SUMMARY OF CONCLUSIONS. 13 



It will be observed in this bulletin tliat the historical method of dis- 

 cussing the subject of forest influences, which consists in adducing gen- 

 eral observations throughout the world, has given place to the scientific 

 method, which relies upon si»ecil3C observations and experiments and 

 upon the ai)plication of well-established physical laws to the espUma- 

 tion of the facts observed. 



SUMMARY OF CONCLUSIONS. 



For those who wish to know only what the present state of the 

 question of forest influences is, we have summarized what conclusions 

 may be drawn from the facts presented in this bulletin, referring them 

 to the body of the report for the basis of these conclusions and the dis- 

 cussion in extenso. This arrangement, we are aware, is not customary 

 and logical, but since the object of this bulletin, to some extent, is to 

 tiimiliarize not only the student but the general public with the subject, 

 it seemed expedient to meet the convenience of the general reader in 

 this manner. For easy reference the pages of this bulletin containing 

 the data upon which each conclusion is reached are given in paren- 

 theses at the end of each paragraph. 



GENERAL, CONSIDERATIONS. 



(1) We must keep separate two main questions, namely. What is the 

 difference of conditions within and without the forest? and How far is 

 the difference of conditions within the forest communicated to the out- 

 side, i. e., how far does the forest influence the conditions outside? 

 (Pp. 23-40.) 



(2) The general climatic conditions in which the forest is situated as 

 well as its situation with reference to elevation and exposure, further- 

 more its composition, whether evergreen or deciduous, its density, its 

 height and extent, the character of the forest floor, and other features 

 which determine its quality, must all combine in producing variety, at 

 least quantitatively, both as to difference of conditions within and 

 w ithout the forest and as to possible exchange of the same, and lience 

 the question of forest influences can be properly discussed only with 

 reference to these other conditions. We must refrain from generaliz- 

 ing too readily from one set of conditions to another set of conditions. 

 (Pp. 40-121.) 



(3) In the matter of forest influence upon waterflow, besides the 

 above mentioned, other conditions, the topography and geology or 

 stratification of soil, must also be taken into account and generaliza- 

 tions without regard to these must be avoided. (Pp. 123-157.) 



(4) No influence upon the general climate which depends upon cos- 

 mic causes can in reason be expected from a forest cover. Only local 

 modifications of climatic conditions may be anticipated; but these 

 modifications if they exist are of gre t practical value, for upon them 



