Logging Longleaf Pine. 395 



maintain their present output by cutting a slightly larger area 

 each year, are, with each acre cut, changing the overmature forest 

 into a thrifty growing form, comparatively safe from loss by 

 fire, rot or insects. In fact, so great is the difference between 

 the powers of resistance of thrifty trees and of old, rotten or sup- 

 pressed trees, that such a cutting might be regarded as the best 

 form of insurance which is available for standing timber. 



The experimental markings and studies of growth the results 

 of which were given here were made by the seniors of the Yale 

 Forest School on the holdings of the Thompson Lumber Com- 

 pany in Tyler county, Texas. The company does not own the 

 land and the marking was made for purposes of instruction 

 only. The timber will be cut clear. Therefore these figures do 

 not represent the results of an actual operation, but are intended 

 to give a definite statement of methods and results which can be 

 obtained by their adoption. 



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