TABLE 4.—Variation in factors associated with Agropyron composition 
Range types, percent variation accounted for 
Artemisia 
arbuscula 
Artemisia 
Independent factor rigida 
Topography: 
Hlevation: 3.22225. Ene 23 
Percent slope ___- 50 pare 
Slope direction —-_- ae ee 
Slope position —_-- a 16 
Microrelief 
Range east ______ S42 a 
Township south __ eas aoe 
Soil: 
TEXCUPE 2 co eae Lo 
stone 7 
depth) 322..2-25< aoe ates 
Total depth _____- Bas 23 
Effective depth ___ 11 ane 
Soil stone ________ =r Beas 
Bedrock fract. ___- oo a 2 
Surface: 
IROGK ee 25 EE S255 an 
Bare ground ____- aa ee 
Erosion 
pavement _____- ok ee 
Litter ___________ BE a2 ets 
QANAOOWWWWAOwppppp 
ss 
Total variability 
accounted for 82 62 
Artemisia 
tridentata Poa 
Pinus 
Festuca 
Pinus 
Agropyron 
Agropyron/ 
SUMMARY 
The classification philosophies of polyclimax 
community groups and continuum gradients 
have been discussed. A continuum in climax 
vegetation is proposed. This philosophy recog- 
nizes: (1) The climax concept, (2) plant spe- 
cies have independent and different ecological 
amplitudes, (8) climate, geomorphology, and 
soils tend to occur in continuum gradients, (4) 
climax communities tend to be continually var- 
liable, (5) abrupt changes in the environment 
are refelcted in abrupt changes in plant com- 
munities, (6) sampling should reflect contin- 
uum tendencies, and(7) plant communities can 
be grouped in any manner suitable to meet 
stated objectives. 
LITERATURE CITED 
Bray, J. R., and Curtis, J. T. 
1957. An ordination of the upland forest communi- 
ties of southern Wisconsin. Ecol. Monogr. 
27: 325-349. 
Curtis, J. T., and McIntosh, R. P. 
1951. An upland forest continuum in the prairie-for- 
oe foe region of Wisconsin. Ecology 32: 
—34, 
Daubenmire, R. 
1952. Forest vegetation of northern Idaho and adja- 
cent Washington, and its bearing on con- 
cepts of vegetation classification. Ecol. Mon- 
ogr. 22: 301-380. 
216 
1955. The use of vegetation to indicate grazing po- 
tentials of forest land. Jn: Soe. Amer. For- 
esters Proc. pp. 35-36. 
Perker, K. W., and Harris, R. W. 
1959. The 3-step method for measuring condition 
and trend of forest ranges; a resume’ of its 
history, development and use. Jn: Tech- 
niques and Methods of Measuring Unders- 
tory Vegetation. U.S. Forest Service South. 
and Southeast Forest Expt. Stas. pp. 55-69. 
