by LeRoy Bandy, Ph.D and Barbara Bandy, M.S.
For references and more information, consult the Bandy's bibliography on clearcutting.
The forestland of Maine is sometimes referred to as the Northern Hardwood-Coniferous Forest, a forest type that is a mixture of tree species found further to the south, with those more prevalent further to the north. Some of these species include softwood coniferous types such as red, black, and white spruce, balsam fir, white pine, hemlock and cedar. Also common to the Maine forests are hardwoods such as beech, red maple, sugar maple, aspen, and yellow and white birch. The proportions of these various species vary from location to location depending on soils, slope and altitude.
A common misconception about the Maine forestland is that disturbances such as frequent large scale fires and windthrows are a natural part of our forests here. Actually, a scientist named Lorimer in the 1970s published research in which he had analyzed land survey records that covered over 4 million acres of Maine for the period from 1793 to 1827. From these records he was able to determine that the average recurrence interval for fire for a given site would have been 800 years. Large-scale windthrows were even more infrequent, occurring on average every 1,150 years for a given site. Thus the forests of Maine prior to European settlement were not subject to frequent large scale disturbances, although that misconception continues to be spread by those who want to promote clearcutting as a form of harvesting that mimics natural disturbance.
There are many important components of a healthy forest ecosystem. We can begin by looking at the soil. The forest soil contains nutrients, many microorganisms, tiny creatures that feed on and break down the leaf litter, and somewhat larger creatures such as salamanders that are important parts of the food web. The way trees are harvested can affect all of these components.
For example, scientists at the USDA Forest Experiment Station in Durham, N.H., analyzed data from six different sites in the eastern United States, including sites in Maine and New Hampshire. They concluded that calcium is in danger of being depleted from forest soils, due to the combined effects of acid rain and whole-tree clear-cutting on 40-year rotations. Magnesium and potassium are also in danger of depletion. Whole-tree harvests remove the entire above-ground portion of trees, including the tops, which contain more than half of the nutrients. Nutrients also leach from the soil after it is exposed by clear-cutting.
Research in Maine has shown that sixteen years after a whole-tree harvest, an area that was clearcut has 25% less organic matter in the soil than adjacent unharvested plots. The level of organic matter in the soil is important for nutrient cycling, water-holding ability, and other properties important for plant growth. Data from the same research site has shown that whole-tree clearcutting has caused long-term disruptions in nitrogen cycling, and potential depletion of phosphorus. In addition to nutrient loss, research at the Hubbard Brook Experimental Forest in New Hampshire showed that aluminum ions in levels toxic to fish and other aquatic organisms were released into streamwaters draining clearcut sites. These effects on water chemistry persisted for three to four years after the harvest. Unfortunately, some of the large industrial landowners are making extensive use of this method of harvest. Champion International for example, is using whole-tree clearcutting on short rotations on forty percent of its lands in Maine, or approximately 360,000 acres.
Among the many important microorganisms in the forest soil are mycorrhizal fungi. Mycorrhizal fungi form associations with the roots of trees and enhance tree growth in various ways. It has been known for some time that these fungi can form networks between the roots of different trees, even between trees of different species. Recently, researchers in British Columbia made an important breakthrough in understanding the ecological significance of these fungal-tree communities. They showed that seedlings of Douglas fir grown in the shade of paper birch received a net transfer of carbon from the birch trees through the fungal connections. This research shows that in a natural forest ecosystem, trees such as paper birch, considered a "weed" species by foresters, may nourish other tree species such as the commercially valuable Douglas fir. These complex interactions may help stabilize the forest ecosystem in the long run and help protect against extremes of moisture, temperature, and against insect outbreaks and disease. Unfortunately, intensive forest management techniques such as clearcutting and herbicide spraying disrupt these complex and beneficial associations between trees and fungi.
Many small animals in the forest soil play important roles in the decomposition of organic matter and nutrient cycling. As they feed on dead organic matter and soil microorganisms, they contribute to soil fertility and improve soil porosity. Tiny insects and mites, known collectively as microarthropods, are among the typical small animals found in forest soil. In one study, researchers found that whole-tree clearcutting resulted in a significant decrease in the number of soil microarthropods when compared to less intensive harvests in which not all trees were cut, and the tops of cut trees were left on the ground. This was probably due to the decrease in organic matter and soil moisture, as well as the extreme temperature conditions found on the clearcut sites.
