Contrasts between the Soil Profiles Developed under Pines and Hardwoods

pact B horizon, high in colloid. There is an obvious relationship between rate of height growth of trees and recognizable quantitative group combinations of factors, such as are summarized, for instance, in a specific soil type of specific slope and exposure. There is even more evident relationship between rate of height growth and specific soil profile characteristics. It has been possible to determine some of these profile characteristics as they are related to good, bad, or indifferent growth rate. These have been briefly described in the foregoing discussion. Summarily speaking, soil features influencing available water seem to be more influential than any others in determining the rate of growth of pine trees. These factors are, of course, degree of slope and its effect on drainage, exposure as affecting surface losses, and the depth, or spatial relationship and physical structure of the horizons.