Deciduous forests are important ecosystems that support multiple life cycles and provide habitat for native populations and wildlife. Located in the most heavily populated areas throughout the globe, these forests are declining because of human activity, including overuse and environmental pollution.
DEFINITION: Natural areas consisting of diverse plant species that lose their leaves annually at the end of each growing season.
The word “deciduous” is derived from the Latin word decidere, which means “fall off.” Deciduous forests did not exist until the end of the last ice age, which was some 20,000 years ago, as the plant species associated with this forest type were unable to adapt to the glacial climate.
There are temperate deciduous forests, and tropical and subtropical deciduous forests, also known as dry forests. Another name for these forests is broad-leaf forests because of the wide, flat leaves on the trees. Trees in tropical deciduous forests lose their leaves in the dry season and regrow them in the rainy season.
Deciduous forests are located mainly in the temperate forest biome, which has very seasonal weather patterns consisting of four seasons with warm summers and cold winters and precipitation in the form of rain and snow throughout the year.
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The leaves of deciduous trees change color and fall off in the autumn and grow back in the spring. The broad, flat leaves of deciduous trees lose water quickly. In the fall season the leaves of deciduous trees change from green to brilliant yellow, orange, red, and brown because of a lack of the green pigment chlorophyll, which they can no longer produce as daylight wanes. Eventually the leaves fall off as they go into dormancy at the end of the growing cycle, and most trees in the temperate deciduous forests remain bare during the winter months.
Temperate deciduous forests grow in 30-60 inches of rain per year. Temperate deciduous forests also have precipitation in the form of snow. Deciduous forests must have at least 120 days without frost. This period can extend to 250 days in some tropical and subtropical deciduous forests.
Winters are cold and summers are warm. Precipitation in this biome happens year round. Because the soil is very fertile and hardwood trees are good for building, this biome has some of the world's largest population centers in it.
The average daily temperatures range between -30°C (-22°F) and 30°C (86°F) with a yearly average of 10°C (50°F). The temperature varies widely from season to season with cold winters and hot, wet summers. The average yearly temperature is about 10°C.
During the fall, trees change color and then lose their leaves. This is in preparation for the winter season. Because it gets so cold, the trees have adapted to the winter by going into a period of dormancy or sleep. They also have thick bark to protect them from the cold weather.
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Temperate deciduous forests are most notable because they go through four seasons: Winter, Spring, Summer, and Fall. The deciduous forest regions are exposed to warm and cold air masses, which cause this area to have four seasons.
Location of Deciduous Forests
The temperate forest is located in the middle latitudes of the earth, and temperate or deciduous forests can be found in eastern North America, eastern Asia, and western Europe. Parts of Australia and New Zealand also contain deciduous forests. Less prominent are the tropical and subtropical deciduous forest biomes that exist in South America and Southern Africa. Plants in these biomes are dependent on seasonal temperatures and rainfall.
Temperate deciduous forests can be found in the eastern part of the United States and Canada, most of Europe and parts of China and Japan.
The map below shows the Earth’s deciduous forests. They are located in North America, Europe and Asia.
Map of Deciduous Forests
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North America's Eastern Deciduous Forest ecosystem stretches over 26 states from Florida up to New England and southern Canada and it extends as far west as Texas and Minnesota.
Two parts of the Eastern Deciduous Forest in the NCR, the Southern Coniferous and Broadleaf Forests and the Appalachian and Mixed Mesophytic Forests, were chosen as part of the "Global 200" list of areas important for global conservation. These areas were selected for recognition for their high biodiversity and their large area compared to similar forests worldwide.
The vast majority of NCR lies within the watershed of the Potomac River. The Potomac is the second-largest tributary of the Chesapeake Bay-America's largest estuary.
The easternmost portion of the NCR, the Coastal Plain is the mostly flat and low-lying area between the Atlantic Ocean and the foothills of the Appalachian Mountains. It is made from layers of sediment primarily eroded from the Appalachian Mountains and deposited by rivers as sediment over the Coastal Plain. The parks that make up National Capital Parks - East, parts of the George Washington Memorial Parkway, and a portion of Prince William Forest Park all fall within the Coastal Plain.
To the west of the Piedmont is the narrow Blue Ridge region. It encompasses the Blue Ridge Mountains, the easternmost part of the Appalachians. Its rocks are the oldest in the National Capital Region.
The westernmost physiographic region in the NCR is the Ridge and Valley, which makes up part of the Appalachian Mountains. Its parallel ridges are made of rocks that are more resistant to erosion than those of the valleys.
Forest Zones and Plant Associations
Temperate deciduous forests have a great variety of plant species. Most have three levels of plants. Lichen, moss, ferns, wildflowers and other small plants can be found on the forest floor. Shrubs fill in the middle level and hardwood trees like maple, oak, birch, magnolia, sweet gum and beech make up the third level. Conifers like spruce, fir and pine trees can also be found mixed in with the hardwood trees in this biome.
Temperate deciduous forests consist of five distinct zones or strata.
The first is the tree stratum. Trees in this zone, including maple, oak, beech, hickory, walnut, chestnut, basswood, linden, elm, and sweet gum species, average from 18 to 30 meters (60 to 100 feet) in height.
The second stratum, the small tree and sapling zone, is made up of younger trees found in the tree stratum.
The third stratum consists of shrubs, including such species as azaleas, rhododendrons, mountain laurels, and huckleberries.
