was shown in graphs o f model-predicted seasonal soil water content
during 1979, a below-average precipitation year (Figures ISA through 15L). Predicted soil
water content in most soil layers decreased to low levels (at or near wilting point) earlier in
the growing season and remained at these low levels throughout the growing season,
especially in horizons with greater proportion o f roots, regardless o f root (species) type.
An apparent implication is that during periods o f low precipitation, and therefore limited
soil water, competition for this soil water may be more severe.
In conclusion, the goals o f reclamation practices to encourage establishment and survival
o f ponderosa pine on selected sites at the Rosebud Mine should be to reduce establishment
and productivity o f grasses and thereby reduce competition for limited soil water.
112
Recommended strategies are based on measured field conditions and knowledge o f soil and
plant water relationships. These strategies may be employed independently or in combination,
depending on site specific goals and conditions. In general, a soil profile which promotes
deeper storage o f soil water is favorable for ponderosa pine establishment and survival and
unfavorable for grasses, thereby reducing potential competition.
Strategies recommended to provide these conditions include selection or creation o f sites
having coarse textured soil materials, with low Water holding capacity, overlying medium
textured, moderate water holding capacity material. This would increase infiltration o f water
deeper into the soil, hence presumably favoring pines at the expense o f grasses. Minimizing
or reducing high soil bulk density and soil compaction at all soil depths is also important for
increased infiltration and creating conditions for more optimal root growth. Site specific
modifications during or immediately following soil reconstruction could also be used to create
conditions favorable to ponderosa pines.
Some strategies regarding soil profile characteristics have been suggested. However,
in my assessment the most important strategy related to the successful establishment o f
ponderosa pine trees is careful, and likely intensive, management to control grass
establishment immediately surrounding pines. Several management strategies were suggested
to reduce the impacts o f grasses on pine seedlings. Although some o f these strategies are
being or have been employed by Western Energy Company at the Rosebud Mine, continued
control o f grasses to reduce competition is important to the survival o f ponderosa pine in
reclamation areas, even after pine trees are apparently established. Periodic control o f grasses
is expected to be especially important during years having lower than average precipitation.
113
Employment o f these general recommendations should produce more favorable
conditions for and therefore increase the survival o f ponderosa pines at the Rosebud Mine,
hopefully to levels required for final bond release. However, planting ponderosa pine into soil
conditions better suited to the production o f cool season grasses may not be the best use o f
available resources. Adjustment o f final bond release criteria may be reasonable, in some
instances, to allow species that support an approved post-mine land use to take precedent.
The following are suggestions for future studies which may help to clarify some o f the
speculations and uncertainties arising from this study. One suggestion is to specifically select
reclamation sites where establishment o f ponderosa pine seedlings is apparently successful
(where seedlings are thriving) and sites with high pine seedling mortality. The soil physical
and hydrologic properties o f these sites could be compared in detail, as could grass and pine
root systems. Comparisons between selected “successful” and “unsuccessful” reclamation
sites should only be made for sites where pines were planted during the same season o f the
same year. This should minimize potential differences in pine establishment due to seasonal
and annual variations in precipitation.
Another suggested study is to create a soil profile or profiles as suggested in this study,
having varying thickness o f coarse textured,, low water holding capacity soil materials
overlying medium textured, moderate water holding capacity material. Then, pine seedlings
could be planted in these “designed” soil profiles and the seasonal soil water status and
response o f seedlings over time monitored.
114
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Woods, TH., G.M. Blake, and F.W. Allendorf. 1983. Amount and distribution o f isozyme
variation in ponderosa pine from eastern Montana. Silvae Genetica 32:5-6.
Woods, TH., G.M. Blake, and F.W. Allendorf. 1984. Using isozyme analysis to aid in
selecting ponderosa pine for coal-mine soil reclamation. NW Sci. 58:262-268.
Wraith, J. M. and D. Or. 1998. Nonhnear parameter estimation using spreadsheet software.
I. Nat. Resour. Life Sci. Educ. 27:13-19.
120
ZwieniecM, M.A., and M- Newton. 1994. Root distribution o f 12-year-old forests at rocky
sites in southwestern Oregon: effects o f rock physical properties. Can. J. For. Res. 24:1791-
1796.
APPENDICES
122
APPENDIX A
SITE DESCRIPTION FORMS
123
SITE D ESC R IPTIO N FO R M
D ate Sam pled: 9/13/96
Site Identification N um ber: 121E-C(s)
Location Inform ation
C ounty Name: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
Location D escription: 250' south, 350' east o f N W comer Section I, TIN , R40E
Q uadrangle Name:
D escription Category: Full pedon description
Slope C haracteristics Inform ation
Slope: 14 percent
A spect: 25 degrees
Shape (horizon./vertical): planar/concave
Position: footslope
Elevation: 3490 feet
Physiography
Local: hill
M ajo r: hills
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
A nnual P recipitation: 13 inches
Flooding Frequency: None
P onding Frequency: None
Perm eability: moderate
N atu ral D rainage Class: well
Classification: fine-loamy, mixed, fiigid Aridic Ustochrept
M oisture Regime: Ustic moisture regime
H ydrologic G rpup: B
/
L anduse: grazeable woodland
P a re n t M aterial
Type: mixed sedimentary
D eposition: residuum and colluvium
V egetation Inform ation
P lan t Symbol: AGSP=3, STVI=3, BRIN=3, RHTR=2, JUSC=2, BRTE=2,
LILE=I, SYAL=I
P lan t Name: bluebunch wheatgrass, green needlegrass, smooth brome,
skunkbrush sumac. Rocky Mtn. juniper, cheatgrass, blue flax, snowberry
(A bundance D ata: l=slight, 2=common, 3= abundant, 4=dbm inant)
Page I o f 2
124
Described by: Tom Keck and Karin Jennings
Site Identification N nm ber: 121E-C(s)
0 —1 to O inches (2.5 to O cm).
A -O to 5 inches (0 to 13 cm); brown (I OYR 4/3) loam, dark brown (I OYR 3/3) moist;
moderate fine and medium granular structure; slightly hard, very friable, slightly sticky and
plastic; many very fine and common fine and medium roots throughout; common very fine,
fine and medium pores; 24 percent clay; noneffervescent; I percent hard angular gravel;
neutral (pH 7.2); clear smooth boundary.
B w -Stdi 15 inches (13 to 38 cm); dark yellowish brown ( I OYR 4/4) loam, brown ( I OYR 4/3)
moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly
sticky and plastic; many very fine, common fine and medium and few coarse roots throughout;
common very fine, fine and medium pores; 24 percent clay; strongly effervescent; 2 percent
hard angular gravel; moderately alkaline (pH 8.0); clear smooth boundary.
Bk1- I S to 29 inches (38 to 74 cm); dark yellowish brown ( I OYR 4/4) loam, brown ( I OYR
4/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly
sticky and slightly plastic; common very fine, fine and medium and few coarse roots
throughout; common very fine, fine and medium pores; 22 percent clay; violently effervescent;
2 percent hard angular rock; moderately alkaline (pH 8.2); gradual smooth boundary.
Bk2- 29 to 40 inches (74 to 101 cm); light brown (7.5YR 6/4) gravely loam, dark brown
(7.5 Y R 3/4) moist; massive structure; slightly hard, friable, slightly sticky and slightly plastic;
few very fine, fine and medium roots throughout; few very fine and fine pores; 20 percent
clay; violently effervescent; 5 percent hard ss/ca, 10 percent rock chips; moderately alkaline
(pH 8.2); gradual smooth boundary.
B C k -40 to 60 inches (101 to 152 cm); brown (7.5YR 5/4) gravely very fine sandy loam,
brown (7.5Y R 4/4) moist; massive structure; slightly hard, friable, slightly sticky and slightly
plastic; few very fine, fine and medium roots in upper portion; 18 percent clay; violently
effervescent; 10 percent hard ss/ca, 20 percent semi-hard rock chips; moderately alkaline (pH
8.4).
Notes:
Page 2 o f 2
125
SITE D E SC R IPTIO N FO R M
D ate Sam pled: 9/13/96
Site Identification N um ber: 121E-C(n)
Location Inform ation
C ounty Name: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
L ocation D escription: 1000' south, 1250' west o f N E comer Section I, TIN , R40E
Q uadrangle Name:
D escription Category: Partial pedon description
Slope C haracteristics Inform ation
Slope: 10 percent
A spect: 55 degrees
Shape (horizon./vertieal): planar/concave
Position: footslope
Elevation: 3520 feet
Physiography
Local: hill
M ajo r: hills
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
■ A nnual Precipitation: 13 inches ■
Flooding Frequency: None
Ponding Frequency: None
Perm eability: moderate
N a tu ra l D rainage Class: well
Classification: fine-loamy, mixed, frigid Aridic Ustochrept
M oisture Regime: Ustic moisture regime
H ydrologic G roup: B
L anduse: grazeable woodland
P a re n t M aterial
Type: mixed sedimentary/scoria
D eposition: residuum and colluvium
V egetation Inform ation
P la n t Symbol: AGSP=3, ANSC=3, STVI=2,‘ BRTE=2, PIPO=2, ANMA=2,
BOCU=2, ERLI= I, RHTR=I
P lan t Name: bluebunch wheatgrass, little bluestem, green needlegrass, cheatgrass,
ponderosa pine, pearly everlasting, sideoat grama, fleabane daisy, sklmkbmsh sumac
(A bundance D ata: l=slight, 2=common, 3=abundant,'4= dom inant)
Page I o f 2
126
D escribed by: Tom Keck and Karin Jennings
Site Idemtiiicatioii N um ber: 121E-C(n)
0 —0.5 to O inches (1.3 to 0 cm); partially decomposed twigs and needles.
A -O to 2 inches (0 to 5 cm); dark brown (7.5 YR 3/4) moist loam; moderate very thin platy
structure; 24 percent clay; noneffervescent; I percent hard angular gravel.
B w - 2 to 12 inches (5 to 30 cm); dark brown (7.5YR 3/4) moist loam; 24 percent clay;
noneffervescent; I percent hard angular gravel.
B k - 12 to 23 inches (30 to 58 cm); reddish brown (5YR 4/4) moist gravely loam; 22 percent
clay; violently effervescent; 15 percent hard angular gravel.
B C k -23 to 36 inches (58 to 91 cm); reddish yellow (5YR 6/6) moist gravely loam; 20
percent clay; violently effervescent; 30 percent hard angular gravel.
R—36 inches (91 cm); fractured scoria beds.
Notes:
Page 2 o f 2
127
SITE D ESC R IPTIO N FO R M
D ate Sam pled: 9/13/96
Site Idemtillcation N um ber: 183E-C(s)
Location Inform ation
C ounty Name: Rosebud
M LR A : 58A
. Soil Survey A rea Name: Western Energy Rosebud Mine
L ocation D escription: 1210' south, 1540' west o f N E comer Section I, TIN , R40E
Q uadrangle Name:
D escription C ategory: Full pedon description
Slope C haracteristics Inform ation
Slope: 12 percent
Aspect: 295 degrees
Shape (horizon./vertical): planar/concave
Position: footslope
Elevation: 3505 feet
Physiography
Local: hill
M ajo r: hills
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
A nnual P recipitation: 13 inches
Flooding Frequency: None
Ponding Frequency: None
Perm eability: moderate
N atu ral D rainage Class: well
Classification: fine-loamy, mixed, frigid Aridic Ustochrept
M oisture Regime: Ustic moisture regime
H ydrologic G roup: B
Landuse: grazeable woodland
P a re n t M aterial
Type: mixed sedimentary, mostly
Deposition: residuum and colluvium
sandstone/scoria
V egetation Inform ation
P la n t Symbol: PIPO=3, AGSP=3, C A L 0 2 , BRTE=2, ARFR=2, ANSC=2,
RH TR=I, BOCU=I, AGDA=I, AGSM =I, ARCA=I, KOCR=I
P lan t N am e: ponderosa pine, bluebunch wheatgrass, prairie sandreed, cheatgrass,
fringed sagewort, little bluestem, skunkbrush sumac, sideoat grama, thickspike
wheatgrass, western wheatgrass, silver sage, prairie Junegrass
(A bundance D ata: l=s!ight, 2=common, 3= abundant, 4=dom inant)
Page I o f 2
128
Described by: Tom Keck and Karin Jennings
Site Identification! N um ber: 183E-C(s)
A-O to 5 inches (0 to 13 cm); reddish brown (5 YR 5/4) loam, dark reddish brown (5YR 3/4)
moist; moderate fine and medium granular structure; slightly hard, very friable, slightly sticky
and slightly plastic; many very fine, common fine and few medium and coarse roots
throughout; few very fine pores; 24 percent clay; noneffervescent; 2 percent gravel rock
chips; neutral (pH 7.2); clear smooth boundary.
