STOCKING NORTHERN GREAT PLAINS SHEEP RANGE 7 



are characteristic. These hilly grass areas are most valuable either 

 as early spring or winter range, when old forage from the previous 

 year's crop is acceptable to sheep. Some protection from the weather 

 is afforded livestock by the hills during early spring storms and the 

 forage is seldom made unavailable by snow. The first green forage 

 in the spring appears in these hilly areas. 



Figure 4. — The level or very gently sloping bottom lands are most productive 

 and constitute an important part of the northern Great Plains range. 



The flood plains of the major streams constitute another important 

 variation of the northern Great Plains range (fig. 4). These areas 

 are characterized by generally heavy, frequently alkaline, clay soils, 

 and level or very gently sloping topography. The heavy soils absorb 

 water very slowly but remain moist longer than lighter soils. Pud- 

 dling of the surface layer caused by trampling of the wet soil or by 

 intense rainfall may retard water absorption and make runoff exces- 

 sive. About a third to a half of the soil surface is normally covered 

 with vegetation, largely perennial grasses, the most important of 

 which is bluestem wheatgrass. Nearly pure stands of bluestem are 

 common on these bottom areas, especially on those portions which 

 are sometimes flooded by runoff from adjacent slopes following heavy 

 rains. Buffalograss, green needlegrass, and Sandberg bluegrass are 

 also important on these bottom lands, and some blue grama may be 

 found on the drier edges. Herbaceous forbs compose a very small 

 and unimportant part of the vegetation. Silver sagebrush is fre- 

 quently present on these heavy soils. Forage production per unit 

 area is higher on these flood plains than on any other part of the 

 northern Great Plains range. This is undoubtedly due to the deep 

 soils and the greater amount of flood water received. 