Salamanders that live on the forest floor are important members of forest food webs. In a study conducted in western North Carolina, the researchers found that salamanders were five times more numerous in mature forest stands than on recent clearcuts. Also, the clearcut areas averaged only about half as many species as did the mature forest sites. One of the most disturbing findings of the study was that 50 to 70 years are required for salamander populations to return to pre-clearcut levels. Keep in mind that landowners using intensive forest management in Maine are cutting on 30 to 50 year rotations. The authors estimated that approximately 70 to 80 percent of salamanders inhabiting mature stands are lost following clearcutting, and most of those probably die due to physiological stress. Other research has shown that clearcutting disrupts the habitat for salamanders by removing shade, reducing leaf litter, and causing dramatic changes in soil surface moisture and temperature. Research conducted in Maine and published in April of 1998, demonstrated that there were significantly lower numbers and fewer species of salamanders in recent clearcuts than in uncut woods. The scientists identified species of amphibians that were especially threatened by intensive forest management. These included red-backed salamanders, spotted and blue-spotted salamanders, and also wood frogs.
Plants that are not trees, but that grow in the understory of forests may play important roles in the forest ecosystem. For example, the trout lily is a widespread forest plant that grows actively in the spring during the period extending from snowmelt until the canopy develops and shades the forest floor. One study found that these small plants incorporate significant amounts of potassium and nitrogen into their tissues during their period of active growth in early spring. If these plants were not present, those nutrients might be lost by leaching from the forest soil during snowmelt and spring runoff. Later in midsummer, the aboveground portions of the trout lily die back and release those nutrients into the soil from which they can be taken up by trees and other plant life.
One study conducted in the southern Appalachians showed that many herbaceous forest understory plants, similar to the trout lily, recover very slowly or not at all from clearcutting. To our knowledge, a similar study has not been undertaken in Maine or in northern New England. However, the widespread use of intensive harvesting methods, short rotations and plantation forestry almost ensure a similar loss of plant diversity here.
There are also good reasons to have a diversity of tree species in our forests. For example, research conducted in New Brunswick showed that the presence of greater than 40 percent hardwoods in mixed balsam fir-hardwood stands could substantially reduce losses during spruce budworm outbreaks, possibly because the presence of greater hardwood content increased the abundance of natural enemies of the budworm such as birds. In spite of such evidence, the paper companies insist on clear-cutting which results in even-aged stands of fir (the preferred food of the budworm), and on spraying herbicides to limit the regrowth of hardwoods.
In a study published in 1989, researchers found that birds exert controls on low-density budworm populations. The largest and most important group of predators was the canopy-feeding wood warblers including Blackburnian, Cape May, Bay-breasted, Yellow-rumped, Magnolia and Black-throated Green Warblers, as well as the Golden-crowned Kinglet. Suitable habitat for these species must be maintained, including a significant hardwood component, and well-developed canopy and subcanopy layers. Unfortunately, intensive forest practices destroy these essential habitat features.
The topic of birds leads to a discussion of John Hagan's research on the diversity and abundance of landbirds in a northeastern industrial forest, published in 1997. This research, which was supported in part by the forest products industry, has been cited frequently by representatives of the paper industry as evidence that Neotropical songbirds benefit from industrial clearcuts. Actually, a careful reading of this paper shows that such a sweeping conclusion is not warranted.
First, it is important to note that this study was not conducted on typical industrial clearcut areas. The regenerating clearcuts had not been sprayed with herbicides, as is common practice on industrial lands. Therefore, one cannot generalize from Hagan's study that all industrial clearcuts are good for birds.
Second, data on relative abundance of birds, such as that collected for this study, do not necessarily indicate successful breeding and reproduction. In fact, an earlier study published by Hagan in 1996, showed that the sudden loss of habitat on clearcut sites forced breeding birds to disperse into adjoining forest fragments or buffer strips where they attempted to re-establish breeding territories. Overall songbird densities were observed to increase above normal levels due to the crowding of birds into the forest fragments. Hagan studied one species, the Ovenbird, in more detail, and found that crowding resulted in decreased mating success. Therefore, just because one counts a relatively large number of birds in or near a clearcut area over a short period of time, that does not mean that the birds are reproducing successfully.
