tire complex of soils and vegetation,—with and 
without livestock and game grazing. 
In this connection, baseline areas are needed 
for checking long-time changes in vegetation 
where disturbance by man is minimum. Re- 
measurement of these areas, with reference to 
climatic conditions, could provide valuable in- 
formation as to long-time changes in plant 
communities. Such measurements will be im- 
proved with better methods and techniques. 
Information is now accumulating as to the 
effect of chemical stimulants or inhibitors 
within biotic communities. As an example, 
analysis of plant selections by certain butterfly 
groups has shown clearly that plant choice has 
a chemical basis (Ehrlich and Raven 1967). 
Knowledge of the factors affecting animal- 
plant relations in range studies may be quite 
enlightening as more is learned of the chemical 
basis for such relations. 
Radioecology and radioactive tracers are re- 
ceiving attention; however, few people trained 
in range ecology are involved in these avenues 
of research. 
The increasing interest in ecosystems makes 
imperative studies to measure all effects of 
grazing (e.g., on native animals, soil, flora, and 
fauna) within a single biotic community. Sys- 
tems analysis using high speed computers 
provides a holistic approach to the analysis of 
complex ecological problems. The approach 
provides techniques and theories for analyzing 
systems of interlocking cause and effect path- 
ways which are common in ecology. Range 
ecologists should be taking greater advantage 
of this new discipline (Watt 1966). 
To supplement ecosystem analysis, more at- 
tention needs to be directed to the efficiency of 
energy conversion. Energy investigations of 
ecosystems are being pursued in some biologi- 
cal research which relates reaction rates, or- 
ganism temperatures, and energy flow at the 
molecular level (Gates 1963). Energy pathway 
studies are limited, however, for biotic com- 
munities involving rangelands. Studies of eco- 
logical processes in terms of energy relations, 
irrespective of utilitarian aspects, are needed. 
Range ecologists have mostly ignored the ge- 
netical basis for plant community events. 
There is evidence that genetical changes 
within a species population can cause impor- 
tant ecological events, e.g., invasion of a spe- 
cies into a plant community, genetic selection 
adapting a particular population of organisms 
to a specific environment, and genetic selection 
in the evolution of a plant community (MacAr- 
thur and Connell 1966). The same deficiencies 
exist in regard to animals of a biotic commun- 
ity. 
TABLE 1.—Significant range research contributions—post World War II period 
Vegetation type Author 
California annual grass Bentley and Talbot 
association. (1951). 
Desert mixed shrub- 
grasslands. 
Reynolds (1959). 
Paulsen and Ares 
(1962). 
Black grama association. 
Johnson (1953), 
Hormay and 
Talbot (1961). 
Beetle et al. (1961). 
Pine-bunchgrass. 
Mountain bunchgrass. 
Alpine ranges. Johnson (1962), 
Smith (1965), and 
Johnson (1965). 
Hurtt (1951), Reed and 
Peterson (1961), 
Holscher and Woolfolk 
(1953), and Houston and 
Woodward (1966). 
Klipple and 
Costello (1960). 
MclIlvain and 
Lagrone (1958). 
Hutchings (1954). 
Northern Great Plains. 
Central Great Plains. 
Southern Great Plains. 
Northern Desert shrub. 
Conclusions 
Intermediate degree of grazing maintained adequate 
litter without apparent soil deterioration or decrease 
in forage plants. 
Perennial grass growth is dependent upon summer 
rains; grazing must be deferred periodically to main- 
tain forage species. 
Drought reduced black grama by the same amount ir- 
respective of the degree of grazing, but recovery was 
more rapid with light use. 
Selective overgrazing by cattle could not be avoided; 
provision should be made for resting the range. 
Litter disappearance was first evidence of range deter- 
ioration; continued heavy grazing caused reduction in 
vigor and loss in cover and production. 
Hairgrass and agoseris were key forage species. 
Amount of grazing varied widely because of drought 
and resultant forage production; heavy grazing reduced 
litter cover, root volume, organic matter, and noncapil- 
lary porespace; plant cover changed with stocking rates 
on summer range but not winter range. 
Short grass reacted slowly to grazing. 
Blue grama and forbs increased with heavy rotation 
grazing. 
Desirable shrubs increased under moderate grazing. 
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