New York Times : "Eastern Forests Change Color As Red Maple Proliferates "

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1 New York Times : "Eastern Forests Change Color As Red Maple Proliferates " By WILLIAM K. STEVENS The forests of the Eastern United States are turning increasingly red, and the growing brilliance of color signals a historic change in the ecological character of a vast region stretching from the Great Lakes to the Atlantic and from Canada well into the South. Eastern deciduous woodlands are famous, of course, for their bright fall yellows, oranges and russets. Now red is coming to the fore, and not only in autumn; much of the forest is acquiring a pervasive rosy blush in the spring as well. The reason is that the soft green springtime hues of hardwoods like oaks and hickories, and the darker greens of northern conifers like pines, are being replaced by the blazing red buds, flowers and fruits of another, more adaptable and aggressive species of native tree: the red maple. Its fruits, small whirlybirds, rain down profusely in the spring, producing new little trees whose early start gives them a competitive advantage over other hardwood species, which do not drop their seeds until the fall. These arboreal hard-chargers are taking over the woods. Long viewed as the maple family's poor relations, they were once confined almost exclusively to low, wet areas. Now they have burst out of the swamps and are marching into the uplands in strength. There they are starting to flaunt a new-found dominance that, if it continues, could signal the downfall of the majestic oaks that have been a mainstay of the deciduous forest for most of the last 10,000 years. A wide range of creatures adapted to the oak-hickory habitat could suffer as a result. The rise of the red maple is part of a larger, continuing transformation of the Eastern forest. The transformation has many causes, all related to humans' impact on the forest ecosystem, but in the case of the maple two stand out. First, people have suppressed fire. Before European settlement, forest fires routinely killed the thin-barked red maples while oaks and hickories were protected by their thicker barks and deep, extensive root systems.

2 Fire also created open spaces ideal for the oaks' light-loving seedlings. Now those spaces are closing up; it so happens that red maple thrives in shade, and its seedlings and saplings are proliferating. Second, red maples spread like weeds onto disturbed ground, and people have disturbed the forest in many ways, not least by chopping it up into a patchwork quilt of disconnected woodland fragments and cleared fields. The maples take enthusiastically to both the forest fragments and the deforested patches between. In fact, they can grow about anywhere in the uplands -- in rich soil or poor, on dry land or wet, in open sunlight or deep shade, in young forests or mature ones. In contrast, the sugar maple is a prima donna that thrives only in a relatively narrow range of moderately moist soil conditions. The upshot is that the red maple not only can colonize fresh ground easily, but it can also grow in the shadow of an already established forest. It is a ''super generalist'' among plants, and its ability to thrive in a wide range of soil conditions, especially, ''is a real rarity in the plant world,'' said Dr. Marc Abrams, a forest ecologist and plant physiologist at Pennsylvania State University in State College. Dr. Abrams has been studying the ecology of the Eastern forest for the last 15 years and has zeroed in especially on the advance of the red maple. Liberated from their swamp ghettos, red maples have become abundant in the understory -- the carpet of saplings and smaller plants under the canopy -- of many forested stretches in the Middle Atlantic States, the Northeast, the Midwest, the Great Lakes region and in higher Southern elevations like the Appalachians and Piedmont. When the oaks and other species of older trees die, red maples will replace them, Dr. Abrams said. In some spots, that has already happened. This is all the more remarkable, he said, because the red maple, though versatile, is not especially robust. In the conventional terms of plant physiology, the faster a plant converts sunlight to energy and the better it is at sucking up nutrients, adapting to drought and ''breathing'' efficiently, the better it can compete with other plants. The red maple is not particularly good at any of these; it is ''toward the low side of average'' in such measures, Dr. Abrams said. ''It's leading me to believe that studies at the physiological level don't tell us very much about the ecological success'' of a plant, he said.

