Temperate deciduous or temperate broad-leaf forests are a variety of temperate forest 'dominated' by deciduous trees that lose their leaves each winter. [1] They represent one of Earth's major biomes, making up 9.69% of global land area. [2] These forests are found in areas with distinct seasonal variation that cycle through warm, moist summers, cold winters, and moderate fall and spring seasons. [3] They are most commonly found in the Northern Hemisphere, with particularly large regions in eastern North America, East Asia, and a large portion of Europe, though smaller regions of temperate deciduous forests are also located in South America. Examples of trees typically growing in the Northern Hemisphere's deciduous forests include oak, maple, basswood, beech and elm, while in the Southern Hemisphere, trees of the genus Nothofagus dominate this type of forest. [1] Temperate deciduous forests provide several unique ecosystem services, [4] including habitats for diverse wildlife, and they face a set of natural and human-induced disturbances that regularly alter their structure. [5]
Located below the northern boreal forests, [6] temperate deciduous forests make up a significant portion of the land between the Tropic of Cancer (23°N) and latitudes of 50° North, in addition to areas south of the Tropic of Capricorn (23°S). [7] Canada, the United States, China, and several European countries have the largest land area covered by temperate deciduous forests, [7] with smaller portions present throughout South America, specifically Chile and Argentina. [1]
Temperate conditions refer to the cycle through four distinct seasons that occurs in areas between the polar regions and tropics. In these regions where temperate deciduous forest are found, warm and cold air circulation accounts for the biome's characteristic seasonal variation. [8]
The average annual temperature tends to be around 10 °Celsius, though this is dependent on the region. [8] Due to shading from the canopy, the microclimate of temperate deciduous forests tends to be about 2.1 °Celsius cooler than the surroundings, whereas winter temperatures are from 0.4 to 0.9 °Celsius warmer within forests as a result of insulation from vegetation strata. [9]
Annually, temperate deciduous forests experience approximately 750 to 1,500 millimeters of precipitation. [8] As there is no distinct rainy season, precipitation is spread relatively evenly throughout the year. [1] Snow makes up a portion of the precipitation present in temperate deciduous forests in the winter. Tree branches can intercept up to 80% of snowfall, affecting the amount of snow that ultimately reaches and melts on the forest floor. [10]
A defining factor of temperate deciduous forests is their leaf loss during the transition from fall to winter, an adaptation that arose as a solution for the low sunlight conditions and bitter cold temperatures. [1] In these forests, winter is a time of dormancy for plants, [8] when broadleaf deciduous trees conserve energy and prevent water loss, and many animal species hibernate or migrate. [1] Preceding winter is fruit-bearing autumn, a time when leaves change color to various shades of red, yellow, and orange as chlorophyll breakdown gives rise to anthocyanin, carotene, and xanthophyl pigments. [1]
Besides the characteristic colorful autumns and leafless winters, temperate deciduous forests have a lengthy growing season during the spring and summer months that tends to last anywhere from 120 to 250 days. [6] Spring in temperate deciduous forests is a period of ground vegetation and seasonal herb growth, a process that starts early in the season before trees have regrown their leaves and when ample sunlight is available. Once a suitable temperature is reached in mid- to late spring, budding and flowering of tall deciduous trees also begins. In the summer, when fully-developed leaves occupy all trees, a moderately-dense canopy creates shade, increasing the humidity of forested areas. [1]
Though there is latitudinal variation in soil quality of temperate deciduous forests, with those at central latitudes having a higher soil productivity than those more north or south, [6] soil in this biome is overall highly fertile. [1] The fallen leaves from deciduous trees introduce detritus to the forest floor, increasing levels of nutrients and organic matter in the soil. [1] The high soil productivity of temperate deciduous forests puts them at a high risk of conversion to agricultural land for human use. [7]
