analogous situation does occur in meandering 
canyons which have slopes facing any direction 
of the compass. It is on these areas that slope 
direction continua are expressed. A second con- 
tinuum gradient may occur as slopes vary from 
0 to 100 percent. A third reflects changes from 
the bottom of a long slope to the top, which may 
be the result of microclimatic changes and soil 
drainage differences. A fourth gradient occurs 
with changes in soil properties, and a fifth oc- 
curs with changes in local climate even though 
topography and soils remain reasonably con- 
stant. The list could be greatly expanded, par- 
ticularly when various factors interact, creating 
an almost infinite variety of continuum grad- 
ients. 
Reasons for the proposal.—tin 1956, I used 
the polyclimax community philosophy in devel- 
oping tentative range condition guides for one 
ranger district where application was quite suc- 
cessful. However, since then, I have mapped 
and analyzed range condition on approximately 
1 million acres in the Blue Mountains of central 
and northeastern Oregon. Experience on these 
1 million acres clearly demonstrated continua in 
environment and the inappropriateness of con- 
dition guides based upon modal community 
groups developed in a limited geographical lo- 
cation. In fact, using these guides approxi- 
mately two-thirds of the land area could not be 
suitably rated for condition. 
Thus, range condition guides or other vege- 
tation management guides based on the modal 
concept of community groups can lead to mis- 
interpretation of site potentials, application of 
management practices not particularly appro- 
priate to many sites, and erroneous mapping 
when based on site potential or range condi- 
tion. Since the land manager is responsible for 
managing each acre under his jurisdicition, 
guides must be developed and written which 
are applicable to as much land area as possible. 
They must be understandable and acceptable to 
field personnel. They must be developed for po- 
lyclimax “transition zones” or “intergrades” as 
well as for modal conditions—which is another 
way of suggesting guides based upon contin- 
uum gradients. 
I have also installed 50 to 75 three-step clus- 
ters and have reread an 100 more as part of 
range allotment analysis. These clusters are lo- 
cated in areas heavily used by livestock and 
thus provide a measure of animal effects on the 
range. Cluster location is further qualified by 
placement in range types reasonably similar to 
major kinds of vegetation in the allotment. Un- 
fortunately, livestock care not for modal condi- 
tions representing community groups, and al- 
lotment or district boundaries are not located 
around modal conditions. As a result, many 
three-step clusters used for administrative pur- 
poses are not placed in modal sites. Polyclimax 
community group condition guides are seri- 
ously deficient in estimating range condition, 
interpreting trend, and appraising manage- 
ment alternatives on these cluster locations. 
Too often, environmental factors measured at 
cluster locations were significantly different 
from those suggested by community group 
guides. 
Repeatble climax communities mean repeata- 
ble environments. Yet climatologists have dem- 
onstrated the variability of climatic gradients 
such as decreasing temperature with elevation, 
increasing precipitation with elevation on 
windward mountain slopes, and decreasing 
precipitation on leeward slopes. Geomorpholo- 
gists have demonstrated continuous variability 
in landform from the steepest mountains to the 
flattest lakebeds. Soil scientists have conceded 
continuum in soils for years and have em- 
ployed soil taxonomists (regional or State soil 
coordinators) to reconcile classification and to 
name soils within this variability. How, then, 
can repeatable, effective environments’ be 
formed from continuous variability in all the 
factors which make up the environment? 
No literature has been found which supports 
the contention that different plant species have 
similar ecologic amplitudes. Daubenmire’s 
(1952) Table 1 (page 304) was used to plot the 
ecologic amplitudes of 19 species according to 
the two-dimensional concept proposed by Cur- 
tis and McIntosh (1951). Considerable diffi- 
culty was encountered in delineating the asso- 
ciations according ecologic amplitudes of spe- 
cies. If species have different ecological ampli- 
tudes and if there is continual variability in 
factors which make up environment, how can 
there be repeatable climax plant communities 
which can be classified into groups suitable for 
mapping or land management? 
Finally, the author, using multivariate 
analysis, found continuum tendencies within 
and between community groups in a study of 
the 5-million-acre Blue Mountain landmass in 
central and northeastern Oregon. 
Importance of the climax continuum philoso- 
phy in ecology and land management. —Range 
condition guides based upon modal plant com- 
munity groups are generally inappropriate be- 
cause actual site potentials within the plant as- 
sociation vary considerably and because transi- 
tion areas are ignored. Regarding varience, 
some areas have a potential for reaching only 
high-fair condition, while other areas have a 
potential somewhere above excellent when the 
modal is considered excellent. This variability 
on condition guides must be recognized and 
must be designed so that range condition can 
be satisfactorily rated on most of the site po- 
tentials within a geographic area. 
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