Of North Woods and Neotropics
by Michael J. Caduto
©2000 All Rights Reserved
(The second of two articles on forest health.
See also: "Tears in the Forest Web.")
Every local action plucks one of the strands that bind the global ecological web and the effects of forest fragmentation ripple out into the biosphere. When forests are cut, the wood that is not made into lumberabout half of the forest biomassis burned, chipped or left to decay. As the wood oxidizes its carbon is released into the atmosphere in the form of CO2. The living forest, as it grows, is a sink that stores vast amounts of carbon and so helps to regulate global climate. Cutting affects the atmosphere with a double-whammy because cleared forests have released much of their carbon into the atmosphere and they are no longer absorbing carbon. Moreover, the young trees that grow into the clearing are capable of storing only a fraction of the carbon that was contained in the living mass of the mature forest. The overall result of widespread fragmentation is an increase in atmospheric carbon, which contributes to the greenhouse effect and global warming.
Taking a global perspective brings to bear a complex set of considerations. Wood is a renewable resource. If a forest is harvested there is a temporary increase in atmospheric carbon until the new forest matures. As the forest grows, it once again absorbs and incorporates atmospheric carbon into living tissues. Other, non-renewable resources, such as steel and cement, require tremendous quantities of fossil fuels in their mining, manufacture and transport, which results in a permanent net gain in atmospheric carbon.
In addition, when we use locally-grown forest products we alleviate the need for burning fossil fuels to transport logs great distances and we arent foisting the environmental costs of our consumption onto distant environments and cultures. Since a substantial portion of our lumber and wood products come from ancient forests and rainforests where more than one third of the worlds species of plants and animals live, it is essential to choose which forests can be harvested sustainably while having the least impact on global biodiversity. Especially vulnerable are the tropical rainforests in Brazil, the Andes, Madagascar, the Caribbean, Borneo, Sumatra and other islands in Southeast Asia.
North by South
Forest fragmentation in both the north country and in the neotropics is depleting the populations of at least 21 species of songbirds in the eastern United States, with the number of some species down by more than half.1 The population of Bicknell's Thrush is just one measure of how much of an impact neotropical forest fragmentation appears to be having on the populations of local songbirds.
"We think its a serious issue," says Chris Rimmer, Director of Research at the
Vermont Institute of Natural Science in Woodstock, Vermont. "The main limiting factors are probably events on the wintering grounds, but we don't yet have the data to prove that. We know that Bicknells Thrush has disappeared from certain breeding areas over the years, like Greylock in Massachusetts, where they historically bred for a long time. There was a steady decline documented through the middle part of this century that culminated in their disappearance: 1972 was the last recorded sighting there. But that's a peripheral population. Other peripheral populations have disappeared from several islands in the Canadian Maritimes. Often a species begins contracting at the peripheries of its range when it's experiencing problems, so this could be a warning signal."
Bicknell's Thrush overwinters primarily in mature, high elevation broadleaf forest which is moist but is not true cloud forest. They prefer forest with a lush canopy and a dense understory. The world's overwintering population of Bicknell's is thought to be concentrated on the island of Hispaniola in the Dominican Republic, a fairly small country of the West Indies in which it is estimated that only 13 percent of the native forest vegetation remains. Although some forested areas are officially designated as preserves, few of these are actually protected.
Rimmer's experience has shown him that "Overpopulation is the core of habitat loss and degradation on the wintering grounds. A lot of people cut down the forests to raise cattle or grow crops at high elevations, including coffee, citrus, as well as subsistence crops. There's a lot of charcoal production and timber extraction. Those three things are the main threats to these forests. Typically those kinds of activities are not done sustainably. It's a slash-and-burn type of operation, or, take the lumber and clear out."
"The habitat, particularly on the wintering grounds, has been whittled away so extensively that there have to have been some consequences. Maybe one impact is that females, perhaps younger birds too, are having to use human-altered habitats where they may not be doing as well. In what we now consider the optimal winter habitats for Bicknell's Thrushes, of the 12 birds that we sampled this winter, 11 turned out to be male. Our suspicion is that males are occupying the best habitats and that females are somehow being forced to use less high-quality habitat, where they may have lower survival. That may account for what we're seeing up north, which appears to be a shortage of females, or, at least, a preponderance of males. We've got a lot of nests that have two individual males coming in to feed nestlings, which is very unusual in long-distance migrant songbirds. It's been shown in other species of migrant birds on their wintering grounds that males and females occupy different habitats, males tend to get the better quality habitats, and females poorer quality habitats, often with differential overwinter survival."
