Old Growth Forest

Old Growth Forest
Old Growth Forest
Ancient ecosystems, old-growth forests consist of trees that have never been harvested. These forests are, in some cases, the only habitat for a number of plant and animal species.

The timber industry views the large, old trees as a renewable source of fine lumber, but environmentalists see them as part of an ancient and unique ecosystem that can never be replaced. In the 1970’s scientists began studying the uncut forests of the Pacific Northwest and the plants and animals that inhabited them.

In a U.S. Forest Service publication, Ecological Characteristics of Old-Growth Douglas-Fir Forests (1981), Forest Service biologist Jerry Franklin and his colleagues showed that these forests were not just tangles of dead and dying trees but rather a unique, thriving ecosystem made up of living and dead trees, mammals, insects, and even fungi.

Old-Growth Forest Ecosystem

The forest usually referred to as old growth occurs primarily on the western slope of the Cascade Mountains in southeast Alaska, southern British Columbia, Washington, Oregon, and Northern California.


The weather there is wet and mild, ideal for the growth of trees such as Douglas fir, cedar, spruce, and hemlock. Studies have shown that there is more biomass, including living matter and dead trees, per acre in these forests than anywhere else on earth.

Trees can be as tall as 300 feet (90 meters) with diameters of 10 feet (3 meters) or more and can live as long as one thousand years. The forest community grows and changes over time, not reaching biological climax until the forest primarily consists of hemlock trees, which are able to sprout in the shade of the sun-loving Douglas fir.

Old-Growth Forest Ecosystem
Old-Growth Forest Ecosystem
One of the most important components of the old-growth forest is the large number of standing dead trees, or snags, and fallen trees, or logs, on the forest floor and in the streams. The fallen trees rot very slowly, often taking more than two hundred years to decompose completely.

During this time they are important for water storage, as wildlife habitat, and as “nurse logs” where new growth can begin. In fact, seedlings of some trees, such as western hemlock and Sitka spruce, have difficulty competing with the mosses on the forest floor and need to sprout on the fallen logs.

Another strand in the complex web of the forest consists of mycorrhizal fungi (mycorrhizae), which attach themselves to the roots of the trees and enhance their uptake of water and nutrients.

The fruiting bodies of these fungi are eaten by small mammals such as voles, mice, and chipmunks, which then spread the spores of the fungi in their droppings. There are numerous species of plants and animal wildlife that appear to be dependent on this ecosystem to survive.

Protecting the Forest

Protecting the Forest
Protecting the Forest
By the 1970’s most of the trees on timber industry-owned lands had been cut. Their replanted forests, known as second growth, would not be ready for harvest for several decades, so the industry became increasingly dependent on public lands for their raw materials.

Logging of old growth in the national forests of western Oregon and Washington increased from 900 million board feet in 1946 to more than 5 billion board feet in 1986.

Environmentalists claimed that only 10 percent of the region’s original forest remained. Determined to save what was left, they encouraged the use of the evocative term “ancient forest” to counteract the somewhat negative connotations of “old growth.”

Then they were given an effective tool in the northern spotted owl. This small bird was found to be dependent on old growth, and its listing under the federal Endangered Species Act in 1990 caused a decade of scientific, political, and legal conflict.

Under law, the U.S. Forest Service was required to protect enough of the owl’s habitat to ensure its survival. An early government report identified 7.7 million acres of forest to be protected for the bird. Later, the U.S. Fish and Wildlife Service recommended 11 million acres.

In 1991 U.S. District Court judge William Dwyer placed an injunction on all logging in spotted owl habitat until a comprehensive plan could be finalized. The timber industry responded with a prediction of tens of thousands of lost jobs and regional economic disaster.

In 1993 President Bill Clinton convened the Forest Summit conference in Portland, Oregon, to work out a solution. The Clinton administration’s plan, though approved by Judge Dwyer, satisfied neither the industry nor the environmentalists, and protests, lawsuits, and legislative battles continued.

As the twentieth century came to an end, timber harvest levels had been significantly reduced, the Northwest’s economy had survived, and additional values for old-growth forests were found: habitat for endangered salmon and other fish, a source for medicinal plants, and a repository for benefits yet to be discovered.

The decades-long controversy over the forests of the North west had a deep impact on environmental science as well as natural resource policy and encouraged new interest in other native forests around the world, from Brazil to Malaysia to Russia.

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