Old Trees, New Problems
From southeastern Alaska to northern California, the Pacific Northwest contains the most magnificent old-growth forests left on the continent. They are a natural wonder, a natural resource, and---naturally---a battleground for competing interests.
The debate usually takes the form of wood products (and jobs) versus wilderness. In Alaska, Congressional committees try to sort out the many opinions on the right way to treat the Tongass National Forest. In Washington and Oregon, the conflict has gone into the courts. Its symbol there is the spotted owl, a species that may be threatened, or even endangered, but maybe isn't. Until recently, no one really studied it.
If the owl is the symbol of the struggle between lumberjacks and environmentalists, the uncertainty of its status is a fair symbol for the state of scientific knowledge about our old-growth forests. But it's hard to blame the scientists themselves for this situation.
Once upon a time, forest science seemed like pretty simple stuff. Its relation to economics was straightforward: identify the most valuable species, assess the best harvest methods, find ways to control insects. Before long there were concerns about wildlife, reforestation, erosion on bare slopes, clogged streams, even side effects from chemicals used to kill the pests. The costs of these effects were quickly realized, for example, as salmon runs died out in silted streams. The more we knew, the more we realized that everything was amazingly interconnected. We could no longer study forests just by studying trees.
So then came the era of ecosystem studies, and if foresters didn't become ecologists, they certainly had to talk to them. We learned more and more. Unpredictable things played surprising roles in the deep woods: a lichen growing on the conifers, for instance, proved to have an important role in nourishing the forests. The lichen fixes nitrogen, taking it directly from the air. Then, in a form useful for the trees, the rain washes the excess down to the roots. The trees themselves play surprising roles at some distance from the forest: in southeastern Alaska, for example, terpenes---natural hydrocarbons exuded by conifers--are an important food for some marine bacteria. The bacteria in turn are eaten by larger organisms, providing the first links in a terpene-based food chain that ends with valuable fisheries.
Even after twenty years of ecological studies on the forests, scientists are still learning more about them---witness the uncertain status of the owls. They are learning more about the trees, and even about economically useful products to be garnered from the trees (right now, medical researchers are testing an extract from the bark of Pacific yew for anticancer properties).
Researchers are also unlearning some of the things they thought they knew. Lumber companies had long been told to clean up harvested areas, to lessen the chances of fire and stream clogging. Biologists now suggest that some downed trees be left in harvested areas to provide shelter and nurseries for tree seedlings that otherwise can't compete with weedier plants. Streams even seem to need some downed wood, to provide habitats for a variety of organisms. To preserve the system, as one forest ecologist put it, "Decadence in moderation is probably a very useful thing."
Now very distant interactions have been added to the lists of things we must take into account. Consider: old-growth forests store enormous amounts of carbon. The temperate rain forests of the Northwest contain more biomass than do the tropical rain forests of Brazil. Brazil is under great pressure to halt forest destruction in the Amazon Basin because of international fears about the greenhouse effect---all that liberated carbon, all that cessation of photosynthesis, means so much more carbon dioxide to tip the global thermostat towards hotter. Yet if they can't cut their forests, why should we be able to cut ours?
It would be nice if we could have a century or two to call a halt to development, to keep studying the old-growth forests and their interactions with everything from salmon streams to global climate, but the world doesn't allow such leisurely pursuit of knowledge. We know we need the forests, but we know we need wood as well. It's up to the scientists to find the vital balance points between the competing interests, and they're working as fast as they can,
