Old-growth forest

The trees stand tall and thick of girth. The air about them is cool and moist. The soil is rich and matted by a thick organic blanket. People marvel at the forest, imbibing its grandeur, coveting its timber. In another area, across the mountains, perhaps, the trees stand stooped and scraggly. The air about them is parched. The soil is coarse, barren, and hardened to the elements. People pass by the forest, ignoring its dignity, rejecting its worth.

These images reflect extremes in old-growth forests. The first is the compelling one: it exemplifies the common perception of a ecosystem at the center of a bitter environmental controversy. The second depicts an equally valid oldgrowth forest, but it is one whose fate few people care to debate.

The controversy over old-growth forests is the result of competition for what has become a scarce natural resource—large, old trees that can be either harvested to produce high value lumber products or preserved as notable relics as a forest proceeds through its stages of ecological succession . This competition is a classic environmental struggle, impelled by radically different perceptions of value and conflicting goals of consumptive and nonconsumptive use.

What is an old-growth forest? Before the modern debates, the definition seemed simple. Old-growth was a mature virgin forest; it consisted of giant old trees, many past their prime, which towered over a shady, multilayered understory and a thick, fermenting forest floor. In contrast to second-growth timber, the stand never had been harvested. It was something that existed in the West, having long since been cut in the East.

In the mid to late 1980s several professional and governmental organizations, including the Society of American Foresters , the U.S. Forest Service , and California's State Board of Forestry, began efforts to define formally "oldgrowth forest" and the related term "ancient forest" for ecological and regulatory purposes. The task was complicated by the great diversity in forest types, as well as by different views of the purpose and use of the definition. For example, 60 years of age might be considered old for one type, whereas 200 or 1,000 years might be more accurate for other types. Moreover, forest attributes other than age are more important for the wellbeing of certain species which are dependent on forests commonly considered old growth, such as the northern spotted owl and marbled murrelet. Nonetheless, some common attributes and criteria were developed.

Old-growth forests are now defined as those in a late seral stage of ecological succession, based on their composition, structure, and function. Composition is the representation of plant species—trees, shrubs, forbs, and grasses—that comprise the forest. (Often, in referring to an old-growth stand foresters limit composition to the tree species present). Structure includes the concentration, age, size, and arrangement of living plants, standing dead trees (called "snags"), fallen logs, forest-floor litter, and stream debris. Function refers to the forest's broad ecological roles, such as habitat for terrestrial and aquatic organisms, a repository for genetic material, a component in the hydrologic and biogeochemical cycles, and a climatic buffer . Each of these factors vary and must be defined and evaluated for each forest type in the various physiographic regions, while accounting for differences in disturbance history, such as wildfires, landslides, hurricanes, and human activities. The problem of specifically defining and determining use of these lands is exceedingly complex, especially for managers of multiple-use public lands who often are squeezed between the opposing pressures of commercial interests, such as the timber industry, and environmental preservation groups. The modern controversy centers primarily around forests in the northwest of United States and Canada—forests consisting of virgin redwoods , Douglas firs, and mixed conifers.

As an example of old-growth characteristics, the Douglas-fir forests are characterized by large, old, live trees, many more than 150 feet (46 m) tall, 4 ft (1.2 m) in diameter, and 200 years old. Interspersed among the trees are snags of various sizes—skeletons of trees long dead, now home to birds, small climbing mammals, and insects. Below the giants are one or more layers of understory—subdominant and lower growing trees of the same or perhaps different species, and beneath them are shrubs, either in a thick tangle providing dense cover and blocking passage or separated and allowing easy passage. The trees are not all healthy and vigorous. Some are malformed, with broken tops or multiple trunks, and infected by fungal rots whose conks protrude through the bark. Eventually, these will fall, joining others that fell decades or centuries ago, making a criss-cross pattern of rotting logs on the forest floor. In places, high in the trees, neighboring crowns touch all around, permanently shading the ground; elsewhere, gaps in the canopy allow sunlight to reach the forest floor.

Proponents of harvesting mature trees in old-growth forests assert that the forests cannot be preserved, that they have reached the carrying capacity of the site and the stage of decadence and declining productivity that ultimately will result in loss of the forests as well as their high commercial value which supports local lumber-based economies. They feel that society would be better served by converting these aged, slow-growing ecosystems to healthy, productive, managed forests. Management proponents also argue that adequate old-growth forests are permanently protected in designated wildernesses and national and state parks. Moreover, they point out that even though most old-growth forests are on public land , many forests are privately owned, and that land owners not only pay taxes on the forests, but they also have made an investment from which they are entitled a reasonable profit. If the forests are to be preserved, land owners and others suffering loss from the preservation should be reimbursed.

Proponents of saving the large old trees and their environments claim that the forests are dynamic, that although the largest, oldest trees will die and rot, they also will be returned to earth to support new growth, foster biological diversity, and preserve genetic linkages. Moreover, protection of the forests will help ensure survival of dependent species, some of which are threatened or endangered. Defenders claim that the trees will not be wasted; they simply will have alternative value. They believe that their cause is one of moral as well as biological imperative. More than 90% of America's old-growth forests have been logged, depriving future generations of the scientific, social, and psychic benefits of these forests. As a vestige of North American heritage, the remaining forests, they believe, should be manipulated only insofar as necessary to protect their integrity and minimize threats of natural fire or disease from spreading to surrounding lands.

See also American Forestry Association; Endangered species; National forest; National Forest Management Act; Restoration ecology

[Ronald D. Taskey ]

RESOURCES

BOOKS

Arrandale, T. The Battle for Natural Resources. Washington, DC: Congressional Quarterly, Inc., 1983.

Kaufmann, M. R., W. H. Moir, and R. L. Bassett. Old-Growth Forests in the Southwest and Rocky Mountain Regions. Proceedings of a Workshop. Washington, DC: U.S. Forest Service, Rocky Mountain Forest and Range Experiment Station, 1992.

OTHER

Spies, T. A., and J. F. Franklin. "The Structure of Natural Young, Mature, and Old-Growth Douglas-Fir Forests in Oregon and Washington." In Wildlife and Vegetation of Unmanaged Douglas-Fir Forests, edited by L. F. Ruggiero, et al. Washington, DC: U. S. Forest Service, Pacific Northwest Forest and Range Experiment Station, 1991.