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{{short description|Aboveground portion of a plant community or crop}}
{{redirect|Overstory|the architectural feature|Clerestory|the novel by Richard Powers|The Overstory}}
[[File:JigsawCanopy.jpg|thumb|The canopy of a forest in [[Sabah]], Malaysia]]
[[File:Havelock Island, Canopy of tropical moist evergreen forest, Andaman Islands.jpg|thumb|Canopy of tropical evergreen forest, [[Andaman Islands]]]]
[[File:Khao Sok primary tropical rainforest, southern Thailand.jpg |thumb|Canopy layers of primary tropical forest, Thailand]]
[[File:Giantkelp2_300.jpg|thumb|''[[Macrocystis pyrifera]]'' – giant kelp – forming the canopy of a [[kelp forest]]]]
[[File:Bamboo Canopy.jpg|thumb|[[Bamboo]] canopy in the [[Western Ghats]] of [[India]] ]]

In [[biology]], the '''canopy''' is the aboveground portion of a [[plant community|plant '''cropping''']] or [[crop]], formed by the collection of individual [[Crown (botany)|plant crowns]].<ref>{{Cite book|last1=Campbell|first1=G.S.|title=Plant Canopies: Their Growth, Form and Function|last2=Norman|first2=J.M.|publisher=Cambridge University Press|year=1989|isbn=978-0-521-39563-2|editor-last=Russell|editor-first=Graham|pages=1–19|chapter=The description and measurement of plant canopy structure|doi=10.1017/CBO9780511752308.002|lccn=87032902|editor-last2=Marshall|editor-first2=Bruce|editor-last3=Jarvis|editor-first3=Paul G.|editor-link3=Paul Gordon Jarvis}}</ref><ref>{{Cite journal|last=Moffett|first=Mark W.|author-link=Mark W. Moffett|date=December 2000|title=What's "Up"? A Critical Look at the Basic Terms of Canopy Biology|journal=[[Biotropica]]|volume=32|issue=4|pages=569–596|doi=10.1646/0006-3606(2000)032[0569:WSUACL]2.0.CO;2}}</ref><ref>{{Cite book|last1=Hay|first1=Robert K.M.|title=The Physiology of Crop Yield|last2=Porter|first2=John R.|publisher=Blackwell Publishing|year=2006|isbn=978-1-4051-0859-1|edition=Second|lccn=2006005216}}</ref>

In [[forest ecology]], canopy also refers to the upper layer or [[habitat]] zone, formed by mature [[tree]] crowns and including other biological organisms ([[epiphyte]]s, [[liana]]s, [[Arboreal|arboreal animals]], etc.).<ref>{{Cite book|last=Parker|first=Geoffrey G.|title=Forest Canopies|publisher=Academic Press|year=1995|isbn=978-0124576506|editor-last=Lowman|editor-first=Margaret D.|editor-link=Margaret D. Lowman|edition=First|pages=73–106|chapter=Structure and microclimate of forest canopies|lccn=94041251|editor-last2=Nadkarni|editor-first2=Nalini M.|editor-link2=Nalini Nadkarni}}</ref> The communities that inhabit the canopy layer are thought to be involved in maintaining forest diversity, resilience, and functioning.<ref>{{Cite journal|last=Nadkarni|first=Nalini M.|date=February 1994|title=Diversity of Species and Interactions in the Upper Tree Canopy of Forest Ecosystems|url=https://academic.oup.com/icb/article/34/1/70/111781|journal=American Zoologist|volume=34|issue=1|pages=70–78|via=Oxford Academic}}</ref>

Sometimes the term canopy is used to refer to the extent of the outer layer of leaves of an individual tree or group of trees.{{citation needed|date=October 2015}} [[Shade tree]]s normally have a dense canopy that blocks light from lower growing plants.

