Historic, Archive Document
Do not assume content reflects current scientific knowledge, policies, or practices.
AW
r est Service
<TP' \ ,'aper RM-91 May 1972
Rocky Mountain Forest and Range Experiment Station
Forest Service
U. S. Department of Agriculture Fort Collins, Colorado
CLASSIFICATION OF DEER HABITAT IN THE PQNDEROSAJyNE FOREST
LACK HILLS, SOUTH DAKOTA
John F. Thilenius
If
02331
BJJI H
Hi I
ABSTRACT
The ponderosa pine forest was classified into 13 habitat units by cluster analysis of a similarity matrix based on the vegetation, soil, and site attributes of 100 randomly located sample stands. Habitat units were defined at a minimum similarity of 60 percent. The comparative use of the habitats by deer was evaluated by analysis of variance of long-term (9 years) data on deer pellet group densities in the sample stands.
Keywords: Wildlife management, forest-wildlife relations, syne-
COlogy, Pinus ponderosa.
USDA Forest Service Research Paper RM-91
May 1972
Classification of Deer Habitat in the Ponderosa Pine Forest of the Black Hills, South Dakota
by
John F. Thilenius, Plant Ecologist Rocky Mountain Forest and Range Experiment Station1
Central headquarters maintained at Fort Collins in cooperation with Colo- rado State University; research reported here was conducted at Rapid City, South Dakota, in cooperation with South Dakota School of Mines and Technology. The cooperation of South Dakota Game, Fish, and Parks Department is gratefully acknowledged. Author is presently located at Laramie in cooperation with the University of Wyoming.
Contents
Page
Study Area 1
Physiography and Geology 1
Climate 2
Forest Vegetation 3
Literature 3
Methods 4
Field Sampling 4
Analytical Methods 5
Results 6
Discussion 23
Habitat Evaluation 26
Summary 27
Literature Cited 28
Classification of Deer Habitat in the Ponderosa Pine Forest
of the Black Hills, South Dakota
John F. Thilenius
Almost 70 percent of the Black Hills of western South Dakota and eastern Wyoming is covered by forest where Pin us ponderosa is the only overstory tree. In 1968, the deer herd using this forest was estimated at over 120,000 animals (Richardson and Schwarting 1969). The majority of these are white-tailed deer (Odocoileus virginianus dacotensis ), but mule deer (O. hemionus hemionus ) are also present.
For many years, the South Dakota Game, Fish, and Parks Department has determined deer population trends in the Black Hills by annual counts of deer pellet groups in sample areas distributed throughout the Black Hills National Forest. The wide geographic distri- bution of these sample areas and the long-term index of deer use on them provided a unique opportunity to define and classify habitats in the ponderosa pine forest, and to evaluate habitat-deer relationships.
STUDY AREA Physiography and Geology
The Black Hills are an elliptically shaped, uplifted dome, over 1.8 million acres in area. The drainage pattern is radial-dendritic, but the majority of the permanent streams flow eastward.
The geology of the Black Hills consists of a series of concentric formations (map 1). The central formation is a region of highly dissected topography composed of metamor- phosed Precambrian quartz-mica schists with a general elevation between 4,000 and 5,500 feet. A large amount of surface rock is ex- posed. Surrounding this is a formation of Paleozoic limestone. The topography here is gently rolling, especially in the northwestern section where the limestone forms a plateau generally above 6,000 feet elevation (map 2). Several points on this plateau exceed 7,000 feet. Along the eastern edge of the Black Hills the same formation rarely exceeds 5,000 feet elevation. Steep cliffs, several hundred feet high, occur along the discontinuity between
Metamorphic quartz-mica schists (Precambrian)
Sandstone and shale (Mesozoic)
Limestone and calcareous Y//////\ Acid-igneous intrusives sandstone (Paleozoic) Y//////\ (Tertiary)
Granitic intrusives (Precambrian)
Shale (Mesozoic)
Map 1. — Geology of the Black Hills.
1
Map 2. — Elevation pattern in the Black Hills.
the limestone and adjacent formations, and along river canyons.
There are two major intrusions in the Black Hills. In the south-central portion is an intrusive massif of Precambrian granite weathered into vertical cliffs and rock spires. Harney Peak (7,241 feet), the highest elevation in the Black Hills, is an isolated summit here, but the general elevation is between 5,500 and 6,500 feet. Along the northern edge of the Black Hills are several intrusions of Tertiary acid-igneous rocks which form a rugged topog- raphy characterized by barren talus slopes. Terry Peak (7,071 feet) is the highest point in this region; most of the area, however, is between 5,000 and 6,500 feet elevation.
Encircling the periphery of the Black Hills is a region of complex geology. The outer portion of this region is a low, narrow hogback ridge of Mesozoic hard sandstone and shale. Between this hogback ridge and the central
mass is a valley formed from reddish colored Triassic and Permian soft shale and sandstone. This "Red Valley" also almost completely en- circles the central mass. Most of this region is below 4,000 feet elevation.
Climate
The precipitation pattern of the Black Hills is closely related to elevation (maps 2 and 3). Mean annual precipitation is over 26 inches at high elevations in the northern region, but
5000-6000 ft.
Map 3.— Precipitation patterns in the Black Hills.
2
less than 18 inches in the foothills and south- western Black Hills (Orr 1959). Most pre- cipitation comes as rain in May, June, and July, although yearly snowfall may exceed 100 inches at high elevations on the limestone plateau.
The temperature regime is typical of a continental climate. Mean annual temperatures in the ponderosa pine forest zone are from 41° F. to 48° F. with an extreme range of 112° F. to -40° F. Strong temperature in- versions are common during the winter, and the temperature at 5,000 feet or higher may be several degrees above freezing while the tem- perature at 3,000 feet is in the subzero range.
Forest Vegetation
The extent of ponderosa pine forest in the Black Hills generally coincides with the 4,000- foot contour, the outer edge of the limestone formation, and the 18-inch isohyete. There are approximately 1.2 million acres of forest dominated solely by Pinus ponderosa, and the general appearance of the Black Hills is that of a monoculture of this tree. Almost the entire forest is in a disturbed condition from logging, livestock grazing, mining opera- tions, wildfire, and fire protection.
Only four other species of arboreal conifers are endemic to the Black Hills. Picea glauca comprises about 4 percent of the timber volume. It is most abundant at high elevation in the northern Black Hills and in the granite area near Harney Peak. In some areas it is an overstory dominant, but more often grows co- dominant or subordinate to Pinus ponderosa. Pinus contorta var. latifolia occurs intermixed with Pinus ponderosa in one 90-acre stand in the central Black Hills. Pinus flexilis is present as a subordinate tree to Pinus ponderosa and Picea glauca in one isolated 6-acre stand near Harney Peak. In the southern Black Hills, Juniperus scopulorum may be codominant with Pinus ponderosa along the foothills.
Deciduous tree species are poorly repre- sented in the ponderosa pine forest. Only three species, Populus tremuloides , B etula papy- rifera, and Quercus macrocarpa, are important. Populus tremuloides, the most abundant, grows as a subordinate tree under the Pinus ponderosa canopy, along the ecotone between the forest and grassland at high elevation in the northern Black Hills, and as a dominant tree on old forest fire burns in the limestone and igneous regions. Be tula papyrifera is much less abundant than Populus tremuloides and is more common
on mesic sites. It usually has a multistemmed growth form. Quercus macrocarpa occurs both as a tree and as a shrub, along the foothills of the Black Hills.
While the number of species of overstory trees in the Black Hills is limited, the under- story is rich in species. Understory shrubs typical of different flora are: Ostrya virginiana (Eastern deciduous forest), Symphoricarpos occidentalis (Great Plains grassland), Juniperus communis (Northern coniferous forest), Cerco- carpus montanus (Mountain brush-type ) , A rcto- staphylos uva-ursi (Western coniferous forest).
Many graminoids (grasses, sedges, and rushes) and forbs are present. The most com- mon graminoids are: Poa pratensis, Danthonia intermedia, Oryzopsis asperifolia, Andropogon scoparius, Agropyron griffithsi, and Carex spp. Important forbs are Achillea millefolium, Cam- panula rotundifolia, Galium biflorum, Anten- naria neglecta, and Viola adunca. The legumes Vicia americana and Lathyrus ochroleucus are also common under the Pinus ponderosa canopy.
LITERATURE
Although the taxonomy of Black Hills vege- tation has been covered by Rydberg (1932) and Mcintosh (1949), there has been very little published on the synecology of the region. Hayward (1928) gave an outline of the plant communities based on the theories of F. E. Clements (1936). All of the ponderosa pine forest was classified in a single category, "western yellow pine association: Rocky Moun- tain montane forest climax." Mcintosh (1949) repeats Hayward's scheme in the plant ecology section of his paper.
In the only other paper dealing directly with synecology in the Black Hills, Leedy and Youngberg 2 described three Pinus ponderosa communities and one Picea glauca community. Although their work was based entirely on reconnaissance information, they did provide morphological descriptions of the soils under- lying these communities.
Radeke and Westin (1963) described three classes of gray wooded soils occurring as the substrate of ponderosa pine forest. These soils have developed from a variety of parent materi- als. As yet, they have not been correlated or
2 Leedy, J.D., and C. T. Youngberg. Conif- erous forest communities in the Black Hills, South Dakota. (Unpublished report, Wheaton Coll. Sci. Sta., 8 p., n.d.)
3
named. A report from the U.S. Soil Conserva- tion Service (1959) gave detailed information on the field characteristics and chemical-physical properties of the profiles described by Radeke and Westin.
The only study directly concerned with the types of deer habitat in the Black Hills was done by R. R. Hill (1946). He confined his work to the northern section and described seven types of habitat in very general terms. Important browse species occurring in the various types were listed and rated for prefer- ence, but no indication of species dominance or abundance was provided, nor was the im- portance of different types of deer habitat discussed. Hill's classification of Black Hills deer habitat is:
1. Mature or dense ponderosa pine (Pinus pon- derosa ).
2. Open ponderosa pine.
3. Northern white spruce (Picea glauca).
4. Birch -Aspen (Betula papyrifera-Populus tremuloides ).
5. Oak (Quercus macrocarpa).
6. Recent burns.
7. Open parks.
The details on the establishment of the pellet group density transects and the sampling procedures used by the South Dakota Game, Fish, and Parks Department are presented in a Pittman-Robertson Job Completion Report (Hart 1957). In 1956, 53 transects (one in each town- ship in the Black Hills National Forest), each 2,000 feet long and 10 feet wide were estab- lished. Since initial establishment the length has been decreased to 1,000 feet, the width to 6 feet, and the number of transects doubled. Six transects have been abandoned because they have been heavily grazed by sheep or logged.
