TIMBER PRODUCTION 47 
transpiration a large number of vessels are consequently 
formed each spring. In a well-stocked wood the 
canopy of each tree is much reduced, and the propor- 
tion of vessels to fibres in the spring wood is much 
smaller. Consequently the timber produced is of 
greater strength. 
The boles.in open canopy tend to be short and taper 
rapidly, so that not only is the gross amount of timber 
in the trunk small, but also in order to obtain planks 
of adequate length there is far more wastage than in a 
long trunk which tapers slowly. 
By far the most serious defect, however, is the early 
production of numerous strong branches, so that the 
trunk is knotty and largely consists of faulty wood. 
Since the practice is for the landowner to sell the 
trees standing to some timber merchant, it will be 
evident that the latter, even in the case of well-grown 
trees, accepts a certain risk in respect to the quality of 
the timber. It is scarcely surprising, therefore, that 
much of the oak growing in this country at the present 
day is practically unsaleable. 
In view of the many adverse conditions, we are 
certainly not justified in forming an estimate of the 
economic soundness of British forestry on the basis 
of the financial results which the average present-day 
woodland yields. This is emphasised when we remem- 
ber that the understocking itself, apart from the corre- 
lated effects, considerably reduces the increment value 
of the forest. 
The extent of the understocking can best be illustrated 
by afew figures. We may take it that a properly stocked 
oakwood between 100 and 120 years old should have 
