> INCREASING THE YIELD. 31 



able trees to 20 inches ; and a third one, made probably 20 years after the 

 first, removing a lower grade, cut to 16 inches. No cutting has thus far 

 removed all of the stand. So long as there remains a large number of 

 trees 14 to 20 inches in diameter, the annual growth in board feet per acre 

 is large, and if cutting is not below a diameter of 18 or 20 inches, com- 

 paratively heavy yields can be obtained every 15 or 20 years from the 

 same tract. As soon, however, as cutting is to a diameter below 10 inches, 

 not only must a very much longer time elapse before another profitable 

 cutting of large timber can be obtained, but there is a loss in converting 

 into lumber, since, while the waste of kerf and slabs in the case of larger 

 timber is only 50 per cent., it is 75 per cent, in the case of small timber. 

 While cutting to too small a diameter over an entire tract is to be avoided, 

 other requirements must be considered. 



There is no single operation or process the use of which will develop 

 the maximum earnings of a forest which contains yellow poplar. The 

 following are the most important points to consider in seeking to develop, 

 and maintain on a tract a high yield of yellow poplar, and to secure a 

 product of high value. 



Management. 



(1) Developing a form of stand which permits intensive operations. 



(2) Cutting trees only at or above a size which indicates maturity. 



(3) Obtaining full-stocked stands by preventing fires and by regu- 



lating grazing. 



(4) Eliminating species of low value from stands. 



(5) Thinning young stands in order to accelerate growth. 



Better Utilization. 



(6) Reduction of waste and closer utilization of timber. 



(7) Selling timber in its most profitable form. 



MAN A CEMENT. 



Developing a desirable form of stand. By procuring a suitable form of 

 stand, the conditions are obtained which are best suited for the replace- 

 ment and most rapid growth of the valuable species in the stand, since 

 yellow poplar requires a large amount of light for its establishment and 

 growth, and its most rapid development takes place in even-aged stands 

 and groups. 



Sprout forms. While young trees sprout sufficiently to be managed as 

 sprout stands, this form of stand can be used only for the production of 

 small timber, such as pulp wood, and is advisable only on good sites where 

 pure stands of yellow poplar can be grown, or mixtures of yellow poplar 



