RANGE AND CATTLE MANAGEMENT DURING DROUGHT. 19 
proper grazing will be agreed to readily as the major factors re- 
sponsible for variation in forage production. Other factors, such as 
“spotted” rainfall, soil, and character of vegetation necessitate ad- 
justments in any general program of production. These adjustments 
are of little purpose, however, unless they are part of a compre- 
hensive plan calculated to meet the conditions resulting from drought 
and from grazing use. 
VARIATION DUE TO DROUGHT. 
It is somewhat difficult to determine from, data available the per- 
centage of depreciation of the range as a direct result of drought, 
because records of changes in vegetation on areas protected against 
grazing have been collected only for the period 1915 to 1919, in- 
clusive, and because part of the protected areas being studied were 
rendered unreliable by sand blowing on them in amounts sufficient to 
create unnatural conditions. However, the data available are im- 
portant because they show, at least approximately, the changes which 
occurred in the main vegetation types during the drought of 1916 to 
1918, and indicate the changes which will probably occur during a 
similar period in future years. 
WINTER OR YEARLONG RANGE. 
For the winter or yearlong type of range figure 5 indicates the 
annual change in density of good perennial forage grasses during 
the period 1915 to 1919, inclusive, with the annual precipitation for 
the same period. The actual amounts of good perennial forage 
grasses, inferior perennial grasses, long-lived weed” vegetation, and 
short-lived plants per unit of area are given in Table 6. Only the 
good perennial forage grasses, mainly black grama and red three- 
awn, are used in establishing the curve indicating the change in con- 
dition of the vegetation, since these species represent the main graz- 
ing values of the range and are the ones most important to maintain. 
The vegetation curve is based upon quadrat chartings and observa- 
tions on two representative areas of grama grass range, one pro- 
tected against grazing from, 1913 to 1919 and one protected from 1916 
to 1919, inclusive. The protected areas were examined frequently 
each year, and quadrats were charted twice annually in 1915 to 1919, 
except 1918, when only one charting was made because of lack of 
vegetative growth early in the year. 
10** Weeds’ aS used in this publication mean all herbaceous vegetation other than 
grasses or grasslike plants. 
