THINNING OS ADVANCED PINE PLANTATIONS. 167 



always observed that pine plantations upon dry gravelly 

 soils assume a light colour after being thinned, and 

 only by slow degrees regain their natural dark-green 

 shade, till another thinning takes place. The annual 

 layers also indicate a corresponding falling off in 

 growth, which is usually greatest the second or third 

 year after the operation has taken place. In very 

 young plantations the injuries are niuch less ob- 

 servable than in older ones, and less upon larch and 

 spruce than upon Scots pine and silver firs. 



Thinning is also injurious in another way — namely, 

 by throwing an unusual and unnatural strain upon 

 the roots of the trees which were formerly protected. 

 The strain is often so severe that the tissues are 

 fractured, and the tree blows over by the first gale ; 

 but even far short of this, much injury is inflicted, 

 especially on conifers, whose juices, on receiving the 

 least injury, crystallise, and thus obstruct the flow of 

 sap during the future life of the tree. 



Th6 only practical remedy for plantations injured 

 by thinning as above indicated, is to encourage under- 

 growth, and even scatter branches over the surface of 

 the ground. 



It may appear to some a bold and gratuitous ques- 

 tion to ask whether thinning, after all, has not done 

 more harm than good. There is no manner of doubt, 

 however, that it has done, and is still doing, a very 

 considerable amount of hann — not because thinning is 

 of itself an evil, but because it is done at the wrong 

 time and in the wrong way. 



