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Do Soil Factors Determine the Distribution
of Spineless Hopsage (Grayia brandegei)?
R. L. Pendleton
S. D. Nelson
R. L. Rodriguez
Juan CO., UT; Montezuma Creek, 6 km n. of Montezuma
Creek, SanJuan Co., UT; Bottle Hollow, 18 km e. ofRoosevelt,
Uintah Co., UT; Capitol Reef, 3 km e. of Notom Exit 24,
Wayne Co., UT; and Henry Mountains, 33 km s. ofHanksville,
Garfield Co., UT. Both tetraploid and diploid populations
were included in th~ study (see Stutz and others 1987).
At each location, on-site and off-site collection areas were
established. On-site samples were taken from within the
hops age community; off-site samples were collected from the
nearest adjacent community devoid of hopsage, keeping
slope and aspect constant whenever possible. On-site characteristics and off-site vegetation are recorded in table 1. At
each collection site, a soil profile was exposed to three feet.
Profiles were described and samples for physical and chemical analysis collected from the surface horizon, in which the
majority of hops age roots were concentrated. Site slope and
aspect were also recorded. Hopsage leaf tissue was collected
from the on-sites and returned to the laboratory for nutrient
analysis.
Abstract-Spineless hopsage (Grayia brandegei) sites are distinguished from adjacent non-hopsage sites by high levels of soluble
salts and by factors relating to small soil particle size and clay
minerology. Spineless hopsage most likely represents a stresstolerant species capable of establishing on steep eroded sites where
the combination of salinity, aridity, and fme soil texture makes
establishment of other species difficult.
Spineless hopsage (Grayia brandegei) is a small chenopod
shrub endemic to the Colorado River drainage. Also known
as Zuckia brandegei var. brandegei (Welsh and others 1987),
spineless hopsage is unusual both in its reproductive system
(Pendleton and others 1988) and in the type of habitat where
it is found. Spineless hopsage typically occurs in monotypic
stands on steep outcrops of weathering and eroded shale
(Stutz and others 1987). These sites are often visually
distinct from surrounding areas in the amount of exposed or
eroded material and lack of other vegetation, appearing as
"mini-badlands. "
Because of its ability to persist on such apparently inhospitable slopes where other species cannot, spineless hopsage
may have value in the revegetation of similarly environmentally challenging sites. However, more must be known about
factors affecting the distribution of this species before this
potential can be explored. This study was undertaken for the
purpose of documenting soil properties of sites where spineless hopsage naturally occurs and determining factors that
distinguish these sites from adjacent areas.
Methods
~~LT
------------------------------------
UTAH
Soil and vegetation samples were collected in June 1986
from nine populations of spineless hopsage growing in Utah,
Colorado, and Arizona (fig. 1). Population locations are given
as follows: Rifle, 12 km nw. of Rifle, Garfield Co., CO; Rabbit
Valley, 16 km w. of Mack, Mesa Co., CO; Round Rock, 16 km n.
of Many Farms, Apache Co., AZ; Moab, 8 km nw. of Moab,
Grand Co., UT; Blue Notch, 20 km se. of Hites Crossing, San
In: Barrow, Jerry R; McArthur, E. Durant; Sosebee, Ronald E.; Tausch,
Robin J., comps. 1996. Proceedings: shrubland ecosystem dynamics in a
changing environment; 1995 May 23-25; Las Cruces, NM. Gen. Tech. Rep.
INT-GTR-338. Ogden, UT: U.S. Department of Agriculture, Forest Service,
Intermountain Research Station.
R L. Pendleton is Ecologist, U.S. Department of Agriculture, Forest
Service, Intermountain Research Station, Shrub Sciences Laboratory, Provo,
UT 84606. S. D. Nelson is Professor of Agronomy, Department of Agronomy
and Horticulture, Brigham Young University, Provo, UT 84602. R L.
