IMPROVEMENT.
Besides utilization and preservation, the third main object of forestry is the improvement of the forest. It is not an uncommon mistake to suppose that the virgin forest is the best forest for human purposes. It is a comparatively new idea, especially in America, that a forest can be improved; that is, that better trees can be raised than those which grow naturally. Lumbermen commonly say, "You never can raise a second growth of white pine as good as the first growth." As if this "first growth" were not itself the successsor of thousands of other generations! There is even a legend that white pine will not grow in its old habitat. Says Bruncken,
Many people probably imagine that a primeval wood, "by nature's own hand planted," cannot be surpassed in the number and size of its trees, and consequently in the amount of wood to be derived from it. But the very opposite is true. No wild forest can ever equal a cultivated one in productiveness. To hope that it will, is very much as if a farmer were to expect a full harvest from the grain that may spring up spontaneously in his fields without his sowing. A tract of wild forest in the first place does not contain so many trees as might grow thereon, but only so many as may have survived the struggle for life with their own and other species of plants occupying the locality. Many of the trees so surviving never attain their best development, being suppressed, overshadowed, and hindered by stronger neighbors. Finally much of the space that might be occupied by valuable timber may be given up to trees having little or no market value. The rule is universal that the amount and value of material that can be taken from an area of wild forest remains far behind what the same land may bear if properly treated by the forester. It is certain, therefore, that in the future, when most American forests shall be in a high state of cultivation, the annual output of forests will, from a much restricted area, exceed everything known at the present day. (Bruncken, North American Forests and Forestry, pp. 134-135.)
It is probable that the virgin forest produces but a tithe of the useful material which it is capable of producing. (Fernow, p. 98.)
Mr. Burbank has demonstrated that trees can be bred for any particular quality,—for largeness, strength, shape, amount of pitch, tannin, sugar and the like, and for rapidity of growth; in fact that any desirable attribute of a tree may be developed simply by breeding and selecting. He has created walnut trees, by crossing common varieties, that have grown six times as much in thirteen years as their ancestors did in twenty-eight years, preserving at the same time, the strength, hardness and texture of their forebears. The grain of the wood has been made more beautiful at the same time. The trees are fine for fuel and splendidly adapted to furniture manufacture. (Harwood, The New Earth, p. 179.)
Nature provides in the forest merely those varieties that will survive. Man, by interfering in Nature's processes but obeying her laws, raises what he wants. Nature says: those trees that survive are fit and does not care whether the trees be straight or crooked, branched or clear. Man says: those trees shall survive which are fit for human uses. Man raises better grains and fruits and vegetables than Nature, unaided, can, and, in Europe, better trees for lumber. In America there has been such an abundance of trees good enough for our purposes that we have simply gone out and gathered them, just as a savage goes out to gather berries and nuts. Some day our descendants will smile at our treatment of forests much as we smile at root-digging savages, unless, indeed, we so far destroy the forests that they will be more angered than amused. In Europe and Japan, the original supply of trees having been exhausted, forests have been cultivated for centuries with the purpose of raising crops larger in quantity and better in quality.
There are various methods used in forest improvement. Improvement cuttings, as the name implies, are cuttings made to improve the quality of the forest, whether by thinning out poor species of trees, unsound trees, trees crowding more valuable ones, or trees called "wolves"; that is, trees unduly overshadowing others. Improvement cuttings are often necessary as a preliminary step before any silvicultural system can be applied. Indeed, many of the silvicultural systems involve steady improvement of the forest.
The pruning of branches is a method of improvement, carrying on the natural method by which trees in a forest clean themselves of their branches.
Seeds of valuable species are often sowed, when the conditions are proper, in order to introduce a valuable species, just as brooks and ponds are stocked with fine fish. In general it may be said that improvement methods are only in their infancy, especially in America.
[Footnote 1:] A concise and interesting statement of the relation of the forest to rain and floods is to be found in Pinchot: Primer of Forestry, Bulletin No. 24, Part II, Chap. III.
[Footnote 2:] For an interesting account of an application of this method, see Ward, p. 35.
[Footnote 3:] To encourage such forest extension, the Forest Service is doing much by the publication of bulletins recommending methods and trees suited to special regions, as, e.g., on Forest Planting in Illinois, in the Sand Hill Region of Nebraska, on Coal Lands in Western Pennsylvania, in Western Kansas, in Oklahoma and adjacent regions, etc.