TREES FOR WATER CATCHMENT AREAS 151 
agriculture, and often produces fine crops of timber. 
Here ash mixed in small quantities amidst the beech 
forms very remunerative thinnings in the middle part 
of the life of the wood, and in all cases should be felled at 
from 60 to 80 years old, for if left longer it becomes unsound. 
In the preliminary survey of large areas for planting, 
situations suitable for ash should be specially looked for. 
These will be found along water courses on the slopes of 
hills, on the sides of ravines where the water percolates 
through from the ground above, and in the valleys on the 
deep soil not far from the banks of the streams. On such 
sites, ash should be freely planted, mingled with other trees, 
like beech, larch, elm, sycamore, and oak. 
Ash should never be planted on poor, dry, or shallow 
soils. It does not thrive on pure sand, on gravel, on dry 
chalk, on stiff clay, or on wet peat. At high altitudes and 
on unsuitable soils it remains small in size, and usually 
decays at an early age, producing timber of little value. 
It becomes black-hearted under such circumstances before 
it reaches fifty or sixty years old. 
Ash is injured when young by late spring frosts in low- 
lying situations, and here requires nurses for its protection. 
The terminal bud is often destroyed, and forked growth 
results. No tree suffers more from rabbits than ash; 
and the cultivation of this species is impossible where 
rabbits are numerous, unless stringent measures are 
adopted to kill these pests and keep them out of the 
plantations. 
Ash should be regularly thinned in order to give the 
best trees the requisite amount of light and space. Such 
thinnings are generally saleable, as young ash provides 
useful wood. Felling may take place when the trees are 
60 to 80 years old or earlier; and if gradually carried 
out, the old stand may be replaced by the seedlings 
which have usually sprung up, and natural regeneration 
be easily effected. In other words, when a group of ash 
is felled, planting is rarely necessary, as the self-sown 
seedlings can be utilised to form the new crop. 