At the time of establishment, data were collected on slope aspect, slope angle, over- story type (pine, deciduous, open, pine-decid- uous, pine-deciduous-spruce, doghair pine), understory type (grass, browse, forbs, litter, or any combination of these four), and percent ground visibility (poor, 0-24 percent; fair, 25-49 percent; good, 50-74 percent; excellent, 75-100 percent) of each 100-foot segment. These data have been misplaced and were not available.
A summary of this preliminary data in the report indicated (1) no relationship between pellet group density and overstory type of ground visibility; (2) a weak relationship be- tween pellet ground density and understory type, with the browse type having the highest use; (3) a preference for southerly slopes with low angles (0-10 percent). These conclusions
were based on only a single year's sample and some of the categories used, for example, browse type, are vague.
Other literature pertinent to methods and techniques are given in the appropriate sections.
METHODS
Field Sampling
The ponderosa pine forest was sampled at 100 locations within the Black Hills National Forest (map 4). All sample sites were located on transects used by the South Dakota Depart- ment of Game, Fish, and Parks to determine the size of the Black Hills deer herd by annual counts of deer pellet group densities. The transects, established several years prior to the start of this study by Department personnel,
»3
Map 4. — Location of sample stands in the Black Hills National Forest.
4
were located in a restricted random manner, two in each survey township within the boun- daries of the Black Hills National Forest.
Each treatment is a belt of one hundred 6- x 10-foot plots (total length 1,000 feet). Vegetation, soil, and site vary considerably within these long belt transects. To minimize this variation, a homogeneous area representa- tive of the most predominant habitat crossed by the transect was selected in the field as the location for the samples used in this study.
A 60- x 100-foot macroplot was established in the selected location by measuring a randomly selected distance (to the nearest 10 feet) from the starting point of the transect. This distance was restricted so the macroplot was within the selected area. Each macroplot represents a relatively homogeneous, independent, random sample of the vegetation, soil, and site attributes of the ponderosa pine forest on which there is a long-term index of the intensity of deer use.
Three randomly located plots 10 x 100 feet were established within the macroplot to sub- sample the floristic attributes. On each of these, the frequency of graminoids, forbs, low shrubs ( < 1.5 feet tall), and tree seedlings ( < 0.5 foot tall) was recorded on one hundred 1- foot -square quadrats arranged in a belt transect along the centerline of the plot. The frequency of tall shrubs ( > 1.5 feet tall) was recorded on a belt transect of twenty-five 4- x 4-foot quadrats coincident with the belt transect of 1-foot-square plots. Trees were sampled by dividing the 10- x 100-foot plot into ten 10- x 10-foot quadrats and recording the fre- quency by 4-inch d.b.h. (stem diameter at 4.5 feet above the ground surface) classes. Plot sizes were selected to give average frequencies between 20 and 80 percent for the most fre- quent taxa (Hyder et al. 1965). Frequency data from all three plots were combined for analysis.
A soil pit was excavated near the center of the macroplot and the soil described to the standards of the U.S. Soil Survey (U.S. Bur. Plant Indus., Soils and Agr. Eng. 1951). The elevation, slope aspect, slope angle, position on the slope, relief features, and percentage of ground surface covered by rock, litter, and bare ground were recorded for each macroplot. The presence of natural and man-caused in- fluences such as fire, wildlife, logging, grazing, mining, and so forth, was also recorded. Geo- logical formations were determined by refer- ence to Darton's (1951) geological map of the Black Hills and from the material excavated
from the subsurface horizons (C and R) of the soil. The precipitation regime was established by reference to Orr (1959).
Analytical Methods
The synecological units of the ponderosa pine forest were determined by grouping the sample plots into sets whose members were similar in vegetation, soil, and site attributes. Table 1 gives the analytical attributes utilized, their units of measurement, and method of encoding. To determine similarity, a numeri- cal cluster analysis procedure was used. The essentials of this program are as follows:
1. An rxc table is prepared with the attribute data as the rows (r) and the sample plots as the columns (c).
2. The diverse attribute data are standardized by setting the maximum attribute value for each row equal to 100 and scaling all other values accordingly: that is, all data are trans- formed to a relative proportion of the maxi- mum value, and thus become additive.
3. An initial matrix of similarity is computed between all possible combinations of sample plots. Sorensen's (1948) coefficient of simi- larity, K = (2c/a+b) 100 is used as the index of similarity. In this formula, "a" is the sum of all standardized attribute data for one sample plot, tfb" is this sum for another sample plot, and "c" is the sum of the lower value for each attribute common to the two sample plots. The range of K is 0 to 100, with 100 equal to complete simi- larity. Bray and Curtis (1957) sampled the same area repeatedly, and found the aver- age value of K to be 82. They concluded that because of sampling error, maximum K is approximately 80 to 85 instead of 100.
4. The initial matrix of similarity is subjected to cluster analysis by the weighted pair- group method (Sokal and Sneath 1963) as follows:
a. The two sample plots in the matrix having the highest similarity are selected and combined into a single unit or cluster.
b. A new matrix of similarity is computed between this cluster and the remaining unclustered sample plots. A simple aver- age, K = Kjj + Khj/2, replaces the two K values of the clustered sample plots. Kij equals the index of similarity be- tween one member (i) of the established
5
Table 1. — Attribute coding for computer analysis
A. Vegetation
1. Frequency of overstory trees (by species and d.b.h. class) in percent.
2. Frequency of large shrubs (by species) in percent.
3. Frequency of small shrubs, grasses, sedges, and forbs (by species) in percent.
B. Soil
1. Number of mineral horizons present.
2. Depth of solum in inches.
3. Thickness of the 01 horizon (litter) in inches.
4. Thickness of the 02 horizon (humus) in inches.
5. Thickness of the Al horizon in inches.
6. Hue of the Al horizon, scaled to give the highest value to red and the lowest to yellow.
a. 10R = 64
b. 2.5YR = 32
c. 5YR = 16
d. 7.5 YR = 8
e. 10YR = 4
f. 2.5Y = 2
g. 5Y = 1
7. pH of the Al horizon to the nearest 0.1 pH unit (elec- trometrically determined).
8. Texture of the Al horizon specified by a particle size "ratio-of-10" derived by rounding off the average per- centage of sand (2.0mm - 0.05mm), silt (0.05mm -
0. 002mm), and clay (-0.002mm) in the 12 textural classes given in the Soil Survey Manual (1951). The sum of the numerals equals 10 in all classes.
a. Sand = 910
b. Loamy sand = 811
c. Sandy clay loam = 712
d. Sandy loam = 541
e. Sandy clay = 514
f. Loam = 442
g. Clav loam = 334
h. Silt" = 181
1. Silt loam = 172
j . Silty clay loam = 163 k. Silty clay = 154 1. Clay = 118
9. Percentage of coarse fragments (+ 2mm) in the Al horizon.
10. Effervescence with HC1 of the Al horizon.
a. Violent 8
b. Strong 4
c. Slight 2
11. Thickness of the A2 horizon (eluviation zone) in inches.
12. Hue of the A2 horizon (see Item 6).
13. pH of the A2 horizon (see Item 7).
14. Texture of the A2 horizon (see Item 8).
15. Percentage of coarse fragments in the A2 horizon.
16. Effervescence with HC1 of the A2 horizon (see Item 10).
17. Thickness of the B2 horizon (illuviation zone) in inches.
18. Hue of the B2 horizon (see Item 6).
19. pH of the B2 horizon (see Item 7).
20. Texture of the B2 horizon (see Item 8).
21. Percentage of coarse fragments in the B2 horizon.
22. Effervescence of the B2 horizon (see Item 10).
23. Hue of the C horizon (see Item 6).
24. pH of the C horizon (see Item 7).
25. Texture of the C horizon (see Item 8).
26. Percentage of coarse fragments of the C horizon.
27. Effervescence of the C horizon (see Item 10). C. Site
1. Slope aspect in degrees from true north.
2. Slope angle in percent.
3. Elevation in feet.
4. Position in percentage of slope below the nearest ridge.
5. Macrorelief of general area.
a. Level = 0
b. Undulating = 5
c. Rolling = 15
d. Hilly = 30
e. Steep = 50
6. Microrelief in immediate vicinity of plot.
a. Concave = 1
b. Flat = 2
c. Convex = 3
7. Percentage of ground .covered by rocks.
8. Percentage of ground covered by litter.
9. Percentage of bare ground.
cluster (i+h) and an unclustered sample plot (j), and K^j is equal to this index for the other member of the established cluster.
c. Steps tca" and tfb" above are repeated until all sample plots have been clustered.
The results of cluster analysis are presented in a dendrogram (fig. 1). The vertical axis of the dendrogram merely separates the sample plots and has no scale. The horizontal axis is scaled in units of K (percentage similarity). Junction points between stems along the hori- zontal axis indicate the sample plots to the left of the junctions are alike at the K value shown on the horizontal axis scale.
The number of groups of sample plots to be designated is determined by drawing a line across the dendrogram parallel to the vertical axis at a designated level of K. The number of stems cut by this line indicates the number of units present. In this paper these units are called "Habitat Units" (hereafter abbreviated "HU").
The level of K at which HU are designated is variable and depends primarily on the use to which the classification is to be put and the ecosystem under consideration (West 1966). Mathematical or statistical tests to determine significant gaps in continuity are not yet avail-
able, and the usual statistical tests of signifi- cance are not applicable (Sokal and Sneath 1963). Whatever level of K is selected, it must be applied uniformly across the whole dendro- gram; in other words, it is not permissible to designate one HU at K = 60 and another at K =70 (Sneath 1962).
RESULTS
The similarity relationships of the 100 stands sampled are shown in figure 1. This dendro- gram is based on 334 attributes of vegetation, soil, and site, and is arranged so the stands occurring at high elevation in the central and northern Black Hills are uppermost.
Habitat Units have been designated at two levels of similarity. These are K>54 and K>60. At K>54 ( 54 percent minimum internal simi- larity in vegetation, soil, and site attributes) three HU are present.
HU-A (40 stands) is found in the high- elevation, moist region of the northwestern and western Black Hills. The ponderosa pine forest understory here has well-developed shrub and herb strata composed of mesophytic taxa, many of which are present at high frequency.
