Selection systems are partial removals of trees based on the silvicultural objectives of the landowner. This method is used when species of shade tolerance or intermediate tolerance are considered desirable. Each tree is assessed, determined to be cut or to be left, measured, tallied, and marked. Although economics always plays some part in determinations, it is not the only factor. Rate of growth, potential for further growth, health, quality, spacing, and species are some of the factors that also must enter each determination.
It is important that a landowner get a graduate forester to do this assessment; a so-called "thinning" or "select cut" can be offered by anyone with a saw in hand. A thinning based only on economic factors can easily become a high-grade. Furthermore, a small tree is not always a younger tree. Although many small trees in the woods are that size because of their youth, just as many are small because of poor genetics, stunted growth, or being a poor or inappropriate species for the site. It takes many years of experience to tell the difference.
I always attempt to do a bit of spacing and some weeding or cleaning while I am conducting a selection system harvest. Part of this method is manipulating the amount of sunlight on the ground to successfully regenerate desired species. Selection system harvesting has the advantage of allowing a timber stand to retain its forested appearance in the years immediately following harvest. It has particular advantages in higher elevations and farther north where shade-tolerant species are considered very desirable. It has disadvantages of providing for slower long-term growth, for allowing undesirable species to predominate, for allowing undesirable epicormic branching on future crop trees, for holding back valuable sun-loving species, and for being an easily and frequently abused method. Furthermore, it is very difficult to use successfully on steep ground due to high potential for heavy logging damage on residual trees.
Selection system harvests can be designed to suit each individual tract, each site, each timber type, and each individual landowner. Each type of selection system has a separate set of objectives for the manipulation of sunlight, reproduction, present crop, and future crop.
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