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Forest

2007 Schools Wikipedia Selection. Related subjects: General Geography; Plants

   Eucalyptus Forest at Swifts Creek in East Gippsland, Victoria,
   Australia. Mostly Eucalyptus albens (white box)
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   Eucalyptus Forest at Swifts Creek in East Gippsland, Victoria,
   Australia. Mostly Eucalyptus albens (white box)
   A dense growth of softwoods (a conifer forest) in the Sierra Nevada
   Range of Northern California
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   A dense growth of softwoods (a conifer forest) in the Sierra Nevada
   Range of Northern California
   A decidous broadleaf (Beech) forest in Slovenia.
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   A decidous broadleaf (Beech) forest in Slovenia.
   A coniferous (pine) forest
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   A coniferous (pine) forest
   A forest on San Juan Island in Washington.
   Enlarge
   A forest on San Juan Island in Washington.
   Maple and Oak (broadleaf, deciduous) forest in Wisconsin in winter.
   Enlarge
   Maple and Oak (broadleaf, deciduous) forest in Wisconsin in winter.

   A forest is an area with a high density of trees (or, historically, a
   wooded area set aside for hunting). There are many definitions of a
   forest, based on various criteria . 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 carbon dioxide levels.

   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 (broadleaf forests) are more species-rich than those
   dominated by gymnosperms (conifer, montane, or needleleaf forests),
   although exceptions exist (for example, species-poor aspen and birch
   stands in northern latitudes). Forests sometimes contain many tree
   species within a small area (as in tropical rain and temperate
   deciduous forests), or relatively few species over large areas (e.g.,
   taiga and arid montane coniferous forests). 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 (see also savanna).

   Among the major forested biomes are:
     * rain forest (tropical and temperate)
     * taiga
     * temperate hardwood forest
     * tropical dry forest

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 (whether they are
   evergreen or deciduous). Another distinction is whether the forests
   composed predominantly of broadleaf trees, coniferous (needle-leaved)
   trees, or mixed.
     * Boreal forests occupy the subarctic zone and are generally
       evergreen and coniferous.
     * Temperate zones support both broadleaf deciduous forests (e.g.,
       temperate deciduous forest) and evergreen coniferous forests (e.g.,
       Temperate coniferous forests and Temperate rainforests). Warm
       temperate zones support broadleaf evergreen forests, including
       laurel forests.

     * Tropical and subtropical forests include tropical and subtropical
       moist forests, tropical and subtropical dry forests, and tropical
       and subtropical coniferous forests.

     * Physiognomy classifies forests based on their overall physical
       structure or developmental stage (e.g. old growth vs. second
       growth).

     * Forests can also be classified more specifically based on the
       climate and the dominant tree species present, resulting in
       numerous different forest types (e.g., ponderosa pine/Douglas-fir
       forest).

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 (6,000 km²) of the nation’s 750 million
   acres (3,000,000 km²) of forestland is lost to urban sprawl and
   development. It is expected that the South alone will lose 20 to 25
   million acres (80,000 to 100,000 km²) 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.
   Retrieved from " http://en.wikipedia.org/wiki/Forest"
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   with only minor checks and changes (see www.wikipedia.org for details
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