B w - 5 to 12 inches (13 to 31 cm); reddish brown (5YR 5/4) silt loam, dark reddish brown
(5YR 3/4) moist; moderate fine and medium subangular blocky structure; slightly hard,
friable, slightly sticky and slightly plastic; common very fine, fine and medium and few coarse
roots throughout; few very fine, fine and medium pores; 24 percent clay; strongly
effervescent; I percent gravel; mildly alkaline (pH 7,8); clear smooth boundary.
B k1- 12 to 18 inches (3 1 to 46 cm); light reddish brown (5YR 6/4) silt loam, reddish brown
(5YR 4/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable,
slightly sticky and slightly plastic; common very fine to coarse roots throughout; few very
fine, fine and medium pores; 26 percent clay; violently effervescent; I percent gravel;
moderately alkaline (pH 8.0); clear smooth boundary.
Bk2- 1 8 to 32 inches (46 to 8 1 cm); pink (5 YR 7/4) silt loam, reddish brown (5YR 4/4) moist;
massive structure; hard, friable, slightly sticky and plastic; common very fine and few fine to
coarse roots throughout; few very fine pores; 26 percent clay; violently effervescent; 2
percent gravel; moderately alkaline (pH 8.4); abrupt smooth boundary.
B C - 32 to 60 inches (81 to 152 cm); reddish yellow (5YR 6/6) gravely silt loam, yellowish
red (5YR 4/6) moist; massive structure; slightly hard, friable, slightly sticky and slightly
plastic; few very fine roots throughout^ 24 percent clay; violently effervescent; 20 percent
hard angular scoria fragments; moderately alkaline (pH 8.4).
Notes:
Page 2 o f 2
129
SITE D ESC R IPT IO N F O R M
D afe Sam pled; 9/13/96
Site Identification N um ber: 183E-C(n)
Location Inform ation
C ounty N ame: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
L ocation D escription: 1210' south, 1540' west o f N E comer Section I, TIN , R40E
Q uadrangle N ame:
D escription C ategory: Partial pedon description
Slope C haracteristics Inform ation
Slope: 9 percent
A spect: 25 degrees
Shape (horizon,/vertical): concave/planar
Position: footslope
Elevation: 3520 feet
Physiography
Local: hill
M ajo r: hills
C lim ate Inform ation
W eather-Station (Name, N um ber): Colstrip, #1905
A nnual Precipitation: 13 inches
Flooding Frequency: None
Ponding Frequency: None
Perm eability: moderate
N atu ral D rainage Class: well
Classification: fine-loamy, mixed, Aridic Ustochrept
M oisture Regime: Ustic moisture regime
H ydrologic G roup: B
Landuse: grazeable woodland
P a re n t M aterial
Type: mixed sedimentary
D eposition: residuum and colluvium
V egetation Inform ation
P la n t Symbol: AGSP=3, BRTE=3, K O CR -2, JUSC=2, ACM U2, GUSA=2,
RACO=2, STVI=I, ARFR=I, ARsp=I, BOCU=I, ARCA=I
P la n t Name: bluebunch wheatgrass, cheatgrass, prairie Junegrass, Rocky Mtn.
juniper, yarrow, snakeweed, prairie coneflower, green needlegrass, fringed sagewort,
green sagewort, sideoat grama, silver sage
(A bundance D ata: I=Slight, 2=common, 3= abundant, 4=dom inant)
Page I o f 2
130
Described by: Tom Keck and Karin Jennings
Site IdemtiEcatiom N um ber: 183E-C(n)
A -O to 3 inches (0 to 8 cm); dark reddish brown (5YR 3/4) moist silt loam; moderate thin
platy structure; 26 percent clay; noneffervescent.
B t - 3 to 19 inches (8 to 48 cm); reddish brown (5 YR 4/4) moist clay loam; 30 percent clay;
few thin clay films; noneffervescent.
Bk1-I O to 40 inches (48 to 102 cm); reddish brown (5 YR 4/4) moist silt loam; 26 percent
clay; violently effervescent; 2 percent soft sedimentary rock chips.
Bk2- 40 to 55 inches (102 to 140 cm); yellowish red (5YR 4/6) moist clay loam; 28 percent
clay; violently effervescent; 3 percent soft sedimentary rock chips.
C r - 55 inches (140 cm); thinly bedded siltstone and shale; violently effervescent.
Notes:
Page 2 o f 2
131
SITE D ESC R IPTIO N F O R M
D ate Sam pled: 9/14/96
Site Idemtlfication N um ber; 493D-A(e)
Location Inform ation
C ounty Name: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
L ocation D escription: 1570' south, 1781' west o fN E comer Section 32, T2N, R41E
Q uadrangle Name:
D escription C ategoryi Full pedon descriptipn
Slope C haracteristics Inform ation
Slope: 15 percent
A spect: 5 degrees
Shape (horizon./vertical): planar/concave
Position: footslope
Elevation: 3430 feet
Physiography
Local: hill
M ajo r: hills
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
A nnual P recipitation: 13 inches
Flooding Frequency: None
P onding Frequency: None
Perm eability: slow
N atu ral D rainage Class: well
Classification: fine, montmorillonitic, frigid Aridic Ustochrept
M oisture Regime: Ustic moisture regime
H ydrologic G roup: D
L anduse: rangeland
P a re n t M aterial
Type: mixed sedimentary
Deposition: residuum and colluvium
V egetation Inform ation
P la n t Symbol: JUSC=2, ARTR=O, STVI=3, SEDGE=O, BOCU=O, ARPU=3,
PIPO=2, RHTR=2, RACO=2, YUGL=I, ARCA=I, M usp=I
P la n t Name: Rocky Mtn. juniper, big sagebrush, green needlegrass, sedge, sideoat
grama, three awn, ponderosa pine, skunkbrush sumac, prairie coneflower, yucca,
silver sage, muhlenbergia
(A bundance D ata: I=Slight9 2=common, 3=abnndamt9 4=domimamt)
Page I o f 2
132
Described by: Tom Keck and Karin Jennings
Site Idemtiflcatiom Nmmben 493D-A(e)
A1-O to 2 inches (0 to 5 cm); light olive brown (2.5Y 5/4) silty clay loam, dark brown (I OYR
3/3) moist; moderate fine and medium granular structure; hard, friable, sticky and plastic;
many very fine, common fine and few medium roots throughout; 32 percent clay,
noneffervescent; trace rock fragments; mildly alkaline (pH 7.6), clear smooth boundary.
A2- 2 to 6 inches (5 to 15 cm); brown ( I OYR 5/3) clay, dark brown (10YR 3/3) moist;
moderate medium granular structure; hard, friable, very sticky and very plastic; many very fine
and common fine and medium roots throughout; 42 percent clay; noneffervescent; I percent
hard angular rock fragments; mildly alkaline (pH 7.8); clear smooth boundary.
B w - 6 to 12 inches (15 to 30 cm);light olive brown (2.5 Y 5/4) clay loam, olive brown (2.5 Y
4/4) moist; moderate medium s'ubangular blocky structure; very hard, very friable, very sticky
and very plastic; common very fine and fine and few medium roots throughout; common very
fine and fine and few medium pores; strongly effervescent; lime segregated in few fine
filaments or threads; moderately alkaline (pH 8.2); clear smooth boundary.
Bk1- 12 to 22 inches (30 to 56 cm); light yellowish brown (2.5Y 6/4) silty clay loam, light
olive brown (2.5 Y 5/4) moist; weak medium subangular blocky structure; very hard, very
friable, very sticky and very plastic; common very fine and few fine roots throughout;
common very fine and fine and few medium pores; violently effervescent; lime segregated in
few medium filaments or threads; moderately alkaline (pH 8.2); trace rock fragments; clear
smooth boundary.
Bk2- 22 to 35 inches (56 to 89 cm); light olive brown (2.5Y 6/4) silty clay loam, light olive
brown (2.5 Y 5/4) moist; massive structure; hard, friable, very sticky and very plastic; common
very fine roots throughout; common very fine and few fine pores; violently effervescent; lime
segregated in few fine filaments or threads; moderately alkaline (pH 8.2); trace rock
fragments; gradual smooth boundary.
B C k -35 to 46 inches (89 to 117 cm); olive yellow (2.5 Y 6/6) silty clay loam, light olive
brown (2.5Y 5/4) moist; massive structure; hard, friable, very sticky and very plastic; few very
fine roots throughout; violently effervescent; moderately alkaline (pH 8.2); I percent hard
angular rocks; abrupt smooth boundary.
R-,-46 inches (117 cm); hard fractured bedrock.
Notes:
Page 2 o f 2
133
SITE D E SC R IPT IO N F O R M
D ate Sam pled: 9/14/96
Site Identificatiom Nmmfoen 493D-A(w)
Location Inform ation
,
C ounty N ame: Rosebud
M LR A : 58A
Soil Survey A rea N ame: W estern Energy Rosebud Mine
Location D escription: 1570' south, 1850' west o f N E comer Section 32, T2N, R41E
Q uadrangle Name:
D escription Category: Partial pedon description
Slope C haracteristics Inform ation
Slope: 26 percent
A spect: 15 degrees
Shape (horizontal/vertical): planar/planar
Position: backslope
Elevation: 3430 feet
Physiography
Local: hill
M ajo r: hills
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
A nnual P recipitation: 13 inches
Flooding Frequency: None
P onding Frequency: None
Perm eability: slow
N atu ral D rainage Class: well
Classification: fine, montmorillonitic (calc), frigid, shallow Aridic Ustorthent
M oisture Regime: Ustic moisture regime
H ydrologic G roup: D
L anduse: rangeland
P a re n t M aterial
Type: shale
Deposition:
V egetation Inform ation
P la n t Symbol: AGSP=3, RHTR=S, ARTR=2, BOCU=2, Musp=2, YUGL=2,
BRTE=2, JUSC=2, ARCA=I, ANSC=I
P la n t Name: bluebunch wheatgrass, skunkbrush sumac, big sagebrush, sideoat
grama, muhlenbergia, yucca, cheatgrass, Rocky Mtn. juniper, silver sage, little
bluestem
(A bundance D ata: l=slight, 2=common, 3= abundant, 4=dominamt)
Page I o f 2
134
Described by: Tom Keck and Karin Jennings
Site Identification N um ber: 493D-A(w)
A -O to 3 inches (0 to 8 cm); olive brown (2.5Y 4/4) moist silty clay loam; noneffervescent.
B w - 3 to 7 inches (8 to 18 cm); silty clay; effervescent.
B C - 7 to 14 inches (18 to 36 cm)‘ silty clay; 50 percent clay; effervescent; 60 percent shale
chips.
C r - 14 inches (36 cm); soft sandy shale; many fine roots throughout; effervescent.
Notes:
Page 2 o f 2
135
SITE D ESC R IPTIO N FO R M
D ate Sam pled: 9/14/96
' Site Idemtiflcatiom Nmmber: 4888-A
Locatiom Imformatiom
Coumty Name: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
Locatiom Descriptiom: 1070' south, 1500' east o f NW comer Section 31, T2N, R41E
Q uadrangle Name:
Descriptiom Category: Full pedon description
Slope C haracteristics Imformation
Slope: 8 percent
A spect: 325 degrees
Shape (horaom tal/vertical): planar/planar
Position: footslope
Elevation: 3430 feet
Physiography
Local: hill
M ajo r: reclamation
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
Ammual P recipitation: 13 inches
Flooding Frequency: N one
Ponding Frequency: None
Perm eability: slow
N atu ral D rainage Class: well
C lassiScation: fine-loamy, mixed (calcareous), frigid Aridic Ustorthent
M oisture Regime: Ustic moisture regime
H ydrologic G roup: D
L anduse: ponderosa pine reclamation
P a re n t M aterial
Type; mixed sedimentary
Deposition: reclamation
V egetation Inform ation
P lan t Symbol: ANGE=S, BOCU=3, CALQ=3, PIPO=3, AGSP=3, MUsp=3,
AGSM=2, JUSC=2, RACO=2, GUSA=I, ROsp=I
P lan t Name: big bluestem, sideoat grama, prairie sandreed, ponderosa pine,
bluebunch wheatgrass, muhlenbergia, western wheatgrass, RockyMtn. juniper, prairie
coneflower, snakeweed, rose
(A bundance D ata: I s=Slight, 2=commom, 3=abumdamt, 4=domimamt)
Page I o f 2
136
Described by: Tom Keck and Karin Jennings
Site Ideiatificatiom Naimber: 4888-A
A1-O to 3 inches (0 to 8 cm); light yellowish brown (2.5Y 6/4) silty clay loam, olive brown
(2.5 Y 4/4) moist; moderate medium granular structure; hard, friable, sticky and very plastic;
many very fine, fine and medium roots throughout; 38 percent clay; strongly effervescent; 2
percent semi-hard angular rocks; moderately alkaline (pH 8.2); clear smooth boundary.
A2- 3 to 7 inches (8 to 18 cm); pale yellow (2.5 Y 7/4) silty clay, dark grayish brown (10YR
4/2) moist; moderate medium to coarse subangular blocky structure; very hard, very friable,
sticky and very plastic; common very fine and fine and few medium roots throughout; few
very fine tubular pores; 42 percent clay; strongly effervescent; trace rock fragments;
moderately alkaline (pH 8.2); clear smooth boundary.