3 The red maple advertises itself partly by the bright, silvery color of its smaller branches and its saplings and by the gray bark of a mature tree's trunk (much like that of a beech). Its leaf shape is classic maple, with three to five serrated lobes attached to a long, slender red stalk. It usually has something red about it in any season. Its leaves in fall are a brilliant scarlet or crimson. Many of the tree's twigs are red, especially in late summer and fall, as are its buds in winter and its flowers in spring. From the flowers sprout long, drooping red stalks to which the red whirlybird seeds are attached. All of this adds up to a kind of beauty that, along with the tree's ability to grow almost anywhere, has made it a favorite shade tree in the suburbs. It can grow to 100 feet tall or more, with a trunk three or four feet thick, and lives for up to 250 years. Old trees have rougher bark. Historically, the red maple was found throughout most of the Eastern United States, and was in fact the country's most widely distributed maple. In any given locality, however, it was a secondary ecological player limited mostly to flood plains, wet, low-lying woodlands and swamps. It has not been considered as valuable a timber tree as other hardwoods, since its wood weighs about the same but is only about three-quarters as strong. Even so, Dr. Abrams said, the red maple's increasing abundance is forcing the timber industry to adapt. ''Nobody is very happy about it,'' he said, ''but it is replacing much more valuable hardwood species.'' Its rise comes in the midst of a wide variety of other changes in the mixed deciduousevergreen forest of the East, and particularly in the Northeast, where the forest is resurgent in terms of tree abundance. What exists today is a remnant of a continuous deciduous band that encircled the earth 10 million years ago. Since then the forest has been frequently disturbed, first by the comings and goings of ice ages and then, within the last 10,000 years, by the clearings A Mixed Deciduous Forest in Fall and burnings of Indians. What greeted the first European arrivals was not unbroken forest, but rather a mosaic of woodland and oak-studded open stretches. Europeans in the Northeast proceeded to cut over all but about 2 percent of the remaining forest to make way for farms in the 18th and 19th centuries. By the 20th century, farmers were moving en masse to better lands in the Midwest, and the Northeastern forest started to regrow.

4 But as the forest expanded, its composition changed. Disease reduced the elms and chestnuts to ecological insignificance. Many exotic species from abroad, like the well-known ailanthus, or tree of heaven, along with the bittersweet, the Norway maple and the Japanese honeysuckle, have invaded parts of the forest. Without fire, oaks are failing to regenerate. Diseases cast shadows over the future of many tree species, including the sugar maple, dogwood, hemlock, white ash, balsam fir and sycamore. The red maple has proved resilient to all of this. Not only is it super-adaptable and aggressive, but it is remarkably resistant to some stresses to which rival species easily succumb. Gypsy moths devour oak leaves; the leaves of red maples contain alkaloid chemicals that repel the moths. The chemicals may further discourage exploding populations of deer from eating the leaves in summer, when browsing does the most damage to trees. There is also evidence, Dr. Abrams said, that red maples are more tolerant of acid rain than other species. Gypsy moth caterpillar Studies of tree rings by Dr. Abrams and colleagues have revealed that red maples were rare in the uplands a century ago. And studies of individual upland forest plots over the last 30 to 50 years show increases in red maple numbers of 200 percent to 400 percent, he said. Red maples are not taking over everywhere; on soil most favorable to sugar maples, for instance, the sugar maples eclipse them. Red maples do not do well in the sandy soil of the coastal plain, and their spread may be slower in the driest areas. But for the most part, said Dr. Abrams, they are coming to rule not only the deciduous forest of most of the East but also the Northeastern pine-hemlock forest. The takeover is accelerated wherever timber operations remove the canopy that shades red maple saplings. ''When you cut that,'' Dr. Abrams said, ''you're converting it to red maple overnight.'' The replacement of oaks by red maples is a major ecological event because so many animals rely on the oaks. Countless insects live in the interstices of the oak's rough bark, and numerous bird species depend on these for food. Many small nut-eating animals also depend on them. Now that the chestnuts are gone and walnuts are in decline, and their nut crops with them, the loss of oaks and their acorns could profoundly change the mixture of species in the forest. The details of this potential change are unclear and are the subject of further studies. If forest managers wanted to alter the trend toward red maple ascendancy, Dr. Abrams wrote in the journal BioScience last year, the periodic setting of controlled, prescribed fires -- now a standard conservation technique -- might be the best strategy. But ''given the current ecology and management of Eastern forests,'' he wrote, ''the increasing dominance of forest overstories by red maple seems inevitable,'' and the eclipse of oaks and pines ''will be a primary consequence.''

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