214 



FORESTRY IN NEW ENGLAND 



diameter and height than is the case in any of the four permanent 

 types. The latter are examples of uneven-aged forests. 



Figures secured recently by the United States Forest Ser- 

 vice ^ in this region indicate that stands of paper birch on first- 

 quality soil will yield, at sixty years, forty cords of wood per 

 acre, and on second quality soil nearly thirty cords of wood per 

 acre. Definite data for poplar stands are not available, but the 



Fig. 73. — A stand of the birch and poplar type 10 to is years old. 



growth should equal or shghtly exceed that made by paper 

 birch stands. The general impression has been that the birch 

 and poplar type was the fastest growing one in the region. 

 This, however, is not the case, although it is a fast growing one. 

 For the first twenty to thirty years it may exceed all others, but 

 after that age the growth falls off. 



The old field type has a much higher average growth when 

 stands of merchantable size are considered and must be classed 

 as the fastest growing one in the spruce region, with the birch 

 and poplar type second. Nevertheless the latter is of great 



* Forest Service Circular, No. 163. 



