Page:A primer of forestry, with illustrations of the principal forest trees of Western Australia.djvu/37

31 CHAPTER IX.

FOREST MANAGEMENT.

It is seldom that a forester reaps the crop which he sows; consequently the management of a forest must be very definitely laid down if the efforts of one man are to be successfully carried on by his successor. It is equally important that a people becoming possessed of a forest growing on a soil suitable only for the growing of trees should not cut out that forest any faster than new trees can grow up to take the place of the trees they are felling. This principle has not yet received recognition in Western Australia, with the result that big mills have been established and big towns have grown up around them. The timber was wastefully cut with no thought of future requirements, with the result that before the new crop was ready the old crop was exhausted, and the mills have had to close. In many places in the South- Western Division of this State, the ruins of townships can be seen where young trees are springing up among the charred foundations of the mill buildings and houses.

The basis of forest management is forest mensuration. It is a simple matter to measure logs lying on the ground, and the volume of timber growing on an acre of forest land can always be determined by chopping down the trees. This is seldom possible, but various systems have been devised whereby the volume of a standing forest may be calculated by measuring up a small number of sample trees which are felled for the purpose. Where forestry has been practised over long periods, as in Germany, the forester is enabled by a series of measurements to determine the volume of timber which a forest of a certain species growing on certain class of country should yield at various ages. By tabulating and averaging the results of many thousands of measurements he compiles "Yield Tables."

By comparing the condition of a forest under his charge with the particulars concerning a "normal forest" of the same age which he finds in the yield tables, he is able to judge the success or failure of the manner in which he has tended the forest.

Yield tables also enable the forester to determine when his forest crop is economically mature. He should know the revenue which each acre of his growing forest must be accumulating in order to be fully utilising the land which it occupies. The yield table shows him the average annual increment in volume which the forest is putting on at various ages, and when the value of this increment drops below the compound interest charges which the forest must bear, then the trees should be felled in order to make way for a fresh crop.

The involved calculations by which the forester tests the financial soundness of a forest crop as an investment comes within the study of "Forest Valuation." Detailed calculations of forest valuation are not possible in a young country such as this, where very little is yet known about the rate of growth of our indigenous species, but sufficient is known to prove that trees are the most valuable crop that can be grown on certain classes of soil.

In order that the practice of forestry may be conducted on sound business lines, there must be a regular "stock taking" of the land comprising a forest and the trees growing upon it. Land surveys and timber surveys form a very essenpart of forest management, and the first step towards organising sylvicultural work and fire protection is to have a survey of the country made.

In order that forest management may serve to improve the condition of a forest and cause it to yield the highest possible returns on the money invested, there must be a continuity of policy regulating the management. The main object of a "Working Plan" is to ensure continuity of working over long periods.