TABLE 2.—Topographic, soil, and soil surface factors analyzed for association with vegetation and 
surface stoniness in the Agropyron/Poa type 
Dependent factor, percent variation accounted for 
Agropyron 
Independent factor Hits Comp. Hits 
Topography: 
Elevation __------- 12 Sane 22 
Percent slope __--- ae oe Joe 
Slope direction —-_-- ae —— 16 
Slope position _____ ae 21 8 
Microrelief ______- ae 14 aed 
Range east ______-_- Saas Saree are 
Township south ___- sone parte ae 
Soil: 
p 
texture 
QAAMAWWWHOwPpPpPpprDy 
Effective depth ____ rt ae Lidl 
Soil stone _________ ee 20 epee 2 
Bedrock fracture _- Ces ae ees 
Surface: 
ROCK ess eeeeku SE oe es. See ae 
Bare ground _____- fe Bey es aes 
Erosion 
pavement _______ eS Resa laps 
duitter’ 222252. 9.424 oe ae ee 
accounted for 40 55 46 
* Indicates these items not tested. 
Multiple-variant analysis again demonstrates 
continuum tendencies between grouped plant 
communities. With the exception of hits on 
Poa, the analysis accounted for 48 to 74 per- 
cent of the variability. 
Table 4 compares factors associated with 
Agropyron composition in six community 
types. The analysis accounted for 45 to 92 per- 
cent of the variability and suggested differ- 
ences in continuum gradient expression. 
Within community types, nonsoils environmen- 
tal characteristics generally account for more 
of the variability in composition. Of particular 
interest, however, is the lack of consistency in 
factors affecting Agropyron. No single factor 
was important in more than half of the com- 
munity types. Since each community type has 
its own set of factors influencing continuum 
gradients, the presence of each type would 
seem to indicate different environments. This 
finding lends some credence to classification of 
214 
Festuca Poa 
Total Surface 
Comp. Hits Comp. production stone 
31 ee 21 z 6 
at 40 oars 4 38 
10 8 13 & se 
«6 Bs fe aa aati 
10 ae a ees ate 
a atte ac i 49 ieee 
ne 6 4137 Jee a) 
2 Oat 45 et 
ae s q@) 
aie ee x 16 re) 
Q) 
ae @ 
ce nae era ® 
65 54 71 uh 66 
plant communities. The real questions are 
whether climax plant communities tend to be 
clustered within a _ continuum _ gradient, 
whether clustering reflects the investigator’s 
subjective determination of sample location, or 
whether complete gradient expression is possi- 
ble in a landmass largely isolated within a 
grass and sagebrush steppe. 
These tables clearly demonstrate that plant 
communities or vegetational patterns cannot be 
evaluated by single-factor analysis. In nearly 
every community type, three or more factors 
had a significant effect on vegetation variabil- 
ity. Since (1) several factors are important 
within a community type and (2) since these 
factors are not universally important between 
community types, identification of environ- 
ments (climax communities) in the field under 
distrubed conditions presents some challenging 
and complex problems. One procedure under 
investigation is the classification of plant com- 
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