Finally, it is important to note that different species of neotropical songbirds have different habitat requirements. Some species do indeed prefer young, regenerating tree growth, and those are the species that Hagan found in greatest abundance in regenerating clearcuts. However, other species require mature forest habitat, and those species are the ones that are suffering the most from intensive forest practices. In fact, in Hagan's own words as quoted from his research paper, "Over the coming decades, if harvest rates are maintained at current levels, bird (and other) species likely to decline in abundance will be species that prefer mature-forest habitats or large tracts of continuous mature forest coverage."
Furthermore, it is important to know that large clearcut areas are not needed to provide habitat for bird species that utilize young tree or shrub growth. A study in Vermont published in 1997, showed that one-acre patch clearcuts within extensive mature hardwood forest provided habitat for several songbird species which thrive in regenerating or immature woods. These smaller patch cuts more closely mimic natural forest gaps, such as those created by a large old tree dying and falling over.
Other research, conducted in New Brunswick and published in 1994, showed that clearcutting, intensive silviculture, and single-species tree plantations, reduced habitat diversity and decreased the density and diversity of breeding birds.
Other types of wildlife are also adversely affected by intensive forest practices. Scientists studying bats in the White Mountain National Forest, for example, published a paper in 1996 in which they hypothesized that prior to European settlement, northeastern bats were inhabitants of extensive tracts of over mature hardwood timber. Bats probably used large dead and dying trees as roosts, and probably fed in small openings created by natural disturbances or over areas of still water. In order to create bat habitat and maintain viable bat populations within the White Mountain National Forest, timber management plans were recommended which created small forest openings, that is group selection cuts and small clearcuts, and retained areas of older hardwoods. Intensive timber harvesting methods would be inappropriate since they would destroy the essential habitat mixture of over mature hardwood and small openings.
Moose are probably Maine's most famous type of wildlife, and they have been thriving by feeding on vegetation found in regenerating clearcut areas, as well as that found on old farm land that has been abandoned. However, research has shown that moose avoid using herbicide-treated clearcuts, and when they are found within treated areas, they are feeding on vegetation that was inadvertently skipped by the spray plane.
In summary, there is a large body of scientific evidence which shows that intensive forest practices such as whole-tree clearcutting on short rotations, herbicide spraying, and the establishment of tree plantations, have adverse effects on all aspects of the forest ecosystem, and we believe these practices threaten the long term health and productivity of our forestlands. We support the use of forest practices such as those promoted by the Maine Low Impact Forestry Project, and practiced by veteran woodlot owners like Mel Ames of Atkinson.
In 1995, the U.S. Forest Service conducted a survey of the Maine woods, and published the data in late 1996. However, neither Maine nor the U.S. Forest Service had prepared a written analysis of the data when, in February 1998, Mitch Lansky produced his own cogent summary of the survey data. Finally, approximately 7 months later the Maine Forest Service in cooperation with the U.S. Forest Service, produced a report which showed clearly that the woods in Maine are being cut faster than they grow, and there will be a shortage of wood if present cutting rates continue.
Unfortunately, the state is advocating the use of more intensive forest practices, including herbicide spraying and tree plantations, to try to make up for the looming shortage of wood fiber.
The people of Maine should not be complacent about the direction the Maine woods is headed. Bernd Heinrich, in his excellent book, The Trees in My Forest, described what has happened in the country of Finland, where, as in Maine, pulp and paper companies dominate. Ninety-eight percent of Finland's tree growth is now in even-aged monocultures of Scots pine and Norway spruce. Finland now has virtually no real forest! It is time for the people of Maine to oppose this move toward more intensive management while we still have some real forest left.
LeRoy Bandy has a Ph.D. in wildlife ecology from Ohio State University. He has conducted research on waterfowl biology and on the movement of DDT in the environment. He has also done environmental survey work, and taught college courses in human ecology, and the ecology and taxonomy of flora and fauna. In recent years he has been conducting surveys of birds found in woodlots which are managed by low-impact harvesting techniques.
Barbara Bandy has an M.S. degree in Botany from the University of Maine. She worked in research labs as a research assistant for 15 years before changing careers to become a registered nurse in cardiac intensive care.
The Bandys have compiled an annotated bibliography of their research. It is posted on FEN's web site. They are available for speaking engagements for classes and organizations. Call FEN at 623-7140 for details.