== Observation ==
Early observations of canopies were made from the ground using binoculars or by examining fallen material. Researchers would sometimes erroneously rely on extrapolation by using more reachable samples taken from the [[understory]]. In some cases, they would use unconventional methods such as chairs suspended on [[vine]]s or hot-air dirigibles, among others. Modern technology, including adapted [[mountaineering]] gear, has made canopy observation significantly easier and more accurate, allowed for longer and more collaborative work, and broadened the scope of canopy study.<ref>{{Cite journal|last1=Lowman|first1=Margaret D.|author-link=Margaret D. Lowman|last2=Wittman|first2=Philip K.|date=1996|title=Forest Canopies: Methods, Hypotheses, and Future Directions|url=https://outonalimb-forestcanopies.com/PDFs/papers/0056.pdf|url-status=live|journal=[[Annual Review of Ecology, Evolution, and Systematics]]|volume=27|pages=55–81|doi=10.1146/annurev.ecolsys.27.1.55|jstor=2097229|archive-url=https://web.archive.org/web/20190207214156/https://outonalimb-forestcanopies.com/PDFs/papers/0056.pdf|archive-date=7 February 2019}}</ref>

== Canopy structure ==
[[File:Monkey Ladder Vine canopy.jpg|thumb|A [[Entada gigas|monkey-ladder vine]] canopy over a road]]
Canopy structure is the organization or spatial arrangement (three-dimensional geometry) of a plant canopy. [[Leaf area index]] (LAI), leaf area per unit ground area, is a key measure used to understand and compare plant canopies.

The canopy is taller than the [[understory]] layer. The canopy holds 90% of the animals in the rainforest. They cover vast distances and appear to be unbroken when observed from an airplane. However, despite overlapping tree branches, rainforest canopy trees rarely touch each other. Rather, they are usually separated by a few feet.<ref>{{Cite web|title=The Rainforest Canopy|url=https://rainforests.mongabay.com/0401.htm|last=Butler|first=Rhett|date=30 July 2012|website=[[Mongabay]]|url-status=live|archive-url=https://web.archive.org/web/20200505223821/https://rainforests.mongabay.com/0401.htm|archive-date=5 May 2020}}</ref>

== Canopy layer of forests ==
{{More citations needed|date=May 2020|section}}
Dominant and co-dominant canopy trees form the uneven canopy layer. Canopy trees are able to [[photosynthesis|photosynthesize]] relatively rapidly due to abundant light, so it supports the majority of primary productivity in forests. The canopy layer provides protection from strong winds and storms, while also intercepting sunlight and precipitation, leading to a relatively sparsely vegetated understory layer.

Forest canopies are home to unique flora and fauna not found in other layers of forests. The highest terrestrial [[biodiversity]] resides in the canopy of [[tropical rainforest]]s.<ref>{{Cite journal|last1=Lowman|first1=Margaret D.|author-link=Margaret D. Lowman|last2=Moffett|first2=Mark|author-link2=Mark W. Moffett|date=March 1993|title=The ecology of tropical rain forest canopies|url=https://www.canopymeg.com/PDFs/papers/0030.pdf|url-status=live|journal=[[Trends in Ecology & Evolution]]|volume=8|issue=3|pages=104–107|doi=10.1016/0169-5347(93)90061-S|pmid=21236120|archive-url=https://web.archive.org/web/20200202043829/https://www.canopymeg.com/PDFs/papers/0030.pdf|archive-date=2 February 2020}}</ref> Many rainforest animals have evolved to live solely in the canopy, and never touch the ground.

The canopy of a [[rainforest]] is typically about 10m thick, and intercepts around 95% of sunlight.<ref name="Garden.org">{{cite web|title=Light in the Rain Forest|url=http://assoc.garden.org/courseweb/course1/week4/page5a.htm|website=garden.org|access-date=23 November 2015|archive-url=https://web.archive.org/web/20151123141518/http://assoc.garden.org/courseweb/course1/week4/page5a.htm|archive-date=23 November 2015|url-status=dead}}</ref> The canopy is below the [[Rainforest#Layers|emergent layer]], a sparse layer of very tall trees, typically one or two per [[hectare]]. With an abundance of water and a near ideal temperature in rainforests, light and nutrients are two factors that limit tree growth from the understory to the canopy.

In the [[permaculture]] and [[forest gardening]] community, the canopy is the highest of seven layers.

The canopy can get as high as 40meters with different animals.

