A comparison of Figs. 120 and 121 shows clearly the difference between a region protected by forest and one unprotected.[1]
Fig. 120. A Protection Forest, Maintaining the Headwaters of Streams. North Carolina. U. S. Forest Service.
Fig. 121. Hillside Erosion. North Carolina. U. S. Forest Service
(2) Productive. All practical foresters have as their first aim the yield of the forest. This distinguishes forestry from landscape architecture, the object of which may equally be the preservation and improvement of a given tract. The crop to be produced is as truly the prime concern of the forester as the raising of agricultural crops is the prime concern of the farmer. It is for this reason that forestry is said to be the same thing as conservative lumbering, Fig. 122. The prejudice of lumbermen against forestry has arisen from a misunderstanding of its aim. Its aim is not to prevent the cutting down of trees, but to direct their cutting in such ways that in the future there will still be trees to cut. "Thru use to a greater use," is the motto of the Forest Service. The difference between destructive lumbering and conservative lumbering is that the former cuts one crop regardless of the future; while the latter plans to cut crop after crop indefinitely. In other words, in conservative lumbering, the trees to be cut are not selected solely with reference to their immediate market value. Not one crop, but many, is the forester's motto.
Fig. 122. Conservative Lumbering. Black Hills National Forest, South Dakota. Note the brush, cord-wood, and logs piled separately,—a fine clean-up. Nothing cut below 12" diameter. U. S. Forest Service.
So long as the supply seemed exhaustless, forests might be and were treated as mines are, i.e., exploited for the sake of immediate profit; but now that lumbermen begin to realize that the end of the supply is in sight, more conservative methods are being adopted. We cannot afford to kill the goose that lays the golden eggs. In order then to obtain as rich harvests as possible, the modern forester makes use of various methods, some negative, some positive.