RESEARCH METHODS IN STUDY OF FOREST ENVIRONMENT. D 



advantage the biological forces active in forest growth, through his 

 ability to modify the environment. Any considerable use of forests 

 means interference with the natural conditions and modification of 

 some of the environmental factors, the sum total of which determined 

 the character of the present forest. Forestry adapts this interference 

 to produce the best results, from the standpoint of human needs. 

 Therefore it has been thought best in this bulletin to take up each 

 of the environmental factors separately, and to introduce only such 

 a discussion of physiological facts as seems necessary to a proper 

 conception of the methods of study of the environment. 



Ecological forest studies deal with all problems which involve the 

 determination of the effect of environmental conditions on repro- 

 duction, initiation, growth, and physiological functions. To this 

 group belong such studies as the seed production of different species 

 in different seasons and conditions; the characteristics of seeds as 

 related to their origin; the correlation between the composition, suc- 

 cession, and growth of forest vegetation on the one hand, and the 

 conditions of the environment on the other; the vast field of prob- 

 lems in natural reproduction and methods of cutting for definite 

 silvicultural purposes; the various phases of forestation, including 

 the germination of seed, requirements for shade and water of the 

 different species, the planting of forest trees, and their competition 

 for moisture and light with herbaceous and shrubby vegetation; and 

 many similar problems. The methods and instruments available for 

 the study of the ecological forest problems are essentially the same 

 as those which are used in the study of the physiology and ecology 

 of plants in general. They involve the measurements of such aerial 

 conditions as precipitation, air temperature, the evaporating power 

 of the air, wind velocity and wind direction, and sunshine intensity; 

 and such subterranean conditions as temperature and moisture of 

 the soil, its depth, structure, and chemical composition. The func- 

 tioning of the trees in response to these conditions must also be meas- 

 ured by the means recognized and used by plant physiologists. The 

 methods and instruments used in physiology, meteorology, and soil 

 physics, therefore, are applicable in a large measure to the study of 

 ecological forest problems, though often with modifications necessi- 

 tated by the character of the plant and of its environment, 



While it is true that in studying the present composition of a 

 forest stand it is necessary, to a certain extent, to have the historical 

 viewpoint in order to determine clearly how this stand was initiated 

 and why it now supports one dominant species rather than another, 

 still it must be recognized that historical studies and conjectures are 

 outside the main domain of ecology. The purpose of ecology as an 

 exact science must always be to measure present conditions and 