B k - 7 to 24 inches (18 to 61 cm); light gray (2.5 Y 7/2) silty clay loam, olive brown (2.5 Y
4/4); massive structure; hard, very friable, sticky and plastic; common very fine roots
throughout; few very fine tubular pores; 34 percent clay; violently effervescent; 5 percent
stones and cobbles and 5 percent soft to semi-hard rock chips; moderately alkaline (pH 8.2);
abrupt smooth boundary.
2Ckr -24 to 32 inches (61 to 81 cm); light yellow brown (2.5 Y 6/4) gravely sandy clay loam,
light olive brown (2.5 Y 5/4) moist; massive structure; slightly hard, friable, slightly sticky and
slightly plastic; common very fine roots throughout; 24 percent clay; strongly effervescent;
25 percent semi-hard gravel; moderately alkaline (pH 8.2); gradual smooth boundary.
2Ck2--32 to 60 inches (81 to 152 cm); light brownish gray (2.5Y 6/2) gravely sandy clay
loam, olive brown (2.5 Y 4/4) moist; massive structure; slightly hard, friable, slightly sticky
and slightly plastic; 24 percent clay; strongly effervescent; 30 percent semi-hard gravel, shale
and sedimentary rock chips; moderately alkaline (pH 8.0).
Notes:
Page 2 o f 2
137
SITE D ESC R IPTIO N FO R M
D ate Sam pled: 9/13/96
Site Idemtification N um ber: 4822-B
Location Inform ation
C ounty Name: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
Location D escription: 850' north, 1570' east o f SW comer Section 4? TIN , R41E
Q uadrangle Name:
D escription C ategory: Full pedon description
Slope C haracteristics Inform ation
Slope: 19 percent
Aspect: 225 degrees
Shape (horizontal/vertical): planar/planar
Position: sideslope - middle
Elevation: 3310 feet
Physiography
Local: hill
M ajo r: reclamation
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
A nnual Precipitation: 13 inches
Flooding Frequency: None
Ponding Frequency: None
Perm eability: mod. slow
N atu ral D rainage Class: well
Classification: fine-loamy, mixed Aridic Haploboroll
M oisture Regime: Ustic moisture regime
H ydrologic G roup: C
L anduse: rangeland
P a re n t M aterial
Type: mixed sedimentary
D eposition: reclamation
V egetation Inform ation
P la n t Symbol: A G CR-4, C A L 0 3 , MEsp=3, LILE=3, BOGR=3, AEFR=2,
GUSA=2, ARCA=I
P la n t Name: crested wheatgrass, prairie sandreed, sweetclover, blueflax, blue grama,
fringed sagewort, snakeweed, silver sage
(A bundance D ata: I=Slight, 2=common, 3= abundant, 4=dom inant)
Page I o f 2
138
D escribed byj Tom Keck and Karin Jennings
Site Idemtificatiom Nmimben 4822-B
A1-O to 3 inches (0 to 8 cm); brown ( I OYR 5/3) fine sandy clay loam, dark brown ( I OYR
3/3) moist; weak very fine granular structure; loose to soft, very friable, slightly sticky and
slightly plastic; many very fine and few fine and medium roots throughout; 22 percent clay;
effervescent (very slight); moderately alkaline (pH 8.2); clear smooth boundary.
A2- 3 to 9 inches (8 to 23 cm); brown ( I OYR 5/3) fine sandy clay loam, dark brown ( I OYR
3/3) moist; massive structure; extremely hard, friable, slightly sticky and plastic; common very
fine roots throughout; few very fine tubular pores; 24 percent clay; noneffervescent; mildly
alkaline (pH 7.4); abrupt smooth boundary.
B k - 9 to 14 inches (23 to 36 cm); yellowish brown ( I OYR 5/4) loam, olive brown (2.5Y 4/4)
moist; massive structure; hard friable, slightly sticky and plastic; common very fine roots
throughout; few very fine and medium tubular pores; 24 percent clay; strongly effervescent;
lime segregated in many medium sized soft masses; moderately alkaline (pH 8.2); abrupt
irregular boundary.
B C - 14 to 30 inches (36 to 76 cm); brownish yellow (10YR 6/6) sandy clay loam, dark
yellowish brown (I OYR 4/4) moist; massive structure; hard, friable, slightly sticky and slightly
plastic; common very fine roots throughout; few very fine and fine tubular pores; 22 percent
clay; effervescent to strongly effervescent; lime commonly segregated in fine soft masses;
moderately alkaline (pH 8.2); abrupt smooth boundary.
C—30 to 42 inches (76 to 107 cm); light gray (I OYR 7/2) sandy loam, yellowish brown
( I OYR 5/4) oxidized, grayish brown ( I OYR 5/2) reduced; massive structure; slightly hard,
very friable, slightly sticky and slightly plastic; 16 percent clay; strongly effervescent; 30
percent semi-hard sedimentary rock fragments; moderately alkaline (pH 8.2).
Notes:
Page 2 o f 2
139
SITE D ESC R IPTIO N FO R M
D ate Sam pled: 9/12/96
Site Idemtification N um ber: 2856-B
Location Inform ation
C ounty Name: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
Location D escription: 500' south, 1290' west o f N E comer Section 8, TIN , R 4 lE
Q uadrangle Name:
D escription C ategory: Full pedon description
Slope C haracteristics Inform ation
Slope: 18 percent
Aspect: 355 degrees
Shape (horizontal/vertical): planar/planar
Position: sideslope - middle
Elevation: 3350 feet
Physiography
Local: hill
M ajo r: reclamation
C lim ate Inform ation
.W eather Station (Name, N um ber): Colstrip, #1905
A nnual Precipitation: 13 inches
Flooding Frequency: None
Ponding Frequency: None
Perm eability: moderate
N atu ral D rainage Class: well
Classification: fine-loamy, mixed Aridic Haploboroll
M oisture Regime: Ustic moisture regime
H ydrologic G roup: B
L anduse: rangeland
P a re n t M aterial
Type: mixed sedimentary
Deposition: reclamation
V egetation Inform ation
P la n t Symbol: MESA=4, BRTE=3, AGCR=2, B R IN -2, A G SP-2, A R CA -2,
POA=2 AFRF=I
P lan t Name: alfalfa, cheatgrass, crested wheatgrass, smooth brome, bluebunch
wheatgrass, silver sage, Poa sp., fringed sagewort
(A bundance D ata: I=Slight, 2=common, 3= abundant, 4=dom inant)
Page I o f 2
140
D escribed by: Tom Keck and Karin Jennings
Site Identification N um ber: 285643
A1-O to 2 inches (0 to 5 cm); brown (10YR 5/3) fine sandy loam, dark brown (10YR 3/3)
moist; single grain structure; loose, loose, slightly sticky and non-plastic; many very fine and
few fine roots throughout; 14 percent clay; non effervescent; mildly alkaline (pH 7.4); clear
smooth boundary.
A2- 2 to 6 inches (5 to 15 cm); brown (10YR 5/3) fine sandy loam, dark brown ( I OYK 3/3)
moist; weak very coarse platy structure; slightly hard, friable, slightly sticky and non-plastic;
common very fine and few fine, medium and coarse roots throughout, few very fine and fine
tubular pores; 14 percent clay; noneffervescent; mildly alkaline (pH 7.6); abrupt smooth
boundary.
B k - 6 to 12 inches (15 to 30 cm); very pale brown ( I OYR 7/4) fine sandy loam, dark
yellowish brown (10YR 4/4) moist; massive structure; hard, friable, slightly sticky and slightly
plastic; common very fine and few fine, medium and coarse roots throughout; few very fine
and fine tubular pores; 18 percent clay; violently effervescent; lime segregated into few fine
soft masses; trace hard rock fragments; moderately alkaline (pH 8.2); clear smooth boundary.
B C - 12 to 18 inches (30 to 46 cm); light olive brown (2.5 Y 5/4) loamy fine sand, olive brown
(2.5Y 4/4) moist; massive structure; hard, very friable, slightly sticky and non-plastic;
common medium and coarse and few very fine and fine roots throughout; 10 percent clay;
noneffervescent; mildly alkaline (pH 7.4); clear smooth boundary.
2Bk—18 to 30 inches (46 to 76 cm); pale yellow (2.5 Y 7/4) fine sandy clay loam, olive brown
(2.5 Y 4/4) moist; massive structure; very hard, friable, slightly sticky and non-plastic; few
very fine and fine roots throughout; few very fine horizontal tubular pores; 22 percent clay;
violently effervescent; trace hard rock fragments; moderately alkaline (pH 8.4); abrupt wavy
boundary.
3C—30 to 60 inches (76 to 152 cm); pale olive (5Y 6/3) silty clay loam, olive (5Y 4/3) moist;
massive structure; very hard, very friable, sticky and plastic; few very fine roots in upper 12
inches; 30 percent clay; violently effervescent; 40 percent soft to semi-hard siltstone with
some shale; mildly alkaline (pH 7.8); abrupt wavy boundary.
Notes:
Page 2 o f 2
141
SITE D E SC R IPTIO N F O R M ■
D ate Sam pled: 9/12/96
Site Identification N um ber: 4881-C
Location Inform ation
C ounty Nam e: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
Location D escription: 1250' west, 1460' east o f NW comer Section 2, TIN , R40E
Q uadrangle N ame:
D escription C ategory: Full pedon description
Slope C haracteristics Inform ation
Slope: 9 percent
Aspect: 355 degrees
Shape (horizon./vertical): planar/concave
Position: footslope
Elevation: 3500 feet
Physiography
Local: hill
M ajo r: reclamation
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
A nnual P recipitation: 13 inches
Flooding Frequency: None
Ponding Frequency: None
Perm eability: moderate
N atu ral D rainage Class: well
Classification: fine-loamy, mixed (calc.), frigid Aridic Ustdrthent
M oisture Regime: Ustic moisture regime
H ydrologic Group:. C
L anduse: rangeland
F a re n t M aterial
Type: mixed sedimentary
Deposition: reclamation
V egetation Inform ation
P lan t Symbol: CALO=3, G U SA -3, BQCU=2, ARsp=I, ARTR=I, Y U G L=I,
RH TR=I, ROSE=I
P lan t Name: prairie sandreed, snakeweed, sideoat grama* sagewort, big sagebrush,
yucca, skunkbrush sumac, rose, (cool season grasses grazed and can’t identify)
(A bundance D ata: l=slight, 2= com #on, 3~ abundant, 4=dom inant)
Page I o f 2
. 'H
'■
■
142
D escribed by: Tom Keck and Karin Jennings
Site Ideiitificatiom N um ber: 4881-C
A 1-O to 2 inches (0 to 5 cm); light yellowish brown (2.5 Y 6/4) loam, olive brown (2,5 Y 4/4)
moist; strong thin to medium platy structure; hard, friable, sticky and plastic; many very fine,
common fine and few medium roots throughout; 26 percent clay; strongly effervescent; trace
rock fragments; moderately alkaline (pH 8.2); clear smooth boundary.
A2- 2 to 6 inches (5 to 15 cm); pale yellow (2.5Y 7/4) loam, olive brown (2.5Y 4/4) moist;
massive structure; very hard, friable, sticky and plastic; common very fine and few fine roots
throughout; few very fine tubular pores; 26 percent clay; strongly effervescent; trace rock
fragments; moderately alkaline (pH 8.2), abrupt smooth boundary.
Bk1- 6 to 19 inches (15 to 48 cm); pale yellow (2.5 Y 7/4) loam, olive brown (2.5Y 5/4)
moist; massive structure; very hard, very friable, sticky and plastic; few very fine roots
throughout; few very fine tubular pores; 26 percent clay; strongly effervescent; trace rock
fragments; moderately alkaline (pH 8.2); clear smooth boundary.
Bk2- 19 to 34 inches (48 to 86 cm); pale yellow (2.5Y 7/4) loam, olive brown (2.5Y 5/4)
moist; massive structure; very hard, friable, sticky and plastic; few very fine roots throughout;
few very fine tubular pores; 26 percent clay; violently effervescent; trace rock fragments;
moderately alkaline (pH 8.4); abrupt smooth boundary.
C1- 34 to 50 inches (86 to 127 cm); light brownish gray (2.5Y 6/2) very gravely loam, dark
grayish brown (2.5 Y 3/2) moist; massive structure; hard, friable, sticky and plastic; few very
fine roots throughout; 26 percent clay; strongly effervescent; 40 percent semi-hard
sedimentary gravel; moderately alkaline (pH 8.2); clear wavy boundary.
C2- 50 to 60 inches (127 to 152 cm); light yellowish brown (2.5Y 6/4) gravely sandy loam,
olive brown (2.5 Y 4/4) moist; massive structure; slightly hard, friable, slightly sticky and
slightly plastic; strongly effervescent; 30 percent semi-hard sedimentary gravel; moderately
alkaline (pH 8.2).