Temperate deciduous forests are characterized by a variety of temperate deciduous tree species that vary based on region. [6] Most tree species present in temperate deciduous forests are broadleaf trees that lose their leaves in the fall, [8] though some coniferous trees such as pines (Pinus) are present in northern temperate deciduous forests. [6] Europe's temperate deciduous forests are rich with oaks of the genus Quercus, European beech trees (Fagus sylvatica), and hornbeams (Fagus grandifolia), while those in Asia tend to have maples of the genus Acer, a variety of ash trees (Fraxinus), and basswoods (Tilia). Similarly to Asia, North American forests have maples, especially Acer saccharum, and basswoods, in addition to hickories (Carya) and American chestnuts (Castanea dentata). [6] Southern beech (Nothofagus) trees are prevalent in the temperate deciduous forests of South America. Elm trees (Ulmus) and willows (Salix) can also be found dispersed throughout the temperate deciduous forests of the world. [1] While a wide variety of tree species can be found throughout the temperate deciduous forest biome, tree species richness is typically moderate in each individual ecosystem, with only 3 to 4 tree species per square kilometer. [3]
Besides the old-growth trees that, with their domed tree crowns, form a canopy that lets little light filter through, a sub-canopy of shrubs [6] such as mountain laurel and azaleas is present. [8] These other plant species found in the canopy layers below the 35- to 40-meter mature trees are either adapted to low-light conditions or follow a seasonal schedule of growth that allows them to thrive before the formation of the canopy from mid-spring through mid-fall. [6] Mosses and lichens make up significant ground cover, though they are also found growing on trees. [1]
In addition to characteristic flora, temperate deciduous forests are home to several animal species that rely on the trees and other plant life for shelter and resources, such as squirrels, rabbits, skunks, birds, mountain lions, bobcats, timber wolves, foxes, and black bears. [3] Deer are also present in large populations, though they are clearing rather than true forest animals. Large deer populations have deleterious effects on tree regeneration overall, and grazing also has significant negative effects on the number and kind of herbaceous flowering plants. The continuous increase of deer populations and killing of top carnivores suggests that overgrazing by deer will continue. [11]
Temperate deciduous forests provide several provisioning, regulating, supporting, and cultural ecosystem services. [4] With a higher biodiversity than boreal forests, [7] temperate deciduous forests maintain their genetic diversity by providing the supporting service of habitat availability for a variety of plants and animal species dependent on shade. [5] These forests play a role in the regulation of air and soil quality by preventing soil erosion and flooding, while also storing carbon in their soil. [5] Provisioning services provided by temperate deciduous forests include access to sources of drinking water, [12] oxygen, [13] food, timber, and biomass. [5] Humans depend on temperate deciduous forests for cultural services, using them as spaces for recreation and spiritual practices. [4]
Natural disturbances cause regular renewal of temperate deciduous forests and create a healthy, heterogeneous environment with constantly changing structures and populations. [5] Weather events like snow, storms, and wind can cause varying degrees of change to the structure of forest canopies, creating log habitats for small animals and spaces for less shade-tolerant species to grow where fallen trees once stood. [6] Other abiotic sources of disturbances to temperate deciduous forests include droughts, waterlogging, and fires. [14] Natural surface fire patterns are especially important in pine reproduction. [6] Biotic factors affecting forests take the form of fungal outbreaks in addition to mountain pine beetle and bark beetle infestations. [14] These beetles are particularly prevalent in North America and kill trees by clogging their vascular tissue. [13] Temperate deciduous forests tend to be resilient after minor weather-related disturbances, though major insect infestations, widespread anthropogenic disturbances, and catastrophic weather events can cause century-long succession or even the permanent conversion of the forest into a grassland. [6]
Rising temperatures and increased dryness in temperate deciduous forests have been noted in recent years as the climate changes. [12] As a result, temperate deciduous forests have been experiencing an earlier onset to spring, [15] as well as a global increase in the frequency and intensity of disturbances. [5] They have been experiencing lower ecological resilience [16] in the face of increasing mega-fires, longer droughts, and severe storms. [12] Damaged wood from increased storm disturbance events provides nesting habitats for beetles, concurrently increasing bark beetle damage. [14] Forest cover decreases with continuous severe disturbances, causing habitat loss and lower biodiversity. [13]
