BIOLOGICAL FACTORS 



209 



"pruned" to the height the animals can reach, standing on their 

 hind legs. Obviously, community structure and development in 

 such areas is completely out of balance. 



Disturbance of natural communities should not be undertaken 

 without a reasonable appreciation of the end results. Management 

 or manipulation of the balance among species of a community may 



FlG. 101. Drained swampland in the Everglades of Florida. Many acres of 

 these muck soils are producing winter truck crops in quantities, now that 

 problems of drainage, tillage, and fertilizing have been worked out.— U. S. 

 Soil Conservation Service. 



frequently be possible but should offer the best prospects of suc- 

 cess when the ecology of the individuals and the community is 

 well understood. 



Man's unconcern for natural resources built up through the 

 years has led to economic losses and a reduction of those resources, 

 which only time can replace. Soil erosion, quite unnecessary if 

 cropping is properly handled, had reached a shameful point before 

 we began to do anything about it. Only recently have we at- 

 tempted to correct overworking of poor soils, mismanagement of 



