XL 
ON THINNING PLANTATIONS. 
THERE is no department in arboriculture more misunder- 
stood or neglected than that of thinning plantations, par- 
ticularly those of the Scotch pine and larch, throughout many 
parts of Scotland. No doubt the native forests are left, for 
the most part, to thin themselves by their own efforts; by 
the provisions of nature, the timber is preserved in health, 
and exempt from suffocation or injurious confinement ; but 
this is never the case with respect to plantations. The native 
and planted forests stand under very different circumstances. 
These will be readily understood by my extracting the fol- 
lowing article, which I sent to Mr. Loudon at the time he 
was writing the Arboretum Britannicum. 
In vol. iv. p. 2181, Mr. Loudon says :—“ After perusing 
Mr. Grigor’s report on the native pine forests of Scotland, 
of which an abstract is given in p: 2165, we wrote to him 
for information on the subjects of thinning and pruning, as 
actually practised in these forests, and also in artificial planta- 
tions ; and as to the effects of the neglect of either or both of 
these operations. To our application Mr. Grigor kindly and 
promptly sent us the following answer :— 
“The old trees of the native Scotch pine forests have 
trunks quite clean and free from old stumps, so that the side- 
branches must have rotted off when the trees were young and 
of a small size. Some of the pines, grown on exposed situa- 
tions, have strong side-branches, but not very near the 
ground ; such branches are commonly found above large clean 
trunks of from fifteen feet to thirty feet in length. When 
the timber of these forests is cut up, loose knots are rarely 
F 
