STOCKING NORTHERN GREAT PLAINS SHEEP RANGE 



25 



the vegetative-density record in table 5 that the stand was still at a 

 low level in 1938. 



In 1942, the first season after grazing was terminated in the pastures, 

 and following the good growing season of 1941 , there were fewer plants 

 of the 4 major elump-forming species per unit of area on the heavily 

 stocked range than on the other grazed areas (table 6). Collectively, 

 blue grama, threadleaf sedge, little bluegrass, and needle-and-thread 

 averaged about 10 and 7 plants per plot on the conservatively and 

 lightly stocked pastures but only about 5 plants on the area heavily 

 stocked. Also, the average size of plants of these 4 clump-forming 

 species was less per plot under heavy stocking than under conservative 

 or light (table 7). On plots ungrazed after early 1938, the plants of 

 these 4 species combined were the fewest in number and the smallest 

 in size of those in all situations. 



Table 7. — Average area of plants, by species, on 2 by 5 decimeter plots 

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

 stocking rates 



Species 



Blue grama 



Threadleaf sedge_. 



Little bluegrass 



Needle-and-thread 



Total 





Con- 





Heavilv 



serva- 



Lightlv 



stocked 



tively 

 stocked 



stocked 



Cm? 



Cm? 



Cm? 



11. 97 



12. 30 



12.47 



2. 21 



1. 62 



1. 71 



1. 53 



1. 33 



1. 66 



3. 11 



5. 16 



7.30 



18.82 



20. 41 



23. 14 



Un- 

 grazed 



Cm? 

 7. 51 

 2. 13 

 1. 89 

 6. 56 



18.09 



BLUE GRAMA 



Individual plants of blue grama were more numerous in 1942 on 

 heavily stocked range than on conservatively and lightly stocked 

 range by 57 and 46 percent, respectively (table 6). The areas pro- 

 tected from sheep grazing from 1 938 to the end of the experiment had 

 fewer blue grama plants than any of the grazed pastures. Although 

 most numerous on plots heavily grazed, the plants were slightly 

 smaller than those on lighter grazed plots (table 7). The closer 

 grazing and more severe trampling associated with heavy stocking 

 prevented small blue grama mats from merging into compact clumps. 

 Heavy stocking also apparently retarded the enlargement of indi- 

 vidual established clumps of blue grama. On protected areas both 

 numbers and size of blue grama plants were restricted by competition 

 with other species for soil moisture and nutrients. 



THREADLEAF SEDGE 



In 1942 the pasture heavily stocked previously had less than three 

 plants or clumps of threadleaf sedge per plot in comparison with 

 nearly eight for the conservatively stocked and live for the lightly 

 stocked (table 6). Even though the plants were slightly linger on the 

 area heavily stocked than elsewhere (table 7), this difference was 

 sufficient to account in part for the 1942 plot densities summarized in 

 table 5. Since threadleaf scnlge plants were less numerous hut slightly 