HU-B (31 stands) occurs at intermediate to low elevations in the northeastern and central
6
Stand
025 034 094 030 065 095 035 085 105 039 061 024 079 041 038 092 037 015 048 044 077 049 056 045 012 070 018 096 001 066 063 019 031 014 088 067 029 004 028 091 064 069 087 062 026 032 042 023 007 040 081 102 046 082 106 020 033 027 022 084 083 086 021 090 078 055 051 053 060 089 059 002 073 068 003 072 099 047 008 076 005 010 101 075 016 009 100 01 I 006 103 013 098 052 080 017 074 043 050 054 104
Figure 1. — Dendrogram showing the simi- larity relationships of the 100 stands sampled.
±3
s
10
12
13
1
85
80
75
70 65 K (percent similarity)
60
55
50
7
part of the Black Hills. Shrubs are still the most important taxa in the understory, but the more mesophytic taxa are much less frequent and a number of xerophytic taxa with prairie affinities are present.
HU-C (29 stands) is present along the northern foothills and in the relatively low- elevation region of the southern Black Hills. Graminoids are the most frequent taxa in the forest understory. Many forbs with prairie affinities are present, and shrub taxa tend to be those adapted to xeric environments.
While the HU designated at K>54 can be related in a general manner to the gross eco- logical and geographic features of the Black Hills, they are highly variable in taxa composi- tion and other attributes. Since HU can be designated at any level of similarity, the in- ternal homogeneity of HU is increased by rais- ing the value of K. The rule followed is to select a level of similarity which maximizes the number of HU containing three or more sample stands. In HU with several stands, the range of within-HU attribute variability
Table 2. --Percent constancy (C) , average percent frequency (F) , and maximum percent frequency (M) of major taxa1 in the habitat units (HU) defined at K>60 , with number of stands (n)
Taxa2
HU- 1 (n=24)
HU-2 (n=9)
HU-3 (n=l)
HU-4 (n=6)
HU-5 (n=25)
OVERSTORY STRATUM
Pinus ponderosa
<4 inches d.b.h.
4-8 inches d.b.h.
8-12 inches d.b.h.
>1 2 i nches d.b.h. Picea glauoa
<4 inches d.b.h.
4-8 inches d.b.h. Populus tremuloides
<4 i nches d.b.h.
4-8 inches d.b.h. Betula papyri fera
<4 inches d.b.h.
4-8 inches d.b.h. Quereus macro carpa
<4 inches d.b.h.
4-8 inches d.b.h.
8-12 i nches d.b.h.
>12 inches d.b.h. Juniperus scopulorum
<4 inches d.b.h.
TALL SHRUB STRATUM
Juniperus communis3 Shepherdia canadensis 3 Potentilla fvuticosa Symphoricarpos occidentalis Prunus virginiana1* Ostrya virginiana Quereus maerocarpa Corylus cornuta Cercocarpus montanus Rhus trilobata
LOW SHRUB STRATUM
Symphoricarpos albus Rosa fendleri Amelanchier alnifolia5 Spiraea lucida Ribes inebrians Amorpha canescens Yucca glauca
|
92 |
30 |
87 |
100 |
55 |
87 |
|
88 |
20 |
50 |
100 |
22 ' |
73 |
|
83 |
1 1 |
30 |
67 |
5 |
13 |
|
75 |
10 |
27 |
33 |
3 |
10 |
|
8 |
6 |
73 |
|||
|
21 |
4 |
53 |
|||
|
54 |
10 |
37 |
44 |
14 |
67 |
|
42 |
4 |
53 |
22 |
1 |
7 |
22 1 1
10
3
|
83 |
27 |
95 |
22 |
-1 |
3 |
|
58 |
6 |
56 |
67 |
14 |
47 |
|
13 |
-1 |
4 |
22 |
2 |
15 |
|
46 |
8 |
40 |
44 |
5 |
24 |
|
100 |
44 |
90 |
100 |
46 |
69 |
|
96 |
20 |
49 |
100 |
23 |
59 |
|
83 |
14 |
50 |
100 |
10 |
23 |
|
63 |
18 |
66 |
78 |
16 |
49 |
|
8 |
1 |
23 |
22 |
-1 |
3 |
Percent
10 10
56 66 85
60 22 4
50
I 00
17
50 100
67 33 67
42 84
•1
22 20
2 1 -1
1
51 39
|
67 |
14 |
53 |
100 |
62 |
100 |
|
67 |
8 |
17 |
88 |
30 |
90 |
|
67 |
10 |
h3 |
64 |
8 |
37 |
|
17 |
1 |
3 |
32 |
2 |
13 |
|
17 |
1 |
3 |
20 |
5 |
47 |
12
12 12
56 56 4
60 8 24
12
7 10
36 52
1
72
1
17
|
100 |
29 |
82 |
|
8o |
13 |
67 |
|
84 |
12 |
44 |
|
68 |
17 |
65 |
|
20 |
-1 |
1 1 |
|
28 |
6 |
85 |
1 All overstory species plus understory taxa with at least 67 percent constancy in a multistand HU or 20 percent frequency in a single-stand HU .
2 Indicator taxa for each HU are underlined.
3 Growing as a low shrub in HU-5.
4 Growing as a low shrub in HU-12.
5 Growing as a tall shrub in HU-2.
8
can be determined, and constancy 3 values for attributes can be computed. For the pon- derosa pine forest a level of K > 60 best fits this rule.
Constancy is a relative expression of the presence and absence of a species in different stands of a community type, based on equal area samples. Frequency is a statistical ex- pression of the representation (presence or absence) of a species in a series of subsamples within a given stand (Cain and Castro 1959).
At K>60, 13 HU can be defined (fig. 1). The following section contains brief descriptions of each of the HU. It proceeds from the most mesic to the most xeric— from top to bottom on the dendrogram (fig. 1). The HU are desig- nated serially from 1 to 13 and by a multi- nomial formed from the scientific names of indicator taxa in the overstory, tall-shrub, low- shrub, and herb strata. Table 2 gives the percent constancy and average and maximum percent frequencies for the major taxa in each HU.
HU-6 (n=4) HU-7 (n=1) HU-8 (n=l) HU-9 (n=7) HU-10 (n=3) HU-11 (n=9) HU-12 (n=9) HU-13 (n=l)
CFM CFMCFM CFM CFM CFM CFM CFM
Percent
|
100 |
22 |
43 |
10 — |
i|t, |
100 |
17 |
47 |
100 |
9 |
20 |
100 |
29 |
63 |
89 |
18 |
43 |
-1 |
|
|
100 |
17 |
27 |
- 43 - |
7 — |
100 |
17 |
37 |
67 |
8 |
17 |
69 |
17 |
27 |
78 |
7 |
23 |
||
|
75 |
13 |
27 |
7 — |
— 13 — |
57 |
10 |
37 |
33 |
2 |
7 |
89 |
13 |
23 |
33 |
2 |
10 |
||
|
50 |
8 |
20 |
29 |
3 |
13 |
67 |
2 |
3 |
56 |
h |
13 |
33 |
2 |
13 |
10
100 53 90 -- _23_ 50 3 7 --7 10
-- ~ — — 3
100 13
20
22
27
56 8 20 11 6 3
50 2 9 — — — — 8
~ — — -- -- - -- 57
-- - -- -- - — -- 8
25 2 8 1 —
100 66 83 -- _5_4 -- -- _77
75 5 20 — — — -- --
100 42 79 — 13 --
25 3 11 ~ — — ~ 31
14
43 28
1
13
76 43
33 2 7
33 8 24
100 85 87 100 10 20
22 44
2
75
22 4 29
11 -1 3
33 22 100
78 29 88
11 -l 1
44 7 35
11-1 1
100 56 81 -- _69_ — -- 36
75 2 5 — — -- - 25
100 37 69 — 2 — — 87
100 25 36 -- 13 -- -- ~3TT
- - - -- - - - 8
50 15 39 — — —
|
57 |
25 |
84 |
100 |
27 |
57 |
|
57 |
19 |
56 |
100 |
2 |
2 |
|
43 |
4 |
16 |
33 |
1 |
3 |
|
14 |
-1 |
2 |
|||
|
29 |
1 |
7 |
67 |
3 |
7 |
|
67 |
-1 |
1 |
67 78 33
22 1 1 1 1
21 4
|
60 |
56 |
13 |
63 |
|
20 |
89 |
3 |
7 |
|
13 |
56 |
13 |
46 |
|
22 |
2 |
12 |
|
|
21 |
|||
|
-1 |
67 |
6 |
1 1 |
|
-1 |
33 |
7 |
41 |
Cont i nued--
9
Table 2. --Percent constancy (C) , average percent frequency (F) , and maximum percent frequency (M) of major taxa1 in the habitat units (HU) defined at K>60 , with number of stands (n) --Cont i nued
Taxa2
HU-1 (n=24)
HU-2 (n=9)
HU-3 (n=D
HU-4 (n=6)
HU-5 (n=25)
Percent
HERB STRATUM
Sh rubs
Berberis repens Arotostaphylos uva-ursi Pinus ponderosa (seedlings) Toxicodendron radioans Artemisia frigida
G rami no i ds
Orysopsis asperifolia Danthonia intermedia Poa pratensis Carex concinna Agropyron griffithsi Carex foenea Bromus inermis Carex heliophila Stipa viridula Schizachne purpuras oens Koeleria cristata Andropogon sooparius Bouteloua curtipendula Agropyron smithii Bouteloua gracilis
Forbs
