Forests and Soils 



119 



FOREST COMMUNITIES 



WHITE OAK 

 BLACK WALNUT 

 RED OAK 

 HARD MAPLE 

 BEECH 

 BASSWOOD 

 WHITE ASH 



Soil, topography, and tree species become adjusted in natural stands. 



slopes and ridges than on moist north 

 slopes because the dry sites are already 

 nearer the critical soil moisture level. 



Cultivation of forest soil immediately 

 reduces its natural porosity and de- 

 stroys its protective litter. Erosion then 

 attacks the body of the soil. 



Experiments conducted by the Cen- 

 tral States Forest Experiment Station 

 and reported in 1945 show that site 

 quality for black locust, black walnut, 

 and yellow-poplar may be predicted 

 on the basis of easily recognizable soil 

 properties, such as permeability to 

 water, depth to subsoil, and slope, 

 position, and aspect. Studies by the 

 Soil Conservation Service in the Pacific 

 Northwest show that growth rates of 

 Douglas-fir and ponderosa pine may 

 be predicted on the basis of the same 

 soil properties. 



Agreement on the relationship be- 

 tween the same set of general soil prop- 

 erties and tree growth in such widely 

 separated and different regions sug- 

 gests that soil-tree relationships are ba- 

 sic and applicable to many more forest 



regions. Predictions of tree suitability 

 to, and rate of growth on, bare land 

 help to set values on land intended for 

 reforestation. These soil-tree relation- 

 ships provide some basis for predicting 

 the eventual site quality of deteriorated 

 land. They assist also in choosing the 

 best tree species for degraded sites and 

 in managing stands to maintain a com- 

 position of more desirable species. 



JOHN T. AUTENJ a soil scientist in 

 the Forest Service, has been engaged 

 in forest-soil investigations since 1929. 

 He was once soil analyst for the Iowa 

 soil survey and professor of chemistry 

 and soils in Pennsylvania State College. 

 He is a graduate of the University of 

 Illinois and of Iowa State College. 



T. B. PLAIR is chief of the Regional 

 Forestry Division, Soil Conservation 

 Service, Pacific Coast Region, and has 

 been primarily concerned with plan- 

 ning forest land use since 1935. He is a 

 graduate of Mississippi State College 

 and the University of California School 

 of Forestry. 



