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Thanks to the many forest scientists who have spent time studying the forests of Oregon, pioneers and homesteaders who have recorded the landscape through journals and pictures, we have a good idea today of what our forests looked like earlier this century— even back to the mid-1800s!

A forest researcher admires the stem of a very large, very old, Douglas-fir tree. A forest worker approaches the stem of a large, old Douglas-fir tree, found in old growth forests of western Oregon.

Forest scientists Bill Ripple and Tom Spies, their colleagues, and their predecessors, have been looking to the past in order to understand the forests of the present. With their work, we can see how our landscape constantly changes, with or without human impacts.

Let's talk about old growth, using western Oregon (everything west of the crest of the Cascades) as an example.

It is estimated that before 1840, the era considered "prelogging," between 40 to 60 percent of the forests of western Oregon were over 200 years old and had characteristics of old growth forests. Large-scale, infrequent disturbances like wildfires, insects and disease, windstorms, and human activities, all combined to create a mix of younger forests in the remaining forest lands. How big were some of these disturbances? Well, in 1849 the Siletz fire in western Oregon burned around 800,000 acres of forest— that equates to 1,250 square miles, or a strip of land 11 miles wide, from Eugene to Portland! Several other wildfires over the last 150 years have also demonstrated the magnitude of disturbance in this forest cycle, including the 240,000 acre Tillamook burn in the early '30s. As a result of these disturbances the old growth in westside forests moved across the forests over long periods of time. This is the cycle of life in western Oregon forests.

As populations and demand for both land and timber increased with the westward migration, so did the harvest of large, old trees. Today, the amount of naturally regenerated forests 80 yrs and older is about 3.2 million acres on federal land (additional amounts of "late successional forest" occur on state and private lands but these do not add much to the total). The amount of forest considered old growth is considerably less.

In one analysis of the Coast Range it is estimated that less than 10% of the federal lands contain forests over 200 years old. Other estimates put the amount of old growth at 10-20% of its level at the time of Euroamerican settlement in the mid 1800's. It is important to remember that the actual amount of old growth is not known because of differences in definitions of "old growth" and inventory methods. Also, the amounts of old growth are least in the Coast Range and most in the Oregon Cascades and Klamath areas.

Similar to the natural disturbances caused by fire, insects and disease, and windstorms, today's management activities of logging and burning remove forest stands in patches. Unlike fire, insects, disease and windstorms, however, logging tends to remove most of the live wood, leave smaller and more uniform patch sizes, and is repeated every 50 to 70 years— catastrophic wildfires revisit western Oregon forests with intensity to replace old growth forests every few-hundred years.

Features associated with old growth.

Old growth forests play an important role in the cycle of life and resources for the plant, animal, and human communities of Oregon. As we learn more about the old growth forests of Oregon, we as forest workers, land managers, and forest land owners can better manage for old growth characteristics should we decide to. Features associated with old growth such as large live trees, large standing snags, and woody debris on the forest floor, can be incorporated into both even-aged and uneven-aged stands.