The herbal or fourth zone consists of short herbal plants, and the rich soils of the forest floor make up the ground stratum, the fifth zone, which includes lichens, mushrooms, and mosses.
Most of the trees are broadleaf trees such as oak, maple, beech, hickory and chestnut. Plants found in these forests include flowers, ferns, mosses and herbs.
The Eastern Deciduous Forest canopy is dominated by oaks (Quercus), hickories (Carya), tulip poplar (Liriodendron tulipifera), American beech (Fagus grandifolia), "hard maples" (Acer spp.), and basswood (Tilia). Important conifers are eastern hemlock (Tsuga canadensis) and eastern white pine (Pinus strobus). All of these are species are common in the NCR except for eastern white pine and eastern hemlock, which is in pest- and disease-related decline. A majority of the ash trees (Fraxinus) in the region have died since 2014 from the devastating effect of the emerald ash borer.
Based on the four geologic and topographic areas described above, forests in each NCR park have somewhat different types of forest and tree species. For example, American holly (Ilex opaca) is common on the Coastal Plain and Piedmont, but largely absent from the more western Blue Ridge and the Ridge and Valley. Chestnut oak (Quercus prinus) is found in many NCR parks, but is most common in Catoctin Mountain Park and Harpers Ferry National Historical Park, in the Blue Ridge.
Animal Species
There is great diversity of life in this biome. Insects, spiders, slugs, frogs, turtles and salamanders are common. In North America, birds like broad-winged hawks, cardinals, snowy owls, and pileated woodpeckers are found in this biome. Mammals in North American temperate deciduous forests include white-tailed deer, raccoons, opossums, porcupines and red foxes.
Temperate deciduous forests flourish with a variety of fauna. Mammals include deer, elk, bears, squirrels, skunks, raccoons, rabbits, opossums, foxes, and porcupines. Other diverse species found in these forests include many varieties of salamanders, frogs, snakes, and spiders. Small and large birds, such as wild turkeys, owls, hawks, and the bald eagle, depend on deciduous forests for habitat.
Animals inhabiting deciduous forests include insects, spiders, reptiles and birds. Mice, rabbits, foxes, deer, otters, bears and humans are just some examples of mammals that live in deciduous forests.
During winter months some of the deciduous forest animals, especially birds, migrate to warmer climates where food is plentiful, while animals such as squirrels slow their metabolisms and store nuts and seeds in the hollows of trees to survive the winter months. Bears are among the animals that hibernate during winters in temperate deciduous forests.
Many animals associated with temperate deciduous forests have long been on the decline, such as bobcats, mountain lions, and timber wolves. Loss of and human slaughter have led to decreases in the populations of several of these species to the extent that they have been recognized as endangered or threatened and in need of protection from extinction.
NCR forests are also home to a diverse assortment of animals and fungi. These organisms not only rely on forests for survival, but also play a key role in maintaining the forests through seed dispersal, disturbance, soil turnover, and nutrient cycling. The NCR Network’s Inventory and Monitoring (NCRN I&M) program monitors some of these animals, like birds and amphibians, to assess population changes and forest dynamics.
Animals that live in the temperate deciduous forest must be able to adapt to the changing seasons. Some animals in this biome migrate or hibernate in the winter.
There are several trophic (food) levels making up the food web in deciduous forests. Organisms sharing a trophic level have the same function in the food web and get their energy from the same source.
The image below illustrates the organisms at each trophic level and their relationship to each other.
Deciduous Forest Food Web
Decomposers in the soil - such as bacteria, fungi and worms - supply nutrients for plants above to use. Plants rely on the presence of sunlight to enable them to produce energy through photosynthesis. In turn, herbivores are the primary consumers which eat the primary producers in the next trophic level. Carnivores and omnivores are secondary consumers and get energy from eating the primary consumers.
Threats to Deciduous Forests
The continual loss of deciduous forests caused by logging, blights, plagues, depletion owing to pollution, and climate change has exacerbated negative effects on all of the species that make their homes in these forests.
How Does Climate Change Affect The Temperate Deciduous Forest? - Ecosystem Essentials
Climate change is also a threat, with warming temperatures and changing precipitation levels shifting the optimal zones for many tree and plant species.
Defenders created the Forests for Wildlife Initiative to advance wildlife conservation in forest planning. We are actively engaged in forest plan revisions on national forests across the country and served on the 2012 Planning Rule Federal Advisory Committee. We work with Congress enact a new Farm Bill in 2018 with a forestry title that protects science-based management and wildlife that depend on forest habitat on private lands.
Today, forest fragmentation, overabundant deer populations, invasive species, pollution, fire suppression, acid rain and other changes in atmospheric chemistry, and human-induced climate change all threaten NCR forests. The American chestnut has been nearly eliminated by a non-native pathogen and most ashes were recently lost to the emerald ash borer. Oaks and hickories are in decline while the shade-tolerant beech (Fagus grandifolia) and maples (Acer spp.), which hold less value for wildlife, are becoming dominant.
NCR parks are still refuge for a wide range of plant and animal life, home to rare natural communities, and offer visitors the opportunity to experience the natural environment in a relatively urbanized area.
While the NCR is part of the vast Eastern Deciduous Forest ecosystem, forests only make up about 3/4 of park landcover. The landscape also features vital grasslands, wetlands, and other habitats.
Many parks, like Catoctin Mountain Park, are engaging in forest management projects to help mitigate challenges to forests. The NCR Inventory & Monitoring Network's long-term monitoring is designed to help us understand how our forests are changing.
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