Notes:
Page 2 o f 2
143
SITE D ESC R IPTIO N FO R M
D ate Sam pled: 9/12/96 '
Site Identification N um ber: 4901-C
Location Inform ation
C ounty Name: Rosebud
MLMA: 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
Location D escription: 1460' south, 1640' east o f NW corner Section 2, TIN , R40E
Q uadrangle N ame:
D escription C ategory: Full pedon description
Slope C haracteristics Inform ation
Slope: 17 percent
A spect: 10 degrees
Shape (horizontal/vertical): planar/convex
Position: sideslope - middle third
Elevation: 3530 feet
Physiography
Local: hill
M ajo r: reclamation
C lim ate Inform ation
W eath er Station (Name, N um ber): Colstrip, #1905
A nnual P recipitation: 13 inches
Flooding Frequency: None
Ponding Frequency: None
Perm eability: moderate
N atu ral D rainage Class: well
Classification: fine-loamy, mixed (calc.), frigid Aridic Ustorthent
M oisture Regime: Ustic moisture regime
H ydrologic G roup: C
L anduse: rangeland
P a re n t M aterial
Type: mixed sedimentary
D eposition: reclamation
V egetation Inform ation
P la n t Symbol: STVI=S, AGDA=S, AGCR=3, CALO=3, MEsp-3 , PIPO=2,
JUSC=2, MESA=2, GUSA=2, BO CU =I, STCO=I, ARsp=I, ARTR=I
P lan t Name: green needlegrass, thichspike wheatgrass, crested wheatgrass, prairie
sandreed, sweetclover, ponderosa pine. Rocky Mtn. juniper, alfalfa, snakeweed,
sideoat grama, needle-and-thread grass, sagewort, big sagebrush
(A bundance D ata: l=s!ight, 2=common, 3= abundant, 4=dom inant)
Page I o f 2
144
D escribed by: Tom Keck and Karin Jennings
Site IdemtiilcatioB N um ber: 4901-C
A1-O to 2 inches (0 to 5 cm); light yellowish brown (2.5Y 6/3) loam, olive brown (2.5Y 4/4)
moist; strong medium granular structure; hard friable, sticky and plastic; many very fine,
common fine and few medium roots throughout; 26 percent clay; violently effervescent;
moderately alkaline (pH 8.2); clear smooth boundary.
A2- 2 to 7 inches (5 to 18 cm); light yellowish brown (2.5 Y 6/3) loam, olive brown (2.5 Y 4/4)
moist; weak coarse granular structure; hard friable, sticky and plastic; common very fine and
few fine and medihm roots throughout; few very fine pores; 26 percent clay; effervescent;
moderately alkaline (pH 8.2); abrupt smooth boundary.
B k - 7 to 26 inches (18 to 66 cm); pale yellow (2.5 Y 7/3) clay loam, olive brown (2.5 Y 4/4)
moist; massive structure; very hard, friable, sticky and plastic; few very fine and fine roots;
few very fine pores; 28 percent clay; violently effervescent; moderately alkaline (pH 8.2);
abrupt smooth boundary.
C--26 to 60 inches (66 to 152 cm); light grayish brown (2.5 Y 6/2) sandy loam, olive brown
(2.5Y 4/3) moist; massive structure; slightly hard, friable, slightly sticky and slightly plastic;
18 percent clay; strongly effervescent; 30 percent soft sedimentary gravel; moderately alkaline
(pH 8.2).
Notes:
Page 2 o f 2
145
SITE D ESC R IPTIO N FO R M
D ate Sam pled: 9/12/96
Site Idemtificatiom N um ber: 3915-C
Location Inform ation
C ounty Name: Rosebud
M LR A : 58A
Soil Survey A rea Name: Western Energy Rosebud Mine
L ocation D escription: 1640' south, 1040' west o fN E cpmer Section 3, TIN , R40E
Q uadrangle Name:
D escription C ategory: Full pedon description
Slope C haracteristics Inform ation
Slope: 9 percent1
A spect: 305 degrees1
Shape (horizontal/vertical): planar/planar
Position: sideslope - middle
Elevation: 3535 feet
Physiography
Local: hill
M ajor: reclamation
C lim ate Inform ation
W eather Station (Name, N um ber): Colstrip, #1905
A nnual P recipitation: 13 inches
Flooding Frequency: None
Ponding Frequency: None
Perm eability: mod. slow
N atu ral D rainage Class: well
Classification: coarse-loamy, mixed (calc.), frigid Aridic Ustorthent
M oisture Regime: Ustic moisture regime
H ydrologic G roup: C
L anduse: rangeland
P a re n t M aterial
Type: mixed sedimentary
D eposition: reclamation
V egetation Inform ation
P lan t Symbol: CALO=3, ANSC=3, PIPQ=2, AGDA=3, AGSP=3, AGSM=3,
STV I-2, G U SA -2, JUSC=2, ROSE=I
P lan t Name: prairie sandreed, little bluestem, ponderosa pine, thickspike wheatgrass,
bluebunch wheatgrass, western wheatgrass, green needlegrass, snakeweed. Rocky
Mtn. juniper, rose
(A bundance D ata: l=slight, 2=common, 3= abundant, 4=dom inant)
Page I o f 2
146
D escribed by: Tom Keck and Karin Jennings
Site Identification N um ber: 3915-C
A1-O to 4 inches (0 to 10 cm); pale brown (10YR 6/3) clay loam, brown ( I OYR 4/3) moist;
moderate fine and medium granular structure; hard, friable, sticky and plastic; many very fine,
common fine and few medium roots throughout; 28 percent clay; effervescent; trace rock
fragments; moderately alkaline (pH 8.2); clear smooth boundary.
A2- 4 to 9 inches (10 to 23 cm); pale brown ( I OYR 6/3) loam, brown (10YR 4/3) moist;
strong coarse to very coarse platy structure; very hard, friable, sticky and plastic; common
very fine and few fine roots throughout; few very fine tubular pores; 26 percent clay;
effervescent; trace rock fragments; moderately alkaline (pH 8.2); clear smooth boundary.
A3- 9 to 17 inches (23 to 43 cm); pale brown ( I OYR 6/3) loam, brown (K)YR 4/3) moist;
massive structure; extremely hard, very friable, sticky and plastic; common very fine and few
fine roots throughout; few very fine tubular pores; 26 percent clay; effervescent; trace rock
fragments; moderately alkaline (pH 8,0); abrupt smooth boundary.
B k - 17 to 30 inches (43 to 76 cm); light yellowish brown (2.5 Y 6/4) sandy loam, olive brown
(2.5 Y 4/4) moist; massive structure; very hard, friable, slightly sticky and slightly plastic; few
very fine roots throughout; few very fine tubular pores, 16 percent clay; violently effervescent;
lime segregated in fine generally rounded or slightly oblong soft masses; trace rock fragments;
moderately alkaline (pH 8.4); clear wavy boundary.
C—30 to 60 inches (76 to 152 cm); fight yellowish brown (2.5Y 6/4) sandy loam, fight olive
brown (2.5Y 5/4) moist; massive structure; slightly hard, friable, slightly sticky and non­
plastic; 10 percent clay, strongly effervescent; 20 percent soft and semi-hard sedimentary
gravel; moderately alkaline (pH 8.2).
Notes: 1Aspect and slope represent calibration site and not either o f the sample sites.
Page 2 o f 2
147
APPENDIX B
MODEL PREDICTED SOIL WATER CONTENTS DURING
THE GROWING SEASONS OF SELECTED YEARS
FOR NATIVE AND RECLAMATION SITES
148
Figure 15E. Model predicted soil water contents during the growing season
of selected years, for native sitel21E-C with pine roots.
A v e r a g e P re c ip ita tio n
1 0 25
0.1
005
180
D ay o fY e a r
Layer 1 ------- Layer2 ------
Layers
Layer4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
0 .2 5
0.2
5 0 .1 5
0.1
180
D ay o fY e a r
Layerl ------- Layer2 ------
Layers
Layer4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
0 .3
.
0.2
0 .0 5
180
D ay o fY e a r
Layer I ------- Layer 2 ------
Layer 3
Layer 4
149
Figure 15F. Model predicted soil water contents during the growing season
______ of selected years, for native sitel21E-C with grass roots.
A v e r a g e P re c ip ita tio n
<E
0 .3
0.2
0 .1 5
0.1
180
D ay o fY e a r
L ay er 1 -— — L ay e r 2
--------
L ay e r 3
L ay er 4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
0 .3
§ 0 .2 5
"
180
D ay o fY e a r
L a y e r 1 ----------
L ayer 2
—
■ Layer 3
L ayer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
§ 0 .2 5
3=0 15
0 .0 5
180
D ay o fY e a r
Layer 1 ------- Layer 2 ------ Layer 3
Layer 4
150
Figure 15G. Model predicted soil water contents during the growing season
o f selected years, for native site!83E-C with pine roots.
A v e r a g e P re c ip ita tio n
Layer 1
L a y e r 2 --------
Layer 3
L ayer 4
1 9 7 8 - A b o v e A v e ra g e P re c ip ita tio n
L ay e ri
L a y e r2
--------
L a y e rs
L a y e r4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
Layer 1
Layers
Layer 3
Layer 4
151
Figure 15H. Model predicted soil water contents during the growing season
_______ o f selected years, for native sitel83E-C with grass roots.
A v e ra g e P re c ip ita tio n
0 .1 5
180
D ay o fY e a r
Layer I
—
—
L ayer 2
---------
L ayer 3
L ayer 4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
= 0 .2 5
O 0.2
5 0 .1 5
0 .0 5
180
D ay of Y ear
L a y e rl
----------
L a y e r 2 --------- L a y e r s
L ayer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
0 .0 5
180
D ay o fY e a r
Layer I ------- Layer 2 ------- Layer 3
Layer 4
152
Figure 151. Model predicted soil water contents during the growing season
o f selected years, for reclamation site 4888-A with pine roots.
A v e r a g e P re c ip ita tio n
<E
0 .3
1 0 .2 5
0.2
0 .1 5
5
0.1
0 .0 5
180
D ay o fY e a r
L a y e r 1 ----------- L a y e r 2 ---------
Layer 3
Layer 4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
180
D ay of Y ear
----------
L a y e r 1 ----------- L a y e r 2
---------
L ayer 3
L ayer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
1 0 .2 5
0.2
0 .0 5
180
D ay o fY e a r
Layer I -------- Layer 2 ------
Layer 3
Layer 4
153
Figure 151. Model predicted soil water contents during the growing season
________ o f selected years, for reclamation site 4888-A with grass roots.
A v e ra g e P re c ip ita tio n
180
D ay o fY e a r
L a y e r 1 ----------
L ayer 2
------ --
L ayer 3
L ayer 4
1 9 7 9 - A b o v e A v e r a g e P re c ip ita tio n
90
120
150
----------
L a y e r 1 -------
180
D ay o fY e a r
L ayer 2
---------
210
L ayer 3
240
L ayer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
5 0 .1 5
o
0 .1
0 .0 5
180
D ay o fY e a r
Layer I -------- Layer 2 ------
Layer 3
Layer 4
270
154
Figure 15K. Model predicted soil water contents during the growing season
__
o f selected years, for reclamation site 3915-C with pine roots.
A v e ra g e P re c ip ita tio n
L ayer I
----------
L ayer 2
Layer 3
L ayer 4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
S? 0 . 3 5
0 3
I 025
015
005
90
120
150
L a y e r 1 ----------
180
D ay o fY e a r
L ayer 2
210
-----------L a y e r 3
240
L ayer 4
1 9 7 9 - B e lo w A v e r a g e P r e c i p i t a t i o n
0 .4
D a y o fY e a r
Layer 1 -------- Layer 2 -------
Layer 3
Layer 4
270
155
Figure 15L. Model predicted soil water contents during the growing season
of selected years, for reclamation site 3915-C with grass roots.
A v e r a g e P re c ip ita tio n
L ay er I
----------
L ay e r 2
---------
L ay er 3
L ay e r 4
1 9 7 8 - A b o v e A v e r a g e P re c ip ita tio n
0.1
0 05
180
D ay o fY e a r
L ayer I
----------
L ayer 2
---------
Layer 3
L ayer 4
1 9 7 9 - B e lo w A v e r a g e P re c ip ita tio n
1 025
0.2
----- 1----180
D ay o fY e a r
Layer 1 ------- Layer 2 -------
Layer 3
Layer 4
156
\
APPENDIX C
MODEL PREDICTED SOIL W ATER STATUS BY WETNESS CLASS
Table 14 A. Model Predicted 34 Year Mean (Standard Error) Number of Days per Month within each Soil Wetness Classes._______
____________________ Native Site 121-C (5): Pine Roots____________________
Matric
Potential
L ayer I
L ayer 2
L ayer 4
Matric
Potential
Mean (Standard Error) Number of Days per Month for 34 Years
Mean (Standard Error) Number of Days per Month for 34 Years
( b a r)
A p r il
M ay
June
J u ly
A u g u st
h = - l/3
0
0
0
0
0
0
3 . 2 ( 5 .4 )
-1 /3 < H < -1
2 4 .7 (6 .9 )
1 7 .4 ( 1 0 .4 )
1 6 .0 ( 8 .9 )
7 .2 (7 9 )
3 .6 ( 4 .9 )
3 .3 ( 5 .5 )
( b a r)
A p r il
M ay
Ju n e
J u ly
A u g u st
S e p t.
