APPENDICES. 
A. OPTIMUM OF TIMBER. 
THIS word is, of course, the neuter form of the Latin optimus, best. It has gradually 
developed a biological application, and it is only of recent years that the use of the term 
has crept into standard dictionaries. Thus in Webster's International of 1910 we 
have it defined as " The most favourable conditions as to temperature, light, moisture, 
food, &c., for the growth and reproduction of an organism. Often used adjectively, 
as optimum conditions, optimum temperature, &c." 
The use of the term is an expression of the terminology of variation which is 
well worthy of consideration. Foresters and ecologists use it, and its use undoubtedly 
tends to clarity of view. In Australia it has a more direct economic bearing with 
timber than with anything else. 
In 1918 I appealed to the Chief of Forest Investigations of the United States 
in regard to the use of the term in the Forest Service, and Professor J. W. Stokes replied 
as follows : 
The term " Optimum " is frequently used in describing the growth and quality of a certain species 
in the rmHt favourable part of its range. The word is also used to describe the most favourable light 
conditions or the density of stand most favourable to the growth of timber of first quality. 
The term " Optimum Light Intensity " is used on page 11, Forest Service Bulletin 92, by R. Zon 
and Henry S. Graves. C. A. Schenck, in " The Art of the Second Growth," Brandon Printing Company, 
Albany, X.Y., 1912, uses the expression frequently and in the most general way, pages 25-26 : " The 
region occupies a big belt stretched across the continent, so that the western and eastern flora join hands 
in it. A typical tree of this region, the white spruce, often forms large pure forests. Other species of the 
zone are . . . cedar and tamarack, the latter here obtaining its optimum." 
On page 27 the term is used as follows in describing the Pacific forest of moderately warm zone : 
" Pinus ponderosa. Height and timber quality dependent on proximity to Pacific Ocean. Optimum 
in Sierra Nevada, where trees 300 feet high are frequently found." 
On page 28 in the same connection is found : " Abies grandis.'The only fir on Vancouver Island. 
Optimum at coast in Oregon, where it grows up to 300 feet high." 
D. T. Mason, in Department of Agriculture Bulletin, 154, " The Life History of Lodge pole Pine in 
the Rocky Mountains " speaks of " Optimum density." 
The use of the word " optimum " in forestry literature is very generally accepted and understood, 
but I have been unable to find it specifically defined." 
We say a species attains a certain size, but we may or may not know its optimum. 
In our very partially botanically explored country we have to exercise a reservation 
as to whether we yet know the conditions or the situation in which the optimum of a 
species has been evolved. A plant may evolve in two directions in the direction of 
exuberance, and in the direction of nanism under hard conditions. It develops 
variously as it seeks to adapt itself to its environment. 