Rodriguez is Wildlife Biologist, U.S. Department of Agriculture, Forest
Service, Dixie National Forest, Cedar City, UT 84720.
lAKlL-C-'lr-y-B-H-I---,------
CR
•
Figure 1-Locations of nine study populations
of spineless hopsage.• = tetraploid popUlations;
0= diploid populations. Population locations are:
Bottle Hollow (BH), Moab (MO), Henry Mountains
(HM), Aound Aock (AA), Aifle (AI), Montezuma
Creek (MZ), Aabbit Valley (AV), Blue Notch (BN),
and Capitol Aeef (CA).
205
Table 1-Characteristics of nine population locations used in the study.
Population
location
Ploidy
leveP
Elevation
(m)
Slope %
Rifle
4X
2,130
70
W
Rabbit Valley
Round Rock
Bottle Hollow
2X
2X
4X
1,445
1,645
1,565
53
28
52
E
NW
NNE
Moab
2X
1,415
40
SW
Blue Notch
2X
1,675
70
NE
Montezuma Creek
2X
1,400
40
W
Capitol Reef
4X
1,585
62
N
Henry Mountains
4X
1,725
30
E
Off-site
vegetation
Aspect
Pinyon, Gambel oak, rose, big sagebrush, ricegrass,
rabbitbrush
Shadscale, snakeweed, groundsel
Shadscale, ricegrass, silver orach, galleta grass
Black sagebrush groundsel, phlox, buckwheat,
snakeweed, western wheatgrass
Yucca, blackbrush, ephedra, silver orach,
ricegrass, galleta grass, rabbitbrush
Blackbrush, galleta grass, pinyon, ephedra,
snakeweed, ricegrass, rabbitbrush
Snakeweed, rabbitbrush, milkvetch, needlegrass,
goldenbush
Rabbitbrush, horsebrush, ephedra, Bigelow
sagebrush, ricegrass, winterfat, snakeweed
Big sagebrush, juniper, needlegrass, ricegrass,
shadscale, Oregon grape, ricegrass, snakeweed
lDetermined by Stutz and others 1987.
principal components analysis (PCA). Percent silt, AWHC,
and extractable Zn, Fe, Mn, Cu were omitted from the
analysis in order to satisfy underlying assumptions of PCA
(no variable can be a linear combination of other variables,
and the number of variables used must be less than the
number of cases). Percent silt and AWHC are linear combinations of other variables. Of the remaining variables,
extractable Fe, Mn, and Cu were considered least likely to be
of biological significance.
The following laboratory analyses were performed on-each
soil sample: soil texture, pH, percent organic matter (%OM),
cationexchangecapacity(CEC),electricalconductivity(EC);
plant available N03-N, P, K; DPTA extractable Zn, Fe, Mn,
Cu; soluble Ca, Mg, Na, K; -0.33 bar moisture, and -15 bar
moisture (Black, part 1 & 2, 1965). Sodium absorption ratio
(SAR) and available water holding capacity (AWHC) were
calculated from the above information. Soil tests were done
by the Plant and Soil Testing Laboratory, Brigham Young
University. The selenium concentration of soil and plant
samples and total Kjeldahl nitrogen of plant samples was
determined by the Analytical Laboratories at Utah State
University. All other analyses of spineless hopsage leaf
material were conducted at the Laboratory of Biomedical
and Environmental Sciences, UCLA, using a mass sp~ctro­
photometer.
Statistical analyses were performed using the PC version
ofSAS (SAS Institute Inc. 1989). Univariate comparisons of
on- and off-sites used the paired-comparison t test. Two
multivariate analyses, principal components analysis (PROC
FACTOR) and discriminant analysis (PROC CANDISC),
were also used. Variable reduction was accomplished using
stepwise forward regression (PROC STEPDISC).
Results
Table 2-Univariate results from paired-comparison t tests on 22
soil variables. Values that differ significantly (p ~ 0.05)
between sites dominated by spineless hopsage and
adjacent non-hopsage sites are marked with an asterisk.
