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{{broader|Plant community}}
{{Use dmy dates|date=January 2023}}
{{Not to be confused with|Woodland}}[[File:
A '''forest''' is an [[ecosystem]] characterized by a dense [[ecological community|community]] of [[tree]]s.<ref>{{cite web |url=http://dictionary.reference.com/browse/forest |title=Forest |website=Dictionary.com |access-date=16 November 2014 |url-status=live |archive-url=https://web.archive.org/web/20141019171930/http://dictionary.reference.com/browse/forest |archive-date=19 October 2014}}</ref> 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.<ref>{{cite web |url=http://www.efi.int/files/attachments/publications/ir_06.pdf |title=Compilation of Forestry Terms and Definitions |first1=Andreas |last1=Schuck |first2=Risto |last2=Päivinen |first3=Tuomo |last3=Hytönend |first4=Brita |last4=Pajari |publisher=[[European Forest Institute]] |location=Joensuu, Finland |year=2002 |access-date=16 November 2014 |url-status=live |archive-url=https://web.archive.org/web/20150605064820/http://www.efi.int/files/attachments/publications/ir_06.pdf |archive-date=5 June 2015}}</ref><ref name="cbd">{{cite web |url=http://www.cbd.int/forest/definitions.shtml |title=Definitions: Indicative definitions taken from the Report of the ad hoc technical expert group on forest biological diversity |date=30 November 2006 |publisher=[[Convention on Biological Diversity]] |access-date=16 November 2014 |url-status=live |archive-url=https://web.archive.org/web/20141219030427/http://www.cbd.int/forest/definitions.shtml |archive-date=19 December 2014}}</ref><ref name="unep">{{cite web |url = http://www.unep.org/vitalforest/Report/VFG-01-Forest-definition-and-extent.pdf |archive-url=https://web.archive.org/web/20100726140947/http://www.unep.org/vitalforest/Report/VFG-01-Forest-definition-and-extent.pdf |url-status=dead |archive-date=26 July 2010 |title=Forest definition and extent |date=27 January 2010 |publisher=United Nations Environment Programme |access-date=16 November 2014}}</ref> 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 (biology)|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."<ref>{{Cite book|url=http://www.fao.org/3/I8661EN/i8661en.pdf |archive-url=https://web.archive.org/web/20190809045851/http://www.fao.org/3/I8661EN/i8661en.pdf |archive-date=9 August 2019 |url-status=live |title=Global Forest Resources Assessment 2020 – Terms and definitions |publisher=[[Food and Agriculture Organization]] |year=2018 |location=Rome}}</ref> Using this definition, ''[[Global Forest Resources Assessment (FRA)|Global Forest Resources Assessment]] 2020'' (FRA 2020) found that forests covered {{convert|4.06|e9ha|e9acre e6sqkm e6sqmi|abbr=off}}, or approximately 31 percent of the world's land area in 2020.<ref>{{Cite book |url=https://doi.org/10.4060/ca8985en |title=The State of the World's Forests 2020. In brief – Forests, biodiversity and people |publisher=[[Food and Agriculture Organization|FAO]] & UNEP |year=2020 |isbn=978-92-5-132707-4 |location=Rome |doi=10.4060/ca8985en |s2cid=241416114}}</ref>
Forests are the largest terrestrial [[
Forests account for 75% of the [[gross primary production]] of the Earth's [[biosphere]], and contain 80% of the Earth's plant [[biomass]]. [[Primary production#Gross primary production and net primary production|Net primary production]] is estimated at 21.9 [[gigatonne]]s of biomass per year for [[tropical forest]]s, 8.1 for [[temperate forest]]s, and 2.6 for [[boreal forest]]s.<ref name="yude" />
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The precise origin of Medieval Latin {{Lang|la-x-medieval|foresta}} is obscure. Some authorities claim the word derives from the [[Late Latin]] phrase ''forestam silvam'', denoting "the outer wood"; others claim the word is a latinisation of the Frankish *''forhist'', denoting "forest, wooded country", and was assimilated to ''forestam silvam'', pursuant to the common practice of Frankish scribes. The Old High German ''forst'' denoting "forest"; [[Middle Low German]] ''vorst'' denoting "forest"; [[Old English]] ''fyrhþ'' denoting "forest, woodland, game preserve, hunting ground" (English ''[[wikt:frith|frith]]''); and [[Old Norse]] ''fýri'', denoting "coniferous forest"; all of which derive from the [[Proto-Germanic]] *''furhísa-'', *''furhíþija-'', denoting "a fir-wood, ''coniferous'' forest", from the [[Proto-Indo-European language|Proto-Indo-European]] *''perk<sup>w</sup>u-'', denoting "a ''coniferous'' or mountain forest, wooded height" all attest to the Frankish *''forhist''.
