20 
TABLE 6.—Amount and class of vegetation on inclo 
BULLETIN 1031, U. S. DEPARTMENT OF AGRICULTURE. 
j 
sures protected from grazing 
and percentage of maximum stand, 1915 to 1919 inclusive (grama grass 
type). ; 
Good _ perennial | Inferior perennial Short- 
forage grasses. forage grasscs. legaes lived 
lived, | Wee 
P de annual 
i vegeta- 
Square Square tion 
Year. centi eee centi- Peal 
meters ! meters ! . . 
per tesa per ena Number | Number 
square eran square Seal plants? | plants 2 
meter i meter P per per 
square | square 
meter meter 
BS Tepe fn red ad re eae ree 511 87.6 7 80 2.6 44,4 
CPE ARE A ae bs See a Re he betes cera 583 100. 0 8 90 _ 3.0 33. 0 
AS We (tee Ce eae ae toes AN BE OER Sel eee 3 537 92. 1 7 80 17.5 61.5 
1918 asst mats te peek Shas 511 87.6 9 100 2.0 82.5 
TUG seis oS a taretere mate mse eye cisae ciiave eee cies ee oie 347 59. 5 8 90 ‘0.9 Bie & 
1 
1 Actual measurement of area of grass tufts in square centimeters 1 inch above the ground on each square 
meter. (The metric system, with area expressed in square centimeters per square meter instead of with 
feet and inches, was used for convenience in the study because a unit of measure less than a squareinch was 
TA Ota ooiEn! of number of individual plants per square meter. 
3 Actual measurement showed 699 square centimeters but contained a considerable amount of dead forage 
mixed in with the living plants. This dead forage was estimated from best method of determination to be 
23 per cent of total stand of vegetation. 
Change in density of the grasses did not conform immediately to 
change in the rainfall. The main reason for this is the fact that 
the vegetation is dependent more directly upon available soil moisture 
than upon current precipitation, and the soil did not dry out to such 
a degree that it affected the growth so materially the first year of 
drought. In addition, however, the vegetation gradually decreased 
in vigor and resistance to unfavorable conditions, and further, there 
was difficulty in determining the percentage or total of dead grass 
until 1919. By 1917, the second year of the drought, the soil was 
becoming quite dry and the vigor of the grass had been considerably 
reduced. In 1918 the soil was so dry that a more nearly average 
rainfall occurring over a short period during the middle of the grow- 
ing season did not materially improve growing conditions, and the 
weakened vegetation continued to die. In 1919 soil moisture was 
materially increased, but in the 1919 examinations considerable grass 
was found to be dead which had been classed as living in previous 
examinations. There was difficulty in determining the grass actually 
dead in 1918 on account of the absence of green growth and per- 
sistence of dry growth from previous years. In 1919, however, the 
dead growth had largely disappeared and the records are considered 
a reliable index of living vegetation. 
The vegetation appeared to have reached its low point prior to 
the 1919 examination. Comparison of the conditions in 1919 with 
those of 1916, therefore, give the extent of range deterioration as a 
result of the drought on grama-grass areas not grazed. This depre- 