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
2 4 .6 ( 7 .0 )
1 6 .8 (1 0 .4 )
1 5 .3 ( 8 .7 )
6 .5 ( 7 .4 )
3 .5 ( 4 .8 )
L ayer I
S e p t.
- l< h < - 2
0
0
0
0
0
0
-l< h < - 2
0
0
0
0
0
0
- 2 < h < -5
2 . 9 ( 3 .7 )
5 .5 ( 4 .3 )
7 .0 ( 3 .6 )
8 .1 ( 5 .3 )
3 .5 ( 4 .3 )
2 .6 ( 3 .7 )
-2 < h < -5
2 .8 ( 3 .6 )
5 .3 ( 4 .0 )
6 .7 ( 3 .8 )
8 .2 ( 5 .4 )
3 .6 ( 4 .3 )
2 .7 ( 3 .9 )
-5 < h < -1 5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
h < -1 5
3 .5 ( 5 .4 )
8 .7 ( 9 .3 )
7 .7 ( 7 .3 )
1 6 .4 ( 9 .8 )
2 4 .0 ( 8 .3 )
2 4 . 2 ( 7 .8 )
h < -1 5
3 .5 ( 5 .3 )
8 .3 ( 9 .2 )
7 .3 ( 7 .4 )
1 5 .6 (1 0 .1 )
2 3 .8 ( 8 .5 )
2 4 .0 ( 8 .1 )
h = - l/3
0
0
0
0
0
0
- l/3 < h < -l
6 .4 (1 0 .8 )
7 .3 (1 1 .4 )
4 .9 (9 9 )
1 .9 (5 9 )
0 .2 ( 1 .4 )
0 .4 ( 2 .0 )
L ayer 2
h = - l/3
0
0
0
0
0
0
-1 /3 < H < -1
6 .7 (1 1 .2 )
1 0 .0 (1 3 .5 )
9 .7 (1 3 .4 )
7 .8 ( 1 2 .4 )
4 .3 ( 1 0 .0 )
1 .0 ( 3 .3 )
-K h < -2
1 .9 (5 .8 )
2 .0 ( 4 .1 )
1 2 ( 3 .1 )
0 .6 ( 1 .7 )
0 .1 ( 0 .8 )
0
- l< h < - 2
1 .8 ( 5 .7 )
1 .5 ( 5 .3 )
1 .4 ( 4 .4 )
1 4 ( 3 .5 )
1 .1 (2 8 )
1 .7 ( 4 .3 )
- 2 < h < -5
0 .5 ( 1 .8 )
1 .8 ( 4 .0 )
1 .0 ( 2 .1 )
L I ( 2 .5 )
0 .1 ( 0 .7 )
0
-2 < h < -5
1.5 ( 5 .4 )
1 .0 ( 3 .3 )
1 .4 (4 8 )
1 .3 ( 3 .4 )
1 7 ( 4 .2 )
1 .3 ( 3 .9 )
- 5 < h < -1 5
2 2 .2 ( 1 2 .8 )
1 9 .9 (1 3 .5 )
2 2 .9 (1 1 .8 )
2 7 .4 ( 8 .7 )
3 0 .5 ( 3 .0 )
2 9 .6 ( 2 .0 )
- 5 < h < -1 5
2 1 .0 (1 3 .3 )
1 8 .4 (1 4 .8 )
1 7 .6 (1 4 .6 )
2 0 .4 (1 3 .9 )
2 3 .8 ( 1 2 .0 )
2 6 .0 ( 9 .6 )
h < -1 5
0 .1 (0 3 )
0 ( 0 .2 )
0 ( 0 .2 )
0 1 ( 0 .2 )
0 ( 0 .2 )
0
h < -1 5
0 .1 ( 0 .3 )
0
0
0
0 .1 ( 0 .3 )
0 ( 0 .2 )
h = - l/3
0
0
0
0
0
0
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
1 .0 ( 5 .3 )
3 4 ( 8 .5 )
2 .6 ( 8 .3 )
2 .6 ( 8 .3 )
1 .1 ( 5 .3 )
0 .9 (5 .1 )
-1 /3 < H < -1
1 .0 ( 4 .9 )
2 .6 ( 7 .4 )
2 .7 ( 8 .5 )
2 . 2 ( 7 .5 )
1 .0 ( 4 .2 )
0
-l< h < - 2
1 .7 ( 6 .8 )
1 .5 ( 5 .8 )
1 .4 ( 5 .2 )
0 .3 ( 1 .2 )
0 . 7 ( 2 .9 )
0
- l< h < -2
1 .7 (6 8 )
L I ( 3 .8 )
0 .8 ( 3 .9 )
0 .3 ( 1 .7 )
0 .6 ( 2 .4 )
0
-2 < h < -5
2 8 . 2 ( 8 .6 )
2 6 .1 (1 0 .1 )
2 5 .8 ( 9 .8 )
2 8 .1 ( 8 .8 )
2 9 . 2 ( 6 .5 )
2 9 .1 (5 .1 )
-2 < h < -5
2 8 .3 ( 8 .4 )
2 7 .3 ( 8 .0 )
2 6 .5 ( 9 .3 )
2 8 .5 (8 .1 )
2 9 .4 (6 .6 )
3 0 .0 ( 0 .0 )
L ayer 3
- 5 < li< -1 5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
h < -1 5
0 .1 ( 0 .3 )
0
0 .1 ( 0 .4 )
0
0
0
h < -1 5
0 .1 ( 0 .3 )
0 ( 0 .2 )
0
0
0 ( 0 .2 )
0
h = - l/3
1 7 .3 ( 1 5 .4 )
1 7 .3 ( 1 5 .4 )
1 7 .6 ( 1 4 .7 )
1 4 .7 ( 1 8 .2 )
-l/3 < h < -l
0
0
0
0
1 8 .2 (1 5 .3 ) 1 7 .6 (1 4 .8 )
0
0
L ayer 4
h = -lZ 3
0
0
0
0
0
0
- l/3 < h < -l
0
0 . 4 ( 2 .0 )
0 .8 ( 4 .7 )
0 . 9 ( 5 .2 )
0 . 9 ( 5 .2 )
0 .3 ( 1 .7 )
-l< h < - 2
0
0
0
0
0
0
- l< h < -2
0
0
0
0
0
0 .5 ( 2 .9 )
- 2 < h < -5
0
0
0
0
0
0
-2 < h < -5
0 .9 ( 5 .2 )
0 .4 ( 2 .4 )
0
0
0
0 .1 ( 0 .5 )
- 5 < h < -1 5
1 3 .6 (1 5 .3 )
1 3 .3 (1 5 .1 )
1 2 .4 (1 4 .8 )
1 2 .8 (1 5 .3 )
1 2 .8 (1 5 .3 )
1 2 .4 (1 4 .8 )
-5 < h < -1 5
3 0 .0 ( 5 .2 )
3 0 .2 ( 3 .2 )
2 9 .1 (5 .1 )
3 0 .1 (5 .2 )
3 0 .1 (5 .2 )
2 9 .1 ( 5 .1 )
h < -1 5
0 .1 ( 0 .3 )
0
0
0
0
0
h < -1 5
0 .1 ( 0 .3 )
0
0 .1 ( 0 .3 )
0
0
0
157
L ayer 3
____________________ Native Site 121-C (5): Grass Roots_______________
Table MB. M odel Predicted 34 Year Mean (Standard Error) Number o f Days per Month within each Soil W etness Classes.
Native Site 183-C (6): Grass Roots
Native Site 183-C (6): Pine Roots
M a tr ic
M a tr ic
Layer I
Layer 3
L ayer 4
M e a n ( S ta n d a r d E r r o r ) N u m b e r o f D a y s p e r M o n th f o r 3 4 Y e a r s
( b a r)
A p r il
M ay
Ju n e
J u ly
A ugust
h = - l/3
0
0
0
0
0
0
3 . 7 ( 5 .9 )
- l/3 < h < -l
2 5 .3 ( 6 .2 )
1 6 .3 ( 9 .8 )
1 5 .5 ( 8 .3 )
6 .9 (7 4 )
3 .6 ( 5 .1 )
3 .6 ( 5 .8 )
(b ar)
A p r il
M ay
June
J u ly
A ugust
S e p t.
h = - l/3
O
0
0
0
0
0
-l/3 < h < -l
2 5 .5 ( 6 .2 )
1 6 .9 ( 9 .9 )
1 5 .8 (8 .5 )
6 9 ( 7 .3 )
3 . 7 ( 5 .2 )
L ayer I
S e p t.
- l< h < - 2
O
0
0
0
0
0
- l< h < - 2
0
0
0
0
0
0
-2 < h < -5
2 . 2 ( 2 .8 )
5 .1 (3 6 )
6 .3 ( 3 .2 )
7 .1 ( 4 .5 )
2 . 9 ( 3 .5 )
2 . 4 ( 3 .2 )
-2 < h < -5
2 . 4 ( 2 .9 )
5 .4 ( 3 .8 )
6 . 2 ( 3 .2 )
6 . 9 ( 4 .5 )
2 .9 ( 3 .7 )
2 .4 ( 3 .2 )
- 5 < h < -1 5
O
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
3 .4 ( 5 .3 )
9 .0 ( 9 .2 )
8 .0 ( 7 .2 )
1 7 .0 ( 9 .3 )
2 4 . 4 ( 8 .0 )
2 3 .9 (8 .1 )
h < -1 5
3 . 4 ( 5 .4 )
9 .3 ( 9 .2 )
8 .3 ( 7 .2 )
1 7 .3 ( 9 .2 )
2 4 .4 ( 8 .1 )
2 4 .0 ( 8 .0 )
h < -1 5
L ayer 2
P o t e n tia l
M e a n ( S ta n d a r d E r ro r ) N u m b e r o f D a y s p e r M o n th f o r 3 4 Y e a r s
P o t e n ti a l
h = - l/3
0
0
0
0
0
0
-1 /3 < H < -1
8 .0 ( 1 2 .0 )
1 0 .6 (1 3 .5 )
7 .5 ( 1 2 .6 )
6 .6 (1 1 .8 )
3 .3 ( 8 .3 )
0 .4 ( 2 .1 )
2 .5 ( 5 .0 )
1 .4 ( 2 .9 )
2 .7 (5 4 )
0 .7 ( 2 .2 )
L I ( 3 .0 )
1 .2 ( 3 .1 )
0 .3 ( L I )
-2 < h < -5
2 .2 ( 5 .4 )
1 3 ( 3 .1 )
2 .6 ( 3 .9 )
0 .8 ( 2 .0 )
0 .8 ( 2 .2 )
1 .2 ( 2 .8 )
2 2 .5 ( 1 2 .7 ) 2 0 . 1 ( 1 2 . 5 )
1 0 .4 (1 1 .5 )
-5 < h < -1 5
6 .6 (1 1 .1 )
9 .7 (1 3 .0 )
1 2 .4 ( 1 2 .8 )
1 8 .6 (1 4 .4 )
1 8 .6 ( 1 2 .9 )
1 1 .9 (1 1 .6 )
1 0 .6 ( 1 2 .6 )
1 8 .6 ( 1 2 .2 )
h < -1 5
1 1 .6 (1 3 .7 )
8 .1 ( 1 2 .9 )
4 .9 ( 9 .9 )
4 .3 ( 1 0 .3 )
7 .2 (1 1 .0 )
1 5 .2 (1 3 .0 )
h = - l/3
O
0
0
0
0
0
-l/3 < h < -l
7 .8 (1 1 .8 )
7 .4 (1 1 .2 )
3 .5 ( 8 .6 )
1 .0 ( 4 .3 )
0 .1 ( 0 .3 )
0 .4 ( 2 .0 )
- l< h < - 2
2 . 2 ( 5 .0 )
2 . 0 ( 3 .9 )
1 .2 (2 1 )
0 .5 ( 1 .5 )
0 .1 ( 0 .8 )
0 .4 (1 8 )
- 2 < h < -5
1 .7 ( 4 .0 )
1 .3 ( 1 .9 )
1 .4 ( 2 .4 )
0 .6 ( 1 .8 )
0 .1 (0 5 )
-5 < h < -1 5
6 .7 (1 0 .6 )
1 1 .3 ( 1 2 .7 )
1 7 .9 (1 2 .2 )
h < -1 5
1 2 .6 ( 1 3 .9 )
9 .0 (1 3 .4 )
6 .0 ( 1 0 .7 )
6 .4 (1 2 .4 )
h = - l/3
0
0
0
0
0
0
- 1 / 3 < i < -1
4 .6 (1 0 .7 )
6 .4 (1 2 .0 )
5 .6 (1 1 .3 )
4 .1 (1 0 .1 )
3 .6 ( 1 0 .0 )
3 .4 ( 9 .4 )
L ayer 2
L ayer 3
h = - l/3
0
0
0
0
0
0
- l/3 < h < -l
2 .4 ( 7 .3 )
3 .3 ( 7 .7 )
3 .1 ( 8 .6 )
2 .6 ( 8 .5 )
1.8 ( 7 .3 )
0 .3 ( 1 .2 )
-l< h < - 2
2 6 .4 (1 0 .8 )
2 4 .6 ( 1 2 .0 )
2 4 .3 (1 1 .4 )
2 6 .9 (1 0 .1 )
2 7 .4 ( 1 0 .0 )
2 6 .6 ( 9 .4 )
-l< h < -2
2 3 .1 (1 3 .1 )
2 2 .2 (1 2 .8 )
2 1 .6 (1 3 .1 )
2 2 .8 ( 1 3 .4 )
2 3 .7 (1 3 .1 )
2 4 .4 (1 1 .4 )
- 2 < h < -5
0
0
0
0
0
0
-2 < h < -5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
h < -1 5
0 .1 ( 0 .3 )
0
0 .1 ( 0 .3 )
0
0
0
h < -1 5
5 .5 (1 1 .8 )
5 .5 (1 1 .8 )
5 .3 (1 1 .4 )
5 .5 (1 1 .7 )
5 .5 (1 1 .8 )
5 .3 (1 1 .4 )
h = - l/3
0
0
0
0
0
0
-1 /3 < H < -1
1 7 .3 ( 1 5 .4 )
1 7 .7 (1 5 .1 )
1 7 .6 ( 1 4 .8 )
1 8 .2 (1 5 .3 )
1 8 .2 (1 5 .3 )
1 7 .6 ( 1 4 .8 )
L ayer 4
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
0 . 9 ( 5 .2 )
1 .0 ( 4 .1 )
0 .8 ( 4 .7 )
0 .9 ( 5 .2 )
0 9 ( 5 .2 )
0 . 9 ( 5 .1 )
-l< h < - 2
0
0
0
0
0
0
-l< h < -2
0
0 .2 (1 .0 )
0
0
0
0
-2 < h < -5
8 .3 ( 1 3 .6 )
8 .7 (1 3 .7 )
7 .9 (1 3 .2 )
8 .2 (1 3 .7 )
8 .2 (1 3 .7 )
7 .9 (1 3 .2 )
-2 < h < -5
0 .1 ( 0 .5 )
0 5 ( 1 .8 )
0 .5 ( 2 .1 )
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
- 5 < h < -1 5
2 4 .6 ( 1 2 .5 )
2 4 .8 (1 1 .8 )
2 4 .2 (1 1 .4 )
2 5 .5 (1 1 .8 )
2 5 .5 (1 1 .8 )
2 4 .7 (1 1 .4 )
h < -1 5
5 .4 (1 1 .6 )
4 .6 (1 1 .0 )
4 .4 (1 0 .6 )
4 .6 (1 1 .0 )
4 .6 (1 1 .0 )
4 .4 (1 0 .6 )
h < -1 5
5 .4 (1 1 .6 )
4 .6 (1 1 .0 )
4 .5 ( 1 0 .6 )
4 .6 (1 1 .0 )
4 .6 (1 1 .0 )
4 .4 (1 0 .6 )
Ul
OO
Table 14C. Model Predicted 34 Year Mean (Standard Error) Number of Days per Month within each Soil Wetness Classes._______
___________________ Native Site 493D-A (3): Pine Roots____________________
Matric
Potential
L ayer I
L ayer 2
L ayer 4
Matric
Potential
Mean (Standard Error) Number of Days per Month for 34 Years
(b ar)
A p r il
M ay
June
J u ly
A u g u st
S e p t.
