SELECTION FORESTS
It would be unprofitable to discuss here all the many methods of forest management which have proved to be best, technically, for given species and combinations of species. Where market and transportation facilities are highly favorable, as in Europe, the timber owner can adopt the method which will bring the best results, but here he has no such choice. He can but bear in mind certain fundamental principles, uniformly applicable to large areas for considerable periods of time. Roughly, however, our Western forests can be classified by their adaptability to the two directly opposite systems, known as clean cutting and selection cutting, of which almost all methods are modifications.
A selection forest is one in which all ages of trees exist, from seedling to maturity. It is the natural growth of species which are tolerant of shade. In a natural state, undisturbed by cutting, it maintains much the same aspect continuously, for as the oldest trees die, their place is taken by younger ones. Obviously such a forest must be composed of species, whether one or several, which can grow beneath its own shade. The understories of varying ages are as dense as their light requirements and the density of the overwood permit.
The common hardwood forests of the East illustrate one type of the natural selection forest. On the Pacific slope an example is afforded by hemlock, either practically pure or mixed with white fir, but probably the most typical is the ordinary Western yellow pine under certain conditions. At its best this tree composes a forest so dense that all young growth is shaded out, but everyone is familiar with the frequent opener stand containing all ages. The younger trees are often called blackjack.