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95% of all the old growth redwood trees in California are on publicly owned state and national park land, much of it donated by private timber companies. [more]

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The News Room » Opinion Editorials » The Giant Sequoia Forest: A Window Into the Past and a Vision for the Future

The Giant Sequoia Forest: A Window Into the Past and a Vision for the Future

We need a new vision for North Americas forests. A vision that restores a productive and harmonious relationship between forests and people. Such a promising view of the future only can be achieved by better understanding our past.

The Mixed-Conifer Forest

The mixed-conifer forest grows in a wide belt along the west slope of the Sierra Nevada. It is composed of such tree species as giant sequoia, sugar pine, ponderosa pine, incense cedar, white fir and black oak. However, the trees that make up the mixed conifer forest did not always live together. They shifted around the landscape independently of one another to form temporary forests that included other species. These ancient forests broke apart and reformed into new forests as the climate cooled and warmed over hundreds of thousands of years. The mixed conifer forest that we know today came into existence only 4,500 years ago after these trees migrated up mountain sides and joined each other at the end of the last Ice Age.

American Indians and Forests

We now have sound scientific evidence from numerous sources that American Indians and their ancestors were deliberately and inadvertently modifying vegetation in North America for at least 12,000 years. During that time they substantially changed forests by cutting trees for building materials and to clear fields for crops. They changed vegetation by digging roots, cultivating plants, collecting berries and nuts, and spreading seeds. Fires set by American Indians, which were more frequent than would have been the case with just lightning, created the greatest and most widespread changes in North Americas forests, especially in the Sierra Nevada.

Studies of fire scars in tree rings show that one or two fires burned each decade in some places, but some protected areas escaped fires for up to 30 years. Since fires were frequent enough to clean up most of the debris on the forest floor, they generally burned as low-intensity surface fires.

Visualizing the Original Forest

Science provides the tools we need to add detail to early accounts and old photographs of the original mixed-conifer forest. Dr. Edward C. Stone (University of California-Berkeley) and I conducted the first and most comprehensive studies of the structure of the original giant sequoia mixed -conifer forests in Kings Canyon National Park.

We measured and mapped every living and dead tree and shrub on an area the size of a football field in one study. In another study we intensively sampled part of a watershed, and finally we did a less intensive sample of complete 3,000 acre watershed. In each case we used statistical methods to role back time and look at the forests as they were. These are the most accurate studies ever done to document the condition of pre-European settlement mixed-conifer forests. What we learned most likely applies to other mixed-conifer forests in the Sierra Nevada.

We found that the early accounts of European observers were accurate. The pre-European settlement mixed-conifer forest did consist of a mosaic of even-aged groups or patches of trees. These patches generally were less than 0.2 acres in size, or five patches to the acre. Other patches were at least 0.8 acres in size, or 1.25 patches per acre. Some patches exceeded an acre in size.

We concluded also that these forests were relatively open as described in early accounts.

Some patches of trees fit today's popular image of old-growth: large trees with a dense understory full of downed wood. Many people think the entire Sierra Nevada consisted of such forests before we arrived. Therefore, they want to increase the area of old-growth. They also think that more dense old-growth will increase the population of California spotted owls.

Surprisingly, this kind of old-growth represented only a small part of the original forest; about 2 percent. However, patches containing large trees with a relatively open understory occupied another 17 percent of the original forest. Even more surprising, about 43 percent of the original forest consisted of openings dominated by seedlings, grasses and forbs, or bare ground. Patches of shrubs occupied another 21 percent of the forest. The remainder of the forest consisted of patches of pole-size trees. Thus the pre-European settlement mixed-conifer forest looked far different than many people believe.

These scientific findings force us to answer a question. How could the California spotted owl have survived when so little of the forest consisted of old-growth? The answer might be found in the patchiness of the original forest, and the relatively small size of the patches. Spotted owls must have been abundant or they would have become extinct long ago. Perhaps the spotted owl is less sensitive to the total amount of old-growth than it is to the diversity of patches interspersed throughout the forest. In other words, the spotted owl might need a variety of habitats to survive like most other wildlife. If so, then the patchiness of the pre-European settlement forest explains why spotted owls were abundant in a forest with little old-growth.

