95 



Bottomland Type 



The bottomland forests of Illinois are not usually even-aged. On 

 the 19 even-aged plots studied there was such a marked variation in yields 

 for a given decade, due to the composition of the stands, that the data 

 were worked up separately to show yields for stands composed dom- 

 inantly of fast-growing species, and yields for stands corhposed dom- 

 inantly of slow-growing species. (Tables 7, 8, pp. 96, 97.) On the 8 

 plots where such rapidly growing trees as cottonwood, sycamore, soft 

 maple and sweet gum dominated, the average tree entered the sawlog class 

 at 40 years and the acre produced 4,180 cubic feet of wood, exclusive of 

 branch wood. 



On the 11 plots where such slow-growing species as oak, elm, 

 ash, and hickory dominated, the average tree entered the sawlog class 

 at 63 years and the acre produced 2,757 cubic feet of wood. Thus the 

 fast-growing species produce approximately 18,000 B. F. per acre in 40 

 years as compared to 12,000 B. F. per acre in 63 years for the slow grow- 

 ing species. The influence of soils is somewhat apparent in the per cents 

 of occurrence of the fast- as compared to the slow-growing species. Thus 

 the cottonwood and soft maple were abundant on the sandy loams, while 

 the oaks, hickories, and ash were abundant on the heavier soils. Honey 

 locust, sycamore, and red gum, trees of rapid growth, seemed to occur 

 with equal frequency on the heavier and lighter soils. 



Yield Tables for Even-aged Stands in Illinois 



(1) Upland Types 



Tabte 4. — Post Oak Type. Based on 14 Plots 



