NORMAL GROWING STOCK. 187 
Normal Growing. Stock. Since the annual valuable 
increase of wood is in proportion to the amount of leaf surface 
on trees of the right kind, size and form, it follows that there 
must always be a certain number of trees of a certain size in 
order to obtain normal annual growth. This material represents 
invested capital, and the highest annual income is dependent 
upon having a normal growing stock upon the land. As a mat- 
ter of fact, this is an ideal thing, and is seldom, if ever, exactly 
attained. The amount of normal growing stock which there will 
be upon one acre will depend upon the species, its age and con- 
ditions, and must be determined in the working plan of the 
forest tract after a careful study of its conditions. 
The Normal Income is the crop of wood that a given tract 
of forest will produce per year under normal conditions. This 
will, of course, vary with the species and conditions. It may be 
harvested by selecting only the large trees from all over the area, 
or by cutting clean over a certain portion of it, as shown in 
chapter X. It is very plain that, if the increase per year is a 
given amount, it may be harvested by either method without 
infringing on the normal growing stock of the whole area. For 
some conditions the selection method is preferred, while for oth- 
ers, such as for even stands of Spruce, which are liable to blow 
down when thinned, it might be better to cut clean, and keep the 
trees in even age groups. In this latter case the tract should be 
divided into as many parts as there are years in the rotation, 
and the timber from one part cut each year. This would mean 
the planting or seeding of a like amount each year. 
Capital Growing Stock. This represents the actual amount 
of trees on the land which is producing wood growth of value. 
The nearer this approaches to the normal growing stock the bet- 
ter the condition of the forest and the larger its returns. " 
Actual Income represents the annual return which a given 
forest tract is producing. 
Increasing Value of Forests. In countries where forestry 
has reached a high degree of development a piece of land is 
regarded as being in forest as soon as it is stocked with trees, 
even if the seedlings are not yet over two inches high and are 
hardly to be seen at a short distance. Such a piece of land 
should have increased value and should be regarded as earning 
a rate of interest. It is so regarded in many of the European 
