184 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
6 inches, which is now being increased by the deposition of 
humus. 
The part of the plantation which consists of pure Douglas fir 
has not as yet been thinned, and the crop has an average height 
of from 47 to 50 feet. The plants were put in at 3 feet apart, and 
in some parts almost every plant has survived, and is growing 
vigorously ; and although in other parts there are many weaklings, 
the plants are almost in every case still alive. Over the whole 
area the trees now stand about 6 feet apart on the average. The 
branches are now dead to a height of from 25 to 30 feet, but they 
still adhere to the stems. The girth of the trees is very irregu- 
lar, varying from 18 inches to 57 inches at 6 feet from the 
ground. If this plantation were now thinned, I should say the 
average girth for the crop left on the ground would be about 
44 inches. 
The Douglas fir in that part of the plantation where they are 
mixed with Zhuya gigantea, Scots pine, and silver fir, have not 
attained to the same height as those in the pure Douglas fir part, 
but they exceed them in girth. The height of the Douglas fir in 
this part is about 38 to 4o feet, and their average girth is about 
45 inches. The Scots pine, and the greater part of the silver 
fir, have been completely suppressed, but the Zhuya gigantea 
have held their own, and compare very favourably with the 
Douglas fir in height and girth, as well as in symmetry of bole. 
As it stands at present, this part of the crop consists of about 
three-fourths Douglas fir to one-fourth 7iuya, with an occasional 
silver fir. In most cases the silver fir fall short of the others in 
height, but, as a rule, they have the advantage in girth. I may 
say, however, that it is only in exceptionally thin parts, or near 
the edges of the rides, where silvers are to be found. In this 
section the trees are thinner on the ground than in the pure 
Douglas fir part, owing to all the Scots pine having died, and 
the distance apart at which they now stand varies from 5 to 
8 feet. 
In the remainder of the plantation, where they are mixed with 
larch, etc., the Douglas fir have outgrown all the others in 
height, but their stems are much rougher, owing, apparently, to 
their having made room for themselves and retained their side 
branches for a longer period than either those grown pure or in 
mixture with Zhuya gigantea. In no case, however, do any of 
the other kinds overtop the Douglas fir. 
