THE ECOLOGY OF THE WOODED AREAS 23 



on these flats, especially where there is "buck-bush." There also 

 nests the Sharp-tailed Grouse and Western Meadowlark. There 

 are other birds more characteristic of the steppe. Every prairie- 

 dog town has its brood or broods of Burrowing Owls. The 

 smaller rodents, as far as we discovered, were those of the steppe 

 and of the open woods. Perhaps the most striking insect is the 

 large brown and white moth which feeds upon the sage bush. 

 For a few clays each summer these "butterfles" are very abundant 

 and conspicuous. 



3. THE WOODED AREAS 



In Harding County there are scattered groves in the Little 

 Missouri Valley especially near Camp Crook. The canyons in the 

 forest reserves are more or less filled with deciduous trees and 

 there is generally a narrow extension along the streams into the 

 plain or steppe. In each of the forest reserves there has been at 

 one time or other a saw mill. The timber cut was chiefly the 

 pine, however. 



i a i It seems evident that the conditions for growth of most 

 sorts of plants are much more favorable here than on the plains. 

 The proximity of springs and running streams indicates that the 

 ground water is within the reach of such trees as grow here. 

 These trees partially shade the other vegetation and protect it 

 somev, hat from the wind. In the canyons, the walls of rock have 

 the same tendencies. The relative humidity is raised both because 

 of the cooler temperatures, and because the ground being shaded 

 it does not dry so quickly after a shower. The daily range of 

 temperature is less. 



(b) Sonic characteristic plants and an'unals: The chief trees 

 are the Cotton wood (Populus), boxelder (Acer). Ash (Fraxinus) 

 and hackberry (Celtis). The Elm (Ulmus) is most abundant and 

 largest about the Cave Hills. The Western Yellow Pine (Pinus) 

 and Aspen (Populus) are locally abundant on the sides of the 

 canyons in the forest reserves, and found to some extent among 

 the deciduous trees in the ravines. Among the larger shrubs are 

 the plum (Prunus), chokecherry (Prunus), buffalo berry (Lepar- 

 gyraea), dogwood (Cornus), Currants and gooseberries (Ribes), 

 buck bush ( Symphorocarpos), Roses (Rosa). In the ravines ad- 

 ditional shrubs are the hawthorne (Crataegus) Service-berry 

 TAmelanchier) and blackhaw (Viburnum). The western poison 



