Forest
A forest is an area with a high density of
trees . Actually, many definitions of a forest exist sts can be found in all regions capable of sustaining tree growth, at altitudes up to the
tree-line, except where natural fire frequency is too high, or where the environment has been impaired by natural processes or by human activities. As a general rule, forests dominated by
angiosperms are more species-rich than those dominated by
gymnosperms , although exceptions exist . Forests sometimes contain many tree species within a small area , or relatively few species over large areas .
Encyclopedia
A
forest is an area with a high density of
trees . Actually, many definitions of a forest exist . These plant communities cover large areas of the globe and function as animal habitats,
hydrologic flow modulators, and
soil conservers, constituting one of the most important aspects of the
Earth's
biosphere. Although often thought of as as
carbon dioxide sinks, mature forests are approximately carbon neutral with only disturbed and young forests acting as carbon sinks . Nonetheless mature forests do play an important role in the global carbon cycle as stable carbon pools, and clearance of forests leads to an increase of atmospheric carbin dioxide leves.
Forests can be found in all regions capable of sustaining tree growth, at altitudes up to the
tree-line, except where natural fire frequency is too high, or where the environment has been impaired by natural processes or by human activities. As a general rule, forests dominated by
angiosperms are more species-rich than those dominated by
gymnosperms , although exceptions exist . Forests sometimes contain many tree species within a small area , or relatively few species over large areas . Forests are often home to many animal and plant species, and
biomass per unit area is high compared to other vegetation communities. Much of this biomass occurs below-ground in the root systems and as partially decomposed plant detritus. The woody component of a forest contains
lignin, which is relatively slow to
decompose compared with other organic materials such as
cellulose or carbohydrate.
Forests are differentiated from
woodlands by the extent of canopy coverage: in a forest the branches and foliage of separate trees often meet or interlock, although there can be gaps of varying sizes within an area referred to as forest. A woodland has a more continuously open canopy, with trees spaced further apart, which allows more sunlight to penetrate to the ground between them .
Among the major forested biomes are:
Classification
Forests can be classified in different ways and to different degrees of specificity. One such way is in terms of the
biome in which they exist combined with leaf longevity of the dominant species . Another distinction is whether the forests composed predominantly of broadleaf trees,
coniferous trees, or mixed.
- Boreal forests occupy the subarctic zone and are generally evergreen and coniferous.
- Temperate zones support both broadleaf deciduous forests and evergreen coniferous forests . Warm temperate zones support broadleaf evergreen forests, including laurel forests.
- Physiognomy classifies forests based on their overall physical structure or developmental stage .
- Forests can also be classified more specifically based on the dominant tree species present, resulting in numerous different forest types .
Forest management
The scientific study of forests is referred to as forest ecology, while the management of forests is often referred to as
forestry, often with the goal of sustainable resource extraction. Forest ecologists concentrate on forest patterns and processes, usually with the aim of elucidating cause and effect relationships. Foresters often focus on wood extraction and silviculture, including tree regeneration and growth processes.
Forests can be altered when
logging,
forest fires,
acid rain,
herbivores, or diseases, among other things, cause damage to trees. In the
United States, most forests have historically been affected by humans to some degree, though in recent years improved forestry practices has helped regulate or moderate large scale or severe impacts. However the United States Forest Service estimates that every year about 1.5 million acres of the nation’s 750 million acres of forestland is lost to
urban sprawl and development. It is expected that the South alone will lose 20 to 25 million acres to development.
Globally two types of forests can be identified. Natural and Anthropogenic.
Natural forests contain only the original patterns of biodiversity. the native species occurring in established seral patterns. These formations and processes have not been impacted by humans with a frequency or intensity to change established seral patterns
Anthropogenic forests have been impacted by humans with a frequency or intensity to change established seral patterns. Often, they contain elements of exotic species.
Notes
References
- Citat: "...The tap roots transfer rainwater from the surface to reservoirs deep underground and redistribute water...increases photosynthesis and the evaporation of water...by 40% in the dry season...During the wet season, these plants can store as much as 10% of the annual precipitation as deep as 13 meters underground, to be tapped during the dry months...tree roots acting like pipes to allow water to shift around much faster than it could otherwise percolate through the soil..."
See also
;General
...
;Activities related to forest
;Forests by country
;Lists
