TREES FOR WATER CATCHMENT AREAS 143 
feeble growth on dry soils, and was killed outright in dry 
situations generally by the great drought of 1911. 
One main use of Japanese larch in this country is to 
produce a crop of pit timber in a short term of years, say 
in 20 to 25 years after planting. Owing to its great 
vigour at the start it can also be used for planting difficult 
sites where other species fail, as, for example, land lable 
to be covered with a matted dense growth of grass, such as 
occurs in districts lying on the western seaboard of Scotland 
and in many parts of Ireland. It will succeed on poor 
shallow soil (Fig. 24) provided there is sufficient moisture. It 
has been recommended for planting areas overrun with furze 
and bracken; but such land if not in too exposed a situation 
will, as a rule, support other species yielding better timber. 
Japanese larch may be used as a main-crop tree in 
localities where pitwood is readily saleable; and is, of 
course, a substitute for European larch in parts of the 
country where the latter suffers severely from canker. 
It may be looked upon as a catch-crop tree, to be planted 
with the idea of getting a speedy return from an area 
difficult to afforest. Land on which Japanese larch had 
been grown for a short rotation of 20 to 30 years would 
be in excellent condition for the planting of another species 
destined for growing valuable timber on a long rotation. 
The growth of Japanese larch seems to be little affected 
by the nature of the soil, provided it contains sufficient 
moisture. The growth in height, while extremely rapid in 
youth, later drops off very considerably. The average 
attained by plantations in this country is about 32 feet 
at 16 years old from seed, 55 feet at 32 years old, and 
65 feet at 37 years old. In young plantations the volume 
comprises much branch wood of little value. The average 
annual increment of plantations 32 years old may be reckoned 
at 100 to 120 cubic feet of timber per acre. 
Western Larch (Larix occidentalis)—This is the finest 
of all the larches, attaining in Western Montana and the 
adjacent districts of Idaho (Fig. 23) and British Columbia 