Today's Forests

The mixed-conifer and other forests of the Sierra Nevada have undergone pronounced changes since they were first seen by European explorers. Large quantities of debris have accumulated onforest floors and many patches of large trees are choked with thickets of understory trees. In addition, patches of saplings have had a chance to grow to pole size because of the elimination of Indian burning and the suppression of lightning fires. The greatest problem exists in national parks, roadless areas and wilderness areas. Thus fire hazards now are extreme, insect and disease infestations are on the rise and some wildlife species are threatened.

Giant sequoia-mixed conifer forests are aging rapidly. Patches of dense old growth have increased from 2 percent to 4 percent due to the invasion of shade tolerant white fir trees into the understory of larger trees. The same thing has happened on the nationalforests. Similarly,patches of large trees with an open understory have increased from 17 percent to 25 percent of the forest mosaic because many dense patches of pole size trees grew to maturity. Even more dramatic, patches of pole-size trees have increased from 17 percent to about 38 percent of the forest. In this case, thick patches of seedlings and saplings grew to pole size because of the lack of fire. If the aging process continues for another century, nearly half of the giant sequoia mixed-conifer forest will consist of patches of large trees, a 263 percent increase. Such an imbalance in the ages of trees cannot be sustained and likely will lead to massive fires. This unnatural increase in the areas occupied by older and denser patches of trees came at the expense of younger trees and openings. Today only 21 percent of the giant sequoia mixed-conifer forest consists of patches of grasses and forbs, tree seedlings or bare areas. This is a major loss of early successional habitat when compared to the 43 percent that existed in the original forest.

There is even less of this open structure represented on the national forests. Patches of shrubs also have dropped from 21 percent of the pre-European settlement forest to only 12 percent of today's forests. This aging and thickening of the forest not only increases fire hazards but it also reduces diversity and shrinks the habitat of many wildlife species.

A Vision for Future Forests

The mosaic of patches that gave the pre-European settlement forest its beauty and diversity can do the same for us. Restoring the historical forest mosaic will reduce the size and destructiveness of wildfires, create habitat for all wildlife species and retain the natural appearance of the forest.

What we cannot fully restore are the Indian and lightning fires that drove the process of disturbance, renewal and growth in the pre-European settlement forest.

The wildfire hazard already is extreme. Because people now live in Sierra Nevada forests, we cannot risk having wildfires sweep through our communities. Nevertheless, lightning fires still can burn in protected areas at high elevations. We can also use prescribed fire as a tool in some places, but it is costly, unpredictable and dangerous. They require tight controls that make them burn in ways that seldom, if ever, come close to Indian and lightning fires. The forests also are thicker and more dead trees lie on the ground than in the past. So prescribed fires pose a serious risk. Air pollution restrictions also will limit opportunities to use prescribed fire.

So the only effective and safe option available for restoring the values we associate with pre-European settlement forests is scientific forest management. Timber harvesting is a key scientific tool that can be used with near surgical precision to recreate the beauty and diversity of the original Sierra Nevada forests.

Timber harvesting can be used to create small openings in the forest shaped to look as if they were formed by natural fires. Snags and fallen logs also can be left behind to further mimic the effects of natural fires. These openings then provide places for young trees, shrubs and other plants to grow. This would maintain the patchiness and the diversity ofplants and wildlife that is essential to a healthy forest. A proportion of the forest mosaic also would include patches of old-growth. These patches of old-growth would exist in different parts of the forest mosaic at different times just as they did in the past. So there is no doubt thatwe can recreate a forest that looks and behaves much like the original.

Most people would like to restore the beauty and diversity that existed in the original Sierra Nevada forests, but we cannot go back in time. Instead, we must look ahead and find a way to restore a new relationship between people and forests that fits our needs just as the old ways fitthe needs of American Indians. Many of the things they wanted from their forests we want as well. We like large trees, open vistas, abundant wildlife and wildflowers. Yet we also need wood. And we want to feel safe from massive wildfires. Today we also want our forests to look natural. We can satisfy all of these needs at once with scientific forest management. A new vision for our forests must reflect such optimism about the future. The best model for that vision is the original forest.

Thomas M. Bonnicksen, Ph.D., is an historian of North American forests and the originator of "restoration forestry." He is professor emeritus of forest science at Texas A&M University, visiting scholar at The Forest Foundation,and author of "America's Ancient Forests" (John Wiley, 2000).

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