Rocky Mountain Juniper
Page 1.
Introduction: discussion of classification, seral assignment and monitoring.
Page 2.
Graph.
Page 3.
Instructions: plot setup and data collection using the Excel spreadsheet.
Page 4.
References.
Caution
Juniper.xls is an Excel workbook containing the datasheet for field data collection. Copy the Excel file to a
PDA. The .xls file will be converted to a Pocket Excel file with a .pxl extension. The file contains a
spreadsheet with formulas that provide calculations necessary for classification of a site, using the variables
defined for this ecological type.
Be careful with the spreadsheet when loaded on a PDA. Although the formulas and cells are protected on the
PC version of Excel, protection of spreadsheets/worksheets is not an option on the Pocket version of Excel. It
is possible to erase formulas and stop the classification system. Be sure to make changes only within the empty
cells, and not in any of the calculation or formula cells such as cov%, probabilities, etc.
In addition, always:
•
Keep a backup copy of the original ‘Juniper.pxl’ file on your PDA and,
•
Save the file under a new name after finishing data collection on each site, e.g. ‘Juniper site1.pxl’,
‘Juniper site2.pxl’…….. to avoid overwriting previous files with data.
Monitoring Seral Stages in Rocky Mountain Juniper- Littleseed Ricegrass Ecological Type
Classification, seral assignment, and monitoring of Rocky Mountain juniper-littleseed ricegrass ecological
type seral stages is according to the method of Uresk (1990). Statistical analysis of field-collected data
indicates the presence of three seral stages: late, intermediate, and early. A site is classified, and assigned to a
seral stage by entering a set of key plant measurements into the set of canonical discriminant functions
developed for this ecological type and estimating posterior probability for each seral stage (SPSS, 1995). The
site monitored is assigned to the stage with the highest posterior probability (See Juniper.xls program for
methods).
For the Rocky Mountain juniper-littleseed ricegrass ecological type the key variables are the basal area of
trees in square feet per acre for Juniperus scopulorum (JUSC), the percent canopy cover of Oryzopsis
micrantha (ORMI) using Daubenmire’s (1959) canopy cover method, and the number of J. scopulorum trees
less than 1” in diameter (STEMS).
The seral stage assigned to a set of plant measurements is always associated with the greatest probability
value. If that value is 1, then succession is at the middle of the assigned seral stage. If the greatest probability
value is less than 1, then the second greatest probability value is used to determine the successional status
relative to middle of the assigned stage. For instance, if the second greatest probability is associated with an
earlier seral stage, succession is at the lower end of the assigned seral stage. On the other hand, if the second
greatest probability is associated with a later seral stage, succession is at the upper end of the assigned stage
(see example below).
When permanent macroplots are established to assess the vegetational trend of a site, re-sampling and
comparing the previously assigned seral stage to the current stage provides information about succession or
retrogression. On a finer scale, within-stage changes in vegetation successional status can be quantified by
comparing the probability values. For example, first-year field measurements collected for basal area and
stems of Rocky Mountain juniper and canopy cover of littleseed ricegrass on a site resulted in the following
values: JUSC=21, ORMI=12, and STEMS=68. Four years later the values obtained were: JUSC=23
ORMI=13, and STEMS=76. Calculating the probabilities, we find:
JUSC ORMI
STEMS
LATE
INT
EARLY
Stage
Year1
21
12
68
.002
.793
.206
INT
Year5
23
13
76
.001
.970
.029
INT
Difference
In both years, the site was classified and assigned to
the intermediate seral stage; the greatest probability
values (.793 in Year1 and .970 in Year5) are
associated with INT.
Placement within the
intermediate seral stage is at the lower end of the
stage, as indicated by the second greatest probability
values (.206 for Year1 and .029 for Year5) which are
associated with an earlier seral stage, EARLY. The
site shows an upward successional change of about
.18, which is the difference between the probabilities
in Year1 and Year5.
.177
Intermediate
.79
Late
Year 1
1.0
.5
Late
1.0
1.0
.5
Intermediate
.97
Early
Year 5
1.0
.5
Late
The figure to the right illustrates this example.
These quantitative changes in the probabilities can
be used to evaluate and monitor the effects of
management alternatives.
