84 OUR NATIONAL FORESTS 



the many problems which confront the Forest offi- 

 cers in the management and the protection of the 

 National Forests ; while the Forest Products Labo- 

 ratory was organized to promote the most profitable 

 utilization and the most economical disposition of 

 the forest products of the National Forests. Both 

 sets of institutions, in doing this, are helping mate- 

 rially to build up the science of American Forestry, 

 which even to-day can hardly be said to exist. 



The Science of Growing Timber. In order to 

 better understand the many diversified problems 

 which are being studied at the Forest Experiment 

 Stations, it is necessary to give the reader a few 

 ideas concerning the science of forest ecology. 

 This science is the basis of all problems dealing with 

 the growing of timber and is therefore a study of 

 the utmost importance to forestry. Forest ecology 

 is the study of the relations of trees and forests to 

 their surroundings. By surroundings (or environ- 

 ment) we mean all the factors which influence their 

 growth and reproduction, such as soil temperature, 

 soil moisture, soil texture, rainfall, light, wind, air 

 temperature, relative humidity, altitude, slope, ex- 

 posure, and surface. Forests, we must remember, 

 are not warehouses of standing logs; they are not 



