136 FORESTS, WOODS, AND TREES 
per acre, corresponding to an annual increment of 90 cubic 
feet per acre. At 1020 feet elevation, in a sheltered 
situation on good damp soil, the volume of a plot 43 
years old amounted to 5610 cubic feet, or an annual 
increment of 130 cubic feet per acre. 
In the Coombe Plantation at Keswick isolated trees of 
spruce varied in height from 48 feet at 1450 feet elevation 
to 35 feet on very exposed ridges at 1520 feet at 60 
years old. Reckoning the average height of a plantation at 
1400 feet to be 45 feet at 60 years old, the yield would 
be 2470 cubic feet per acre, an increment of 40 cubic feet 
per annum. Such a yield would justify the planting of 
spruce at this elevation from a financial point of view. 
At Durris, in Scotland, spruce felled at 60 years old 
averaged 5600 cubic feet per acre in a plantation at 800 
feet elevation, equivalent to an average annual increment of 
over 90 cubic feet per acre. In the Kilworth plantation, 
County Cork, at 300 feet elevation on good alluvial soil, a 
plot of spruce, 78 years planted, measured about 12,000 
cubic feet per acre, corresponding to an annual increment 
of about 150 cubic feet per acre. These figures show the 
great yields of spruce under varying conditions of altitude. 
In hilly districts on suitable soil with moderate or slight 
exposure, spruce may be expected to yield 90 to 100 cubic 
feet per acre annually if grown in large areas in close order. 
At higher altitudes it will produce enough timber to pay 
for the expenses of planting; and below such high belts of 
spruce other plantations will flourish better on account of 
the protection afforded. 
Sitka Spruce.—This tree is so important for the affores- 
tation of the worst sites in our planting areas that some 
account of its occurrence in its native habitat will be of 
interest. It is a native of the Pacific Coast region from 
Alaska to Northern California, where it grows along the 
shore and inland for a few miles, ascending even in the far 
north to 2000 to 3000 feet altitude on mountain slopes 
exposed to the sea. It is unharmed either by the strong 