h = - l/3
0
0
0
0
0
0
- l/3 < h < -l
1 5 .7 (7 .7 )
6 .5 ( 6 .7 )
6 .8 (5 8 )
2 .3 ( 3 .8 )
1 4 ( 2 .4 )
Mean (Standard Error) Number of Days per Month for 34 Years
( b a r)
A p ril
M ay
June
J u ly
A u g u st
h = - l/3
0
0
0
0
0
0
1 .3 ( 3 .6 )
- l/3 < h < -l
1 6 .0 ( 7 .8 )
6 .9 ( 7 .0 )
7 .8 ( 6 .4 )
2 . 7 ( 4 .2 )
1 .7 ( 3 .0 )
1 .4 ( 3 .7 )
L ayer I
S e p t.
-l< h < - 2
3 . 4 ( 1 .7 )
2 . 4 ( 2 .1 )
2 .9 (1 9 )
1 .3 ( 1 .5 )
0 .6 ( 1 .0 )
0 . 4 ( 0 .8 )
- 1< h < - 2
3 .0 (1 9 )
2 .2 ( 1 .9 )
2 . 7 ( 1 .6 )
1 4 ( 1 .5 )
0 .6 ( 1 .0 )
0 .5 ( 0 .8 )
-2 < h < -5
4 .6 ( 3 .5 )
6 .8 ( 4 .9 )
8 .6 ( 4 .0 )
6 .5 ( 4 .7 )
3 . 2 ( 3 .9 )
1 .7 ( 2 .4 )
-2 < h < -5
4 .6 ( 3 .5 )
6 .8 ( 4 .7 )
8 .3 ( 3 .8 )
6 .8 ( 4 .8 )
3 .2 (3 8 )
1 9 ( 3 .2 )
- 5 < h < -1 5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
h < -1 5
7 .3 ( 7 .3 )
1 5 .4 (9 .4 )
1 1 .8 (7 .2 )
2 0 .9 ( 8 .1 )
2 5 .8 ( 6 .5 )
2 6 .6 ( 5 .0 )
h < -1 5
7 . 2 ( 7 .3 )
1 5 .1 (9 .2 )
1 1 .2 (7 .2 )
2 0 .2 ( 8 .5 )
2 5 .4 ( 6 .8 )
2 6 .2 ( 5 .7 )
h = - l/3
0
0
0
0
0
0
h = - l/3
0
0
0
0
0
0
- l/3 < h < -l
8 .8 (1 2 .7 )
7 .0 (1 1 .5 )
3 . 0 ( 8 .0 )
0 .5 ( 2 .2 )
0
0 .3 ( 1 .9 )
- l/3 < h < -l
9 .2 (1 3 .0 )
1 1 .7 (1 4 .7 )
9 .1 (1 3 .1 )
6 .2 (1 1 .9 )
L I ( 3 .8 )
0 .4 ( 2 .0 )
0 .7 ( 2 .2 )
L ayer 2
-l< h < - 2
4 . 9 ( 9 .6 )
4 .5 ( 7 .1 )
2 .1 ( 4 .4 )
0 9 ( 2 .5 )
0
0 .1 ( 0 .2 )
- l< h < -2
4 .9 ( 9 .4 )
2 .1 ( 5 .2 )
2 . 9 ( 5 .6 )
1 .6 ( 3 .9 )
2 .8 ( 5 .2 )
- 2 < h < -5
3 . 4 ( 7 .3 )
3 .2 ( 4 .6 )
3 .1 (3 9 )
1 .3 ( 2 .8 )
0 4 ( 1 .3 )
0 .5 ( 1 .8 )
-2 < h < -5
3 .9 (7 2 )
3 .8 ( 6 .4 )
4 .3 ( 6 .3 )
2 . 4 ( 4 .5 )
2 .7 (5 .1 )
1 7 ( 4 .0 )
- 5 < h < -1 5
1 3 .8 (1 3 .5 )
1 6 .2 (1 3 .0 )
2 1 .6 (1 0 .6 )
2 8 .3 ( 6 .7 )
3 0 .6 ( 1 .3 )
2 9 .1 (3 .3 )
-5 < h < -1 5
1 2 .9 (1 3 .0 )
1 3 .3 ( 1 3 .0 )
2 4 .4 (1 1 .5 )
2 7 .2 (6 .3 )
h < -1 5
0 .1 ( 0 .3 )
0 .1 ( 0 .2 )
0 .1 (0 3 )
0
0
0
h < -1 5
0 .1 ( 0 .4 )
0 ( 0 .2 )
0 ( 0 .2 )
0 ( 0 .2 )
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
2 .5 ( 8 .0 )
1 .6 ( 5 .8 )
1 .8 ( 7 .1 )
1 .7 ( 6 .8 )
0 . 9 ( 5 .2 )
0 .2 (1 4 )
Layer 3
1 3 .6 (1 3 .0 ) 2 0 .7 ( 1 3 .2 )
0 ( 0 .2 )
0 ( 0 .2 )
h = - l/3
0
0
0
0
0
0
- l/3 < h < -l
2 .3 ( 7 .6 )
2 .1 ( 6 .6 )
1 .8 ( 7 .1 )
1 .3 ( 5 .6 )
0 .3 ( 1 .7 )
0
- l< h < - 2
0 .1 ( 0 .7 )
1 .2 (4 8 )
0 .1 ( 0 .8 )
0 .1 ( 0 .7 )
0 . 4 ( 2 .4 )
0 .6 ( 3 .7 )
- l< h < - 2
0 .3 ( 1 .4 )
1 .2 ( 3 .7 )
0 . 7 ( 2 .9 )
0 . 4 ( 2 .2 )
0 .4 ( 2 .2 )
0
-2 < h < -5
0 .8 ( 4 .4 )
0 .6 ( 2 .5 )
1 4 ( 5 .5 )
0 2 ( 1 .0 )
0 .5 ( 2 .9 )
0 .4 ( 2 .5 )
- 2 < h < -5
0 .7 ( 4 .I)
1.5 ( 5 .0 )
1 .6 ( 4 .7 )
0 .3 ( 1 .2 )
0 .6 ( 2 .7 )
0 .4 ( 2 .5 )
- 5 < h < -1 5
2 7 .5 ( 9 .5 )
2 7 .6 ( 9 .4 )
2 6 .7 (9 .1 )
2 9 .0 ( 7 .3 )
2 9 . 2 ( 7 .3 )
2 8 .6 ( 5 .7 )
-5 < h < -1 5
2 7 .6 (9 .1 )
2 6 .1 (1 0 .7 )
2 5 .9 ( 9 .6 )
2 9 .0 ( 7 .3 )
2 9 .7 ( 5 .7 )
2 9 .5 ( 2 .9 )
h < -1 5
0 .1 ( 0 .4 )
0
0
0 ( 0 .2 )
0
0 ( 0 .2 )
h < -1 5
0 .1 ( 0 .3 )
0 ( 0 .2 )
0 ( 0 .2 )
0 ( 0 .2 )
0
0 .1 ( 0 .3 )
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
0
0
0
0
0
0
Layer 4
h = - l/3
0
0
0
0
0
0
- l/3 < h < -l
0
0
0
0
0
0
-l< h < - 2
3 0 . 9 ( 0 .3 )
3 1 .0 (0 .0 )
3 0 .0 ( 0 .0 )
3 1 .0 (0 .0 )
3 1 .0 (0 .0 )
3 0 .0 ( 0 .0 )
- l< h < - 2
0
0
0
0
0
0
-2 < h < -5
0
0
0
0
0
0
-2 < h < -5
0 . 9 ( 4 .9 )
1 .0 ( 4 .3 )
0 .6 ( 3 .2 )
0
0
0
- 5 < li< -1 5
0
0
0
0
0
0
- 5 < h < -1 5
3 0 .1 (5 .2 )
3 0 .0 ( 4 .3 )
2 9 .4 ( 3 .2 )
3 1 .0 ( 0 .0 )
3 1 .0 (0 .0 )
3 0 .0 ( 0 .0 )
h < -1 5
0 .1 ( 0 .3 )
0
0
0
0
0
h < -1 5
0 .1 ( 0 .3 )
0
0
0
0
0
159
L ayer 3
___________________ Native Site 493D-A (3): Grass Roots______________
Table 14D. Model Predicted 34 Year Mean (Standard Error) Number of Days per Month within each Soil Wetness Classes.______
_________________Reclamation Site 4888-A (4): Pine Roots_________________
Matric
Potential
L ayer I
L ayer 2
L ayer 4
Matric
Potential
Mean (Standard Error) Number of Days per Month for 34 Years
(b a r)
A p ril
M ay
June
Ju ly
A u g u st
S e p t.
h = - l/3
0
0
0
0
0
0
- V 3 < h < -1
5 .0 ( 3 .9 )
5 .0 ( 4 .0 )
5 .4 (3 6 )
3 .1 ( 3 .2 )
1 .4 ( 2 .4 )
L I ( 1 .9 )
-l< h < -2
L I (L I)
2 .9 ( 2 .2 )
3 .3 ( 2 .0 )
2 4 ( 2 .1 )
1 .5 ( 2 .0 )
1 9 ( 1 .5 )
-2 < ti< -5
1 .4 ( 2 .3 )
5 0 ( 3 .6 )
5 .3 ( 2 .9 )
6 .9 (4 5 )
2 7 ( 3 .1 )
2 .4 ( 3 .3 )
L ayer I
Mean (Standard Error) Number of Days per Month for 34 Years
( b a r)
A p ril
M ay
June
July
A ugust
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
6 .1 ( 3 .5 )
4 .9 ( 4 .6 )
5 .4 ( 3 .5 )
2 .5 ( 3 .1 )
1 .5 ( 2 .5 )
1 0 ( 1 .7 )
-l< h < -2
1 4 ( 1 .1 )
2 .6 (2 1 )
3 .1 ( 2 .0 )
2 .1 ( 2 .1 )
L I ( 1 .5 )
0 .8 ( 1 .3 )
-2 < h < -5
2 .3 ( 2 .5 )
5 .7 ( 3 .7 )
6 .5 ( 3 .3 )
6 .1 ( 3 .9 )
2 .6 ( 3 .5 )
2 .1 ( 3 .1 )
S e p t.