Achillea millefolium Fragaria vesca Galium biflorum Viola adunca Vicia americana Lathy rus ochroleucus Campanula rotundifolia Zizia aptera Antennaria neglecta Thermopsis rhombifolia Erigeron subtrinervis Lupinus argenteus Monarda fistulosa Aster laevis
Apocynum androsaemi folium Solidago oocidentalis Anemone patens Astragalus alpinus Clematis hirsutissima Solidago nemoralis Potentilla hippiana Iris missouriensis Antennaria rosea Smilacina stellata Maianthemum canadense Sanicula marilandica Lupinus parviflorus Artemisia ludoviciana Phlox hoodii Zygadenus elegans Hymenoxys acaulis Musineon divaricatum Grindelia squarrosa Leucocrinum montanum Geum triflorum Phlox alyssiofolia Polygala alba Echinacea angusti folia Chrysopsis villosa
96 92 71
29
42
91 56
|
83 |
27 |
75 |
|
^3 |
19 |
85 |
|
71 |
18 |
87 |
|
71 |
7 |
29 |
|
50 |
Z) |
24 |
|
63 |
1 0 |
67 |
|
1 7 |
2 |
20 |
|
29 |
2, |
58 |
|
38 |
2 |
1 6 |
|
8 |
- ] |
4 |
|
1 7 * 1 |
-1 |
Li |
|
h |
1 |
16 |
|
100 |
25 |
52 |
|
100 |
26 |
57 |
|
100 |
22 |
58 |
|
100 |
8 |
23 |
|
96 |
10 |
29 |
|
88 |
22 |
65 |
|
88 |
3 |
13 |
|
79 |
6 |
17 |
|
79 |
4 |
18 |
|
75 |
6 |
34 |
|
71 |
7 |
29 |
|
71 |
6 |
33 |
|
67 |
6 |
28 |
|
54 |
2 |
1 1 |
|
29 |
1 |
10 |
|
42 |
2 |
23 |
|
50 |
6 |
39 |
|
13 |
3 |
52 |
|
17 |
2 |
28 |
|
8 |
-1 |
3 |
|
13 |
1 |
13 |
|
54 |
1 |
8 |
|
33 |
2 |
30 |
|
8 |
-1 |
3 |
|
13 |
-1 |
8 |
|
38 |
5 |
24 |
1 17
|
100 |
56 |
91 |
|
100 |
4 |
10 |
|
22 |
6 |
48 |
|
78 |
5 |
13 |
|
78 |
40 |
80 |
|
56 |
6 |
33 |
|
67 |
7 |
25 |
|
78 |
16 |
50 |
|
67 |
24 |
70 |
|
22 |
2 |
21 |
|
56 |
5 |
21 |
|
1 1 |
1 |
7 |
|
22 |
1 |
8 |
|
56 |
6 |
16 |
|
44 |
1 |
7 |
|
100 |
18 |
27 |
|
89 |
16 |
33 |
|
89 |
6 |
13 |
|
67 |
9 |
34 |
|
22 |
1 |
7 |
|
67 |
5 |
14 |
|
100 |
6 |
13 |
|
44 |
2 |
9 |
|
100 |
1 1 |
21 |
|
44 |
18 |
74 |
|
44 |
5 |
22 |
|
56 |
8 |
50 |
|
56 |
8 |
25 |
|
100 |
1 1 |
26 |
|
78 |
8 |
22 |
|
67 |
3 |
9 |
|
44 |
2 |
9 |
56 33
22 10
21
20 4
17
1 1
21 21
|
17 |
8 |
48 |
|
83 |
1 |
3 |
|
33 |
3 |
17 |
|
50 |
7 |
41 |
|
67 |
18 |
50 |
|
100 |
74 |
98 |
|
17 |
-1 |
1 |
|
17 |
6 |
36 |
|
67 |
23 |
62 |
|
67 |
5 |
10 |
33 33
50
•1 2 4 13
|
100 |
37 |
55 |
|
100 |
12 |
29 |
|
67 |
20 |
52 |
|
67 |
4 |
8 |
|
67 |
8 |
31 |
|
83 |
5 |
14 |
|
67 |
it |
9 |
|
50 |
1 |
3 |
|
100 |
10 |
16 |
|
50 |
1 1 |
39 |
|
67 |
7 |
16 |
|
33 |
-1 |
1 |
|
67 |
l |
3 |
|
50 |
1 1 |
49 |
|
67 |
10 |
27 |
|
67 |
5 |
29 |
|
67 |
3 |
16 |
|
67 |
1 |
5 |
|
50 |
2 |
22 |
15 46
|
88 |
39 |
87 |
|
100 |
9 |
30 |
|
20 |
3 |
34 |
|
8 |
-1 |
k |
|
60 |
13 |
52 |
|
92 |
14 |
71 |
|
52 |
4 |
44 |
|
80 |
15 |
83 |
|
40 |
3 |
22 |
|
24 |
2 |
22 |
|
8 |
1 |
9 |
|
40 |
7 |
44 |
|
8 |
-1 |
6 |
|
4 |
-1 |
1 |
|
36 |
1 |
14 |
|
44 |
7 |
56 |
|
8 |
1 |
13 |
|
88 |
9 |
37 |
|
68 |
6 |
36 |
|
64 |
3 |
23 |
|
68 |
2 |
7 |
|
36 |
2 |
14 |
|
44 |
7 |
31 |
|
76 |
3 |
12 |
|
28 |
-1 |
7 |
|
84 |
5 |
30 |
|
32 |
3 |
17 |
|
48 |
2 |
18 |
|
44 |
2 |
20 |
|
84 |
6 |
34 |
|
68 |
40 |
|
|
56 |
2 |
14 |
|
44 |
3 |
36 |
|
k |
-1 |
22 |
|
24 |
-1 |
5 |
|
4 |
-1 |
3 |
|
52 |
1 |
7 |
|
60 |
4 |
23 |
4 12 12
44
2 13
1 All overstory species plus understory taxa with at least 67 percent constancy in a multistand HU or 20 percent frequency in a single-stand HU.
2 Indicator taxa for each HU are underlined.
JO
|
HU-6 |
(n= |
=4) |
HU-7 (n=D |
HU-8 (n=l) |
HU-9 |
(n= |
7) |
HU- |
10 (n |
=3) |
HU- |
11 (n |
=9) |
HU- |
12 (n |
=9) |
HU-13 (n=l) |
|
C |
F |
M |
C F M |
C F M |
C |
F |
M |
C |
F |
M |
C |
F |
M |
C |
F |
M |
C F M |
|
100 |
73 |
82 |
34 — |
1 1 |
1 |
7 |
|||||||||||
|
50 |
1 |
4 |
-- 24 -- |
43 |
14 |
37 |
33 |
-1 |
-1 |
33 |
1 |
6 |
1 1 |
2 |
19 |
||
|
75 |
12 |
29 |
86 |
5 |
19 |
33 |
-1 |
1 |
78 |
9 |
25 |
78 |
5 |
19 |
|||
|
100 |
it |
5 |
2 -- |
1 1 |
-1 |
-1 |
44 |
1 |
3 |
||||||||
|
43 |
5 |
1 8 |
100 |
g |
1 7 |
22 |
6 |
39 |
1 1 |
2 |
1 7 |
27 -- |
|||||
|
75 |
34 |
70 |
14 |
1 |
7 |
22 |
4 |
37 |
|||||||||
|
1 00 |
26 |
60 |
6 -- |
1 00 |
40 |
59 |
1 1 |
5 |
41 |
33 |
2 |
1 1 |
|||||
|
1 00 |
20 |
67 |
18 — |
CO J*- |
1 00 |
99 |
67 |
1 |
â– x j |
33 j j |
c, |
23 |
56 |
40 |
98 |
||
|
2:,5 ^ — > |
1 |
43 |
7 |
29 |
33 |
2 |
7 |
33 |
1 |
7 / |
1 1 |
-1 |
3 |
||||
|
25 |
-1 |
1 |
14 -- |
71 |
8 |
39 |
1 00 |
24 |
46 |
44 |
2 |
1 1 |
|||||
|
75 |
16 |
34 |
75 -- |
57 |
1 1 |
41 |
67 |
1 1 |
20 |
67 |
1 7 |
72 |
33 |
4 |
25 |
||
|
14 |
-1 |
3 |
1 1 |
-1 |
5 |
||||||||||||
|
50 |
12 |
37 |
43 |
1 |
4 |
22 |
-1 |
2 |
22 |
2 |
10 |
2 -- |
|||||
|
33 |
-1 |
-1 |
67 |
13 |
38 |
56 |
6 |
29 |
|||||||||
|
62 — |
|||||||||||||||||
|
100 |
16 |
26 |
100 |
14 |
20 |
89 |
4 |
10 |
44 |
I |
18 |
12 — |
|||||
|
25/ • |
2 |
6 |
|
1 __ |
14 |
4 |
28 |
100 |
38 |
57 |
100 |
37 |
82 |
78 |
36 |
85 |
79 — |
|
14 |
2 |
10 |
100 |
19 |
36 |
56 |
2 |
7 |
1 1 |
2 |
16 |
-- ~24~ -- |
|||||
|
56 |
26 |
84 |
22 |
1 |
6 |
||||||||||||
|
33 |
1 |
4 |
22 |
2 |
1 5 |
- _68 -- |
|||||||||||
|
100 |
10 |
23 |
-- -1 - |
15 — |
100 |
12 |
1 5 |
1 00 |
3 |
4 |
78 |
5 |
13 |
44 |
5 |
34 |
|
|
75 |
2 |
4 |
29 |
1 |
6 |
33 |
-1 |
-1 |
44 |
2 |
6 |
||||||
|
50 |
l| |
10 |
21 -- |
— 55 -- |
57 |
7 |
28 |
67 |
4 |
10 |
44 |
3 |
16 |
44 |
6 |
26 |
|
|
100 |
5 |
10 |
33 -- |
57 |
1 |
2 |
33 |
-1 |
-1 |
44 |
2 |
8 |
44 |
2 |
1 |
||
|
100 |
5 |
7 |
3 __ |
— Ik — |
29 |
1 |
5 |
33 |
2 |
5 |
67 |
7 |
16 |
1 1 |
l] |
6 |
|
|
100 |
1 1 |
31 |
6 — |
3 __ |
14 |
-1 |
2 |
44 |
12 |
||||||||
|
50 |
1 |
3 |
5 -- |
71 |
4 |
1 1 |
67 |
-1 |
-1 |
67 |
2 |
4 |
56 |
! |
7 |
3 __ |
|
|
25 |
-1 |
1 |
|
14 |
-1 |
2 |
44 |
2 |
12 |
||||||||
|
75 |
1 |
2 |
-- -1 - |
12 — |
57 |
2 |
10 |
33 |
-1 |
-1 |
22 |
1 |
10 |
33 |
-1 |
3 |
|
|
75 |
2 |
5 — |
29 |
5 |
37 |
22 |
_1 |
1 |
|||||||||
|
1 00 |
1 2 |
33 |
48 -- |
71 |
1 |
5 |
1 1 |
-1 |
-1 |
56 |
7 |
||||||
|
25 |
-1 |
1 |
12 — |
29 |
4 |
19 |
67 |
-1 |
1 |
44 |
V<1' |
7 |
1 1 |
_1 |
5 |
||
|
50 |
2 |
5 |
2 — |
15 — |
57 |
4 |
21 |
1 1 |
-1 |
1 |
33 |
24 |
|||||
|
_1 |
8 -- |
86 |
2 |
7 |
100 |
7 |
8 |
67 |
10 |
32 |
44 |
_1 |
3 |
||||
|
14 |
2 |
10 |
33 |
-1 |
-1 |
1 1 |
-1 |
4 |
|||||||||
|
3 __ |
71 |
5 |
l 4 |
1 1 |
1 |
8 |
33 |
j |
|||||||||
|
14 |
-1 |
1 |
22 |
3 |
|||||||||||||
|
-1 -- |
29 |
5 |
3 |
33 |
-1 |
l |
|||||||||||
|
25 |
1 |
71 |
4 |
20 |
67 |
3 |
7 |
78 |
2 |
5 |
1 1 |
_1 |
-1 |
||||
|
75 |
3 |
6 |
44 __ |
20 -- |
43 |
5 |
30 |
33 |
2 |
7 |
33 |
_1 |
9 |
||||
|
75 |
it |
1 1 |
11 -- |
||||||||||||||
|
75 |
2 |
5 |
|||||||||||||||
|
25 |
-1 |
2 |
29 |
3 |
1 1 |
33 |
-1 |
1 |
56 |
2 |
13 |
1 1 |
2 |
17 |
|||
|
3 __ |
43 |
3 |
10 |
100 |
18 |
27 |
56 |
2 |
22 |
78 |
1 1 |
44 |
|||||
|
67 |
7 |
14 |
1 1 |
-1 |
1 |
||||||||||||
|
29 |
-1 |
2 |
67 |
5 |
13 |
||||||||||||
|
100 |
2 |
3 |
33 |
2 |
8 |
22 |
3 |
25 |
— 16 — |
||||||||
|
67 |
4 |
7 |
33 |
-1 |
2 |
||||||||||||
|
67 |
1 |
1 |
|||||||||||||||
|
67 |
1 |
1 |
78 |
2 |
5 |
||||||||||||
|
67 |
-1 |
1 |
|||||||||||||||
|
14 |
1 |
8 |
67 |
6 |
19 |
||||||||||||
|
1 1 |
-1 |
5 |
~ 29 ~ |
— 26 -- 20 --
1 1
HU-1: Pinus ponderosa/Juniperus communis / Symphoricarpos albus/Berberis repens (fig. 2).