Variable
On-site
mean
7.9
PH
23.3
CEC (me/100g)
0.35
%OM
8.4
N03-Nay (ppm)
4.8
Pay (ppm)
274.8
Kay (ppm)
3.5
EC (dS/m)
0.35
ZN (ppm)
FE (ppm)
27.7
MN (ppm)
7.8
CU (ppm)
0.67
131.8
Ks (ppm)
161.3
CAs (ppm)
44.3
MG. (ppm)
1136.4
NAs(ppm)
302.2
SAR
29.1
%SAND
32.7
%SILT
%CLAY
38.2
-0.33 bar (%)
20.7
-15 bar (%)
15.0
AWHC(%)
5.7
----------------------------------
Soil Analyses
Spineless hopsage sites differed significantly (p ~ 0.05)
from adjacent sites in having higher levels of available K and
soluble Ca, higher EC values, and proportionately less sand
and more clay (table 2). A number of other variables were
marginally significant (0.05 ~ p ~ 0.10), suggesting that a
suite of interrelated variables distinguish hops age sites
from non-hopsage sites.
A multivariate approach for evaluating overall soil chemistry of on- and off-sites was subsequently performed using
206
Off-site
mean
7.7
15.5
0.38
3.31
5.4
171.0
0.6
0.28
28.3
13.0
0.52
7.1
46.3
11.1
68.2
53.0
39.7
28.2
32.0
15.8
10.7
5.1
Prob>ltl
1.9124
2.1507
-0.4407
2.0683
-1.1995
3.4558
3.9175
2.1953
-0.0350
-0.8410
1.0504
1.3104
2.3219
2.0765
1.9482
1.7427
-2.6018
1.2803
2.6789
2.0695
1.9021
0.3658
0.0922
0.0637
0.6711
0.0724
0.2647
0.0086*
0.0044*
0.0594
0.9729
0.4248
0.3242
0.2264
0.0488*
0.0715
0.0872
0.1196
0.0315*
0.2363
0.0280*
0.0723
0.0937
0.7240
Table 3-Principal components analysis of surface horizon
characteristics collected from 18 spineless hopsage and
non-hopsage sites. Variable units are given in table 1.
4
3
Eigenvalue
cumulative variance (%)
Character
PH
CEC
%OM
N03-N av
Pav
Kav
EC
Zn
Ks
CAs
MG s
NAs
SAR
%SAND
%CLAY
-0.33 bar
015 bar
Factor 1
6.2944
37.0
Factor 2
3.5333
57.8
Factor 3
2.5057
72.6
ORI
2
----------------- Factor pattern ----------------0.21301
-0.64383
0.40121
-0.44744
-0.38672
0.73322
-0.41205
0.74781
-0.01717
-0.33662
-0.47472
0.42378
-0.11384
0.62648
0.11563
-0.21547
0.07780
0.23178
-0.10680
-0.28413
0.88439
0.36730
0.66578
0.58412
0.71359
0.02896
0.66291
-0.41120
0.32557
0.46705
0.44978
0.18830
0.73408
0.61927
0.06328
0.75957
-0.01720
0.61502
0.73664
0.75227
-0.22998
-0.32603
-0.62525
0.35190
0.62493
-0.13796
-0.23816
0.83919
-0.17597
0.06501
0.84163
N
Moe
....
MOO
....00
co
LL
eRI
CR" BN
0
RVe"~R
OCR
BH e OBHOSN
eHM
ORV
QHM
-1
OMZ
ORR
-2
--r-----~---~---l
-2
-1
o
1
2
3
Factor 1
Figure 2-Principal component analysis of soil
characters from nine locations. Open symbols represent hopsage on-sites; filled symbols represent
values from adjacent off-sites. Population locations are: Bottle Hollow (BH), Moab (MO), Henry
Mountains (HM), Round Rock (RR), Rifle (RI),
Montezuma Creek (MZ), Rabbit Valley (RV), Blue
Notch (BN), and Capitol Reef (CR).
Results from principal components analysis are given in
table 3. Only the first three components (factors), representing over 70% of the variance, are reported. Factor one relates
both to high overall salt content and to a high percentage of
clay in the soil. High loadings (standardized regression
coefficients for each variable) were obtained for EC, SAR,
and soluble K, Mg, and Na. -0.33 bar moisture, CEC, and
-15 bar moisture are positively correlated with clay content.