== Forest canopy ecology ==
Forest canopies have unique structural and ecological complexities and are important components of the overall forest ecosystem. They are involved in critical functions such as rainfall interception, light absorption, nutrient & energy cycling, gas exchange, as well as providing habitats for a diverse range of wildlife.<ref name=":0">{{Cite book|url=https://www.worldcat.org/oclc/162129566|title=Forest canopies|date=2004|publisher=Elsevier Academic Press|others=Margaret Lowman, H. Bruce Rinker|isbn=978-0-12-457553-0|edition=2nd|location=Amsterdam|oclc=162129566}}</ref> The canopy also plays a role in modifying the internal environment of the forest by acting as a buffer for incoming light, wind, and temperature fluctuations.<ref name=":0" />

=== Species diversity ===
The forest canopy layer supports a diverse range of flora and fauna. It has been dubbed “the last biotic frontier” as it provides a habitat that has allowed for the evolution of countless species of plants, microorganisms, invertebrates (e.g. insects), and vertebrates (e.g. birds and mammals) that are unique to the upper layer of forests.<ref name=":1">{{Citation|last=Nadkarni|first=Nalini M.|title=Forest Canopies, Plant Diversity|date=2013-01-01|url=https://www.sciencedirect.com/science/article/pii/B9780123847195001581|work=Encyclopedia of Biodiversity (Second Edition)|pages=516–527|editor-last=Levin|editor-first=Simon A|place=Waltham|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-384719-5.00158-1|isbn=978-0-12-384720-1|access-date=2022-02-26|last2=Merwin|first2=Mark C.|last3=Nieder|first3=Jurgen}}</ref> Due to this, forest canopies are arguably considered some of the most species-rich environments on the planet.<ref>{{Citation|last=Erwin|first=Terry L.|title=Forest Canopies, Animal Diversity|date=2013-01-01|url=https://www.sciencedirect.com/science/article/pii/B9780123847195000575|work=Encyclopedia of Biodiversity (Second Edition)|pages=511–515|editor-last=Levin|editor-first=Simon A|place=Waltham|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-384719-5.00057-5|isbn=978-0-12-384720-1|access-date=2022-02-26}}</ref> It is now believed that the communities found within the canopy layer play an important role in the functioning of the forest, as well as maintaining diversity and [[ecological resilience]].<ref name=":1" />

=== Climate regulation ===

==== Forest climate ====
Forest canopies contribute to forest microclimate by controlling and buffering variations in climatic conditions. Forest canopies intercept rain and snowfall, thereby buffering the effects of precipitation on the local climate.<ref name=":2">{{Cite journal |last=Nakamura |first=Akihiro |last2=Kitching |first2=Roger L. |last3=Cao |first3=Min |last4=Creedy |first4=Thomas J. |last5=Fayle |first5=Tom M. |last6=Freiberg |first6=Martin |last7=Hewitt |first7=C. N. |last8=Itioka |first8=Takao |last9=Koh |first9=Lian Pin |last10=Ma |first10=Keping |last11=Malhi |first11=Yadvinder |date=2017-06-01 |title=Forests and Their Canopies: Achievements and Horizons in Canopy Science |url=https://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(17)30059-9 |journal=Trends in Ecology & Evolution |language=English |volume=32 |issue=6 |pages=438–451 |doi=10.1016/j.tree.2017.02.020 |issn=0169-5347 |pmid=28359572}}</ref> Forest canopies also buffer the effects of temperature within forests by creating vertical light gradients.<ref>{{Cite journal |last=Pfeifer |first=Marion |last2=Gonsamo |first2=Alemu |last3=Woodgate |first3=William |last4=Cayuela |first4=Luis |last5=Marshall |first5=Andrew R. |last6=Ledo |first6=Alicia |last7=Paine |first7=Timothy C. E. |last8=Marchant |first8=Rob |last9=Burt |first9=Andrew |last10=Calders |first10=Kim |last11=Courtney-Mustaphi |first11=Colin |date=2018-01-08 |title=Tropical forest canopies and their relationships with climate and disturbance: results from a global dataset of consistent field-based measurements |url=https://doi.org/10.1186/s40663-017-0118-7 |journal=Forest Ecosystems |volume=5 |issue=1 |pages=7 |doi=10.1186/s40663-017-0118-7 |issn=2197-5620}}</ref> Variations in forest microclimate are also driven by the structure and physiology of canopy trees and epiphytes. This produces feedback loops where forest microclimate both determines and is determined by the species identity, growth traits and forest stand composition of canopy trees.<ref name=":2" />

