Editing Forest (section)

=== Types ===
[[File:La foresta sopra la vista del lago di Ridracoli.jpg|thumb|[[Foreste Casentinesi, Monte Falterona, Campigna National Park|Casentinesi Forests]], Italy]]

Forests are classified differently and to different degrees of specificity. One such classification is in terms of the [[biome]]s in which they exist, combined with leaf longevity of the dominant species (whether they are [[evergreen]] or [[deciduous]]). Another distinction is whether the forests are composed predominantly of broadleaf trees, [[conifer]]ous (needle-leaved) trees, or mixed.
* [[Boreal forest]]s occupy the [[subarctic]] zone and are generally evergreen and coniferous.
* [[Temperate]] zones support both broadleaf deciduous forests (e.g., [[Temperate broadleaf and mixed forests|temperate deciduous forest]]) and evergreen coniferous forests (e.g., [[temperate coniferous forests]] and [[temperate rainforest]]s). Warm temperate zones support broadleaf evergreen forests, including [[laurel forest]]s.
* Tropical and [[subtropical]] forests include [[Tropical and subtropical moist broadleaf forests|tropical and subtropical moist forests]], [[Tropical and subtropical dry broadleaf forests|tropical and subtropical dry forests]], and [[tropical and subtropical coniferous forests]].
* Forests are classified according to physiognomy based on their overall physical structure or [[Ecological succession|developmental stage]] (e.g. [[old growth]] vs. [[Secondary forest|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).

The number of trees in the world, according to a 2015 estimate, is 3 trillion, of which 1.4 trillion are in the tropics or sub-tropics, 0.6 trillion in the temperate zones, and 0.7 trillion in the coniferous boreal forests. The 2015 estimate is about eight times higher than previous estimates, and is based on tree densities [[Forest inventory|measured]] on over 400,000 plots. It remains subject to a wide margin of error, not least because the samples are mainly from Europe and North America.<ref>{{cite web |last1=Amos |first1=Jonathan |title=Earth's trees number 'three trillion' |url=https://www.bbc.co.uk/news/science-environment-34134366 |publisher=BBC |access-date=3 September 2015 |date=3 September 2015 |url-status=live |archive-url=https://web.archive.org/web/20150903082255/http://www.bbc.co.uk/news/science-environment-34134366 |archive-date=3 September 2015}}</ref>

Forests can also be classified according to the amount of human alteration. [[Old-growth forest]] contains mainly natural patterns of biodiversity in established [[seral]] patterns, and they contain mainly species native to the region and habitat. In contrast, [[secondary forest]] is forest regrowing following timber harvest and may contain species originally from other regions or habitats.<ref name="Chazdon">{{cite journal|last=Chazdon|first=Robin L.|author-link=Robin Chazdon|year=2008|title=Beyond deforestation: restoring forests and ecosystem services on degraded lands|url=http://lerf.eco.br/img/publicacoes/2008_2411%20Beyond%20Deforestation%20Restoring%20Forests%20and%20Ecosystem%20Services%20on%20Degraded%20Lands.pdf|url-status=live|journal=Science|volume=320|issue=5882|pages=1458–60|bibcode=2008Sci...320.1458C|doi=10.1126/science.1155365|pmid=18556551|archive-url=https://web.archive.org/web/20161021132745/http://lerf.eco.br/img/publicacoes/2008_2411%20Beyond%20Deforestation%20Restoring%20Forests%20and%20Ecosystem%20Services%20on%20Degraded%20Lands.pdf|archive-date=21 October 2016|s2cid=206511664}}</ref>

Different global forest classification systems have been proposed, but none has gained universal acceptance.<ref name=wcmc>{{cite book |last1=Jenkins |first1=Martin D. |last2=Groombridge |first2=Brian |title=World Atlas of Biodiversity: Earth's Living Resources in the 21st Century |publisher=[[World Conservation Monitoring Centre]], [[United Nations Environment Programme]] |url=https://books.google.com/books?id=_kHeAXV5-XwC&q=UNESCO+forest+and+woodland+subformations&pg=RA3-PA81 |isbn=978-0-520-23668-4 |year=2002}}</ref> [[United Nations Environment Programme|UNEP]]-[[World Conservation Monitoring Centre|WCMC]]'s forest category classification system is a simplification of other, more complex systems (e.g. [[UNESCO]]'s forest and woodland 'subformations'). This system divides the world's forests into 26 major types, which reflect climatic zones as well as the principal types of trees. These 26 major types can be reclassified into 6 broader categories: temperate needleleaf, temperate broadleaf and mixed, tropical moist, tropical dry, sparse trees and parkland, and forest plantations.<ref name=wcmc/> Each category is described in a separate section below.

