24 



BULLETIX 1031, U. S. DEPARTMENT OF AGEICULTURE. 



actual amount of living forage. It is undoubtedly true, howeverj 

 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 hj 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. 



jSunimer 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 lightly 

 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 onlv observations were made. 



Table 7. — Amount of vegetation, percentage of maximum stand, and jjercentage 

 of maximum volume of forage on tohosa-grass range, 1915 to 1919. 



Year. 



Amount 



of grasses 



(square 



centimeter) 



per square 



meter. 



Percentage 



of 



maximum 



year. 



Volume of 

 forage pro- 

 duced, in 

 percentage 

 cf maxi- 

 mum year. 



1915 



92S 

 928 

 930 

 935 

 656 



100.0 

 100.0 

 100.0 

 100.0 

 70.1 



100.0 



1916 



100.0 



1917 



45.0 



1918 . . 



55.0 



1919 



70.1 







The density of the forage on the tobosa-grass range remained 

 practically stationar}^ 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 c^nt, 

 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 



