ON ESTABLISHING AN EXPERIMENTAL FOREST AREA, 165 
The soil of the selected area should, in any case, be of such a 
nature as to allow a normal rate of growth to be made by the 
species represented on it. For Scots pine, larch, Douglas fir, and 
most conifers, a porous gravel is suitable, the first-named being less 
fond of moisture than the other two. As these trees are really of 
most economic importance in Scotland, at least two-thirds of the 
soil should be adapted to their growth, while, if possible, the 
remainder should be of a better nature, so as to accommodate oak, 
beech, ash, etc. Very thin soils, or those containing iron-pan, 
should be avoided as much as possible, while peat-bog is also ill- 
adapted for the purpose in view, as we already know that cases of 
profitable forestry are not found upon soils of this class. 
Elevation and Exposure. 
As a general rule, the greater the elevation the thinner the soil. 
If the conditions as to the latter are observed, therefore, there is 
little danger of too great an elevation being reached for profitable 
timber growth, which usually has its upper limit at 1200 or 1500 
feet above sea-level in Scotland, according to species and exposure. 
On a southern aspect, trees ascend to greater heights than on 
northern exposures; but in a climate like that of Scotland, with an 
excess of cloud and moisture, a sunny aspect undoubtedly produces 
better ripened wood, and ultimately better timber, than one on 
which the direct rays of the sun rarely fall. On undulating 
ground exposures vary, of course, but on a limited area the ground 
usually has a tendency to slope one way or the other, and we should 
pronounce in favour of a southern, south-western, or south-eastern 
aspect—preferably the first or last, as a south-western slope has 
always to bear the brunt of prevailing winds and gales. With a 
southerly exposure, the growth of oak and beech would be 
possible at a higher elevation, and the productive power of 
the area increased generally. 
Size of Area. 
Financial considerations compel us to limit the size of our area 
to the smallest dimensions compatible with the objects in view. 
Organised working, on the assumption of a perpetual yield being 
one of our guiding principles, too small an area would allow too 
little play in regard to fellings and revisions of working plans, 
