Forests Case

A central tenet of forestry is sustainability--ensuring that the products, services, values, and inherent productivity of the resources are sustained over time. An old concept in forestry is sustained yield, meaning that the amount of resources removed from a forest is equal to the amount grown or produced in that forest. This concept has traditionally been most used to define the limits of sustainable timber production: No more timber should be removed from the forest than is grown in any given cycle. Similar concepts apply to the production of wildlife, grasses for forage or livestock, and nontimber ecosystem services such as berries, floral greenery, mushrooms, and so on.

Forest stands in which trees are roughly the same age are typically managed over rotations of twenty to over one hundred years, depending on species, site quality, and specific management objectives. Multiaged stands--which include multiple age classes of trees--are managed over cutting cycles that may range from five to over fifty years. Ideally, stands are maintained at different stages of development, so the forest as a whole may include a variety of stand ages and stand structures.

Many stands are managed to form simple structures that consist of a single tree species planted at consistent spacings and possibly with similar genotypes. Other stands are grown to have many species and multiaged structures. A regulated forest has an arrangement of stand structures that yields a constant production over time. This arrangement represents an ideal that is rarely met, because, over the long time span of forest growth, there are often changes in land ownership patterns, management directives, and regulations that affect how and which lands are managed, as well as disturbances such as fire.

Forestry also involves the management of fuels and their arrangement in forest stands. Forest fires occur over broad areas every year in both temperate and tropical forests and result in massive carbon emissions. Insects and pathogens represent another potential hazard to forests that may increase fuels and fire hazards, lead to large-scale carbon emissions, and reduce the ability of the forest to meet other needs. Forests that are resistant to disturbance present an opportunity to conserve carbon on a large scale. Forests with natural functions and processes, endemic levels of insects and pathogens, and normal levels of biodiversity are said to be healthy. Regardless of specific objectives for any forest land, maintenance of forest health is a common, overriding objective for managed forests.

Forests store large amounts of carbon in living, above-ground stems, branches, and foliage; belowground root structures and fine roots; dead, woody objects, such as logs, decomposing foliage, and twigs; and soil. Forest management activities affect these components and therefore affect a site's carbon balance. A clear-cut harvest will remove