DEFINITION OF SUSTAINED YIELD FORESTRY

Definiton of Sustained yield forestry is a concept that designs timber cutting and regrowing of timber crops to provide a perpetual yield of timber from a particular forest landscape. Initially, this concept embodied the commitment to non-declining timber yields over time.

However, the determination of annual cuts under sustained yield forestry has commonly been overly optimistic when considering both tree growth rates and the portion of a forest landscape that is suitable for the cutting and growing of timber crops over time. Thus, as a result, “sustained timber yields” have tended to decline through time as a result of excessive cutting rates that cannot be matched by the rate of regrowth of timber and by extraction of timber from land that subsequently proves to be unsuitable for timber growth and/or necessary to protect for non-timber forest uses.

Sustained yield forestry confuses timber or trees with forest ecosystems and fails to recognize that fully functioning forests are necessary to have trees, which are necessary to have timber. In contrast, an ecosystembased approach protects forest functioning at all scales through time as the first priority; and then seeks to sustain, within ecological limits, a diversity of human and non-human uses across the forest landscape.

DEFINITION OF FOREST STANDS | FOREST PATCHES

Definition of Forest Stands or Forest Patches refer to the ecosystem scale at which a relatively homogenous forest unit can be identified. The composition, structure, and ecological functions within a stand are similar enough that an ecologically responsible forest use prescription can be applied uniformly within the stand, without encountering changes in ecological parameters that may produce unexpected or undesirable results.

In conventional forestry, “stands” have largely been defined by narrow timber characteristics, which were in turn driven by short-term economic variables. However, in order to plan and carry out ecologically responsible forest uses within an ecosystem-based approach, stands must be defined in relation to whole ecosystem factors that are required to maintain fully functioning forests at the landscape and stand levels.

In other words, the boundaries of a stand are not determined by rigid human management criteria such as timber size and timber quality, but by the full spectrum of ecosystem parameters that have been shaped by natural disturbance patterns and that reflect the movement of energy, nutrients, water, and animals into and out of a particular ecosystem.

Human scales are closest to forest scales at the stand or patch level. For example, the stand or patch level is the scale where visible human modification occurs. However, an ecosystem-based approach must always consider that what occurs at the stand or visible scale will also have impacts on a variety of other scales, from the large landscape to the microscopic.