USES OF LAND 171 



During the last fifty years the world has been living upon accumu- 

 lated reserves, not only of forest timbers, but also to some extent 

 of the soil fertility of land cleared of forest, wherever the original 

 fertility has not been maintained. Generally speaking, the limits 

 have been reached within the temperate zone, with one or two 

 exceptions, in the process of converting large forest areas into 

 productive pastoral and agricultural land. It follows, therefore, 

 that the entire question requires to be viewed from the new stand- 

 point of conservation not only of timber supplies, but also of the 

 fertility of agricultural land so far as it is controlled by the 

 existence of forests and woodlands. 