"We know there's much less forest cover than there used to be. We're watching these broadleaf forests disappear before our eyes in parts of the wintering range. How could that not be affecting them? We just don't know how plastic their behavior and ecology are, whether it will allow them to adapt. I hope if you ask me in five years I'll have a more optimistic response. Part of the solution is to work with people to develop sustainable practices, and not just kick them out of all these areas, although some areas absolutely do need to be protected because they are vital refuges. There's a balance that needs to be achieved."
The Forest Future
deep-seated genetic characteristic, to continue unceasingly to lay waste the forests, again and again, with the replacement forest each time a little bit less well adapted to its environment?2
The Dying of the Trees
What lies ahead for our forests? Each day we paint their future with brushes both fine and broad, subtle and of great force. With the purchase by public and private conservation groups, states and the federal government of tens of thousands of acres of forests for protection from development, it is tempting to relax and celebrate what has been accomplished. But there are plans to continue large-scale logging on many of these lands that do not use the best stewardship practices available, and to allow other uses that are not always in the best interest of the plants and animals who live there. We need to do more than just prevent subdivision: we must continue to preserve large tracts and to protect habitat. And we need to focus more energy toward conserving ecological and aesthetic values as well as providing for deep forest recreation and wilderness experiences. In a kind of positive, self-perpetuating conservation feedback loop, life-affirming nature experiences, in turn, foster the yearning to help protect the wild forests that nurture our world-weary souls.
"When I was younger," says Charles Johnson, Vermont's former State Naturalist, "the details that we're thinking about now never even occurred to us. The fact that we are trying to devote a lot of energy to maintaining large blocks of forest land, and other land, is really positive. It's not perfect, but it's a step in the right direction. We have one million acres of forest land in the use value appraisal program, which, in Vermont, means it's under a form of conservation management. Under the use value appraisal program, which is known locally as "current use," rather than taxing lands at their "fair market" value, which usually means development value, lands are taxed at a lower "use" value for agriculture and conservation. That doesn't mean that you have a unified approach to wildlife habitat protection at all, because the goal of the current use program is to get forest into good management for sustainable timber production. That's OK, but it would be nice if the program allowed people to enter for the purpose of wildlife habitat protection, as well."
When people speak of forest fragmentation, and of the future, population control is not always the first thing that comes to mind. But, according to many biologists and resource managers, it ought to be. "We won't be able to come to grips with these problems until we really get a handle on our numbershow many of us there are in the world," Charles Johnson laments, "which I fear we never will. And once we're here most of us need to have a home, drive a car on roads, etc. So wildlife habitat, in the scenarios we're seeing, will always give way to a human need."
"Adaptability is a wonderful thing for survival.," says Johnson. "An animal can adapt right down to living in a cage, but is that what we're after here? To me, it's much more important to look at the whole thing. That's what worries me about single species management. You can focus so hard on what a species needs and, in the process, lose everything else. What are we managing for in that case?"
"Conservation biology is good, but I would want to bring in the David Orrs and the Barry Lopez's and the E.O. Wilsons and some of the other abstract thinkers about who we are and how we approach the land. I don't think science by itself is going to solve anything. It's a combination of science and something else, call it feeling or emotion. We could engineer solutions down to a square inch of ground, but is that the kind of world we want to live in?"
1. Charles E. Little, The Dying of the Trees: The Pandemic in America's Forests. (New York: Penguin
Books, 1995), pp. 229.
2. Little, The Dying of the Trees, pp. 131-32.
"Sky Island Songbirds," by Christopher C. Rimmer and Kent P. McFarland. Natural History. vol. 108, no.
7 (September 1999), pp. 34-39.
"A Closer Look: Bicknell's Thrush," by Christopher C. Rimmer. Birding. vol. 28, no. 2 (1996), pp. 118-123.
About the Author
Michael J. Caduto, of Norwich, Vermont is an naturalist, educator, storyteller and author of more than a
dozen books including Pond and Brook: A Guide to Nature in Freshwater Environments (University Press of New England, 1990) and the Keepers of the Earth ® series (Fulcrum Publishing, 1988-1994). His Earth Tales from Around the World (1997) received the Aesop Prize. He also co-authored Native American Gardening: Stories, Projects and Recipes for Families (1996). His most recent book is Remains Unknown: The Final Journey of a Human Spirit (Bennington, Vermont: Images from the Past, 1999).
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©2000 by Michael J. Caduto. All Rights Reserved. Please contact:
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