88 FORESTRY IN NEW ENGLAND 



by a thinned stand than by a similar one un thinned. There may 

 be as much as thirty per cent added volume produced by the 

 thinned stand. This increased production is made possible be- 

 cause the yield from the thinnings largely utihzes material which 

 in an unthinned stand dies and decays before the final cutting. 

 The struggle between the trees is slowly kilhng the weaker 

 individuals. As the stand grows older, they pass from the co- 

 dominant to the intermediate class, then to the suppressed, and 

 finally are numbered among the dead. The great difference in 

 number of trees per acre between young and mature stands 

 (both fully stocked), which is apparent on the most casual inves- 

 tigation, gives an idea of the large number of trees and quantity 

 of material lost through decay in an unthinned stand. Besides 

 utilizing material otherwise wasted, the one thinned when ready 

 for harvesting will have as great or sometimes even greater vol- 

 ume than the unthinned stand. 



A higher grade product, taking the average for the whole 

 stand, is furnished by the thinned than by the unthinned stand. 

 In the latter there may be a few exceptionally fine trees, but 

 with them are many inferior specimens, merchantable only for 

 cordwood. In the former a smaller number of trees per acre 

 will be found on which the growth has been concentrated. 

 Individually none of them may contain such high-grade timber 

 as the exceptional tree in the unthinned stand, but, on the other 

 hand, every tree can be used for better products^ than cordwood 

 and the average value per tree is much higher. 



Thinnings raise the grade of the final product in another way: 

 by enabling the forester to eliminate worthless species from the 

 stand when it is young. Oftentimes in unthinned stands a 

 species of low lumber value will be found occupying a prominent 

 place in mature stands, but in properly thinned stands this need 

 never happen. 



Theoretically thinnings should be begun as soon as the com- 

 petition between the trees becomes strong. This occurs usually 

 when a stand is ten to twenty years of age. Thinnings in such 



^ With light thinnings timber of high technical value can be produced. 



