VARIOUS SYSTEMS OF FOREST MANAGEMENT. 61 



the pame time in other tracts those trees or bushes 

 which encroach upon other trees, and felling such trees as 

 have passed their maturity and are going to decay. The 

 same operation is done during the next decade in the next 

 tract, and so forth, till all the tracts are fully exploited, 

 when the cycle of successive fellings will be recommenced 

 again. These cuttings can, if desired, always be so ar- 

 ranged as gradually to arrive at groups of trees of the 

 same age and description, and finally at blocks with high 

 forest trees worked in rotation. At all events, the fel- 

 lings are so conducted as to secure simultaneously and 

 without prejudice to one or another part of the forest: 



(1) A continually sustained supply of a desired variety 

 of forest products. 



(2) A sure reproduction of the forest, either by self- 

 sown seed, by shoots and suckers from stumps and roots 

 of felled trees, or by seeding and planting. 



(3) A progressive and improved condition of the 

 forest, in place of former deterioration. 



In these three points there are concentrated the ob- 

 jects which scientific managers of forests in Germany 

 and France have in view, and which are being accom- 

 plished, not there alone, but also in other European 

 countries to which students of forest science have brought 

 the knowledge of advanced management of forests. 

 This revolution in the management of forests was 

 brought forth by the calculations made in finding the 

 exact amount of the net proceeds obtained from the 

 usual forest exploitation. 



The mode of ascertaining the proceeds of a capital in- 

 vested in forest culture is as follows : The value of 

 the lands and all expenses, from the time of begin- 

 ning the plantation, or cultivation till the time of 

 cutting, are figured up, and compound interest from 

 the time of incurring the expenses till the cutting time 

 is added. This sum forms the debit account. The credit 