Humans rely on wood from temperate deciduous forests for use in the timber industry as well as paper [13] and charcoal production. [17] Logging practices emit high levels of carbon while also causing erosion because fewer tree roots are present to provide soil support. [13] During the European colonization of North America, potash made from tree ashes was exported back to Europe as fertilizer. [18] At this time in history, clearcutting of the original temperate deciduous forests was also performed to make space for agricultural land use, so many forests now present are second-growth. [1] Over 50% of temperate deciduous forests are affected by fragmentation, [2] resulting in small fragments dissected by fields and roads;[ citation needed ] these islands of green often differ substantially from the original forests [19] and cause challenges for species migration. [6] Seminatural temperate deciduous forests with developed trail systems serve as sites for tourism and recreational activities, such as hiking and hunting. [13] In addition to fragmentation, human use of land adjacent to temperate deciduous forests is associated with pollution that can stunt the growth rate of trees. [6] Invasive species that outcompete native species and alter forest nutrient cycles, such as common buckthorn (Rhamnus cathartica), are also introduced by humans. [20] The introduction of exotic diseases, especially, continues to be a threat to forest trees and, hence, the forest. [21]
A method for preserving temperate deciduous forests that has been used in the past is fire suppression. The process of preventing fires is associated with the build-up of biomass that, ultimately, increases the intensity of incidental fires. As an alternative, prescribed burning has been put into practice, in which regular, managed fires are administered to forest ecosystems to imitate the natural disturbances that play a significant role in preserving biodiversity. [7] To combat the effects of deforestation, reforestation has been employed. [14]
A biome is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. Biomes may span more than one continent. A biome encompasses multiple ecosystems within its boundaries. It can also comprise a variety of habitats.
A forest is an ecosystem characterized by a dense community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' Food and Agriculture Organization (FAO) defines a forest as, "Land spanning more than 0.5 hectares with trees higher than 5 meters and a canopy cover of more than 10 percent, or trees able to reach these thresholds in situ. It does not include land that is predominantly under agricultural or urban use." Using this definition, Global Forest Resources Assessment 2020 found that forests covered 4.06 billion hectares, or approximately 31 percent of the world's land area in 2020.
Taiga, also known as boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, and larches. The taiga or boreal forest is the world's largest land biome. In North America, it covers most of inland Canada, Alaska, and parts of the northern contiguous United States. In Eurasia, it covers most of Sweden, Finland, much of Russia from Karelia in the west to the Pacific Ocean, much of Norway and Estonia, some of the Scottish Highlands, some lowland/coastal areas of Iceland, and areas of northern Kazakhstan, northern Mongolia, and northern Japan.
In the fields of horticulture and botany, the term deciduous means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, after flowering; and to the shedding of ripe fruit. The antonym of deciduous in the botanical sense is evergreen.
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur naturally on all continents except Antarctica and are found in most ecoregions of the Earth. Furthermore, grasslands are one of the largest biomes on Earth and dominate the landscape worldwide. There are different types of grasslands: natural grasslands, semi-natural grasslands, and agricultural grasslands. They cover 31–69% of the Earth's land area.
A savanna or savannah is a mixed woodland-grassland biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses. Four savanna forms exist; savanna woodland where trees and shrubs form a light canopy, tree savanna with scattered trees and shrubs, shrub savanna with distributed shrubs, and grass savanna where trees and shrubs are mostly nonexistent.
The Valdivian temperate forests (NT0404) is an ecoregion on the west coast of southern South America, in Chile and Argentina. It is part of the Neotropical realm. The forests are named after the city of Valdivia. The Valdivian temperate rainforests are characterized by their dense understories of bamboos, ferns, and for being mostly dominated by evergreen angiosperm trees with some deciduous specimens, though conifer trees are also common.
Tropical forests are forested ecoregions with tropical climates – that is, land areas approximately bounded by the tropics of Cancer and Capricorn, but possibly affected by other factors such as prevailing winds.
Temperate rainforests are rainforests with coniferous or broadleaf forests that occur in the temperate zone and receive heavy rain.
Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes. Tropical rainforests are a type of tropical moist broadleaf forest, that includes the more extensive seasonal tropical forests. True rainforests usually occur in tropical rainforest climates where no dry season occurs; all months have an average precipitation of at least 60 mm (2.4 in). Seasonal tropical forests with tropical monsoon or savanna climates are sometimes included in the broader definition.
