FOREST AND FORESTRY DEFINED. 87 



during the last century and with greater precision 

 during the last thirty to forty years, that forest 

 growth serves an object in the economy of nature 

 and of man which under certain conditions may 

 become equally if not more important than this 

 direct primary one. 



We have learned that in general all conditions 

 in nature are interrelated, and in particular that 

 the condition of the surface cover of the ground not 

 only influences more or less potently the condition 

 of the soil and meteorological factors under the 

 cover, but that this influence reaches even beyond 

 the limits of the cover to its neighborhood ; and, with 

 the recognition of this influence upon soil, temper- 

 ature, and water conditions a new important forest 

 use, namely, as a protective cover and climatic 

 factor, has become established, so that we may dis- 

 tinguish, according to whether the one or the other 

 purpose becomes more prominent, supply forests 

 and protection forests, although the latter invariably 

 also furnish supplies, and finally, when pleasure 

 and game cover are the main objects, we may speak 

 of luxury forests. 



To fulfil either or both of the first two, more 

 important functions satisfactorily or continuously, 

 to furnish most useful material and to act as a 

 protective cover, it is needful that the woodland 

 designated as forest exhibit what we have called 

 "forest conditions." 



A forest in the sense in which we use the term, 



