104 OUR FORESTS AND WOODLANDS 
advantageously be left to form a subsequent 
chapter by itself. 
The growth of oak in highwoods may either be 
pure or else in mixed crops along with other kinds - 
of trees. Pure woods of oak can only be grown 
to the best advantage on soils that are fertile, 
deep, and fresh. Where there is a tendency to 
moistness in the soil, it is better to grow it along 
with ash, elm, maple, and sycamore, or even with 
alder, on land inclined to be marshy. On drier 
land, especially where the soil is at all limy, oak 
can best be grown along with beech, which pro- 
tects and improves the soil, and keeps it as cool 
and fresh as circumstances permit. 
Whether planted pure, or only in groups on 
the better parts forming patches throughout a 
matrix of beech or other kinds of hardwood trees, 
the treatment of the oak is based on the ruling 
principle that, as it is to form the ultimate crop 
of timber to be harvested, it shall throughout all 
the operations of tending and thinning receive 
the chief consideration. Other species interfering 
with its growth are to be removed in favour of it 
whenever necessary, and individuals of its own 
species must also be removed whenever they 
