INCREASING FORAGE YIELDS ON INTERMOUNTAIN WINTER RANGES 30 
production are very infrequent. They occurred only twice during the 
13 years of study—in 1937 and 1941—when spring and summer rainfall 
was greater than usual. To insure the survival and growth of seedlings 
under such circumstances, moderate rates of stocking are virtually 
mandatory not only after establishment but before (fig. 16). 
F-—427012 
Figure 16.—Many Indian ricegrass seedlings became established on this deteriorated 
winter range after 4 years of conservative grazing and a favorable seed year in 1941. 
BLAcK SAGEBRUSH SUBTYPES 
In 1934 a large range area in Antelope Valley that was potentially 
a black sagebrush-winterfat subtype was divided and one part of the 
area was fenced. At the time of fencing the two parts were essentially 
similar, the vegetation consisting primarily of winterfat and small 
rabbitbrush, with small amounts of black sagebrush and grass (table 9). 
One part was placed under moderate grazing while heavy grazing was 
continued on the other part. Herbage production was recorded for 
these two areas in 1934, 1938, and 1947. 
Following 1934, a year of low rainfall, yields of herbage on both the 
moderately and heavily grazed parts of the subtype increased. How- 
ever, the computed yields of forage show a marked increase under 
moderate grazing. The yield was twice as large in 1938 and more than 
three times as large in 1947 as that produced in 1934. Meanwhile, the 
amount of usable forage on the heavily grazed area remained practically 
unchanged (fig. 17), despite the increase in total herbage. The esti- 
mates of usable forage were obtained by multiplying the herbage yield 
for each species on the area by its utilization percentage listed in table 1. 
The pronounced increase in forage on the moderately grazed range 
was brought about largely by a shift in the species composition and by 
a higher total production. Herbage production of most of the palatable 
