210 ILLINOIS STATE ACADEMY OF SCIENCE 



GROWTH STUDIES OF CERTAIN BOTTOMLAND 

 SPECIES IN SOUTHERN ILLINOIS 



C. J. Telford, Natural History Survey, Urbana 



The study of tree growth has always had a certain 

 scientific interest. Now since we know that the virgin 

 stand of timber amounting to 138,000,000 acres out of an 

 original stand of 822,000,000 acres will be cut out, in all 

 probability, within the next 50 or 100 years and that 

 we must turn to the cut over lands and to plantations as 

 future sources of supply, growth studies assume greater 

 economic importance. 



The two great classes of lumber — hardwoods or broad 

 leaved trees and softwoods or conifers — are graded ac- 

 cording to different specifications. The hardwoods are 

 graded largely upon appearance and beauty; the soft- 

 woods largely upon strength, which in their case can be 

 secured from immature trees, but clear lengths can not, 

 this having been well exemplified in the choice of Sitka 

 spruce for aeroplane stock. 



In general, hardwoods require better^ soil, produce 

 fewer trees to the acre and have a slower rate of growth 

 than conifers. They must be carried over a long inter- 

 val to produce the desired grades and sell for but little 

 more than softwoods in the market. 



Among the hardwoods the growth rate varies widely 

 as to species ; within the species also the growth rate var- 

 ies as to site, but the height growth rate for the same 

 species on similar sites is remarkably uniform, so that 

 it is used in site classification. 



The fact that different species grow at different rates 

 is so well known that it needs no proof. That the same 

 species may have a very different growth rate upon up- 

 land than upon bottomland sites is brought out in the 

 study of sycamore (Platanus occidentalis). At fifty 

 years of age sycamore growing upon the uplands in Ran- 

 dolph county averages sixty feet in height as compared 

 with ninety-two feet for the same age on the Mississippi 

 bottomlands of Union County. The fifty year upland 

 tree has an average diameter on the stump inside the 

 bark of 8 inches and the bottomland tree of 24.2 inches. 



