TIMBER PRODUCTION 55 
in this country, as a result of which large areas have 
been planted with a single species which would have 
yielded much more profitable results planted as a mixed 
wood. 
It must not be thought that in criticising the 
methods of forestry in this country that the blame 
lies entirely at the door of the forester. The wonder is 
that he has accomplished so mich against the number- 
less disadvantages with which he has had to contend. 
It is the duty of the ecologist to Supply those accurate 
data in need of which the forester stands, and my plea 
is for co-operation between the practical man who has 
his hands full enough already looking after his nursery, 
his plantations, and his timber, and the scientist whose 
function is the provision of exact information and 
advice. 
In no respect is such accurate information more 
scanty than with regard to association of species. The 
data as to those which occur together naturally on the 
different-soils cannot fail to aid in the choice of trees 
for mixed planting, such as will not interfere with each 
other’s development and yet contribute to the incre- 
ment yield. And still more will such information 
supply a warning as to what species should not be planted 
together. Mixtures indicated by our present knowledge 
are— 
Calcareous soils: (ash and wych elm) and (beech 
and yew). 
Non-calcareous soils: (Q. sessiliflora and Spanish 
chestnut), (Q. sess. and Fagus), (Q. robur and Populus 
tremula). 
The phases of succession which occur naturally on 
