24 BULLETIN 1031, U. S. DEPARTMENT OF AGRICULTURE. 
actual amount of living forage. It is undoubtedly true, however, 
that depreciation is much greater in the third year of drought than 
in either the first or second year, on account of the increased desicca- 
tion of the soil and lowered vitality of the vegetation. Adding to 
this depreciation in stand the estimated 20 per cent decrease in vol- 
ume due to decrease in height and number of leaves produced per 
living plant in 1917 and 1918, the volume of forage by years was 
about 100 per cent in 1916, 73.6 per cent in 1917, 70.0 per cent in 
1918 and 59.5 per cent in 1919. 
Summer range-—Table 7 and figure 6 show what occurred in the 
density of vegetation on the main summer range type during the 
drought on a representative area protected from grazing during the 
summer and fall of each year. Since at other times of the year for- 
age on this type is of low palatability and therefore but lghtly 
grazed, the area used is representative of yearlong protection. The 
quadrat on this area was charted and observations made annually, 
with the exception of 1917, when the vegetation was too. dry to 
chart and only observations were made. 
TABLE 7.—Amwuni of vegetation, percentage of maximum stand, and percentage 
of maximum volume of forage on tobosa-grass range, 1915 to 1919. 
Amount Volume of 
Oi grasses | Percentage) forage pro- 
TEs (Square oi | duced,in 
eos _centimeter)) maximum | percentage 
|persquare}| year. | oimaxr 
| meter. | mum year. 
| 
Bist es = RR ce Set SI ER ee oe pee Se 928 | 
1916 ee rae ea eee ee a eee G28 | 
Livi. 2. Ss wea Bee Ce eo Bite fs ie uk | 930 
MOSK. Sek Se Se Sone Se ees oe Se eee oe eee | Q35 
0 Sn ee a id Sa ee oo oe 656 | 
The density of the forage on the tobosa-grass range remained 
practically stationary during 1916, 1917, and 1918, so far as it was 
possible to determine. During 1919, as the result of the accumulated 
effect of the drought, it decreased 30 per cent. It is probable that 
part of the 30 per cent died prior to 1919, although final removal 
of dead grass did not occur until 1919. 
Height growth and foliage production were reduced about 55 per 
cent in 1917 and 45 per cent in 1918, but were approximately average 
in 1919. Considering the volume of forage in 1916 as 100 per cent, 
the estimated volume in 1917 was 45 per cent; in 1918, 55 per cent; 
and in 1919, 70.1 per cent. 
The results from the study of the tobosa or summer-range type 
show a greater reduction in volume of forage produced in dry years 
as compared with protected grama-grass range, but density of the 
