334 the study of plant communities ■ Chapter XII 



unnatural conditions. The artificial environment of cultivation re- 

 sults in soil erosion, a modified soil flora and fauna, and changes in 

 water relations. Also we have more diseases of crop plants and 

 more insect pests than ever before. 



These are ecological problems. Intelligent land use minimizes 

 some of them. Practices like contour plowing, terracing, and strip 

 cropping are moves in the direction of reducing them. But when 

 the ecology of crop plants is studied further, especially in terms 

 of natural vegetation, some of our methods of use and management 

 may require revision. 



Pasture Problems.— Above, it was suggested that the same atten- 

 tion to management should be given to pastures as to plowed land. 

 This would be a reversal of the usual point of view since pastures 

 are, more often than not, largely on the poorest land and are given 

 little or no attention. With the steady expansion of dairying, espe- 

 cially into sections of the country where adequate pastures do not 



FlG. 180 (1). An Indiana field after fall plowing showing severe erosion. 

 Picture taken when it was decided to retire field to permanent pasture with 

 contour furrows. 