HU-1 is found on the limestone plateau of the northwestern and western Black Hills (map 4). The average elevation of the 24 sample stands is 6,315 feet (range: 5,675 to 6,775 feet). Most of the stands occur between the 22- and 24-inch isohyets, which makes this the most mesic HU of the ponderosa pine forest.
The relatively high constancy and frequency of all sizes classes of Pinus ponderosa indicates this HU provides good growing conditions for this species. The presence of Picea glauca and Populus tremuloides in many stands is a further indication of the mesic nature of this HU.
The understory in most of the stands is characterized by a tall-shrub stratum of Juni- perus communis 3 feet or more in height, and a low-shrub stratum with Symphoricarpos albus as the most frequent species. Shrubs are also important components of the herb stratum. Dense mats of the prostrate, woody perennial A rctostaphylos uva-ursi are a common feature. However, the most characteristic shrub in the herb stratum is Berberis repens.
Many species of graminoids and forbs are present at high constancy and frequency in the herb stratum. Among the most important are Oryzopsis asperifolia, Achillea millefolium, Fragaria vesca, Galium biflorum, and the in- digenous legumes Vicia americana and Lathy- rus ochroleucus. It should be noted that except for Berberis repens, all of the important species in the HU also occur in several other HU. Because we are dealing with subdivisions of a larger entity with a common dominant attribute, that is, a forest dominated by Pinus ponderosa, the presence of many of the same species in several HU is not unexpected.
All of the soils described in this HU are developed from limestone parent material. They have well-developed sola with an A1/A2/B2/C horizon sequence. The average solum depth is 15.0 inches (range: 8.0 to 37.0 inches) and the reaction is neutral to basic through the entire solum, with strong effervescence with hydro- chloric acid in the lower horizons.
Figure 2.—HU- 1:
Pinus ponderosa / Juniperus communis / Symphoricarpos albus/Berberis repens
1 2
Figure 3.—HU- 2:
Pinus ponderosa /Shepherdia canadensis / Symphoricarpos albus / Arctostaphylos uva- ursi
HU-2: Pinus ponderosa /Shepherdia canaden- sis /Symphoricarpos albus /Arctostaphy- los uva-ursi (fig. 3).
HU-2 is present in the same general geo- graphic region of the Black Hills as HU-1 (map 1), but at lower elevations (mean: 5,660 feet; range: 5,575 to 6,000 feet) and on noncalcareous geologic material. Annual precipitation for all stands is between 20 and 22 inches.
Constancy and frequency of the two smallest size classes of Pinus ponderosa are slightly greater than in HU-1. Picea glauca did not occur in any of the nine sample stands included in HU-2, but Populus tremuloides and Betula papyrifera are occasional members of the over- story canopy. Betula papyrifera is usually most abundant on and around outcrops of vertically oriented rock, a common feature of the HU-2 landscape.
Shepherdia canadensis is the most frequent member of the tall-shrub stratum, but it is present at relatively low constancy and fre- quency. Juniperus communis is much less frequent than in HU-1. The most important low shrubs are Symphoricarpos albus, Rosa fendleri, and Amelanchier alnifolia. Arcto- staphylos uva-ursi is the shrub dominant in the herb stratum. Berberis repens is com- pletely absent.
The constancy and both mean and maxi- mum frequencies of graminoids and forbs are lower in HU-2 than in HU-1. Danthonia inter- media and Agropyron griffithsi are the most common graminoids. Oryzopsis asperifolia has relatively high constancy, but low frequency. Achillea millefolium, Apocynum androsaemi- folium, Antennaria neglecta, and Campanula rotundifolia are high-constancy forb species. Thermopsis rhombifolia, present at high fre- quency in four of the nine stands included in the HU, is rare elsewhere in the ponderosa pine forest.
Soils in HU-2 are developed from either micaceous schists or metamorphosed rocks which are high in iron. All but one of the nine profiles described have the A1/A2/B2/C horizon sequence. The exception is located on a steep talus slope covered by an overlay of colluvium, and has an Al/C/R sequence. Soil reaction is acidic throughout the sola (mean: pH 5.7; range pH 5.1 to 6.1). The average depth to the C horizon is 15.2 inches (range: 4 to 27 inches).
1 3
HU-3: Pinus ponderosa/Potentilla fruticosa/ Symphorocarpos albus /Frag aria vesca (fig. 4).
HU-3 is represented by a single stand on the north side of an exposed limestone ridge at an elevation of 6,895 feet, the highest stand sampled.
The overstory is a stand of Pinus ponderosa predominantly in the 4 to 8 d.b.h. class. No other species of trees are present.
The understory is characterized by a well- developed tall-shrub stratum, with Potentilla fruticosa as the most frequent species. This is the only HU in the ponderosa pine forest where Potentilla fruticosa is present at more than 8 percent frequency. In the Black Hills, it usually grows on the ecotone between moun- tain grasslands and ponderosa pine-white spruce (Picea glauca) forest on the limestone plateau. It appears to be confined to soils derived from calcareous parent materials. Shepherdia cana- densis and Juniperus communis are both present at high frequency in the tall-shrub stratum. The low-shrub stratum is dominated by Sym- phoricarpos albus with Rosa fendleri as a species of secondary importance.
The herb stratum is poorly developed. Both Arctostaphylos uva-ursi and Berberis repens are absent. Only five species of graminoids and forbs exceed 20 percent frequency, and only 13 herb species are present. Of these, Fragaria vesca is the most frequent.
The solum is stony throughout with a weakly developed, clayey surface (Al) horizon about 9 inches thick. Below 9 inches the soil is approximately 80 percent limestone rock with a range in pH of 7.7 to 8.1.
HU-4: Pinus ponderosa/Symphoricarpos Occi- dent alis /Rosa fendleri /Poa pratensis (fig. 5).
HU-4 occupies the ecotone between dense ponderosa pine forest and adjacent meadows dominated by Poa pratensis. It is present at elevations averaging 5,900 feet (range: 5,100 to 6,450 feet) on a variety of geologic formations in the central region of the Black Hills. Aver- age annual precipitation for all stands is 20 inches or more.
The Pinus ponderosa overstory is open, and the trees occur at much lower constancy and frequency than in any of the previously described HU.
The major species in the tall-shrub stratum is Symphoricarpos occidentalis . This species
Figure 4.—HU- 3:
Pinus ponderosa / Potentilla fruticosa /Symphoricarpos al- bus/Fragaria vesca
is indigenous to meadows at low to moderately high elevations in the Black Hills, and is com- mon on the prairies to the east. It does not appear to be well adapted to calcareous soils since it is absent from the meadows on the limestone plateau.
The low-shrub stratum has Rosa fendleri and Rosa suffulata as the most important com- ponents. Since these two species were difficult to identify on the basis of vegetative character- istics they have been combined in table 2 under Rosa fendleri.
Poa pratensis is by far the most important species in the herb stratum; all other graminoids are present at much lower constancy and fre- quency. The presence of Stipa viridula and
1 4
Figure 5.—HU- 4:
Pinus ponderosa / Symphori-
carpos occidentalis / Rosa
fendleri/Poa pratensis
Car ex heliophila in two-thirds of the stands sampled indicates the grassland affinities of the herb stratum. The relationship to adjacent grasslands is supported by the presence of such forbs as Solidago nemoralis , Potentilla hippiana, and Iris missouriensis, all of which are common meadow species in the Black Hills.
The soils in HU-4 are much deeper than in any of the previously described HU. Average depth of the solum is 23.0 inches (range: 17.0 to 34.0 inches). All horizons are dark colored and high in organic material. All but one of the described profiles have an A1/A2/B2/C horizon sequence. The A2 horizon is missing from the exception. B2 horizons are clayey with strong, angular blocky structure; soil drain- age appears to be restricted by this horizon. Average soil reaction in the B2 horizon is pH 6.4.
HU-5: Pinus ponder osa/Symphoricarpos al- bus /Arctostaphylos uva-ursi (fig. 6).
Twenty-five stands are classified in HU-5 which is the most widely distributed unit in the ponderosa pine forest (map 4). It occurs over a large range in elevation in the north- eastern, central, and southern Black Hills. The mean elevation of the 25 stands is 5,000 feet (range: 3,725 to 6,100 feet). All but three stands are on noncalcareous geologic material — mainly the micaceous schists of the central region. Those on calcareous material are located along the eastern edge of the limestone plateau at elevations between 4,000 and 5,000 feet. A majority of the stands in this HU receive less than 22 inches average annual precipitation, and in several, precipitation is below 20 inches a year.
Figure 6.—HU- 5:
Pinus ponderosa/ Symphori-
carpos albus /Arctostaphylos uva-ursi
1 5
Pinus ponderosa trees in the < 4 -inch and 4- to 8-inch d.b.h. classes are very common, and several stands have such a dense over- story of small d.b.h. trees that the understory is only minimally developed. These dense stands of Pinus ponderosa occur only in HU-5. The causes of their origin have not been deter- mined, but interruption of the more or less cyclic pattern of forest fires which occurred previous to settlement of the Black Hills may be an important factor in their development. Seedlings of Pinus ponderosa reach their great- est constancy and frequency in this HU. Popu- lus tremuloides , Betula papyrifera, and Quercus macrocarpa are occasional members of the forest overstory.
