22 



CIRCULAR 8 4, U. S. DEPARTMENT OF AGRICULTURE 



conservative, light, and ungrazed plots increased 297, 370, and 508 

 square centimeters, respectively, on the average. 



Without any grazing in 1942 and following the favorable rainfall 

 of 1941, the perennial vegetation made remarkable recovery in density 

 on all plots. For the 5 years 1938-42, total perennial vegetative 

 density increased 749, 849, 1,143, and 1,172 square centimeters, 

 respectively, on the heavily, conservatively, and lightly grazed and 

 ungrazed plots. 



Table 5. — Average density of important range vegetation on meter- 

 square experimental plots, by stocking rate and year, 1938-42 



Stocking rate 

 and vear 



Blue 

 grama 



Heavv : 



1938 



1939 



1940_.__ 

 1941__._ 

 1942 



Conservative 



1938 



1939 



1940 



1941 



1942 



Light : 



1938 



1939___. 



1940 



1941 



1942 



Ungrazed: 2 



1938 



1939___. 



1940 



1941 



1942 



Cm. 2 

 158 

 300 

 545 

 765 



1,267 



96 



217 



357 



737 



1,427 



100 

 221 

 441 

 856 

 1, 612 



135 

 273 

 570 

 949 

 1, 512 



Bluestem 

 wheat- 

 grass 



Cm. 2 

 7 

 14 

 26 

 30 

 38 



18 

 23 

 32 

 55 

 50 



29 

 48 

 51 

 81 

 73 



17 

 31 

 38 



77 

 73 



Little 

 blue- 

 grass 



Cm. 2 



588 



290 



158 



55 



36 



683 



418 



247 



99 



35 



630 



484 

 382 

 133 



107 



667 

 495 

 295 

 140 

 62 



Other 





perennial 



Peren- 



grass and 



nial 



grasslike 



forbs 



plants 





Cm. 2 



Cm. 2 



12 







27 



3 



60 



5 



90 



6 



139 



4 



Total, all 

 Browse perennial 

 species 



Cm. 2 







1 



4 



15 



30 



12 

 18 

 40 

 51 

 104 



17 

 28 

 43 

 46 

 93 



31 



58 



101 



178 



345 





 2 

 3 

 5 



4 







5 



25 



23 



22 





 2 



4 

 5 



4 



0) 







4 

 28 

 38 





 

 9 



17 

 12 



IS 

 26 



Cm.* 

 765 

 635 

 798 

 961 

 1,514 



809 

 678 

 683 

 975 

 1,658 



776 



785 



951 



1, 156 



1,919 



850 



859 

 1,008 

 1,367 

 2,022 



1 Less than 1 Cm. 2 



2 These areas were fenced in 1938 and thereafter entirely protected from sheep 

 grazing. 



BLUE GRAMA 



In 1938, blue grama covered 1 to 2 percent of the ground surface 

 on the average and composed 12 to 20 percent of the total perennial 

 vegetative cover. There was a greater density of blue grama on plots 

 in the heavily stocked pasture at that time than in any of the other 

 pastures or the ungrazed areas. During the 4 years of grazing, 1938- 

 41, blue grama density increased through the establishment of new 

 plants and the enlargement of old ones by 814, 756, and 641 square 

 centimeters per plot on the ungrazed, lightly, and conservatively 

 stocked pastures, respectively, but under heavy stocking the increase 

 was only 607 square centimeters per plot. In the relatively good 

 rainfall year of 1942, when none of the pastures was grazed, blue grama 

 made striking density increases on all plots; 502, 690, 756, and 563 



