SECTION K.—BOTANY. 
SOME ASPECTS OF FOREST BIOLOGY 
ADDRESS BY 
PROF. A. W. BORTHWICK, O.BE., 
PRESIDENT OF THE SECTION. 
THE forest with its associated flora and fauna is a highly complex and 
delicately balanced community. In it we find an abundance of material 
upon which much of our prosperity depends. Perhaps the best proof 
of this statement is that the consumption of forest products and the 
destruction of forests is increasing at a rate which, in well-informed 
quarters, gives rise to serious apprehension as to the ability of the forests 
to withstand increasing and continued unscientific exploitation. 
The first users of the forest cared little for its timber. It was used 
principally for shelter and the chase. Later on, as population and settle- 
ment increased, wood was required for housing and fuel. In those early 
times whatever wood was handy and whatever trees seemed suitable to 
supply any requirement were utilised without any thought as to reproduc- 
tion and maintenance of supplies. Thus began the system of forestry 
which at the present day, under more organised methods, is known as the 
selection forest. In the selection forest only trees of a certain diameter 
may be removed, the number and volume of the trees to be felled annually 
or periodically being regulated by measurements of rate of growth in the 
forest. The regeneration is a natural one. Seedlings in due course take 
_ possession of the spots from which the mature trees have been removed. 
We have thus all ages and kinds of trees in irregular mixture singly, or in 
very small groups, scattered throughout the forest. This system preserves, 
more closely than any other, the conditions which prevail in and characterise 
the primeval forest. It has many advantages, but the main disadvantage 
is that the volume, and perhaps the quality of the timber as a whole, is 
not so high as that which can be obtained under more artificial systems 
of forestry. It is here that the main problems in regard to success or 
failure arise. When man interferes too much with Nature, she inevitably 
replies by countering his efforts, unless they comply within certain limits 
to natural laws. ‘The endeavour to grow pure forests of trees on wide 
areas, in dense, uniform, even-aged masses, irrespective of changes in soil 
conditions and climate, is not in accordance with natural laws. In 
converting the virgin forest or the selection forest into the modern 
artificial forest, the principal aim was to secure uniformity, and that branch 
of forestry known as forest management came into existence. The 
Principal aim in forest management was to obtain the highest yield in the 
Shortest time. For the sake of ease in regularity of yield or utilisation, 