==== Global climate ====
Forest canopies are significantly involved in maintaining the stability of the global climate. They are responsible for at least half of the global Carbon dioxide exchange between terrestrial ecosystems and the atmosphere. Forest canopies act as carbon sinks which reduce the increase of atmospheric CO<sub>2</sub> caused by human activity. The destruction of forest canopies would lead to the release of carbon dioxide which would result in an increased concentration of atmospheric CO<sub>2</sub>. This would then contribute to the greenhouse effect, thereby causing the planet to become warmer.<ref>{{Citation|last=Didham|first=R. K.|title=ECOLOGY {{!}} Forest Canopies|date=2004-01-01|url=https://www.sciencedirect.com/science/article/pii/B0121451607000132|work=Encyclopedia of Forest Sciences|pages=68–80|editor-last=Burley|editor-first=Jeffery|place=Oxford|publisher=Elsevier|language=en|doi=10.1016/b0-12-145160-7/00013-2|isbn=978-0-12-145160-8|access-date=2022-02-26|last2=Fagan|first2=L. L.}}</ref>

==See also==
{{cmn|
*[[Canopy (grape)]]
*[[Canopy research]]
*[[Canopy soils]]
*[[Canopy walkway]]
*[[Crown shyness]]
*[[Hemispherical photography]]
*[[Size-asymmetric competition]]
*[[Stratification (vegetation)]]
*[[Treefall gap]]
*[[Tropical forest]]
*[[Wildfire]]
}}

==References==
{{Reflist}}

==Further reading==
*{{Cite book|title=Forest Canopies|publisher=Academic Press|year=1995|isbn=978-0124576506|editor-last=Lowman|editor-first=Margaret D.|editor-link=Margaret D. Lowman|edition=First|lccn=94041251|editor-last2=Nadkarni|editor-first2=Nalini M.|editor-link2=Nalini Nadkarni}}
*{{Cite book|last=Moffett|first=Mark W.|title=The High Frontier: Exploring the Tropical Rainforest Canopy|url=https://archive.org/details/highfrontierexpl00moff|url-access=registration|publisher=Harvard University Press|year=1994|isbn=978-0674390386|lccn=93016935|author-link=Mark W. Moffett}}
*{{Cite book|title=Plant Canopies: Their Growth, Form and Function|publisher=Cambridge University Press|year=1989|isbn=978-0-521-39563-2|editor-last=Russell|editor-first=Graham|doi=10.1017/CBO9780511752308.002|lccn=87032902|editor-last2=Marshall|editor-first2=Bruce|editor-last3=Jarvis|editor-first3=PaulG.|editor-link3=Paul Gordon Jarvis}}
*{{Cite journal|last1=Jucker|first1=Tommaso|last2=Hardwick|first2=Stephen R.|last3=Both|first3=Sabine|last4=Elias|first4=Dafydd M.O.|last5=Ewers|first5=Robert M.|last6=Milodowski|first6=David T.|last7=Swinfield|first7=Tom|last8=Coomes|first8=David A.|display-authors=1|date=23 September 2018|title=Canopy structure and topography jointly constrain the microclimate of human‐modified tropical landscapes|journal=[[Global Change Biology]]|volume=24|issue=11|pages=5243–5258|doi=10.1111/gcb.14415|pmid=30246358|bibcode=2018GCBio..24.5243J|doi-access=free}}

==External links==
{{Commons category|Tree canopies}}
*[http://internationalcanopynetwork.org/ International Canopy Access Network]

{{Authority control}}

[[Category:Biology terminology]]
[[Category:Forest ecology]]
[[Category:Habitat]]
[[Category:Rainforests]]

Canopy (biology) - Revision history

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