Editing Forest (section)

{{Short description|Dense collection of trees covering a relatively large area}}
{{About|a community of trees}}
{{Broader|Plant community}}
{{Not to be confused with|Woodland}}
{{pp-semi-indef|small=yes}}
{{Use dmy dates|date=January 2023}}
[[File:Aerial view of the Amazon Rainforest.jpg|thumb|upright=1.4|The [[Amazon rainforest]] alongside the [[Solimões River]], a [[tropical rainforest]]. These forests are the most [[biodiverse]] and productive [[Ecosystem|ecosystems]] in the world.]]
[[File:Proportion and distribution of global forest area by climatic domain, 2020.svg|thumb|upright=1.4|Proportion and distribution of global forest area by climatic domain, 2020<ref>{{Cite book|doi=10.4060/ca8753en|title=Global Forest Resources Assessment 2020 – Key findings|publisher=FAO|year=2020|isbn=978-92-5-132581-0|location=Rome|s2cid=130116768}}</ref>]]

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]]'' 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 ecosystem|terrestrial ecosystems]] of [[Earth]] by area, and are found around the globe.<ref name=yude>{{cite journal |title=The Structure, Distribution, and Biomass of the World's Forests |first1=Yude |last1=Pan |first2=Richard A. |last2=Birdsey |first3=Oliver L. |last3=Phillips |first4=Robert B. |last4=Jackson |journal=Annu. Rev. Ecol. Evol. Syst. |year=2013 |volume=44 |issue=1 |pages=593–62 |url=http://www.nrs.fs.fed.us/pubs/jrnl/2013/nrs_2013_pan_001.pdf |doi=10.1146/annurev-ecolsys-110512-135914 |bibcode=2013AREES..44..593P |url-status=live |archive-url=https://web.archive.org/web/20160807012240/http://www.nrs.fs.fed.us/pubs/jrnl/2013/nrs_2013_pan_001.pdf |archive-date=7 August 2016}}</ref> 45 percent of forest land is in the [[Tropical forest|tropical latitudes]]. The next largest share of forests are found in [[subarctic climate]]s, followed by [[Temperate rainforest|temperate]], and [[subtropic]]al zones.<ref name="auto">{{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, Italy |doi=10.4060/ca8985en |s2cid=241416114}}</ref>

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" />

Forests form distinctly different [[biome]]s at different latitudes and elevations, and with different precipitation and [[evapotranspiration]] rates.<ref>{{Cite book|last=Holdridge |first=L.R. |url=http://reddcr.go.cr/sites/default/files/centro-de-documentacion/holdridge_1966_-_life_zone_ecology.pdf |archive-url=https://web.archive.org/web/20161005035018/http://reddcr.go.cr/sites/default/files/centro-de-documentacion/holdridge_1966_-_life_zone_ecology.pdf |archive-date=5 October 2016 |url-status=live |title=Life zone ecology |publisher=Tropical Science Center |location=San Jose, Costa Rica}}</ref> These biomes include boreal forests in subarctic climates, [[tropical and subtropical moist broadleaf forests|tropical moist forests]] and [[tropical and subtropical dry broadleaf forests|tropical dry forests]] around the [[tropics|Equator]], and [[temperate forest]]s at the [[middle latitudes]]. Forests form in areas of the Earth with high rainfall, while drier conditions produce a transition to [[savanna]]. However, in areas with intermediate rainfall levels, forest transitions to savanna rapidly when the percentage of land that is covered by trees drops below 40 to 45 percent.<ref>{{cite web |last1=Edwards |first1=Lin |title=Forest and savanna can switch quickly |url=https://phys.org/news/2011-10-forest-savanna-quickly.html |website=Phys.org}}</ref> Research conducted in the [[Amazon rainforest]] shows that trees can alter rainfall rates across a region, releasing water from their leaves in anticipation of seasonal rains to trigger the wet season early. Because of this, seasonal rainfall in the Amazon begins two to three months earlier than the climate would otherwise allow.<ref>{{cite web |last1=Rasmussen |first1=Carol |title=New study shows the Amazon makes its own rainy season |url=https://climate.nasa.gov/news/2608/new-study-shows-the-amazon-makes-its-own-rainy-season/ |website=nasa.gov|date=17 July 2017 }}</ref><ref>{{cite web |last1=Loomis |first1=Ilima |title=Trees in the Amazon make their own rain |url=https://www.science.org/content/article/trees-amazon-make-their-own-rain}}</ref> [[Deforestation]] in the Amazon and anthropogenic [[climate change]] hold the potential to interfere with this process, causing the forest to pass a threshold where it transitions into savanna.<ref>{{cite web |last1=Kimbrough |first1=Liz |title=More droughts are coming, and the Amazon can't keep up: Study |url=https://news.mongabay.com/2022/09/more-droughts-are-coming-and-the-amazon-isnt-ready-study/ |website=Mongabay|date=16 September 2022 }}</ref>

Deforestation threatens many forest ecosystems. Deforestation occurs when humans remove trees from a forested area by cutting or burning, either to harvest [[timber]] or to make way for farming. Most deforestation today occurs in tropical forests. The vast majority of this deforestation is because of the production of four commodities: [[wood]], [[beef]], [[soy]], and [[palm oil]].<ref>{{cite web |last1=Derouin |first1=Sarah |title=Deforestation: facts, causes & effects |url=https://www.livescience.com/27692-deforestation.html |website=Live Science|date=6 January 2022 }}</ref> Over the past 2,000 years, the area of land covered by forest in [[Europe]] has been reduced from 80% to 34%. Large areas of forest have also been cleared in [[China]] and in the eastern [[United States]],<ref>{{cite web |title=Deforestation |url=https://education.nationalgeographic.org/resource/deforestation/ |publisher=National Geographic}}</ref> in which only 0.1% of land was left undisturbed.<ref>{{cite web |title=Eastern Deciduous Forest (U.S. National Park Service) |url=https://www.nps.gov/im/ncrn/eastern-deciduous-forest.htm |website=nps.gov}}</ref> Almost half of Earth's forest area (49 percent) is relatively intact, while 9 percent is found in fragments with little or no connectivity. Tropical rainforests and boreal coniferous forests are the least fragmented, whereas subtropical dry forests and temperate oceanic forests are among the most fragmented. Roughly 80 percent of the world's forest area is found in patches larger than {{convert|1|e6ha|abbr=off}}. The remaining 20 percent is located in more than 34 million patches around the world – the vast majority less than {{convert|1000|ha}} in size.<ref name="auto"/>

Human society and forests can affect one another positively or negatively.<ref>{{cite book |chapter=Global Societies and Forest Legacies Creating Today's Forest Landscapes |pages=30–59 |title=Forests and Society: Sustainability and Life Cycles of Forests in Human Landscapes |editor-last=Vogt |editor-first=Kristina A |year=2007 |publisher=CABI |isbn=978-1-84593-098-1}}</ref> Forests provide [[ecosystem services]] to humans and serve as tourist attractions. Forests can also affect people's health.<!--Specific statements supported by refs in "Relationship to human society" section--> Human activities, including unsustainable use of forest resources, can negatively affect forest ecosystems.<!--See same section for refs--><ref>{{Cite web|date=7 February 2019 |title=Deforestation and Its Effect on the Planet |url=https://www.nationalgeographic.com/environment/article/deforestation |archive-url=https://web.archive.org/web/20210219023929/https://www.nationalgeographic.com/environment/article/deforestation |url-status=dead |archive-date=19 February 2021 |access-date=21 July 2021 |website=[[National Geographic]] Environment |language=en}}</ref>