Approaches to Ecologically Based Forest Management, PART I: Ecological concepts upon which forest management is based

Although trees are sometimes viewed as a crop, a forest is more than a collection of trees and bears little resemblance to agricultural plantings. In order to manage forests, a resource professional must try to understand them as functioning ecosystems.

Ecosystems are comprised of all living and nonliving components that interact on a particular segment of a landscape. For research or management purposes, boundaries between different terrestrial ecosystems can arbitrarily be established, but absolute or "natural" boundaries between adjacent ecosystems cannot be objectively defined. No one can claim sufficient functional understanding of even the simplest of ecosystems to the degree necessary to manipulate them with fully predictable results. Thus, what is called "ecosystem management" is more of an approach to management rather than a cause and-effect method of control, which is the more common meaning of the term "management."

The goal of forest ecosystem management is to develop methods of extracting human commodities and amenities from forest ecosystems in ways that do not greatly alter the processes that shape the development of natural forest communities. We are not attempting to control ecosystem processes directly, since we do not fully understand them. Rather, we wish to alter them as little as possible. Considering the limits of our current knowledge, I believe this approach is the best way to assure sustainability of those ecosystem outputs upon which societies, as well as individual landowners, depend.

"Natural" or native forests are assemblages of regional plant and animal species able to coexist in a particular environment. This composition is in a constant state of flux as individual populations react to changes in their immediate environments brought about by internal and external forces. Natural forests can be simple or complex in terms of species composition and arrangement of age classes (structure), depending on their developmental stage and on a site's physical limitations. Many ecologists now agree that on a landscape scale, and over long periods of time, naturally developed forest communities result in the greatest amount of biological diversity possible under the prevailing climatic and soil conditions in a given region.

Managed forests are manipulated to produce specific commodities or benefits. Traditionally, wood production and consumptive wildlife have been the dominant commodities. Managed forests are generally less complex than natural forests because management typically attempts to optimize only a few species - usually those of high commercial value; those which are characterized by fast growth (high productivity); or those that can be grown in pure stands or in relatively simple mixtures. Economic considerations often lead to additional structural and compositional limitations, such as rotation age, maximum diameter, fixed spacing and elimination of competing vegetation.

The simplified composition and structure of managed forests reduce the number of possible niches in a forest ecosystem, resulting in lower regional biodiversity than might otherwise be possible. However, there is as yet no convincing scientific evidence that such simplified managed communities necessarily lose long-term productivity, resiliency or health. A consensus is emerging among scientists that the concepts of forest health and forest productivity can be framed only in the context of management goals and objectives.