Coarse woody debris (CWD) or coarse woody habitat (CWH) refers to fallen dead trees and the remains of large branches on the ground in forests and in rivers or wetlands. A dead standing tree – known as a snag – provides many of the same functions as coarse woody debris. The minimum size required for woody debris to be defined as "coarse" varies by author, ranging from 2.5–20 cm (1–8 in) in diameter.
An old-growth forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Nations defines primary forests as naturally regenerated forests of native tree species where there are no clearly visible indications of human activity and the ecological processes are not significantly disturbed. One-third of the world's forests are primary forests. Old-growth features include diverse tree-related structures that provide diverse wildlife habitats that increases the biodiversity of the forested ecosystem. Virgin or first-growth forests are old-growth forests that have never been logged. The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris.
The Carolinian forest refers to a life zone in eastern North America characterized primarily by the predominance of deciduous (broad-leaf) forest. The term "Carolinian", which is most commonly used in Canada, refers to the deciduous forests which span across much of the eastern United States from the North Carolina northward into southern Ontario, Canada. These deciduous forests in the United States and southern Ontario share many similar characteristics and species hence their association. Today the term is often used to refer to the Canadian portion of the deciduous forest region while the portion in the United States is often referred to as the "Eastern deciduous forest".
A secondary forest is a forest or woodland area which has regenerated through largely natural processes after human-caused disturbances, such as timber harvest or agriculture clearing, or equivalently disruptive natural phenomena. It is distinguished from an old-growth forest, which has not recently undergone such disruption, and complex early seral forest, as well as third-growth forests that result from harvest in second growth forests. Secondary forest regrowing after timber harvest differs from forest regrowing after natural disturbances such as fire, insect infestation, or windthrow because the dead trees remain to provide nutrients, structure, and water retention after natural disturbances. Secondary forests are notably different from primary forests in their composition and biodiversity; however, they may still be helpful in providing habitat for native species, preserving watersheds, and restoring connectivity between ecosystems.
Fire ecology is a scientific discipline concerned with the effects of fire on natural ecosystems. Many ecosystems, particularly prairie, savanna, chaparral and coniferous forests, have evolved with fire as an essential contributor to habitat vitality and renewal. Many plant species in fire-affected environments use fire to germinate, establish, or to reproduce. Wildfire suppression not only endangers these species, but also the animals that depend upon them.
Nothofagus cunninghamii, commonly known as myrtle beech or Tasmanian myrtle, is the dominant species of cool temperate rainforests in Tasmania and Southern Victoria. It has low fire resistance and grows best in partial shade conditions.
An oak forest is a plant community with a tree canopy dominated by oaks. In terms of canopy closure, oak forests contain the most closed canopy, compared to oak savannas and oak woodlands.
Drought deciduous, or drought semi-deciduous plants refers to plants that shed their leaves during periods of drought or in the dry season. This phenomenon is a natural process of plants and is caused due to the limitation of water around the environment where the plant is situated. In the spectrum of botany, deciduous is defined as a certain plant species that carry out abscission, the shedding of leaves of a plant or tree either due to age or other factors that causes the plant to regard these leaves as useless or not worth keeping over the course of a year. Deciduous plants can also be categorised differently than their adaptation to drought or dry seasons, which can be temperate deciduous during cold seasons, and in contrast to evergreen plants which do not shed leaves annually, possessing green leaves throughout the year.
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial factor in shaping plant community, biodiversity, metabolic processes and ecosystem dynamics for montane ecosystems. Dense montane forests are common at moderate elevations, due to moderate temperatures and high rainfall. At higher elevations, the climate is harsher, with lower temperatures and higher winds, preventing the growth of trees and causing the plant community to transition to montane grasslands and shrublands or alpine tundra. Due to the unique climate conditions of montane ecosystems, they contain increased numbers of endemic species. Montane ecosystems also exhibit variation in ecosystem services, which include carbon storage and water supply.
The Eastern Temperate Forests is a Level I ecoregion of North America designated by the Commission for Environmental Cooperation (CEC) in its North American Environmental Atlas. The region covers much of the Eastern and Midwestern United States, the U.S. Interior Highlands, and parts of Ontario, Quebec, and the Maritimes.