- Also called:
- temperate deciduous forest
- Key People:
- Emma Lucy Braun
Deciduous forest
What is a deciduous forest?
Where are deciduous forests found?
Why do deciduous trees lose their leaves?
What types of animals are found in deciduous forests?
Deciduous forest, temperate forest biome composed primarily of broad-leaved trees that shed their leaves seasonally. Deciduous forests undergo striking changes throughout the year, from the emergence of new leaves and flowers in spring to dense green canopies in summer, colorful foliage in autumn, and bare branches in winter. They occur principally in three middle-latitude regions with a temperate climate characterized by a winter season and year-round precipitation: eastern North America, western Eurasia, and northeastern Asia. Deciduous forest also extends into more arid regions along stream banks and around bodies of water. For the deciduous forest of tropical regions, see monsoon forest.
Environment and ecology
Climate strongly influences the structure and composition of deciduous forests. Differences in temperature, moisture, and elevation may cause the formation of distinct plant associations within the deciduous-forest pattern. The dominance of beeches and maples in the northern part of the eastern North American deciduous forest and that of oaks and hickories along the southern extension of this vegetation are typical examples. The geographic distribution of deciduous forests is not fixed, however. As climate changes, suitable environmental conditions can shift toward higher latitudes or elevations, causing the ranges of some forest species to shift as well. Such changes have already been documented in a number of deciduous forest species in response to rising temperatures and altered precipitation patterns attributable to modern anthropogenic climate change.
Seasonal changes in temperature, precipitation, and light strongly influence the ecology of deciduous forests (see also photoperiodism). In autumn, declining temperatures and shorter days trigger many trees to shed their leaves, and during winter they enter a period of dormancy. The fallen leaves form a layer of litter on the forest floor, where fungi, bacteria, and invertebrates break down the organic matter and return nutrients to the soil. In spring, rising temperatures and rain stimulate new growth. Before the tree canopy fully develops, abundant sunlight reaches the forest floor, allowing many herbaceous plants, including spring ephemerals and other wildflowers, to grow and bloom. By summer, the dense canopy shades the understory and reduces the amount of light available to plants below, though warm temperatures and abundant rain fuel the growth of trees and shrubs. Ripening fruits in late summer and autumn are important foods for animals preparing for winter.
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Importance and threats
Deciduous forests are ecologically important as reservoirs of biodiversity and as complex communities of interacting organisms. They also provide numerous benefits to humans through the ecosystem services they perform. Like other forests, they store carbon, protect watersheds, help regulate local climates, provide habitat for game and other wildlife, and supply timber, food, and other forest products. Deciduous forests also have considerable cultural and aesthetic importance: Their seasonal changes, particularly the emergence of spring foliage and the brilliant colors of autumn leaves, have long inspired art and literature and made these forests valued settings for recreation and appreciation of nature.
Because many deciduous forests occur in regions with long histories of dense human settlement and agriculture, large areas have been cleared or substantially altered. Agricultural expansion, urban development, logging, and other changes in land use continue to cause significant forest loss and fragmentation in some regions. Other threats include invasive species such as common buckthorn (Rhamnus cathartica) and the Asian longhorned beetle (Anoplophora glabripennis), plant diseases such as Dutch elm disease, and acid rain. Climate change also threatens the health and ecology of deciduous forests, altering temperature and precipitation patterns, shifting the ranges of tree species, and affecting the timing of seasonal events such as leaf emergence and leaf fall. Protecting remaining forests and restoring previously cleared or degraded areas can help conserve biodiversity while maintaining the important ecosystem services deciduous forests provide.
Flora and fauna
Oaks, beeches, birches, chestnuts, aspens, elms, maples, and basswoods (or lindens) are the dominant trees in mid-latitude deciduous forests. They vary in shape and height and form dense growths that admit relatively little light through the leafy canopy. Shrubs are found primarily near clearings and forest edges, where more light is available, and herbaceous flowering plants are abundant within the forest in the spring, before the trees come into full leaf.
Snails, slugs, insects, and spiders are common inhabitants of the deciduous forest, and many cold-blooded vertebrates, such as snakes, frogs, salamanders, and turtles, are also present. Birds are represented by warblers, flycatchers, vireos, thrushes, woodpeckers, hawks, and owls. Prominent mammals include mice, moles, chipmunks, rabbits, weasels, foxes, bears, and deer.
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Soils
The soils upon which deciduous forests thrive are gray-brown and brown podzols. They are slightly acidic and have a granular humus layer known as mull, which is a porous mixture of organic material and mineral soil. Mull humus harbors many bacteria and invertebrate animals such as earthworms.