==== Temperate needleleaf<span class="anchor" id="Coniferous forests"></span> ====
[[Temperate coniferous forest|Temperate needleleaf forests]] mostly occupy the higher latitudes of the [[Northern Hemisphere]], as well as some warm temperate areas, especially on nutrient-poor or otherwise unfavourable soils. These forests are composed entirely, or nearly so, of coniferous species ([[Coniferophyta]]). In the Northern Hemisphere, [[pine]]s ''Pinus'', [[spruce]]s ''Picea'', [[larch]]es ''Larix'', [[fir]]s ''Abies'', Douglas firs ''[[Pseudotsuga]]'', and hemlocks ''[[Tsuga]]'' make up the canopy; but other taxa are also important. In the [[Southern Hemisphere]], most coniferous trees (members of [[Araucariaceae]] and [[Podocarpaceae]]) occur mixed with broadleaf species, and are classed as broadleaf-and-mixed forests.<ref name=wcmc/>

====Temperate broadleaf and mixed====
[[File:Namdapha2.jpg|thumb|upright|Broadleaf forest in [[Bhutan]]]]

[[Temperate broadleaf and mixed forest]]s include a substantial component of trees of the [[Anthophyta]] group. They are generally characteristic of the warmer temperate latitudes, but extend to cool temperate ones, particularly in the southern hemisphere. They include such forest types as the mixed deciduous forests of the United States and their counterparts in China and Japan; the broadleaf evergreen [[rainforest]]s of Japan, [[Chile]], and [[Tasmania]]; the [[sclerophyllous]] forests of Australia, central Chile, the [[Mediterranean Basin|Mediterranean]], and California; and the southern beech [[Nothofagus]] forests of Chile and New Zealand.<ref name=wcmc/>

==== Tropical moist ====
There are many different types of [[Tropical and subtropical moist broadleaf forests|tropical moist forests]], with lowland evergreen broad-leaf [[tropical rainforest]]s: for example [[Várzea forest|várzea]] and [[Cantão#Natural Communities|igapó]] forests and the terra firme forests of the [[Amazon Basin]]; the [[peat swamp forest]]s; [[dipterocarp]] forests of [[Southeast Asia]]; and the [[high forest]]s of the [[Congo Basin]]. [[Seasonal tropical forest]]s, perhaps the best description for the colloquial term "[[jungle]]", typically range from the rainforest zone 10 degrees north or south of the [[equator]], to the [[Tropic of Cancer]] and [[Tropic of Capricorn]]. Forests located on mountains are also included in this category, divided largely into upper and lower [[Montane ecology|montane]] formations, on the basis of the variation of physiognomy corresponding to changes in altitude.<ref>{{cite book|first1=S|last1=Chape|first2=M|last2=Spalding|first3=M|last3=Jenkins|url=https://books.google.com/books?id=HuaGXdMTTmcC&q=Tropical+moist+forests+include+many+different+forest+types&pg=PA53|title=The world's protected areas: status, values and prospects in the 21st century|publisher=Univ de Castilla La Mancha|year=2008|isbn=978-0-520-24660-7}}</ref>

==== Tropical dry ====
[[Tropical and subtropical dry broadleaf forests|Tropical dry forests]] are characteristic of areas in the tropics affected by seasonal drought. The seasonality of rainfall is usually reflected in the deciduousness of the forest canopy, with most trees being leafless for several months of the year. Under some conditions, such as less fertile soils or less predictable drought regimes, the proportion of evergreen species increases and the forests are characterised as "[[sclerophyllous]]". [[Deserts and xeric shrublands|Thorn forest]], a dense forest of low stature with a high frequency of thorny or spiny species, is found where drought is prolonged, and especially where grazing animals are plentiful. On very poor soils, and especially where fire or herbivory are recurrent phenomena, [[savanna]]s develop.<ref name=wcmc/>

==== Sparse trees and savanna ====
Sparse trees and [[savanna]] are forests with sparse tree-[[Canopy (biology)|canopy]] cover. They occur principally in areas of transition from forested to non-forested landscapes. The two major zones in which these [[ecosystem]]s occur are in the [[boreal ecosystem|boreal]] region and in the seasonally dry tropics. At high latitudes, north of the main zone of boreal forestland, growing conditions are not adequate to maintain a continuously closed [[forest cover]], so tree cover is both sparse and discontinuous. This vegetation is variously called open [[taiga]], open [[lichen]] woodland, and forest tundra. A savanna is a mixed [[woodland]]–[[grassland]] [[ecosystem]] characterized 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 that consists primarily of grasses. Savannas maintain an open canopy despite a high tree density.<ref name=wcmc/>

==== Plantations ====
Forest plantations are generally intended for the production of timber and [[pulpwood]]. Commonly mono-specific, planted with even spacing between the trees, and intensively managed, these forests are generally important as habitat for native [[biodiversity]]. Some are managed in ways that enhance their biodiversity protection functions and can provide ecosystem services such as nutrient capital maintenance, [[Drainage basin|watershed]] and soil structure protection and carbon storage.<ref name=Chazdon/><ref name=wcmc/>