Factor 2 relates to soluble salt chemistry, having high
loading values for soluble Na and K, as well as SAR. Factor
three is not readily interpretable but may relate to soil
fertility, being positively correlated with %OM, P, and Zn
concentrations and negatively correlated with pH.
A graph of site values for factors one and two reveals that
spineless hopsage sites tend to have higher values for factor
one and lower values for factor two than do non-hops age
sites (fig. 2). Hopsage sites, therefore, tend to be higher in
total salt content and heavier in texture than adjacent areas.
The Moab on-site is somewhat atypical, having more silt
than clay. However, even at this location, the move from onto off-site is accompanied by a decrease in factor one and an
increase in factor two. Factor three was not useful in distinguishing between on- and off-sites.
The forward selection procedure of STEPDISC was used
to select the subset of soil variables best revealing differences between on- and off-sites while retaining the maximum amount ofinformation. Seven variables were selected,
all of which contributed significantly in distinguishing
hopsage sites from adjacent areas (table 4). Multivariate
tests using these seven variables found highly significant
differences between on- and off-sites (table 5).
A discriminant function based on the selected variables
was obtained using the CANDISC procedure. This procedure derives a linear combination of variables that best
Table ~Partial R2 values and probability levels for seven variables
selected using forward stepwise discriminant analysis.
Variable units are given in table 1.
Variable
Kav
EC
ZN
Ks
NAs
%SAND
%CLAY
Partial
R**2
F
Prob> F
0.3503
0.6507
0.3542
0.6294
0.6174
0.7403
0.7529
5.391
18.630
5.485
16.984
16.136
28.512
30.476
0.0426
0.0015
0.0412
0.0021
0.0025
0.0003
0.0003
Table 5-Multivariate statistics and exact F statistics from discriminant
analysis using a subset of seven selected soil variables.
Num and Den refer to the numerator and denominator
degrees of freedom, respectively.
Statistic
Value
0.08087744
Wilks' Lambda
0.91912256
Pillai's Trace
Hotelling-Lawley Trace 11 .36438669
11.36438669
Roy's Greatest Root
207
F
16.2348
16.2348
16.2348
16.2348
Num Den
OF OF Pr> F
7
7
7
7
10
10
10
10
0.0001
0.0001
0.0001
0.0001
Table 6-Total canonical structure of the
discriminant function separating
spineless hopsage sites from
adjacent vegetation. Variable
units are given in table 1.
Variable
Table 7-Mineral element concentrations in leaf tissue of spineless
hopsage collected from nine locations.
Variable
N(%)
P (%)
Na(%)
K (%)
Ca(%)
Mg (%)
Si (%)
Zn (ppm)
Cu (ppm)
Fe (ppm)
Mn (ppm)
B (ppm)
AI (ppm)
Ti (ppm)
Mo (ppm)
Cr (ppm)
Sr (ppm)
Ba(ppm)
Li (ppm)
Se (ppm)
Coefficient
K
0.602867
0.684130
-0.392774
0.317005
0.461758
0.325935
0.301164
EC
%SAND
%CLAY
Na
..
K
ZN
distinguishes among groups. The squared canonical correlation between the resulting discriminant function and the
classification variable of on- or off-site was extremely high
(R 2= 0.919). The structure of the discriminant function is
given in table 6. Available Kand EC had the highest positive
coefficients or loadings, followed by water soluble Na and K,
% clay, and extractable Zn. Percent sand was negatively
correlated with a moderate loading value.
Individual site scores for the discriminant function are
plotted in figure 3. Separation of hops age on- and off-sites is
complete, confirming that the discriminant function obtained from this analysis can successfully identify/classify
these particular sites accurately. However, before it could be
used on a more universal basis, additional testing using data
obtained from other locations would be necessary. The
equation was used on soil data from one additional hopsage
site located in Antelope Valley,4kmnw. of Sterling, UT. The
resultant canonical score of 3.49 correctly identified this
location as a hopsage site.
