162 THINNING. 



plants, although the latter are equally as important to 

 the tree as the former. 



Now, if a pine or fir plantation such as this, grown 

 upon a dry gravelly soil, with the roots extended and 

 ramified all over, and within an inch or so of the sur- 

 face, it is neither unreasonable nor unlikely that, when 

 a sudden opening is made amongst the trees by cutting- 

 one or more, and letting in a stream of sunny rays to 

 heat or scorch the delicate, sensitive roots, so long 

 nursed, protected, and shaded under a canopy of 

 branches, is it strange, we might well ask, that a 

 change should take place with the roots of the trees, 

 or that the heat of the sun should crystallise the fluids 

 in the roots, and stop the flow of sap which was wont 

 to nourish the tree ? To this chemical change in the 

 roots I attribute the sickly appearance referred to. 



Another Scots fir plantation was thinned at about 

 thirty-five years' growth, which had not been thinned 

 during the preceding fifteen years. After thinning, 

 it became sickly and death-like, and but for the im- 

 portant place it occupied in the landscape, would in 

 all likelihood have been cut down. It, however, was 

 allowed to stand, and after the fourth or fifth year 

 began to assume its natural colour, and is now in an 

 excellent state of health. 



After a few years the trees generally recover, as the 

 result of having made new roots suited to their new 

 condition of life ; but while some recover, others go 

 back and perish. 



From the foregoing results it must appear obvious 

 that thinning is a very delicate and precarious opera- 

 tion, and is attended with much danger and risk to a 

 crop of trees. If thinning could be entirely dispensed 

 with, so much the better ; and in the case of natural 