Early
1.0
.5
Intermediate
.18
1.0
Early
Change
1.0
.5
1.0
.5
1.0
Page 1 of 4
Monitoring Seral Stages in Rocky Mountain Juniper- Littleseed Ricegrass Ecological Type
Rocky Mountain Juniper-Littleseed Ricegrass
Ecological Type by Seral Stages
160
Basal Area,Canopy Cover, Stems
140
Basal Area (ft2 /acre)
Ricegrass (%)
# Stems <1" (plot)
120
100
80
60
40
20
0
LATE
INTERMEDIATE
EARLY
Mean Values
Basal area (ft2 /a)
Littleseed ricegrass (%)
Number of Stems <1”
67
17
16
48
11
135
16
2
23
Mean Rocky Mountain juniper basal area (ft2/acre), % cover littleseed rice grass, number of Rocky
Mountain juniper stems less than 1 inch DBH in a 20x40 meter plot through three stages of
succession in a Rocky Mountain Juniper-Littleseed Ricegrass ecological type. Smoothed lines
connect the means for each key plant variable at each stage. Graph provides a guide for an
approximate mixture of variables at each seral stage.
Page 2 of 4
Monitoring Seral Stages in Rocky Mountain Juniper- Littleseed Ricegrass Ecological Type
DATA COLLECTION,
30m
SUMMARIZATION
OR
40m
10m
20m
40m
40m
20m
30m
30m
AND
30m
CALCULATIONS
VEG TYPE LIMITS
Juniper
Enter Juniper DBH only
DBH
BA
7.9
49
11.1
97
10.4
85
9.6
72
12.7
127
7.2
41
13.0
133
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Enter Daubenmire classes 1 through 6
Littleseed Ricegrass
Xsect
Frm
COV
1
1
1
1
2
1
3
1
4
1
1
5
1
1
6
4
1
7
1
1
8
2
1
9
3
1
10
1
11
3
1
12
1
1
13
1
14
1
1
15
1
1
16
2
1
17
2
1
18
1
1
19
1
1
20
4
1
21
1
1
22
1
23
1
24
1
25
2
1
26
1
1
27
2
1
28
2
1
29
1
1
30
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
2
4
3
2
5
3
ORMI Mean COV %
12
JUSC Basal Area
21
Enter # of Juniper STEMS
68
1
2
2
1
1
1
1
2
3
2
1
2
2
1
1
1
Seral Stage Posterior Probability
LATE
INT
ERLY
0.002
0.793
0.206
Assigned Stage
INTERMEDIATE
PLOT LIMITS
TRANSECT
1. Within the Rocky Mountain Juniper-Littleseed Ricegrass
type, establish a permanent plot with an area of 800m2.
Ideal plot dimensions are 20m x 40m; however, on some
sites it may be necessary to use two 10m x 40m plots.
Along the plot boundaries, establish two 30m transects, a
minimum of 20m apart. (See figure above)
Recommendations are to monitor two sites per section
(640 acres) within the ecological type. Sites should be at
least ¼ mile apart.
2. Using the ‘Juniper.xls’ spreadsheet (see figure at left)
installed on your PDA:
Record the DBH in inches of each Juniperus scopulorum
(JUSC) tree 1” or greater in diameter within the 800m2
plot.
Record the number of Juniperus scopulorum trees < 1”
diameter (STEMS) within the plot.
Record canopy cover of Oryzopsis micrantha (ORMI)
within a 20cm x 50cm quadrat at one-meter intervals along
each transect (30 readings/transect) using Daubenmire
(1959) class codes 1 through 6.
Class Code
1
2
3
4
5
6
Cover Class
>0 - 5%
5 - 25%
25 - 50%
50 - 75%
75 - 95%
95 – 100%
Mid Point
2.5%
15%
37.5%
62.5%
85%
97.5%
The spreadsheet calculates basal area for each tree and for the
site, and mean percent canopy cover for littleseed ricegrass
for the site. It also provides classification probabilities by
seral stage and the seral stage assignment.
‘Juniper.xls’ Calculations
Basal area per tree (in inches) = DBH2 / 4 x 3.14.
BA (ft2 / acre) = Sum basal of all trees on plot, divided by 144 to
convert basal in inches to basal in feet. BA (ft) x 5.06 converts BA
per 800m2 to BA per acre.
Cover (%) = Sum of Daubenmire cover class midpoint values for
Oryzopsis micrantha divided by 60.
Page 3 of 4
Monitoring Seral Stages in Rocky Mountain Juniper- Littleseed Ricegrass Ecological Type
REFERENCES
Daubenmire, R. 1959. A canopy-coverage method of vegetational analysis. Northwest Science.
33(1):43-64.
SPSS 12.0 for Windows. 1989-2003. SPSS Inc. 444 N Michigan, Ave, Chicago, IL 60611.
Uresk, D. W. 1990. Using multivariate techniques to quantitatively estimate ecological stages in a
mixed grass prairie. J. Range Mgt. 43(4):282-285.
Page 4 of 4