The understory is sparsely developed with a greater incidence of bare ground and litter, and a tall-shrub stratum is absent. Juniperus communis and Shepherdia canadensis are pres- ent in some stands, but do not exceed 3 feet in height and are widely scattered. Symphori- carpos albus forms an open low-shrub stratum, but its mean frequency is greatly reduced from that of the previously described HU. Mats of Arctostaphylos uva-ursi are a common feature of the herb stratum, although it too is slightly reduced in constancy and frequency when com- pared to the more mesic HU previously described.
Danthonia intermedia and Carex concinna are the most frequent graminoids. Achillea millefolium is again the leading forb species. There is a distinct reduction in the constancy and frequency of all the forb species, however, which reflects the more xeric environmental conditions generally present.
Average solum depth is 14.8 inches (range: 6.0 to 30.0 inches). Upper soil horizons are quite rocky and exposed, and vertically oriented rock outcrops are a common feature of the landscape. The subsoil is generally acidic except on limestone, where it may reach pH 8.5. The horizon sequences are either A1/A2/B2/C or A1/B2/C. An A2 horizon is present in 17 of the 25 profiles. All but one of the soils without an A2 horizon have B2 horizons; the exception has an Al/AC/C sequence.
HU-6: Pinus ponder osa-Quercus macrocarpa/ Prunus virginiana/Symphoricarpos al- bus/Berberis repens (fig. 7).
HU-6 is represented by four stands, all located along the northern edge of the Black Hills at elevations between 3,850 and 4,550 feet. All of the stands are on calcareous geologic material and lie between the 20- and 22-inch isohyets.
Small Quercus macrocarpa are the most frequent overstory species, but the average height of these trees is less than that of the intermixed Pinus ponderosa. Both species have been logged in the past. Many large-diameter stumps of Quercus macrocarpa are present, and many of the small trees have sprouted from old root crowns.
The tall-shrub stratum is well developed. Prunus virginiana, Quercus macrocarpa, and Amelanchier alnifolia all occur at high constancy and frequency, and may exceed 6 feet in height.
Figure 7.—HU- 6:
Pinus ponderosa - Quercus macrocarpa /Prunus virgini- ana / Symphoricarpos albus/
Berberis repens
1 6
The first and last of these tall shrubs are present over much of the ponderosa pine forest, but are usually not over 1.5 feet tall. Ostrya virginiana forms a tall-shrub stratum over 10 feet high in three of the four stands. Quercus macrocarpa and Ostrya virginiana are sympatric along much of the northern edge of the Black Hills. The low shrub stratum is dominated by Symphoricarpos albus and Spiraea lucida. Ber- beris repens occurs at high frequency in the herb stratum and Toxicodendron radicans is present at low frequency in all stands.
Many graminoids and forbs are present at high frequency in the herb stratum in spite of the dense shrub strata. Many of these are species also found throughout the ponderosa pine forest, but two species, Maianthemum canadense and Sanicula marilandica, are rare except in this HU.
The soils in HU-6 are deeper than in most of the other HU of the ponderosa pine forest. The average solum thickness is 24.3 inches with a range of 14.0 to 29.0 inches. All four profiles are well developed with the A1/A2/B2/C horizon sequence and have neutral to basic reaction. The 01 horizon (litter) is thicker than in any other HU because of the accumulation of leaves from Quercus macrocarpa and the many deciduous shrubs.
HU-7: Pinus ponderosa-Quercus macrocarpa/ Prunus virginiana /Symphoricarpos al- bus /Schizachne purpuras c ens -Car ex foenea (fig. 8).
HU-7 is represented by a single stand on the eastern edge of the central Black Hills at an elevation of 4,300 feet. It is related to HU-6 in several attributes, but differs in that it occurs on a very acidic soil, has a greater frequency of large-diameter Quercus macro- carpa in the overstory, and a herb stratum dominated by graminoids.
Quercus macrocarpa is codominant in the overstory with Pinus ponderosa. A few Quer- cus macrocarpa trees larger than 12 inches d.b.h. are scattered through the stand. Many large-diameter stumps suggest that Quercus macrocarpa may have been the dominant species prior to logging. Pinus ponderosa in the 4- to 8-inch d.b.h. class is presently the most frequent overstory species.
Figure 8.—HU- 7:
Pinus ponderosa - Quercus macrocarpa /Prunus virgini- ana /Symphoricarpos albus/ Schizachne purpurascens - Car ex foenea
Prunus virginiana is the most frequent species in the tall-shrub stratum, and Sym- phoricarpos albus is the low-shrub dominant. Neither Berberis repens nor Toxicodendron radi- cans are present in the herb stratum. Car ex foenea and Schizachne purpurascens both occur at high frequency in the herb stratum. Schizachne purpurascens is rare elsewhere in the ponderosa pine forest. The forb Smilacina stellata is also present with moderate frequency and gives the herb stratum a distinctive appear- ance.
The solum has an A1/A2/B2/B3 horizon sequence, and is more than 36 inches deep. The B2 horizon is very acidic (pH 4.5) which may account for the absence of Berberis repens. A litter horizon (01) and a well-defined humus horizon (02) are present.
HU-8: Pinus ponder os a/ Prunus virginiana/ Amelanchier alnifolia/ Galium biflorum (fig. 9).
HU-8 is represented by one stand at the base of a steep limestone cliff along one of the major streams (Little Spearfish Creek) in the northern Black Hills. This very mesic, protected, semiriparian site is between the 22- and 24-inch isohyets, although the elevation is only 5,200 feet.
The overstory is a rather open stand of small-diameter Pinus ponderosa. A few Betula papyrifera up to 15 feet tall are scattered through the stand. The tall-shrub stratum is composed of Prunus virginiana, Shepherdia canadensis, and Corylus cornuta. This is the only HU in the ponderosa pine forest where Corylus cornuta is present at high frequency. Cornus stolonifera, present at low frequency, indicates the mesic nature of this HU since in the Black Hills it grows only along streams.
The low-shrub stratum is well developed with Amelanchier alnifolia present at high fre- quency. Symphoricarpos albus, Spiraea lucida, and Rosa fendleri occur at moderately high frequency. Berberis repens and Arctostaphylos uva-ursi are prominent but do not dominate the herb stratum. Poa pratensis is the only graminoid to exceed 20 percent frequency. Several forb species are present at frequencies exceeding 20 percent. Galium biflorum is the herb stratum dominant. Monarda fistulosa
is also abundant.
The soil is developed from limestone colluvi- um. The solum is 20.0 inches deep, rocky throughout, and has a basic reaction. An 01 horizon 1-1/2 inches thick and a 1/2-inch-thick 02 horizon are present. The horizon sequence is A1/A2/B2/R.
Figure 9.—HU- 8:
Pinus ponderosa /Prunus vir- giniana / Amelanchier alni- folia / Galium biflorum
1 8
Figure 10.— HU- 9:
Pinus ponderosa / Poa pra- te ns is - Danthonia intermedia
HU-9: Pinus ponderosa /Poa pr -at ens is -Dan- thonia intermedia (fig. 10).
HU-9 is represented by seven stands, five in the southern Black Hills (map 4). The other two are located on exposed sites in old forest fire burns. The average elevation of all stands is 5,250 feet (range: 4,950 to 5,500 feet). Most lie between the 18- and 20-inch isohyets. Five of the stands occur on granitic material, one on calcareous material, and one on micaceous shale.
Pinus ponderosa is the only overstory species. The overstory canopy is open, and all d.b.h. classes are present at low frequency. Many of the trees are short with heavy limbs.
No shrub species are present at more than 67 percent constancy, and the general appear- ance of the HU is that of an open pine stand with a grassy understory. Poa pratensis is by far the most frequent species in the herb stratum; in one stand it occurred at 99 percent frequency. Danthonia intermedia and Koeleria cristata are also present in all stands, but always at lower frequencies than Poa pratensis. Achillea millefolium is the only forb species with 100 percent constancy. Most of the forbs present are species common to moderately moist grasslands at moderate elevations in the Black Hills.
Sola average 12.0 inches in thickness. The B2 horizon is absent from five of the seven soil profiles, and the general horizon sequence is Al/AC/C/R. One of the two soils with a B2 horizon is located on old forest fire burn in the central Black Hills. The other is in a moist draw on calcareous parent material. B2 horizons appear to develop more readily on calcareous than on noncalcareous parent materials.
1 9
HU-10: Pinus ponderosa-Juniperus scopu- lorum/Cercocarpus montanus /Sym- phoricarpos albus/Andropogon sco- parius (fig. 11).
HU-10 is represented by three stands in the southwestern Black Hills (map 4). The mean elevation of the stands is 5,225 feet (range: 5,000 to 5,475 feet). Mean annual precipitation is 18 to 20 inches.
The overstory is characterized by an open stand of Pinus ponderosa with scattered Juni- perus scopulorum.
The tall-shrub stratum is a dense stand of Cercocarpus montanus. Individual plants exceed 10 feet in height and grow so closely together that movement through the stand is very difficult. Cercocarpus montanus is very localized in the Black Hills. It grows only on the limestone formations along the south- western, southern, and southeastern periphery of the Black Hills. In spite of the limited number of representative stands, this HU is a distinct unit, easily recognizable in the field. The three stands have a minimum similarity of K>70. HU-10 resembles the mountain brush type found at low to moderate elevations throughout much of the central Rocky Moun- tain region.
A number of other shrub species which are uncommon elsewhere in the ponderosa pine forest of the Black Hills are found in this HU. Among these are Rhus trilobata, Ribes inerme, and Yucca glauca. Symphoricarpos albus is frequent in the low-shrub stratum.
The major species in the herb stratum are graminoids and forbs with prairie affinities. Andropogon scoparius, Agropyron smithii, Bouteloua curtipendula, and Koeleria cristata are the more important graminoids. Artemisia ludoviciana, Phlox hoodii, Anemone patens, Zygadenus elegans, and Hymenoxys acaulis are present in all stands. The presence of Musineon divaricatum, Grindelia squarrosa, and Leucocrinum montanum, even with less than 100 percent constancy, is a further indication of the prairie affinities of the herb stratum.
The soil parent material under all stands is limestone. The horizon sequence is Al/ AC/C/R, and soil texture is a stony or gravelly loam throughout the solum. Solum depths range from 7 to 31 inches, with strong hydro- chloric acid effervescence in all horizons.
