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In biology, the canopy is the aboveground portion of a plant community or crop, formed by the collection of individual plant crowns. (1989). 9780521395632, Cambridge University Press. ISBN 9780521395632 (2025). 9781405108591, Blackwell Publishing. ISBN 9781405108591 In forest ecology, the canopy is the upper layer or habitat zone, formed by mature tree crowns and including other biological organisms (, , Arboreal, etc.). (1995). 9780124576506, Academic Press. ISBN 9780124576506 The communities that inhabit the canopy layer are thought to be involved in maintaining forest diversity, resilience, and functioning. normally have a dense canopy that blocks light from lower growing plants.
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 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 broaddened the scope of canopy study.
Dominant and co-dominant canopy trees form the uneven canopy layer. Canopy trees are able to photosynthesis relatively rapidly with 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 canopies of tropical rainforests. Many rainforest animals have evolved to live solely in the canopy and never touch the ground. The canopy of a rainforest is typically about thick, and intercepts around 95% of sunlight. The canopy is below the 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 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. Forest canopies are arguably considered some of the most species-rich environments on the planet. It is believed that the communities found within the canopy layer play an essential role in the functioning of the forest, as well as maintaining diversity and ecological resilience.
A PNAS study measuring variations in temperature across city neighborhoods found that areas of the city with greater canopy cover were substantially cooler than otherwise similar areas of the city.
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