1-19 



Forests as a Crop on Soils of Different Qualities 

 introductory 



The practice of forestry, or forest culture, will produce crops of 

 timber yielding from 50 to 100 per cent more per acre in annual 

 growth than the average now being harvested, of less than 45 cubic feet 

 per acre. A considerable proportion of these increased yields will be 

 obtained in the form of thinnings in even-aged stands. When no cutting 

 is done in a stand or crop until it is finally ready to harvest, the surviving 

 trees which make up the crop at that time constitute a very small per 

 cent of those originally composing the stand. When it happens, as in 

 plantations for post timber, that all the planted trees, thanks to an even 

 start, survive for a time, the rate of growth in diameter soon shows a 

 marked falling off and the growth on the whole stand tends to stagnate 

 until the numbers are reduced by competition and the survivors obtain 

 the increased crown-space required for thrifty development. 



In cultivated stands of timber this reduction of numbers, instead of 

 being left to nature, with consequent injury to the stand and loss by 

 decay of the dead trees, is forestalled by removing a sufficient number of 

 trees at from 5 to 10-year intervals to release those selected for the 

 final crop. The ultimate number per acre will depend on the age and 

 size of the crop which is desired. Plantations seldom have over 2000 

 trees per acre, and unless very early thinning is possible they will not 

 be set closer than about 6X6 feet apart, or 1310 trees per acre. At 15 

 years, post timbers may be cut from such plantations. At 40 years, under 

 natural conditions, this number would not be over 800 trees. At 60 

 years it would have diminished to 450. while at 80 years, about 370 

 trees would survive on an acre. Normally, but one half to two thirds 

 of this number should be permitted to survive. 



Without including the income possible from such thinnings or ad- 

 vance yields, the value of the final crops produced on typical acres of 

 Illinois woodland can be calculated. 



PLANTATIONS IN STARK, OGLE, AND CHAMPAIGN COUNTIES 



The possibility of supplying home-grown posts on prairie farms is 

 illustrated by yields of catalpa plantations at 15 years from time of 

 planting. Many such plantations in the state have been absolute fail- 

 ures, but this is due to ignorance as to the soil requirements of the tree. 

 Catalpa will not develop even into post timber unless planted on land of 

 high fertility and supplied with abundant moisture. 