Figure 11.— HU-10:
Pinus ponderosa - Juniperus scopulorum / Cercocarpus montanus / Symphoricarpos albus / Andropogon scoparius
2 0
Figure 12.—HU-11:
Pinus ponderosa / Andro- pogon scoparius
HU-11: Pinus ponderosa/ Andropogon scoparius (fig. 12).
HU-11 is confined to the southwestern part of the Black Hills, a relatively low and dry region with rolling topography. The ponderosa pine forest is interspersed among extensive dry prairies, and generally occurs along water- courses and the mesic aspects of hills and canyons. The average elevation of the nine stands representing this HU is 5,165 feet (range: 4,825 to 5,475 feet). Most of the stands are between the 18- and 20-inch isohytes, with several stands having less than 18 inches mean annual precipitation. The limestone plateau is very extensive in this part of the Black Hills, and all of the stands are located on this geo- logic formation.
The Pinus ponderosa overstory is relatively dense. Trees greater than 4 inches d.b.h. are frequent, as are seedlings. Larger Pinus ponderosa trees are usually limby and flat- topped. Juniperus scopulorum is sometimes present as a subordinate tree. Only two species of low-shrubs, Rosa fendleri and Symphori- carpos albus, are present. Neither exceeds 67 percent constancy and they occur only at low frequency and are rarely more than 1 foot in height.
The herb stratum is related to the surround- ing prairie. Andropogon scoparius is the most frequent species and the only one with 100 percent constancy. Koeleria cristata is present in all but one stand, but never exceeds 10 percent frequency. The presence of Leuco- crinum montanum and Phlox alyssifolia in many stands indicates the prairie affinities of the herb stratum.
Sola are relatively deep (mean: 19.7 inches; range: 10.0 to 26.0 inches) and have an Al/ B2/C/R horizon sequence. Soil reaction is neu- tral to basic (pH 7.2 to 8.0) in the subsurface horizons and only slightly acid in the surface horizons. The surface horizons are relatively deep and dark colored from the presence of fibrous roots of graminoid species.
2 1
HU-12: Pinus ponderosa/Prunus virginiana/ Andropogon scoparius (fig. 13).
HU-12 is represented by nine stands on the periphery of the Black Hills at elevations below 4,700 feet (mean: 4,265 feet; range: 3,925 to 4,675 feet). The northern and extreme southern stands are on calcareous geologic material, while those in the east-central foothills are underlain by either granitic or metamorphosed formations. Mean annual precipitation for all stands is between 18 and 20 inches.
The overstory is open and trees are short with large limbs. Seedlings of Pinus ponderosa are relatively common. Small Quercus macro- carpa are present in several stands, and the general appearance of the overstory is that of an impoverished HU-6. Juniperus scopu- lorum was present in one stand.
The understory is also quite open and without a tall-shrub stratum. The low-shrub
stratum has Prunus virginiana as the most frequent species; plants are almost always under 2 feet high when mature. Rosa fendleri is the second most constant shrub. Both Symphori- carpos occidentalis and S. albus are present, but at low constancy, although occasionally at high frequency. Amorpha canescens is also common in the low shrub stratum.
Andropogon scoparius is the most frequent species in the herb stratum. Lupinus parvi- florus and Artemisia ludoviciana are also com- mon constituents.
Soil depths are variable. Two of the stands have soils with shallow sola (1.5 and 12.0 inches) and an Al/C/R horizon sequence. The other seven stands have deep sola (mean: 28.1 inches; range: 23.0 to 41.0 inches) with an A1/B2/C/R sequence. The subsoil reaction on the soils developed from limestone is as high as pH 9.0. On noncalcareous soils the subsoil is acidic (pH 6.0 to 6.6).
Figure 13.— HU-12:
Pinus ponderosa / Prunus virginiana /Andropogon sco- parius
HU-13: Pinus ponderosa/Andropogon scopari- us-Bouteloua gracilis (fig. 14).
The single stand representing HU-13 is located in the extreme southeastern Black Hills at an elevation of 4,675 feet. This is the most xeric part of the region, with an annual pre- cipitation between 16 and 18 inches.
Only scattered Pinus ponderosa are present in this area. No tree size Pinus ponderosa are present on the sample plot and the general appearance of the site is that of an Andro- pogon scoparius grassland. A few Pinus pon- derosa seedlings are present which indicates the area can support the species.
Li
Figure 14.— HU-13:
Pinus ponderosa / Andro- pogon scoparius -Bouteloua gracilis
The only shrub species present is Artemisia frigida. Andropogon scoparius, Bouteloua gra- cilis, and B. curtipendula are the most frequent graminoids. Stipa comata and Andropogon gerardii are present at low frequency. Several of the forb species occur only in this HU. Among these are Polygala alba, Echinacea an- gustifolia, Chrysopsis villosa, Paronychia de- pressa, and Hackelia virginiana. All are prairie species.
The soil in this HU is derived from lime- stone and has an Al/AC/C profile. Depth to the top of the C horizon is 22 inches. The Al horizon is dark colored and high in grass roots. Soil reaction is pH 7.4 or greater throughout the solum.
DISCUSSION
The purpose of habitat classification for wildlife management is to separate a large, heterogeneous habitat into more homogeneous units which are enough alike to be administered, manipulated, or evaluated in groups. Previous- ly, habitats have been grouped almost entirely by subjective methods. While this may be satisfactory for extensive management, or where distinctly different kinds of habitats exist sym- patrically, more objective classification methods, particularly those based on quantitative evalu- ation of actual features or attributes of the area under consideration, are needed for intensive management. This is particularly true for habi- tats such as the ponderosa pine forest of the Black Hills which cover extensive areas, or have a relatively homogeneous feature such as a closed canopy tree overstory which makes the understory or other habitat variations difficult to distinguish.
The application of computers to the solution of classification problems in plant taxonomy and ecology has received a great deal of atten- tion in recent years. Techniques are available to make ordered and logical arrangements of heterogeneous entities. The method used in this study, cluster analysis, is only one of the many available. It may be defined as an agglomerative (combination of individual en- tities into a whole) mathematical procedure which groups together entities with the great- est number of shared attributes.
Although HU may be designated at minimum levels of similarity higher than K>60, both
23
the total number of HU and the percentage of HU containing three or less stands increase greatly (table 3).
The number of HU approximately doubles for each 5 percent increase in K, while the percentage of HU containing three or less stands increases from 39 percent at K>60, to 57 percent at K >65, and to 91 percent at K>70. Increasing the minimum level of simi- larity higher than K>60 apparently defeats the purpose of classification, which is to obtain groups of relatively similar stands.
At K>84, all HU consist of a single stand, and an ordination of stands is obtained. For some purposes, ordination may be a useful technique of analysis, especially where strong environmental gradients are present. It should be noted that there is an element of ordination in the arrangement of the dendrogram (fig. 1): there is a general decrease in precipitation, elevation, etc., from top to bottom. However, there are also abrupt changes in other environ- mental features of the Black Hills such as geological formation, and these are reflected in abrupt changes in species composition and other attributes. Therefore, classification of stands appears to be a more appropriate tech- nique of analysis.
In assessing the validity of the classification of the ponderosa pine forest ecosystem, several
points must be emphasized. First, as with any classification, only the things being classified— in this instance, the sample stands— are real in the sense that they actually occur in nature. Each stand has a set of measurable (or at least recordable) attributes of vegetation, soil, and site which characterize it. These attributes are the result of a sequence of environmental events, the majority of which are usually un- known. Furthermore, the combination of attri- butes which characterize a stand exist only at the specific time at which they were recorded due to succession, disturbance, and chance. Because of their dynamic nature, no two stands can be expected to be exactly alike.
Second, any classification unit, such as an HU, is an abstraction based on the modal char- acteristics of a number of sample stands which usually are widely separated geographically. The range of attribute characteristics of a unit depends on the attribute variability of the included stands, and the level of homogeneity at which it has been defined. This level of homogeneity, in turn, depends upon the purpose for which the classification has been made. For some purposes, very high levels of homogeneity may be desirable; for other pur- poses, lower levels may be adequate, or even necessary. Because of the interdependence of homogeneity and purpose, there does not ap-
|
Table 3." |
•Number of stands for |
nab i tat units 1 eve Is of s i m |
(HU) with one, two, three, ilarity of K>60 , K>65 , and |
or more k>70 |
i nc 1 uded |
|||
|
Number of i ncl uded stands |
HU |
at |
K>60 |
HU |
at |
K>65 |
HU |
at K>70 |
|
Number |
Percent |
Number |
Percent |
Number |
Percent |
|||
|
1 |
k |
31 |
5 |
19 |
29 |
57 |
||
|
2 |
5 |
19 |
13 |
26 |
||||
|
3 |
1 |
8 |
5 |
19 |
k |
8 |
||
|
k+ |
8 |
61 |
11 |
43 |
5 |
9 |
||
|
Total |
13 |
100 |
26 |
100 |
51 |
100 |
pear to be an intrinsic level of homogeneity at which classification units must, or should, be defined.
Third, synecological classification units such as HU are best defined on a multi-attribute basis, although they often may be recognized and described by relatively few important or "indicator" attributes. A stand which is said to "belong" to a given HU need not possess all of the attributes which define the HU. Furthermore, since the HU are defined on this multi-attribute basis, the effect of the presence or absence of a single attribute is minimal. This minimal effect is enhanced, of course, when attributes are unweighted and/or standardized.
Finally, there is the question: What con- stitutes a "good" classification? For syne- cological purposes, units in a good classification show close relationship with what occurs in nature. The classification must provide a logical separation of the landscape into units, examples (stands) of which may be easily recognized in the field, and which may be related to the environmental regime.
The 13 HU defined at K > 60 appear to con- stitute a realistic classification of the ponderosa pine forest of the Black Hills. There is a reasonable number of units, examples (stands) of which can be easily recognized in the field by the presence and prevalence of certain attri- butes, particularly plant species.
The major (multistand) HU show a good relationship with environmental features of the Black Hills, especially geological formation and precipitation regime, neither of which were directly used in the calculation of the similarity matrix. The general regions of the Black Hills where a given HU can be expected to pre- dominate can be mapped (map 4).
The major multistand HU, HU-1 (Pinus ponderosa/ Juniperus communis /Symphoricar- pos albus/Berberis repens ) and HU-5 ( Pinus ponderosa /Symphoricarpos albus /Arctostaphy- los uva-ursi) are the most extensive subdivisions of the ponderosa pine forest. In general, they occupy separate geographic regions of the Black Hills and, although many plant species are common to both, there are distinct differences in both overstory and understory character- istics and in environment which make them distinguishable in the field.