Uses of ''forest'' in English to denote any uninhabited and unenclosed area are presently considered archaic.<ref name="oed" /> The [[Norman conquest of England|Norman rulers of England]] introduced the word as a legal term, as seen in Latin texts such as
These hunting forests did not necessarily contain any trees. Because that often included significant areas of woodland, "forest" eventually came to connote woodland in general, regardless of tree density.{{Citation needed|date=May 2009}} By the beginning of the fourteenth century, English texts used the word in all three of its senses: common, legal, and archaic.<ref name="oed">{{cite web |url=http://www.oed.com/ |title=forest, noun |website=[[Oxford English Dictionary]] online edition |publisher=[[Oxford University Press]] |access-date=22 May 2009 |url-status=live |archive-url=https://web.archive.org/web/20080111125659/http://www.oed.com/ |archive-date=11 January 2008}}</ref> Other English words used to denote "an area with a high density of trees" are ''firth'', ''frith'', ''holt'', ''weald'', ''wold'', ''wood'', and ''woodland''. Unlike ''forest'', these are all derived from Old English and were not borrowed from another language. Some present classifications reserve ''woodland'' for denoting a locale with more open space between trees, and distinguish kinds of woodlands as ''open forests'' and ''closed forests'', premised on their [[crown cover]]s.<ref>{{cite web |url=http://www.daff.gov.au/brs/forest-veg/nfi/forest-info/what-is |website=Australian Government/Department of Agriculture, Fisheries, and Forestry/Rural Areas |title=What is a Forest? |date=28 March 2007 |access-date=25 November 2010 |archive-url=https://web.archive.org/web/20091009061955/http://www.daff.gov.au/brs/forest-veg/nfi/forest-info/what-is |archive-date=9 October 2009}}</ref> Finally, ''sylva'' (plural ''sylvae'' or, less classically, ''sylvas'') is a peculiar English spelling of the Latin ''silva'', denoting a "woodland", and has precedent in English, including its plural forms. While its use as a [[synonym]] of ''forest'', and as a [[Latin]]ate word denoting a woodland, may be admitted; in a specific technical sense it is restricted to denoting the ''species'' of trees that comprise the woodlands of a region, as in its sense in the subject of [[silviculture]].<ref>Confer John Evelyn, FRS, ''[[Sylva, or A Discourse of Forest-Trees and the Propagation of Timber|Sylva, or A Discourse of Forest-Trees and the Propagation of Timber in His Majesty's Dominions]]'' (1664); and the title of and use ''passim'' in Edward Step, FLS, ''Wayside and Woodland Trees: A Pocket Guide to the British Sylva'' (Frederick Warne and Company Limited, London and New York, [many editions]).</ref> The resorting to ''sylva'' in English indicates more precisely the denotation that the use of ''forest'' intends.
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[[File:Hellyer Gorge, Tasmania.jpg|thumb|[[Temperate rainforest]] in Tasmania's [[Hellyer Gorge]]]]
Forests account for 75% of the [[gross primary productivity]] of the Earth's [[biosphere]], and contain 80% of the Earth's plant biomass.<ref name="yude" /> [[Biomass (ecology)|
Forest ecosystems broadly differ based on [[climate]]; latitudes 10° north and south of the [[equator]] are mostly covered in [[tropical rainforest]], and the latitudes between [[53rd parallel north|53°N]] and [[67th parallel north|67°N]] have [[boreal forest]]. 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. The trees that form the principal structural and defining component of a forest may be of a great variety of species (as in [[tropical rainforest]]s and [[temperate deciduous forest]]s), or relatively few species over large areas (e.g., [[taiga]] and arid [[montane]] coniferous forests). The biodiversity of forests also encompasses [[shrubs]], herbaceous plants, [[moss]]es, [[fern]]s, [[lichen]]s, [[fungi]], and a variety of [[animal]]s.
