STOCKING NORTHERN GREAT PLAINS SHEEP RANGE 9 



THE FORAGE AND ITS UTILIZATION 



Of the many plant species which compose the northern Great Plains 

 range, nearly all provide forage for sheep at some time during the 

 year. Their forage values are unequal and palatability varies with 

 many factors. The bulk of the forage is provided by about 25 

 species. Still a smaller number, mostly perennial grasses, normally 

 provide forage yearlong. These, blue grama, bluestem wheatgrass, 

 needle-and-thread, and threadleaf sedge, are considered key species. 

 Good range management aims to maintain and improve the density 

 and vigor of key species on the range. Certain weed and browse 

 species are also of high importance, particularly for the variety they 

 furnish, but these will ordinarily not be grazed too heavily when 

 stocking is conservative and is regulated by the estimated allowable 

 use of the important key grasses or grasslike plants. 



Growth and Development of the Forage 



Spring growth of the range forage begins generally in late March 

 or early April and ends during late July or occasionally early August. 

 Some additional growth may occur following fall rains in August or 

 early September. Either inadequate soil moisture or too low tem- 

 perature may limit growth at the start of the season but of the two 

 factors, lack of soil moisture is perhaps the more influential. It is 

 not uncommon to find green forage present as soon as the snow melts, 

 provided the snow has melted slowly and the soil has absorbed some 

 moisture. If snow removal is rapid and runoff excessive, soil moisture 

 is likely to be low and the start of growth somewhat retarded unless 

 spring rains follow soon after. Forage growth is closely correlated 

 with April to September precipitation, which is about 70 percent of 

 the 13.06-inch annual long-time average for Miles City (fig. 6). Most 

 of the forage is produced during May and June, which are normally 

 the 2 months of greatest rainfall. 



Sandberg bluegrass and threadleaf sedge start growth earliest in 

 spring (table 2). The production of forage by these early starting 

 species is extremely important because it materially lengthens the 

 grazing season. These species complete their growth cycles early in 

 the season and frequently produce fair amounts of forage in years 



20 



1 



m 



935 



1936 



1938 1939 



YEAR 



1940 



Figu 



Growing season {April - September ) |__J Remainder of year 



re 6. — Annual and growing-season precipitation, Miles City, Mont., 1935-42' 

 8211S3°— 40 2 