- 5 < h < -1 5
0
0
0
0
0
0
- 5 < ti< -1 5
0
0
0
0
0
0
h < -1 5
2 3 .5 ( 6 .1 )
18 .1 ( 6 .2 )
1 6 .0 ( 6 .3 )
1 8 .6 ( 8 .0 )
2 5 .4 ( 6 .9 )
2 5 .6 ( 6 .2 )
h < -1 5
2 1 .3 ( 5 .7 )
1 7 .9 (6 .3 )
1 5 .0 ( 6 .1 )
2 0 .3 ( 7 .7 )
2 5 .8 ( 6 .6 )
2 6 .1 ( 5 .7 )
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
13 .1 (1 3 .1 )
10 .1 ( 1 2 .2 )
3 7 ( 7 .9 )
0 .9 ( 3 .0 )
0
0 .3 ( 1 .9 )
L ayer 2
h = -l/3
0
0
0
0
0
0
- l/3 < h < -l
1 3 .7 ( 1 3 .3 )
1 0 .5 (1 2 .7 )
6 .2 ( 1 1 .2 )
2 .6 ( 7 .2 )
0
0 .3 ( 1 .9 )
-l< h < -2
4 .4 ( 7 .5 )
2 .7 ( 4 .1 )
2 .3 (3 8 )
0 .9 ( 2 .5 )
0 .1 ( 0 .3 )
0 .2 ( 1 .2 )
- l< h < - 2
4 .3 ( 7 .7 )
2 .6 ( 3 .9 )
1 .6 ( 3 .5 )
1 4 ( 2 .9 )
0 .2 ( 0 .7 )
0 ( 0 .2 )
-2 < h < -5
9 .0 (1 2 .3 )
1 5 .5 ( 1 3 .4 )
2 0 .8 (1 1 .6 )
2 4 .9 (1 1 .0 )
2 3 .7 (1 0 .9 )
12 .1 ( 1 2 .4 )
-2 < h < -5
8 .2 ( 1 1 .9 )
1 4 .2 (1 3 .3 )
1 8 .7 ( 1 3 .0 )
2 2 .8 (1 2 .1 )
2 3 .2 (1 1 .2 )
1 2 .1 (1 2 .5 )
- 5 < h < -1 5
1 .7 ( 4 .8 )
0 .9 ( 5 .2 )
2 .0 (7 0 )
3 .4 ( 9 .5 )
6 .0 (9 4 )
1 2 .3 ( 1 2 .1 )
- 5 < h < -1 5
1 .7 ( 4 .8 )
0 .9 ( 5 .2 )
2 .0 (7 2 )
3 .3 ( 9 .2 )
6 .1 ( 9 .8 )
1 3 .3 ( 1 2 .2 )
h < -1 5
2 .7 ( 6 .6 )
1 .7 ( 5 .8 )
1 2 ( 5 .3 )
0 .9 ( 5 .2 )
1 .3 ( 5 .5 )
5 .0 (9 .8 )
h < -1 5
3 .0 ( 7 .2 )
2 .7 ( 7 .6 )
1 .5 ( 6 .0 )
0 .9 (5 2 )
1 4 ( 5 .5 )
4 .3 ( 9 .4 )
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
6 .3 (1 2 .3 )
6 .7 (1 2 .4 )
6 .1 ( 1 2 .0 )
6 .4 ( 1 2 .5 )
5 .2 ( 1 1 . 0 )
4 .4 (1 0 .6 )
L ayer 3
h = -l/3
0
0
0
0
0
0
- l/3 < h < -l
6 .3 (1 2 .3 )
6 .4 ( 1 2 .0 )
6 .1 ( 1 2 .0 )
6 .4 ( 1 2 . 5 )
5 .0 ( 1 1 . 1 )
4 .4 ( 1 0 .6 )
- l< h < - 2
1.8 ( 7 .3 )
1 .9 ( 7 .3 )
2 .6 ( 8 .5 )
2 .1 ( 7 .3 )
1 .9 (6 2 )
1 .8 (7 .1 )
-l< h < -2
1 .8 ( 7 .3 )
2 .2 ( 7 .5 )
2 .6 ( 8 .5 )
2 .0 ( 6 .8 )
2 .1 ( 7 .0 )
1 .8 (7 1 )
-2 < h < -5
2 2 .9 (1 3 .6 )
2 2 .4 ( 1 3 .6 )
2 1 .2 (1 3 .7 )
2 2 .5 (1 3 .5 )
2 3 .9 ( 1 2 .9 )
2 3 .8 ( 1 2 .1 )
-2 < h < -5
2 2 .9 (1 3 .6 )
2 2 .4 (1 3 .6 )
2 1 .2 (1 3 .7 )
2 2 .5 ( 1 3 .4 )
2 3 .9 ( 1 2 .9 )
2 3 .8 (1 2 .1 )
-5 < h < -1 5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
h < -1 5
0 .1 ( 0 .3 )
0 ( 0 .2 )
0 .1 (0 3 )
0
0 .1 ( 0 .2 )
0
h < -1 5
0 .1 ( 0 .3 )
0 (0 .2 )
0 .1 ( 0 .5 )
0 .1 ( 0 .2 )
0 ( 0 .2 )
0
h = - l/3
0
0
0
0
0
0
h = - l/3
0
0
0
0
0
- l/3 < tt< - l
0
0
0
0
0
0
- l/3 < h < -l
1 7 .3 (1 5 .4 )
1 7 .3 ( 1 5 .4 )
1 7 .6 ( 1 4 .7 )
1 8 .2 (1 5 .3 )
1 8 .2 (1 5 .3 )
L ayer 4
. 0
1 7 . 6 ( 1 4 .8 )
- l< t i< - 2
1 7 .3 (1 5 .4 )
1 7 .3 (1 5 .4 )
1 7 .6 (1 4 .7 )
1 8 . 2 ( 1 5 .3 )
1 8 .2 ( 1 5 .3 )
1 7 .6 ( 1 4 .8 )
-l< h < -2
0
0 .4 ( 2 .0 )
0 (0 .2 )
0
0
0
-2 < h < -5
1 3 .6 (1 5 .3 )
1 3 .7 (1 5 .4 )
1 2 .4 (1 4 .7 )
1 2 .8 ( 1 5 .3 )
1 2 .8 ( 1 5 .3 )
1 2 .4 ( 1 4 .8 )
-2 < h < -5
1 3 .6 ( 1 5 .3 )
1 3 .3 (1 5 .1 )
1 2 .4 ( 1 4 .8 )
1 2 .8 ( 1 5 .3 )
1 2 .8 ( 1 5 .3 )
1 2 .4 ( 1 4 .8 )
- 5 < h < -1 5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
h < -1 5
0 .1 ( 0 .3 )
0
0
0
0
0
h < -1 5
0 .1 ( 0 .3 )
0
0
0
0
0
160
L a y e rS
_________________ Reclamation Site 4888-A (4): Grass Roots___________
Table 14E. Model Predicted 34 Year Mean (Standard Error) Number of Days per Month within each Soil Wetness Classes.______
_________________Reclamation Site 3915-C (7): Pine Roots_________________
Matric
Potential
L ayer I
L ayer 2
L ayer 3
L ayer 4
_________________ Reclamation Site 3915-C (7): Grass Roots___________
Matric
Potential
Mean (Standard Error) Number of Days per Month for 34 Years
Mean (Standard Error) Number of Days per Month for 34 Years
(b a r)
A p ril
M ay
June
July
A ugust
h = - l/3
0
0
0
0
0
0
1 .2 (2 .7 )
- l/3 < h < -l
1 4 .9 ( 4 .3 )
5 .2 ( 5 .5 )
5 .1 (5 .1 )
1 7 ( 3 .2 )
1 .0 (2 .0 )
1 2 ( 2 .8 )
0 .5 ( 0 .9 )
0 .5 ( 0 .9 )
- l< h < - 2
2 .1 ( 1 .3 )
1 6 ( 1 .6 )
2 .3 ( 1 .6 )
0 .9 ( 1 1 . 1 )
0 .6 (1 .0 )
0 .4 ( 0 .8 )
0 .9 ( 1 .3 )
0 .8 ( 1 .2 )
-2 < h < -5
1 .7 ( 1 .2 )
2 .6 ( 2 .4 )
2 .1 ( 1 .7 )
L I ( 1 .3 )
0 .7 ( L I )
0 .8 ( 1 .2 )
( b a r)
A p ril
M ay
Ju n e
Ju ly
A u g u st
Sep t.
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
1 5 .0 ( 4 .2 )
6 .5 ( 6 .4 )
6 .5 ( 5 .9 )
2 .6 ( 3 .7 )
1 .2 (2 2 )
-l< h < -2
2 .1 ( 1 .8 )
1 .9 ( 2 .6 )
1 .9 ( 1 .4 )
0 .8 ( 1 .2 )
-2 < h < -5
1 .6 ( 1 .2 )
2 .6 ( 2 .2 )
2 .5 ( 1 .7 )
1.5 ( 1 .6 )
L ayer I
Sept.
