60 THE SOUTHERN APPALACHIAN FOBESTS. 



Yellow poplar. While yellow poplar forms only a small proportion of the 

 forest, it is one of the most valuable timber trees of the Southern Appalachians. 

 Like other hard woods it is late in reaching commercial maturity, seeming to be 

 even later than most of the trees with which it is associated, as even on the best 

 soils it can not be regarded as being financially mature before it is 160 years old 

 and 20 inches in diameter. Much smaller trees than this are being cut, but they 

 yield very low-grade lumber, which is largely sap, and the propriety of cutting 

 them is doubtful. 



Summary of measurements of five trees of yellow poplar, growing under unfavorable conditions, near 



Lineville, Mitchell County, N. C. 



[Elevation, 4,000 feet; aspect, easterly; soil, well drained and gravelly.] 



Age years . . 215 



Diameter of stump, inside bark inches. . 26 



Average increase in diameter of stump for each decade do... 1.2 



Increase in diameter for last ten years do... 0.4 



Height feet. . 98 



Length of merchantable timber do. . . 46 



Merchantable timber feet B. M. . 780 



At low elevation, on deep, moist, fertile soil in sheltered hollows, the growth 

 is far more rapid, and trees 200 years old scale nearly four times as much as 

 under poor conditions. 



Summary of measurements of twelve poplar trees on Yellow Creek, Graham County, N. C. 



[Soil, good; elevation, 2,100 feet; aspect, northerly.] 



Age years. . 208 



Diameter of stump, inside bark inches. . 34 



Average increase in diameter of stump for each decade do... 1.7 



Increase in diameter for last ten years do. . . 0. 9 



Height feet. . 133 



Length of merchantable timber do. . . 63 



Merchantable timber feet B. M.. 2,710 



The rate of accretion which is shown by this last group is probably made on 

 all of the best soils at low elevations and in warm, southern hollows, and on 

 limestone soils in East Tennessee. 



When compared with chestnut, yellow poplar makes slower growth, both in 

 single trees and in pure groups, until after the 100th year, when the increment 

 of the chestnut decreases on account of the abrupt culmination of its height 

 growth. The height growth of poplar, on the other hand, is much prolonged. 

 Poplar, in fact, begins to overtop chestnut about the 80th year, and on good soil 

 old trees will overtop chestnuts growing beside them from 10 to 30 feet. 



