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Jun 1, 2024 · A forest is an ecosystem dominated by trees. According to the parameters established by the FAO, an area must cover at least half a hectare, or about one and a quarter acres, to be considered a ...
Although a forest is usually defined by the presence of trees, under many definitions an area completely lacking trees may still be considered a forest if it grew trees in the past, will grow trees in the future, [20] or was legally designated as a forest regardless of vegetation type. [21] [22]
- Overview
- Types of forests
- Abiotic conditions
- Flora and fauna
A forest is a complex ecological system in which trees are the dominant life-form. A forest is nature’s most efficient ecosystem, with a high rate of photosynthesis affecting both plant and animal systems in a series of complex organic relationships. Forests can develop under various conditions, and the kind of soil, plant, and animal life differs according to the extremes of environmental influences.
What are the main types of forests?
There are three main types of forests, defined by latitude: taiga (boreal) forests, temperate forests, and tropical forests.
How are forests classified?
Forests are distinguished from each other according to species composition (which develops in part according to the age of the forest), the density of tree cover, soil types, and the geologic history of the forest region.
What are the minimum climate requirements for a forest ecosystem?
Forests can occur wherever the temperatures rise above 10 °C (50 °F) in the warmest months and the annual precipitation is more than 200 mm (8 inches). They can develop under a variety of conditions within these climatic limits, and the kind of soil, plant, and animal life differs according to the extremes of environmental influences.
Britannica Quiz
Ecosystems
In cool high-latitude subpolar regions, forests are dominated by hardy conifers such as pines (Pinus), spruces (Picea), and larches (Larix). In the Northern Hemisphere, these forests, called taiga, or boreal forests, have prolonged winters and between 250 and 500 mm (10 and 20 inches) of rainfall annually. Coniferous forests also cover mountains in many temperate parts of the world.
In more temperate high-latitude climates, mixed forests of both conifers and broad-leaved deciduous trees predominate. Broad-leaved deciduous forests develop in middle-latitude climates, where there is an average temperature above 10 °C (50 °F) for at least six months every year and annual precipitation is above 400 mm (16 inches). A growing period of 100 to 200 days allows deciduous forests to be dominated by oaks (Quercus), elms (Ulmus), birches (Betula), maples (Acer), beeches (Fagus), and aspens (Populus).
In the humid climates of the equatorial belt are tropical rainforests, which support incredible plant and animal biodiversity. There heavy rainfall supports evergreens that have broad leaves instead of needle leaves, as in cooler forests. Monsoon forests, which are the deciduous forests of tropical areas, are found in regions with a long dry season followed by an intense rainy season. In the lower latitudes of the Southern Hemisphere, the temperate deciduous forest reappears.
Soil conditions are distinguished according to depth, fertility, and the presence of perennial roots. Soil depth is important because it determines the extent to which roots can penetrate into the earth and, therefore, the amount of water and nutrients available to the trees. The soil in the taiga is sandy and drains quickly. Deciduous forests have brown soil, richer than sand in nutrients, and less porous. Rainforests and savanna woodlands often have a soil layer rich in iron or aluminum, which give the soils either a reddish or yellowish cast. Given the vast amounts of rain they receive, the soil is often poor in tropical rainforests, as the nutrients are quickly leached away.
The amount of water available to the soil, and therefore available for tree growth, depends on the amount of annual rainfall. Water may be lost by evaporation from the surface or by leaf transpiration. Evaporation and transpiration also control the temperature of the air in forests, which is always slightly warmer in cold months and cooler in warm months than the air in surrounding regions.
Forests are among the most complex ecosystems in the world, and they exhibit extensive vertical stratification. Conifer forests have the simplest structure: a tree layer rising to about 30 metres (98 feet), a shrub layer that is spotty or even absent, and a ground layer covered with lichens, mosses, and liverworts. Deciduous forests are more complex; the tree canopy is divided into upper and lower stories, while rainforest canopies are divided into at least three strata. The forest floor in both of these forests consists of a layer of organic matter overlying mineral soil. The humus layer of tropical soils is affected by the high levels of heat and humidity, which quickly decompose whatever organic matter exists. Fungi on the soil surface play an important role in the availability and distribution of nutrients, particularly in the northern coniferous forests. Some species of fungi live in partnership with the tree roots, while others are parasitically destructive.
Animals that live in forests have highly developed hearing, and many are adapted for vertical movement through the environment. Because food other than ground plants is scarce, many ground-dwelling animals use forests only for shelter. In temperate forests, birds distribute plant seeds and insects aid in pollination, along with the wind. In tropical forests, fruit bats and birds effect pollination and seed dispersal. The forest is one of nature’s most efficient ecosystems, with a high rate of photosynthesis affecting both plant and animal systems in a series of complex organic relationships.
- The Editors of Encyclopaedia Britannica
Nov 6, 2019 · To summarize, forests are historically and colloquially considered to be larger than woods, and scientifically considered to be more dense. Jungles are technically forests, too, since jungleis a ...
The term forest is usually only applied where trees exceed two metres in height and the canopy shades more than 20 per cent of the ground surface. Botanists have developed systems for describing differing forest structures within that broad grouping, taking into account things like the height of the tallest trees, area of canopy or overstorey, type of understorey, dominant species, and ...
A forest species is a species that forms part of a forest ecosystems or is dependent on a forest for part or all of its day-to-day living requirements or for its reproductive requirements. Therefore, an animal species may be considered a forest species even if it does not live most of its life in a forest. Native species
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A forest is a complex ecological system in which trees are the dominant life-form. A forest is nature’s most efficient ecosystem, with a high rate of photosynthesis affecting both plant and animal systems in a series of complex organic relationships. Forests can develop under various conditions, and the kind of soil, plant, and animal life ...
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