CHAPTER, 1X 
TREES FOR WATER CATCHMENT AREAS AND FOR 
GENERAL PLANTING 
Or equal importance with the selection of suitable situa- 
tions for planting is the proper choice of species. A great 
many kinds of trees have been tried in the British Isles; 
and so much information has been amassed concerning them 
that there is no difficulty in assigning to each species its 
exact value as a forest tree in this country. Some species 
are of especial value for shelter. Others are suitable for 
the formation of a protection zone at high altitudes. A few 
species, producing timber in a short period of years in great 
quantity and of good quality, are fitted to constitute the 
main crop. In any planting scheme regard must be paid to 
the varying requirements of each species on soil and situation. 
Conifers are chosen in the main for new plantations on 
account of the ease with which they can be planted, and 
because, as a rule, they yield large returns and can be 
grown on short rotations. Nevertheless, there is always 
room for valuable broad-leaved species. The ash, for 
example, should be planted in small groups on patches of 
good soil, such as occur in valleys and near streams. The 
importance of the beech must always be recognised, on 
account of the improvement of the soil which it effects by 
its great shade and abundant leaf-fall. It kills the grass, 
the great enemy to tree growth; and, mixed with main- 
crop trees, it stimulates their vigour and increases their 
production of timber. 
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