TIMBER PRODUCTION 51 
is the information regarding the requirements of the 
various species, 
Recent ecological research on the distribution of 
natural woodland types has done much towards placing 
our information on this subject on a sounder basis. 
For it may be fairly argued that if a particular species 
of tree forms pure woods on a particular type of soil 
under the stress of natural competition, that same tree 
will grow, at all events, no less vigorously when the 
struggle with other species is eliminated by artificial 
protection. 
To illustrate the value that ecological work may have 
in this direction, I cannot do better than quote an 
example that has come prominently under my notice 
during the last ten years. There are in this country 
two native species of oak, viz. the common oak (Quercus 
robur) and the durmast oak (Q. sessiliflora). In many 
of the older works on forestry the distinction between 
these two was either ignored, or if recognised was not 
made the basis for any distinction of treatment. In the 
more modern and better works the two are usually 
stated to require the same cultural conditions. 
One is indeed led to assume that in general it is of 
no consequence which species is planted either on 
account of the soil conditions or the timber produced, 
The study of plant communities has led to the real- 
isation that marked preferences as to soil and situation 
are often far more pronounced between closely allied 
species than in those which are wholly unrelated. And 
perhaps in no case is this more striking than in the 
natural distribution of the two native oaks as brought 
to light by the ecological work of recent years. 
