24 



CIRCULAR 8 0-4, U. S. DEPARTMENT OF AGRICULTURE 



percent on the conservatively grazed pasture, and only 79 percent 

 with light stocking and protection. By 1942 little bluegrass made up 

 only 2 to 6 percent of the vegetative cover on the plots. 



OTHER PERENNIAL GRASSES AND GRASSLIKE PLANTS 



The group of other perennial grasses and grasslike plants, composed 

 of species such as sand dropseed, needle-and-thread, and threadleaf 

 sedge, recovered very slowly under all degrees of stocking. Greater 

 competition from the principal perennial species which were recover- 

 ing rapidly under conservative and light stocking retarded recovery 

 of this group more than did heavy grazing and somewhat less competi- 

 tion in the small pasture. 



By late 1942, the density of this group had just about doubled as 

 compared with the 1941 level on plots in the areas previously stocked 

 conservatively and lightly. On the heavily grazed plots the increase 

 after grazing was slightly more than 50 percent above the 1941 level. 

 The trend under protection was comparable with that on the conserva- 

 tively and lightly stocked plots. 



PERENNIAL FORBS AND BROWSE 



Browse species and perennial forbs, although common on the ex- 

 perimental range, were very sparse or entirely absent from all plots 

 in 1938. They increased slowly under all situations throughout the 

 study but none became important constituents of the plots. 



Effects on Number and Size of Plants 



Under average weather and with good grazing management, the 

 principal clump-forming forage species in the northern Great Plains 

 are vigorous and well-spaced, but they seldom form a complete cover. 

 Severe drought in 1934 and 1936 greatly reduced the stand of perennial 

 forage plants in the northern Great Plains (6) and it is evident from 



Table 6.' — Average number of plants, by species, on 2 by 5 decimeter 

 plots randomly located in 1942, after 6 years oj sheep grazing at various 

 stocking rates 



Species 



Clump-forming : 



Blue grama 



Threadleaf sedge 



Little bluegrass 



Needle-and-thread _ _ 



Total 



Single stem: 



Bluestem wheatgrass 

 Threadleaf sedge 



Total 



All annual species 



Heavily 

 stocked 



Number 



1. 18 



2. 66 

 . 71 

 . 16 



4. 71 



8.73 

 .87 



9. 60 



64. 74 



Con- 

 serva- 

 tively 

 stocked 



Number 



0. 75 



7.73 



.43 



.68 



9. 59 



8. 19 

 .40 



8. 59 



13. 65 



Lightly 

 stocked 



Number 



0.81 



5. 20 



.37 



.41 



6.79 



13.82 

 .24 



14.06 



34. 17 



Un- 

 grazed 



Number 



0.47 



1.02 



1. 19 



. 12 



2. 80 



21. 36 

 2. 93 



24. 29 



67. 53 



