

48 PRACTICAL FOREST MANAGEMENT. 



quantity of the forest produce required for the daily wants of the 

 population, as well as to guarantee an adequate supply of timber 

 ior large public works. It is therefore essential that each forest 

 division ba worked for a sustained annual yield to meet these 

 demands, and that it should be our aim to produce the greatest 

 possible amount of forest products with the smallest poaaible 

 .forest capital. The attainment of this maximum yield is only 

 possible with complete stocking, careful tending of the growing 

 stock and a proper series of age gradations. The neglect of 

 the principle of the sustained annual yield has had the most 

 disastrous consequences in America. Industries migrated and 

 villages disappeared because there was no more merchantable 

 timber to cut ; without a sustained yield the continuity of the 

 forest and the industries depending on it cannot be insiired. In 

 Pensylvania and the Lake States the decay of agriculture, the 

 migration of forest and wood using industries and the decline of 

 previously prosperous villages have followed the destruction of the 

 .forests. 20 The whole science of forestry is dependent on this 

 principle. Neither silviculture, fire protection nor utilization are 

 by themselves competent to maintain prosperity. Once the prin- 

 ciple of the sustained yield has been adopted everything else 

 .follows as a matter of course. Good silviculture is necessary to 

 produce the best quality stands and normal reproduction, fire 

 protection is necessary to preserve the growing stock and good 

 utilization to make the most of the prescribed annual yield. In a 

 normal forest the sustained yield will equal the current annual 

 increment of the growing stock, representing the interest on the 

 forest capital. 



, fhe The normal state of a forest, under a given set of conditions, 



normal dfepends chiefly on the presence in it of 

 f orest - (1) A normal increment. 



(2) A normal distribution of the age classes. 



(3) A normal growing stock. 



"Regulation of the cut, Samuel T. Dana, Journal of Forestry, March, 1922. 