N
Mean
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
1.85
0.17
1.31
1.19
1.40
1.54
0.14*
22.1
6.1
463.1 *
234.3
28.9
304.1*
18.3*
0.8
0.2
190.4
13.4
8.4
11.8
Standard
deviation
0.49
0.09
0.59
0.30
0.50
0.71
0.14
11.9
3.7
431.0
131.6
16.1
235.8
25.6
0.4
0.3
123.5
10.0
10.9
26.9
Range
1.36 - 2.94
0.09 - 0.40
0.76 - 2.56
0.85 -1.68
0.84 - 2.47
0.69 - 2.85
0.05 - 0.50
9.2 - 43.1
2.4 - 13.8
214.3 -1503.0
89.8 - 473.7
9.1 - 53.4
120.2- 848.3
1.4 - 79.7
0.1 -1.5
0.03 - 0.98
41.6-413.7
1.8 - 29.3
1.1 - 36.8
0.1 - 83.0
*Relatively high levels may indicate dust contamination.
reported for Grayia spinosa. Mg concentrations in Grayia
spinosa plants growing at the Nevada Test Site were consistently higher than those of other shrub species (E. M.
Romney, letter dated August 26, 1987). Grayia spinosa also
accumulates high concentrations ofK(Wallace and Romney
1972). In contrast, P and K concentrations in spineless
hopsage were relatively low when compared with other
desert shrubs growing at the Nevada Test Site. B, Mo, and
Cr concentrations are also somewhat low.
Spineless hopsage has been identified as a facultative
selenium absorber (Kingsbury 1964). Selenium concentrations in plant samples collected from the nine study populations ranged, for the most part, from 0.1 to 8.2 ppm. However, one plant sample obtained from Capital Reef had a
selenium concentration of83.0 ppm, a value consistent with
those of other secondary absorbers (Mayland 1985). The
relatively low concentration of selenium in hopsage leaf
tissue is consistent with soil selenium concentrations. Selenium concentrations in the five soils submitted for analysis
were beneath detectable levels «0.5 ppm). Unfortunately,
due to insufficient sample material, the soil sample from
Capital Reef was not included.
Plant Tissue Analyses
Mineral element concentrations in leaf tissue samples of
spineless hopsage are reported in table 7. Kjeldahl N concentration corresponds to a crude protein value of 11.5 percent,
a value consistent with those of other shrub species (Welch
and Monsen 1981). Na concentrations are fairly high compared with most other desert shrubs, but similar or even
lower than those reported for Lycium and some Atriplex
species, (Wallace and Romney 1972; Romney and Wallace
1980; Romney and others 1980; Wallace and others 1980a,b).
Mg and Mn concentrations are also high, similar to levels
Discussion ------------------------------I
-6
I
•••••
I
-5
I
I
-4
I
I
-3
I
I
-2
I
-1
In arid portions of the western United States, soil development often proceeds at a very slow rate (Buol and others
1980). Plant distribution is largely affected by soil parent
material. This is particularly true for the Colorado drainage
system, where geologic strata are exposed essentially unmodified over vast areas (Welsh and others 1987). Many
endemics present on the Colorado Plateau are edaphically
restricted specialists occurring on specific outcrops of raw
parent material (Welsh 1978).
oI
o
3
4
5
Canonical scores
Figure 3-Site scores from discriminant analysis
using seven selected soil variables. Open symbols represent hopsage on-sites; filled symbols
represent values from adjacent off-sites.
208
Spineless hopsage follows a similar pattern, occurring
exclusively on fine clay and clay loam soils derived from
exposed and eroding shales in the Colorado River drainage.
Parent formations on which it is found include the Duchesne
River, Uinta, Kaiparowits, Summerville, Morrison, Chinle,
Moenkopi, Colton, and Green River formations (Welsh and
others 1987; Pendleton and others 1988), and probably
others as well. These shales are Triassic to early Tertiary in
origin. Many are highly colored due to copper, iron, cobalt,
nickel, and vanadium compounds that coat particle surfaces
and whose colors reflect various oxidation states.