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* Serving as a source of woodlands and trees for millions of people dependent almost entirely on forests for subsistence for their essential fuelwood, food, and fodder needs.<ref>{{Cite book|url=https://doi.org/10.4060/ca8642en|title=The State of the World's Forests 2020 – Forests, biodiversity and people|publisher=FAO & UNEP|year=2020|isbn=978-92-5-132419-6|location=Rome|doi=10.4060/ca8642en|s2cid=241858489}}</ref>
The main ecosystem services can be summarized in the next table:<ref>{{cite web |title=Primary Forests: Boreal, Temperate, Tropical |url=https://www.woodwellclimate.org/primary-forests-boreal-temperate-tropical/ |website=Woodwell
{| class="wikitable"
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==Management==
{{main|Forest management|
[[File:World Production Of Selected Forest Products.svg|thumb|World production of selected forest products]]
[[File:Checkerboard forest in Idaho.jpg|alt=Priest River winds through mountains with a checkerboard design of trees to its east|thumb|[[Priest River (Idaho)|Priest River]] winding through Whitetail Butte with lots of [[forestry]] to the east—these lot patterns have existed since the mid-19th century. The white patches reflect areas with younger, smaller trees, where winter snow cover shows up brightly to the astronauts. Dark green-brown squares are parcels]]
Humans have generally decreased the amount of forest worldwide. Anthropogenic factors that can affect forests include logging, [[urban sprawl]], human-caused [[forest fire]]s, [[acid rain]], [[invasive species]], and the [[slash and burn]] practices of swidden agriculture or [[shifting cultivation]]. The loss and re-growth of forests lead to a distinction between two broad types of forest: primary or [[old-growth forest]] and [[secondary forest]]. There are also many natural factors that can cause changes in forests over time, including [[forest fires]], [[Forest pathology#Animals|insects]], [[Forest pathology|diseases]], weather, competition between species, etc. In 1997, the [[World Resources Institute]] recorded that only 20% of the world's original forests remained in large intact tracts of undisturbed forest.<ref>World Resources Institute (1997). [http://www.intactforests.org/pdf.publications/Last.Frontier.Forests.1997.pdf The Last Frontier Forests: Ecosystems and Economies on the Edge] {{webarchive|url=https://web.archive.org/web/20170813235644/http://www.intactforests.org/pdf.publications/Last.Frontier.Forests.1997.pdf |date=13 August 2017 }}.</ref> More than 75% of these intact forests lie in three countries: the boreal forests of Russia and Canada, and the rainforest of Brazil.
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===United States===
In the United States, most forests have historically been affected by humans to some degree, though in recent years improved [[forestry]] practices have helped regulate or moderate large-scale impacts. The [[United States Forest Service]] estimated a net loss of about {{convert|2|e6ha|abbr=off}} between 1997 and 2020; this estimate includes conversion of forest land to other uses, including urban and suburban development, as well as afforestation and natural reversion of abandoned crop and pasture land to forest. In many areas of the United States, the area of forest is stable or increasing, particularly in many northern states. The opposite problem from flooding has plagued national forests, with loggers complaining that a lack of thinning and proper forest management has resulted in large forest fires.<ref>{{cite web|url=http://www.wildrockiesalliance.org/issues/wildfire/enn.html|archive-url=https://web.archive.org/web/20130509225620/http://www.wildrockiesalliance.org/issues/wildfire/enn.html|archive-date=9 May 2013 |title=Wildfires Ignite Forest Management Debate |publisher=Wildrockiesalliance.org |access-date=3 July 2013}}</ref><ref>{{cite book|first=Emily K.|last=Brock|title=Money Trees: The Douglas Fir and American Forestry, 1900–1944|publisher=Oregon State University Press|year=2015}}</ref>
==See also==
{{Portal|Ecology|Environment|Trees}}
{{Columns-list|colwidth=15em|
* [[Bioproducts]]
* [[Close to nature forestry]]
* [[Cloud forest]]
* [[Dendrology]]
* [[Dendrometry]]
* [[Forest dynamics]]
* [[Forest migration]]
* [[Forest pathology]]
* [[Kelp forest]] (A forest made mostly if not entirely of [[Kelp]]; an underwater forest)
* [[List of countries by forest area]]
* [[List of old-growth forests]]
*[[Mangrove forest]]
* [[Permaforestry]]
* [[REDD-plus]]
* [[Urban forest]]
* [[Wilderness]]
* [[Woodland management]]
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