13i TRAXSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



strictly out over the whole area. Before many acres have been 

 thinned the operator will have got the resulting density so fixed 

 in his mind that he no longer has need to count. The degree of 

 thinning will vary from one forest to the next, according to the 

 activity of vegetation and other factors, which it is the operator's 

 business to understand. The result of the first thinning will 

 enlighten him, those of the second will confirm his experience, 

 while the third will make him a finished forester. Later, the 

 amattur will probably become overbold ; the professional will 

 remain cautious. 



The thinning of crops beyond seventy years old can hai'dly be 

 profitably discussed on paper, the propoi'tions being so diverse 

 and the conditions so complex, according to the variations of soil, 

 aspect, mixture, etc., that it would be rash to give any definite 

 figures. Still, as a last instance, may be considered the case of a 

 much too dense pole crop, whose dominated story has disappeared, 

 and which contains on the average some 400 to 480 stems of 

 10 inches diameter per acre. An incautious thinning may 

 imperil the whole crop, but if not thinned it will languish. 

 By removing only one tree out of every eight or ten, the risk will 

 be very small. By renewing the operation every four years, the 

 total number will in twenty yeai's' time be reduced to half. A 

 sluggish crop will have been awakened into active growth, and 

 perhaps some 2800 cubic feet of timber per acre may have been 

 realised in five operations. Each operation will be a guide to the 

 next. 



