Forest Science Trumped By Politics

By John Stuart, Ph.D.

I get worried when policymakers get carried away prescribing forest management practices. It can't be good for the forest.

But it may happen again, what with various battles embroiling forests from the North Coast to the Sierra Nevada and the Giant Sequoia National Monument.

Forest management is an incredibly complex science and no two forests are alike. Yet prescriptive regulations treat all forests the same and set inflexible restrictions.

Take the concept of "old growth." Old growth is so complex not even scientists agree how to define it. Yet all too often, policymakers debate the need to "save" it and propose simplistic rules for doing so.

Forget for a moment that trying to preserve old growth as it is defies the laws of nature-that trying to maintain a dynamic ecosystem in a static state is unnatural and impossible to accomplish. What's alarming is that in the debate over our forests' future. science is too often trumped by politics.

Old growth is already protected in California. The California Department of Forestry and Fire Protection estimates that 96Vo of old-growth stands are set aside in parks and other state and federal ownerships. The 4% on private land are subject to the state's stringent forest practice laws.

Still, old growth is a powerful political term. Two of the more popular ideas thrown around by policymakers relative to old growth are age restrictions and diameter limits-the idea being to restrict tree cutting past a certain age, and/or beyond a certain diameter. But, these ideas are popular because they are easy concepts to understand, not because they represent the culmination of scientific study or consensus of forestry professionals

For instance, what's old to a Monterey pine is practically infancy to a giant sequoia, so how does a single age limit make sense? Furthermore, the best way to determine a tree's age is to bore into it and count the rings.

Boring into every tree in Califomia that looks old would be incredibly expensive, time consuming and practically impossible.

Arbitrary age restrictions don't translate to good forest practices, but they sound good. It is easy to envision the forest as it may have been at any point in history, say the time of California's statehood or before European settlers arrived, and to establish an emotional connection to trees that were alive at that time.

Nor can diameter serve as an indicator of tree age. Many things, including species, access to water and nutrients, available growing space and canopy closure determine the diameter of any given tree. A 3O-inch diameter tree in certain growing conditions could be very young, whereas a 300year old tree crowded out and forced to compete for water and sunlight may never reach 18 inches across.

Tree size can be very misleading, and therefore a dangerous metric on which to base legislation. A 2-foot diameter lodgepole pine is a big tree; a

2-foot wide redwood is small. Plus, if you're focusing on individual trees, you're not looking at the forest as a whole.

Forest management aims at desired conditions at the landscape level. With responsible management, foresters can mimic the characteristics of a mature forest without age becoming the dominant factor. Trees spaced to grow quickly can provide ample habitat for species that prefer later-stage forest environments.

There is a difference between saving old growth and managing the forest landscape to ensure the steady presence of old stands of trees. The former increases the risk of destroying what it seeks to preserve. It allows an already high risk of devastating wildfire to get even worse by cordoning off large sections of forest laden with an unnatural accumulation of fuels. The latter responsibly allows all stages of the forest cycle to thrive dynamically, ensuring a diversity of all tree ages and sizes and providing the full range of wildlife habitat.

If policymakers truly want to ensure abundant old growth forests now and for the future, they should concentrate on setting goals and task land managers with attaining those goals. They should give greater voice to forest science and the experts who work the land when considerins forest policy.

- John Stuart, Ph.D. has been a proJessor of forestry at Humboldt State University for 23 years. He teaches and conducts research in the fields of dendrology, forest ecology, and fire ecology. This essay is adapted from an article in the Summer 2005 issue o/California Forests.