- 5 < h < -1 5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
h < -1 5
1 2 .3 ( 5 .0 )
2 0 .0 ( 8 .1 )
1 9 .1 ( 6 .3 )
2 6 .1 ( 5 .5 )
2 8 .4 ( 3 .9 )
2 7 .5 ( 4 .1 )
h < -1 5
1 2 .3 ( 4 .3 )
2 1 .5 ( 6 .9 )
2 0 .5 ( 6 .2 )
2 7 .4 ( 4 .9 )
2 8 .7 (3 .5 )
2 7 .7 (3 .9 )
h = - l/3
0
0
0
0
0
0
- V 3 < h < -1
1 7 . 4 ( 1 3 .7 )
1 0 .8 (1 2 .0 )
2 .8 ( 6 .7 )
0 .4 ( 2 .4 )
0 .1 ( 0 .3 )
0 .5 ( 2 .1 )
L ayer 2
h = - l/3
0
0
0
0
0
0
- l/3 < h < -l
1 7 .7 ( 1 3 .7 )
1 8 .5 ( 1 4 .3 )
9 .8 ( 1 2 .0 )
3 .6 ( 7 .6 )
0 .2 ( 1 .0 )
0 .4 (2 0 )
- l< h < - 2
2 .2 ( 4 .9 )
3 .8 ( 4 .0 )
2 .3 ( 4 .5 )
0 .5 ( 1 .6 )
0
0 .3 ( 1 .2 )
- l< h < - 2
3 .7 ( 7 .6 )
2 .0 (4 6 )
5 .2 ( 6 .4 )
2 .8 ( 4 .8 )
0 .6 ( 2 .4 )
0 .5 ( 1 .9 )
- 2 < h < -5
3 .0 (5 3 )
1 .3 ( 1 .7 )
1.1 ( 1 .7 )
0 .3 ( 0 .9 )
0
0 .2 ( 0 .9 )
-2 < h < -5
3 .1 ( 6 .7 )
0 9 ( 2 .1 )
2 .0 ( 2 .4 )
1 .3 ( 2 .0 )
0 .3 ( L I )
0 .3 ( L I )
- 5 < h < -1 5
2 .7 ( 5 .3 )
1 .4 ( 2 .2 )
1 .4 ( 1 .8 )
0 .4 ( 1 .0 )
0 .1 ( 0 .5 )
0 .2 ( 0 .7 )
- 5 < h < -1 5
2 .3 ( 5 .7 )
1 .6 ( 2 .9 )
2 .1 ( 2 .5 )
1 .4 ( 2 .0 )
1 0 ( 2 .2 )
0 .6 (2 .5 )
h < -1 5
5 .7 ( 7 .8 )
1 3 .8 (1 2 .5 )
2 2 .5 ( 1 0 .5 )
2 9 .4 ( 4 .8 )
3 0 .8 ( 0 .6 )
2 8 .8 (3 .8 )
h < -1 5
4 .3 ( 7 .0 )
8 .0 (1 2 .1 )
1 0 .9 (1 2 .5 )
2 1 .9 (1 2 .4 )
2 8 .9 (5 .7 )
2 8 .3 ( 5 .0 )
h = - l/3
0
0
0
0
0
0
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
0
0
0
0
0
0
L ayer 3
- l/3 < h < -l
0
0
0
0
0
0
-l< h < -2
2 .7 ( 8 .2 )
4 .9 (1 0 .2 )
2 .7 ( 7 .2 )
0 .5 ( 1 .9 )
0
0
- l< h < - 2
2 .7 ( 8 .4 )
5 .9 ( 1 1 . 2 )
6 .0 ( 1 1 . 2 )
2 .1 ( 6 .8 )
0 .1 ( 0 .7 )
0 .3 ( 1 .9 )
-2 < h < -5
1 .8 ( 6 .5 )
0 .6 ( 2 .5 )
2 .3 ( 5 .6 )
0 .9 ( 3 .7 )
0
0
-2< & < -5
2 .1 ( 7 .0 )
0 .8 ( 3 .3 )
1 .8 ( 5 .7 )
3 .1 (6 5 )
1 .6 ( 5 .6 )
0.1 ( 0 .8 )
-5 < h < -1 5
1 .9 ( 6 .2 )
2 .4 ( 6 .3 )
1 .2 (2 9 )
1 .3 ( 3 .2 )
0 .3 ( 1 .9 )
0
- 5 < h < -1 5
1 .8 ( 5 .9 )
2 .4 ( 7 .0 )
0 .2 ( 0 .7 )
2 .3 ( 5 .2 )
1.8 ( 4 .5 )
1 .0 ( 3 .2 )
h < -1 5
2 4 .7 (1 1 .5 )
2 3 .1 ( 1 2 .6 )
2 3 .8 (1 1 .7 )
2 8 .3 ( 7 .4 )
3 0 .7 ( 1 .9 )
3 0 .0 ( 0 .0 )
h < -1 5
2 4 . 4 ( 1 1 .7 )
2 1 .8 (1 3 .4 )
2 2 .1 ( 1 3 .0 )
2 3 .6 (1 2 .6 )
2 7 .4 (8 .8 )
2 8 .6 ( 5 .5 )
h = - l/3
0
0
0
0
0
0
-1/3<1 i < -1
0
0
0
0
0
0
L ayer 4
h = - l/3
0
0
0
0
0
0
-1 /3 < H < -1
0
0
0
0
0
0
2 5 .6 (1 0 .6 )
-l< h < -2
2 5 .6 (1 1 .6 )
2 6 .4 (1 1 .0 )
2 5 .6 (1 0 .6 )
2 6 .4 (1 1 .0 )
2 6 .4 (1 1 .0 )
2 5 .6 (1 0 .6 )
- l< h < - 2
2 5 .6 (1 1 .6 )
2 6 .4 (1 1 .0 )
2 5 .6 ( 1 0 .6 )
2 6 .4 (1 1 .0 )
2 6 .4 ( 1 1 .0 )
-2 < h < -5
0
0
0
0
0
0
-2 < h < -5
0
0
0
0
0
0
-5 < h < -1 5
0
0
0
0
0
0
- 5 < h < -1 5
0
0
0
0
0
0
h < -1 5
5 .4 ( 1 1 . 6 )
4 .6 ( 1 1 . 0 )
4 .4 (1 0 .6 )
4 .6 (1 1 .0 )
4 .6 ( 1 1 . 0 )
4 .4 (1 0 .6 )
h < -1 5
5 .4 ( 1 1 .6 )
4 .6 (1 1 .0 )
4 .4 (1 0 .6 )
4 .6 ( 1 1 . 0 )
4 .6 ( 1 1 .0 )
4 .4 (1 0 .6 )
Table HF. Model Predicted 34 Year Mean (Standard Error) Number of Days per Month within each Soil Wetness Classes.______
_________________ Reclamation Site 4901-C (8); Pine Roots_________________
Matric
Potential
L ayer I
L ayer 2
L ayer 3
L ayer 4
_________________ Reclamation Site 4 9 0 1-C (8): Grass Roots___________
Matric
Potential
Mean (Standard Error) Number of Days per Month for 34 Years
(b a r)
A pril
M ay
Ju n e
Ju ly
A ugust
S e p t.
h = -l/3
0
0
0
0
0
0
-l/3 < h < -l
1 1 .2 ( 3 .7 )
6 .5 ( 6 .8 )
6 .0 ( 4 .9 )
2 .9 (3 7 )
1.3 ( 2 .2 )
1 .0 ( 2 .3 )
L ayer I
Mean (Standard Error) Number of Days per Month for 34 Years
(b a r)
A pril
M ay
Ju n e
July
A u g u st
h = - l/ 3
0
0
0
0
0
0
-l/3 < h < -l
1 1 .5 ( 3 .6 )
4 6 ( 5 .0 )
4 .4 (4 .5 )
1 .7 ( 2 .9 )
0 8 ( 1 .6 )
1.0 ( 2 .3 )
S ept.
-l< h < -2
2 .0 ( 1 .6 )
1 .3 ( 1 .5 )
1 4 ( 1 .2 )
0 .9 (1 0 )
0 .4 ( 0 .8 )
0 .3 ( 0 .6 )
- l< h < - 2
2 0 ( 1 .4 )
1 .3 (1 3 )
1.8 (1 .5 )
0 8 ( 1 .0 )
0 .6 (0 .9 )
0 .3 ( 0 .5 )
-2 < h < -5
L I ( 1 .0 )
1.7 ( 1 .5 )
I 6 ( 1 .3 )
L I ( 1 .6 )
0 .4 ( 0 .8 )
0 .6 ( 1 .0 )
-2 < h < -5
1 6 ( 1 .5 )
1.6 ( 1 .6 )
1 6 ( 1 .2 )
0 .7 ( 0 .9 )
0 .4 (0 8 )
0 .4 ( 0 .8 )
- 5 < h < -1 5
0
0
0
0
0
0
-5 < h < -1 5
0
0
0
0
0
0
h < -1 5
1 6 .7 ( 4 . 9 )
2 1 .5 (7 .9 )
2 0 .9 ( 5 .7 )
2 6 .1 ( 5 .2 )
2 8 .8 (3 .4 )
2 8 .1 ( 3 .3 )
h < -1 5
1 5 .9 ( 4 .1 )
2 3 .5 (6 .3 )
2 2 .2 ( 5 .5 )
2 7 .8 ( 4 .3 )
2 9 .2 ( 2 .9 )
2 8 .3 ( 3 .1 )
h = - l/3
0
0
0
0
0
0
-l/3 < h < -l
1 1 . 9 ( 1 3 .3 )
5 .1 ( 8 .6 )
1 .5 (4 6 )
0 .3 ( 1 .7 )
0
0 .3 ( 1 .9 )
L ayer 2
h = - l/ 3
0
0
0
0
0
0
- l/3 < h < -l
1 2 .7 ( 1 4 .1 )
1 1 .0 ( 1 3 .0 )
4 .3 (8 .3 )
0 .5 ( 2 .7 )
0
0 .3 ( 1 .9 )
-l< h < -2
3 .4 (6 8 )
4 .5 ( 5 .5 )
1 .2 ( 2 .5 )
0 .4 ( 1 .2 )
0 .1 ( 0 .3 )
0 .1 ( 0 .7 )
- l< h < - 2
3 2 ( 8 .2 )
3 .2 ( 5 .5 )
3 .3 (5 .2 )
1 .8 (3 8 )
0 ( 0 .2 )
0 ( 0 .2 )
-2 < h < -5
2 .7 ( 5 .3 )
3 .0 (3 4 )
1.9 ( 3 .7 )
0 .4 ( 1 .4 )
0
0 .2 ( 1 .0 )
-2 < h < -5
2 .9 ( 6 .5 )
2 .4 ( 4 .0 )
2 .4 (3 .9 )
1 .6 (3 2 )
0 .3 ( 1 .2 )
0 .2 ( 1 .0 )
- 5 < h < -1 5
2 .3 ( 3 .5 )
1 .4 ( 2 .0 )
L I ( 1 .7 )
0 .1 ( 0 .4 )
0 ( 0 .2 )
0 .3 ( 0 .9 )
-5 < h < -1 5
2 .8 ( 5 .7 )
1 .2 (2 5 )
1 2 ( 1 .5 )
0 .8 ( 1 .4 )
0.1 (0 .5 )
0 .3 ( L I )
h < -1 5
1 0 .7 ( 1 1 .5 5 )
1 7 . 0 ( 1 2 .5 )
2 4 .2 ( 9 .2 )
2 9 .8 ( 4 .0 )
3 0 .9 ( 0 .4 )
2 9 .1 ( .3 4 )
h < -1 5
9 .3 (1 1 .0 )
1 3 . 3 ( 1 3 .4 )
1 8 .9 (1 2 .8 )
2 6 .4 (8 .5 )
3 0 .6 (1 .9 )
29.1 ( 3 .2 )
0
h = - l/3
0
0
0
0
0
0
h = - l/ 3
0
0
0
0
0
- l/3 < h < -l
2 .1 ( 6 .9 )
4 .0 ( 9 .1 )
2 .8 ( 7 .6 )
0 .5 ( 2 .2 )
0
0
L ayer 3
-l/3 < h < -l
2 .7 ( 8 .2 )
5 .5 ( 1 1 . 0 )
5.1 (1 1 .0 )
1 .8 ( 6 .5 )
0 .2 ( 1 .2 )
0
-l< h < -2
2 .8 ( 7 .9 )
1 .9 ( 5 .5 )
2 .6 ( 6 .4 )
2.1 ( 5 .5 )
0 .3 ( 1 .7 )
0
- l< h < - 2
2 .4 ( 7 .5 )
L I ( 4 .4 )
2 .6 (7 .7 )
3 .9 ( 9 .4 )
2 .5 ( 7 .1 )
L I ( 5 .2 )
-2 < h < -5
0 .3 ( 1 .9 )
1.8 ( 5 .6 )
0 4 ( 1 .7 )
0 5 ( 1 .5 )
0 .2 ( 0 .9 )
0
-2 < h < -5
0 .3 ( 1 .5 )
1 3 ( 5 .4 )
0 .3 (1 .1 )
0 .6 ( 2 .2 )
L I (3 .0 )
0 .3 ( 1 .7 )
-5 < h < -1 5
1.4 ( 5 .7 )
L I ( 4 .3 )
1.4 ( 4 .8 )
0 .6 (1 .7 )
0 .4 ( 1 .8 )
0
- 5 < h < -1 5
1 .4 (5 .6 )
0 .8 ( 4 .4 )
0 .4 ( 2 .0 )
0 .9 ( 3 .1 )
0 .9 ( 2 .7 )
0 .6 ( 2 .4 )
h < -1 5
2 4 4 (1 1 .7 )
2 2 .3 (1 .3 4 )
2 2 .7 ( 1 2 .4 )
2 7 .3 ( 8 .9 )
3 0 .1 ( 4 .0 )
3 0 .0 ( 0 .0 )
h < -1 5
2 4 .3 (1 1 .9 )
2 2 .3 (1 3 .5 )
2 1 .6 ( 1 3 .2 )
2 3 . 8 ( 1 2 .4 )
2 6 .3 ( 1 0 .4 )
2 8 .0 (7 .0 )
h = -l/3
0
0
0
0
0
0
-l/3 < h < -l
2 5 .6 (1 1 .6 )
2 6 .4 ( 1 1 . 0 )
2 5 .6 ( 1 0 .6 )
2 6 .4 (1 1 .0 )
2 6 .4 ( 1 1 . 0 )
2 5 .6 (1 0 .6 )
L ayer 4
h = - l/ 3
0
0
0
0
0
0
-l/3 < h < -l
2 5 .6 ( 1 1 .6 )
2 6 .4 ( 1 1 . 0 )
2 5 .6 ( 1 0 .6 )
2 6 .4 ( 1 1 .0 )
2 6 .4 ( 1 1 .0 )
2 5 .6 ( 1 0 .6 )
- l< h < - 2
0
0
0
0
0
0
- l< h < - 2
0
0
0
0
0
0
-2 < h < -5
0
0
0
0
0
0
- 2 < h < -5
0
0
0
0
0
0
-5 < h < -1 5
0
0
0
0
0
0
-5 < h < -1 5
0
0
0
0
0
0
h < -1 5
5 .4 ( 1 1 . 6 )
4 .6 (1 1 .0 )
4 4 ( 1 0 .6 )
4 .6 ( 1 1 . 0 )
4 .6 ( 1 1 . 0 )
4 .4 ( 1 0 . 6 )
h < -1 5
5 . 4 ( 1 1 .6 )
4 .6 (1 1 .0 )
4 .4 ( 1 0 .6 )
4 6 ( 1 1 .0 )
4 6 ( 1 1 .0 )
4 .4 (1 0 .6 )
MONTANA STATE UNIVERSITY LIBRARIES
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