STOCKING NORTHERN GREAT PLAINS SHEEP RANGE 21 



with reference to the wind and freedom to graze and rest alternately 

 for short periods is beneficial to the sheep and the range. Frequent 

 changes of bed grounds and overnight camps make for better dis- 

 tribution over the range and uniform use of the forage. Many well- 

 distributed water developments will also aid in more uniform grazing 

 use. Predator losses can be decreased through the presence of a 

 vigilant herder. All of these factors, coupled with conservative 

 stocking, help to improve the welfare of range sheep and safeguard 

 the range. 



EFFECTS OF HEAVY, CONSERVATIVE, AND LIGHT 



STOCKING 



For several years prior to 1936, the first year of the sheep-grazing 

 experiment, the experimental range was grazed conservatively each 

 summer by a band of herded sheep and a few horses. This conservative 

 use preceding the experiment permitted the range to maintain high 

 vigor and productivity until severe drought struck in 1934. Nearly 

 normal rainfall occurred in 1935, but the range failed to recover from 

 the effects of the previous drought year. Severe drought occurred 

 again in 1936, accompanied by grasshopper infestations, and vege- 

 tation density and herbage production were reduced even below the 

 low levels reached in 1934. On adjacent similar ranges grazed con- 

 servatively by cattle, total vegetative density was reduced by these 

 two drought years to 9 percent of its 1933 level (6'). 



Recovery of short-grass range from the effects of severe drought was 

 slower on the pasture heavily stocked for 6 years than on the pastures 

 conservatively and lightly stocked. This was manifest in the thinner 

 vegetative cover, smaller sized plants, shorter plant heights, and 

 reduced herbage production per unit area on the heavily stocked 

 pasture. Low-value annual species were more abundant at the end 

 of the grazing experiment on the heavily stocked pasture than on the 

 others and in 1942 then herbage made up a high proportion of the 

 weight of the vegetation harvested from a series of plots. To the 

 stockman these effects of heavy stocking mean less forage, a shorter 

 grazing season, greater drought and winter risks, and higher produc- 

 tion costs. 



Effects on Density of the Vegetation 



In 1938, the third season of grazing, when effects of the 1934 and 

 1936 droughts were still evident, meter-square chart quadrats, here- 

 after referred to as plots, in all stocking intensities and in areas fenced 

 that year had rather low total densities; 765 square centimeters on 

 the heavy, about the same on the light, and 809 and 850, respectively, 

 on the conservatively grazed and on plots recently fenced (table 5). 



Practically no recovery from this low level was shown in 1939. 

 The decline in little bluegrass just about offset the increase in blue 

 grama and other dependable perennial grasses on the lightly stocked 

 and ungrazed plots. Under heavy and conservative stocking, an 

 actual decline in total density occurred. 



After 1939 the total density improved on all plots regardless of 

 grazing use. By 1941 total density of perennial specie9 under heavy 

 stocking had increased 326 square centimeters per plot, while the 



