60 THE PRINCIPLES OF HANDLING WOODLANDS 



select the trees more rapidly and hence mark more 

 cheaply than an unskilled man. 



4. Simplicity of Silviculture. — The simpler the prob- 

 lem, the more rapid the selection of the trees. 



5. Ease of Mechanical Work. — A marking crew can 

 work faster when travel is easy, when the trees can be 

 readily seen at some distance, and when the trees are 

 easily blazed, than under the opposite conditions. 



Defects of a Rigid Diameter Limit 



In the northeastern woods it has been for a good 

 many years customary for lumbermen to restrict their 

 cuttings to the largest trees. They set a diameter limit, 

 and instruct the cutting crews to take only trees above 

 that size. All merchantable timber above the limit is 

 cut, and none below, except such as may be required in 

 the logging operations. It is assumed that there is a 

 supply of medium-sized timber which will constitute the 

 next cut. As a matter of fact, there is often a deficiency 

 of thrifty trees just below the diameter limit capable of 

 growth, and not uncommonly a large number of these 

 are cut for skids, bridges, and other purposes in log- 

 ging the mature timber. 



Cutting to a fixed diameter limit disregards entirely 

 the condition of the trees from the standpoint of health 

 and possibilities of growth. The theory of the whole 

 plan is that there are half-grown trees which will in a 

 short time grow to full merchantable size. There are, 

 howevei", in every virgin forest manv trees below the 



