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Figure 26.4 A scene within the eastern deciduous forest. (Courtesy Robert A. Schlising)

Temperate Deciduous Forest

Most deciduous trees are broad-leaved species that shed their leaves annually during the fall and remain dormant during the shorter days and colder temperatures of winter. Most temperate deciduous forests (Fig. 26.4) occur, like the taiga, on large continental masses in the Northern Hemisphere. In North America, an example of this type of forest occurs from the Great Lakes region south to the Gulf of Mexico and roughly extends from the Mississippi River to the eastern seaboard, although some do not consider the eastern coastal plain to be part of the temperate deciduous forest biome.

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Temperatures within the area vary a great deal but normally fall below 4°C (39°F) in midwinter and rise above 20°C (68°F) in summer. The climax trees of the forest are well adapted to subfreezing temperatures as long as the cold is accompanied by precipitation or snow cover. Most of the annual precipitation, which totals between 50 and 165 centimeters (20 to 65 inches), occurs in the summer.

Some of the most beautiful of all the broad-leaved trees are found in a variety of associations in this biome. In the upper Midwest, sugar maple and American basswood predominate. Sugar maple, birch, and oak are also found to the Northeast, where they tend to be associated with the stately American beech. In the west-central part of the forest, oak and hickory abound. Oaks also are abundant along the eastern slopes of the Appalachian Mountains, where the American chestnut was once a conspicuous part of the flora. The chestnut has now virtually disappeared, having succumbed to chestnut blight disease that was introduced and began killing the trees during the early 1900s. Oak and hickory extend into the southeastern United States, where they become associated with pine and other tree species, such as the bald cypress.

Before the arrival of European immigrants, a mixture of large deciduous trees that included maple, ash, basswood, beech, buckeye, hickory, oak, tulip tree, and magnolia was found on the eastern slopes and valleys of the Appalachian Mountains. Some of the trees grew over 30 meters (100 feet) tall and had trunks up to 3 meters (10 feet) in diameter. Except for a few protected pockets in the Great Smoky Mountains National Park, the largest trees of this rich forest have been all but eliminated through logging. A smaller-treed extension of this forest is found in an area northeast of Baton Rouge, Louisiana, western Tennessee and Kentucky, and in southern Illinois. The American elm, also once a part of the forest, is rapidly disappearing as Dutch elm disease fells both wild trees and those planted along city streets. One small midwestern town that had some 600 elm trees planted along its streets found itself left with only six live trees within a year or two after Dutch elm disease struck.

A mixture of deciduous trees and evergreens occurs on the northern and southeastern borders of the forest. Hemlock and eastern white pine are found from New England west to Minnesota and south to the Appalachians. The once vast stands of eastern white pine are now largely gone, their valuable lumber having been used for construction and other purposes. Some have been lost to still another tree disease, white pine blister rust, but scattered trees remain, particularly where they have been protected. Various pines dominate the eastern coastal plain from New Jersey to Florida and westward to east Texas, with pitch pine being common in New Jersey. Some of the southern pines (e.g., long-leaf, slash, loblolly) are now cultivated in the southeastern United States for wood pulp, turpentine, lumber, and other commercially valuable products.

During the summer, the trees of the deciduous forests form a relatively solid canopy that keeps most direct sunlight from reaching the floor. Many of the showiest spring flowers of the region (such as bloodroot, hepatica, trillium, and violet) flower before the trees have leafed out fully and complete most of their growth within a few weeks. Other plants that can tolerate more shade, principally members of the Sunflower Family (e.g., aster and goldenrod), flower in succession in forest openings from midsummer through fall.

Animal life in the eastern deciduous forest includes red and gray foxes; raccoons; opossums; many rodents, such as gray squirrels; snakes, such as copperheads and black rat snakes; salamanders; and a wide variety of birds, including hawks, flickers, and mourning doves.

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