42 ENGLISH ESTATE FORESTRY 



able to take advantage of it. In gravelly or sandy soils, 

 again, they are able to reach the plant food lying within a 

 considerable depth of the surface, and the aridity and poverty 

 of the surface stratum do not affect them in the same way as 

 agricultural plants are affected. 



Such soils as these are not peculiar to any particular 

 geological formation, but will be found more or less on forma- 

 tions ranging from the primary rocks to the gravel beds of 

 recent origin. It must, however, be admitted that the 

 geological formation has a decided influence on the chemical 

 composition of the soil, and to a less extent on its physical 

 condition, and these affect the growth of different species to 

 a marked extent. It is a well-known fact that plants closely 

 allied botaiiically often show a marked difference in their 

 liking for particular soils. The Austrian pine, for instance, 

 delights in a calcareous soil, while Scots pine rarely lives to 

 great age in it, and the pinaster almost refuses to grow in it 

 at all. Certain species, again, seem quite indifferent to the 

 chemical character of the soil, but are easily affected by its 

 physical condition, especially as regards moisture and porosity. 

 Ash on a dry shallow soil is shortlived, and at the same time 

 rarely thrives in a stiff wet clay. Shallow-rooters, such as 

 spruce or larch, are affected as much by climate as soil, and 

 so on. Any attempt to judge the fitness of soil for forestry 

 purposes from the geological formation on which it rests must 

 give results of little practical value, for clays, loams, gravels, 

 sands, and peat are found on all formations. But when the 

 physical or mechanical property of a soil is known, together 

 with the geological formation from which it has been derived, 

 we are in possession of data which enable a fairly accurate 

 estimate to be made of its suitability for forestry purposes, 

 although actual inspection of the ground is the only safe 

 guide in the case of a specified area. 



As a general principle, it may be stated that no land can 

 be considered suitable for growing profitable forest crops 

 which has less than 2 feet of gravel, sand, or other soil 

 overlying the solid rock. We may get trees to grow on 

 almost bare rock, but, unless that rock is so shattered and 

 broken up to a fair depth as to resemble gravel in character, 

 we never yet saw trees grow on it at a profitable rate, unless 



