CHAPTER I 



THE INFLUENCE OF FORESTS ON CLIMATE 



The influence of forests on climate is undoubted, though 

 perhaps less than is generally supposed. The subject^ is a 

 difficult one to study ; and on many points no agreement 

 has been arrived at amongst engineers and foresters. The 

 latter usually hold that the presence of forests is beneficial, 

 in increasing the amount of rain in a district or country, 

 and in diminishing the erosion (Frontispiece) and the con- 

 sequent great losses of the soil on hill and mountain slopes. 

 The foresters agree with Humboldt's saying : " How foolish 

 is man in destroying the mountain forests, as thereby he 

 deprives himself of wood and water at the same time." 



The desolation that now prevails in parts of Spain, 

 Algeria, and other Mediterranean lands is generally ascribed 

 to the gradual drying up of the climate, consequent on the 

 lessened rainfall brought about through the steady clearing 

 of the forests by human agency. It is, howeter, well 

 established that great climatic changes of cosmic origin 

 occur in the course of centuries ; and the disappearance of 

 the forests in those countries may be possibly not the cause 

 but the result of lessened rainfall in the present epoch as 

 compared with Eoman times. 



Numerous observations taken over short periods of years 

 in France, Germany, and the United States show that 

 forests exert in the districts which they cover a definite 

 influence on the temperature of the air and of the soil, on 

 the rainfall, on the melting of the snow, on the water supply 



1 B 