HU-2 (Pinus ponder osa/Shepherdia cana- densis/Symphoricarpos albus/Arctostaphylos uva-ursi) is in many attributes intermediate between HU-1 and HU-5. It might be described as a mesic phase of HU-5. It also has close
relationship to HU-1; the major differentiating attributes are the absence of Berberis repens and the occurrence on noncalcareous geological materials. These, of course, are interrelated, since Berberis repens is apparently confined to calcareous soils in the Black Hills. Although it occurs in the same general geographic area and at similar elevations, HU- 4 (Pinus pon- derosa /Symphoricarpos occidentalis /Rosa fend- leri/Poa pratensis) is easily distinguished from the above three HU by the dominance of Sym- phoricarpos occidentalis in the tall-shrub stratum and the very open overstory of Pinus ponderosa.
Except for HU-10 (Pinus ponderosa- Juni- perus scopulorum/Cercocarpus montanus /Sym- phoricarpos albus /Andropogon scoparius) which is distinct due to the dominance of Cercocarpus montanus in the understory, the remaining multistand HU are less easy to define. In general, they represent the transition zone between ponderosa pine forest and the Northern Great Plains. HU-9 (Pinus ponderosa/Poa pra- tensis-Danthonia intermedia) occupies the most mesic sites in this more xeric region of the Black Hills. HU-12 (Pinus ponderosa/Prunus virginiana/ Andropogon scoparius) occurs on exposed locations in the more mesic northern and eastern foothills, and shows relationships in a few attributes to HU-6 (Pinus ponderosa- Quercus macrocarpa/Prunus virginiana/Sym- phoricarpos albus/Berberis repens ) and HU-7 (Pinus ponderosa-Quercus macrocarpa/Prunus virgin iana /Sym ph o ricarpos albus /Sch izach n e purpurascens-Carex foenea) particularly in the presence of Quercus macrocarpus at low fre- quency in some of the stands. HU-11 (Pinus ponderosa/Andropogon scoparius ) occupies the most xeric sites with a Pinus ponderosa over- story. The general appearance of most of the stands is that of a ponderosa pine savanna.
The four single-stand HU defined at K > 60 are distinct in many attributes. Two of them, HU-3 (Pinus ponderosa/Potentilla fruticosa/ Symphoricarpos albus /Fragaria vesca) and HU-8 (Pinus ponderosa/Prunus virginiana/ Amelan- chier alnifolia/ Galium biflorum ) occur in mesic environments, the former in a high elevation, high precipitation zone and the latter on a shaded river bench in a deep canyon. The third, HU-7 (Pinus ponderosa-Quercus macro- carpus /Prunus virginiana/Schizachne purpura- scens ) has close similarities with HU-6 ( Pinus ponderosa/Quercus macrocarpus /Prunus vir- giniana/Berberis repens) and at K>59 these would be combined. There are distinct differ- ences in understory species composition and soil attributes, however, which distinguish HU-6
25
from HU-7. The final single-stand unit, HU-13 (Pinus ponderosa/Andropogon scoparius-Bou- teloua gracilis) is more representative of the Northern Great Plains than the ponderosa pine forest. It was the final stand to be incor- porated into the cluster analysis, which em- phasizes its lack of similarity with the other 99 stands.
The disturbed condition of all 100 stands makes any discussion of the successional status of the HU rather tentative. There is a degree of floristic similarity between all stands, and if the HU had been defined only on floristics, this possibility of successional stages might be difficult to resolve. However, soil-site attri- butes were also utilized in the classification of the stands into HU, and these less easily al- tered attributes also show a considerable degree of within-HU similarity, it is believed the HU represent distinct climax types (in the sense of Tansley 1949, not Clements 1936), although in a disclimax stage mainly due to man-caused disturbances.
As with any classification scheme, the classification of the ponderosa pine forest pre- sented here should and will be modified as knowledge of the subject increases. However, in its present form it provides a framework for studies of practices to improve forage pro- duction, utilization, nutrition, and habitat carry- ing capacity. As such, it can be a useful tool for deer habitat management in the Black Hills.
HABITAT EVALUATION
Long-term data on pellet group densities collected by the South Dakota Game, Fish, and Parks Department on segments of the 1,000- foot transect within the 60 x 100-foot macroplot were used to evaluate the degree of deer use of the HU defined at K > 60. No attempt has been made to convert pellet group densities to animal numbers; they were used directly, and only as an index of the comparative use of the habitat units by deer as suggested by Riney (1957).
Differences in mean pellet group densities (table 4) between HU were analyzed by analy- sis of variance— one-way classification, with unequal sample sizes (Li 1957). The results of this analysis indicated there was a significant difference (p = .05) in the mean pellet group densities.
To test the significance of differences be- tween means, the multiple range test (Duncan 1955) was applied. The results of this test are shown in table 4 by the underscored lines.
The following explanation of the variable deer use of the HU is based on studies by the South Dakota Game, Fish, and Parks Depart- ment, the Wildlife Habitat Research Unit of the Rocky Mountain Forest and Range Experi- ment Station, and personal experience of the author in the Black Hills. In assessing the validity of the explanation, some points should be kept in mind. First, although ponderosa pine forest is the most widespread habitat
Table 4. --Mean pellet group densities1 (1960-68) for the 13 Habitat Units (HU)
defined at K>60
Hab i tat Un i t
tern
Number of stands
Mean pel let g roup dens i ty
6 4 7 8 10 2 9 1 12 5 1 1 3 13
461 1 397 24 9 25 911
10.0 9-7 6.6 5.7 4-9 4.8 4.4 4 .2 4.0 3.0 2.6 0.6 0.1 NSD2 a = .05
NSD a = .05
NSD a = .05
Density recorded on a 6- by 100-foot plot. Nonsignificant difference.
26
available to deer in the Black Hills, other habitats such as quaking aspen (Populus tre- muloides) woodland, old forest fire burns, and mountain meadows, not included in this classi- fication are also important deer habitats. Second, the juxtaposition of the ponderosa pine forest with these other habitats influences use by deer. Third, the white-tailed deer in the Black Hills are noticeably more migratory than is usually expected for this species, and tend to move considerable distances and occupy distinct winter, spring, and summer-fall ranges.
HU-6, HU-4, and HU-7 had the highest mean pellet group densities (10.0 to 6.6). HU-6 occurs only in the northern foothills of the Black Hills, and is an area where deer concentrate during the winter. Low elevation and relatively little snow, plus the presence of several palatable species of browse, combine to make this HU attractive to deer during the winter. HU-4 represents important spring deer range in the Black Hills. During April and May this HU and adjacent meadows are favored feeding areas for deer. Their diet during this period consists mostly of Poa pratensis4 which is the dominant herb species in HU-4. HU-7 is also a low- elevation winter range, and is similar to HU-6 in many attributes.
The six HU with moderate pellet group densities (5.7 to 4.0) range from mesic, high- elevation forest (1, 2, 8) to xeric, low-elevation forested shrubland (9, 10) and forested grass- land (12). Three (8, 10, 12) are winter range in various parts of the Black Hills, one (9) is spring range, and the remaining two (10, 2) are important summer-fall deer range.
Of the four remaining HU, with low pellet group densities (3.0 to 0.1), HU-5 is the most widely distributed, and, because of its location at moderate elevations, is probably both year- long and transition range. While it has only relatively low deer use, because of its wide distribution it is still important deer habitat. HU-11 is located mainly in the southwestern Black Hills at low elevation and is winter range. The remaining two HU (3, 13) represent extremes in the ponderosa pine forest, and are each represented by a single stand. The former is located at almost the maximum elevation possible in the Black Hills, and has an under- story dominated by a dense stand of the un- palatable shrub, Potentilla fruticosa; the latter is an open grassland in the most xeric portion of the Black Hills and provides little in the way of forage or cover for deer.
Dietz, Donald R. Personal communication.
SUMMARY
Cluster analysis of a similarity matrix de- rived from the ecological attributes (vegetation, soil, and site characteristics) of 100 stands located throughout the ponderosa pine forest of the Black Hills produced a classification of the forest into 13 Habitat Units (HU) with a minimum internal similarity of 60 percent.
The coefficient of similarity, K = 2c/a + b, was used to construct the initial matrix, and the weighted-pair group method of cluster analysis was used to separate this matrix into the Habitat Units (groups of similar stands).
The indicator species of the overstory , shrub , and herb strata and the number of stands included in each HU are:
HU-1: Pinus ponderosa/ J uniperus communis / Symphoricarpos albus/Berberis repens (24 stands)
HU-2: Pinus ponderosa /Shepherdia canaden- sis/Symphoricarpos albus /Arctostaphy- los uva-ursi (9 stands)
HU-3: Pinus ponderosa /Potentilla fruticosa/ Symphoricarpos albus /Frag aria vesca (1 stand)
HU-4: Pinus ponderosa/Symphoricarpos occi- dentalis /Rosa fendleri/Poa pratensis (6 stands)
HU-5: Pinus ponderosa/Symphoricarpos albus/ Arctostaphylos uva-ursi (25 stands)
HU-6: Pinus ponderosa-Quercus macrocarpa/ Prunus virginiana/Symphoricarpos al- bus/Berberis repens (4 stands)
HU-7: Pinus ponderosa-Quercus macrocarpa/ Prunus virginiana/Symphoricarpos al- bus /Schizachne purpurascens-Carex foe- nea (1 stand)
HU-8: Pinus ponderosa /Prunus virginiana/ Amelanchier alnijolia/ Galium biflorum (1 stand)
HU-9: Pinus ponderosa/Poa pratensis-Dan-
thonia intermedia (7 stands) HU-10: Pinus ponderosa- Juniperus scopulorum/
Cercocarpus montanus /Sym ph o ricarpos
albus/ Andropog on scoparius (3 stands) HU-11: Pinus ponderosa/ Andropog on scoparius
(9 stands)
HU-12: Pinus ponderosa/Prunus virginiana/
Andropogon scoparius (9 stands) HU-13: Pinus ponderosa/Andropogon scopari- us-Bouteloua gracilis (1 stand) Data on pellet group density collected in the sample stands over a 9-year period were analyzed to evaluate the comparative use of the different HU by deer. The results of this analysis indicated HU-6, -4, and -7 received
27
significantly higher deer use (mean pellet group densities 10.0 to 6.6) than the other HU; HU-8, -10, -2, -9, -1, and -12 received moderate deer use (mean pellet group densities 5.7 to 4.0) and HU-5, -11, -3, and -13 received only light deer use (mean pellet group densities 3.0 to 0.1).
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Agriculture— CSU, Ft. Collins
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