Shales in arid environments generally weather to fine
textured soils containing illite or montmorillonite clay minerals, and are frequently highly alkaline, saline, and sodic
(Buol and others 1980). High concentrations of sodium,
selenium, potassium, and micronutrients are common
(Tisdale and others 1993). The soils in our spineless hops age
study sites showed little evidence ofhorizonation, and largely
consisted of slightly weathered shales that were relatively
unleached. Our soils data show sites occupied by spineless
hopsage to have moderate levels of soluble saIts, but high
levels of exchangable sodium and potassium. SAR values for
many ofthe sites were sufficiently high (81-1286)to preclude
growth of most plant species. With the exception of zinc,
these soils also have high micronutrient levels. It can be
concluded that these sites are typical of the majority of
recently exposed soils developed from the afore-mentioned
geologic formations, and do not reflect the extreme soil
chemical and physical properties of formations such as
Mancos shale (Potter and others 1985).
Our tissue data show that spineless hopsage can accumulate selenium, and tends also to selectively accumulate
magnesium and sodium, properties it shares with related
chenopod shrubs including species of the genusAtriplex and
Grayia spinosa. Calcium and magnesium levels in spineless
hopsage leaf tissue were essentially equal in our study,
while most desert shrubs tend to have much larger Ca:Mg
ratios (Wallace and Romney 1972). One curious paradox is
potassium leaf tissue concentrations are low despite high
soil test values, which may reflect low root absorption of
tightly bound potassium. However, this is in contrast to
what other investigators have observed, particularly with
the congener Grayia spinosa (Wallace and Romney 1972).
Spineless hopsage represents a highly stress-tolerant
species (Grime and others 1988) able to survive and reproduce on steep outcrops of eroding and weathered shale
where the combination of aridity (exacerbated by steepness
of the slope), salinity (particularly Na), and high expandable-clay content makes establishment of other species difficult. Where geologic parent material changes or is covered
by alluvium, or where soils are more developed, other plant
species are able to establish and grow. Principal component
analysis of soils data reveals that the transition to other
vegetation is accompanied by a decrease in soluble salt and
clay content of the soil (Factor 1) as well as a change in cation
composition (Factor 2).
Grime's model of ecological strategies predicts that a
highly stress-tolerant species would be correspondingly poor
in competitive ability (Grime and others 1988). The lack of
spineless hopsage on immediately adjacent areas suggests
that it is indeed unable to establish in the presence of other
vegetation despite the presence of a nearby seed source, and
that its restriction to such inhospitable sites is therefore a
reflection of poor competitive ability as well as tolerance of
extreme growing conditions.
The usefulness of spineless hopsage for revegetation will
likely be limited to specialized situations where the abovementioned suite of conditions are met. However, in certain
problem areas or degraded sites where other species cannot
establish, spineless hopsage could prove a useful candidate
for slope stabilization projects. A discriminant function such
as was generated in this study may prove useful in identifying such sites. Further testing of this function will be
required, however, before its usefulness as a predictive
equation can be determined.
References -------------------------------Black, C. A; Evans, D. D.; White, J. L.; Ensminger, L. E.; Clark,
F. E., eds. 1965. Methods of soil analysis, parts 1 and 2. Madison,
WI: American Society of Agronomy, Inc. 1572 p.
Buol, S. W.; Hole, F. D.; McCracken, R. J. 1980. Soil genesis and
classification. Ames, IA: Iowa State University Press. 404 p.
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ecology. London, UK: Unwin Hyman Ltd. 742 p.
Kingsbury, J. M. 1964. Poisonous plants of the United States and
Canada. Englewood Cliffs, NJ: Prentice-Hall, Inc. 626 p.
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Wallace, A; Romney, E. M.; Hunter, R. B. 1980a. Relationship of
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Bamburg, S. A. 1980b. Parent material which produces saline
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