Get the Latest in Your Inbox
Want to stay up to date on the state of the world’s forests? Subscribe to our mailing list.
Subscribe
Talking about Tree Cover
The Global Forest Review (GFR) frequently refers to tree cover when talking about forest extent, loss and gain. Tree cover is a convenient metric for monitoring forest change because it is easily measurable from space using freely available, medium-resolution satellite imagery. This means that tree cover can be monitored frequently, at low cost, and over large geographic scales. However, the existence of tree cover does not always make a forest, tree cover loss does not always imply forest loss or deforestation, and tree cover gain does not always imply forest gain or restoration. Measuring these variables directly poses technical challenges, since most definitions of forest involve a combination of tree cover and land use. The latter is much more difficult, if not impossible in some cases, to monitor using satellite imagery.
The tree cover data used in this report is based on Hansen et al. (2013) and Potapov et al. (2022) and defines tree cover as woody vegetation with a height of at least five meters (m) and a canopy density of at least 30 percent at 30-m resolution. This definition includes planted forests and tree crops (such as oil palm or apple orchards) as well as managed and unmanaged natural forests. The definition excludes areas of sparse tree cover (less than 30% canopy density), such as in the North African Sahel or the Brazilian Cerrado, as well as individual trees in agricultural landscapes that may be critical for ecosystem functions.
The Trees Outside Forests Indicator page uses Tropical Tree Cover (TTC) from Brandt et al. (2023) for all calculations. TTC defines a tree as woody vegetation that is either >5 meters in height regardless of canopy diameter, or is between 3 and 5 meters in height with a crown of at least a 5-meter diameter. Tall herbaceous vegetation such as sugarcane, bananas and cacti, and short woody crops such as tea and coffee are excluded. Trees on non-forested land such as agroforestry, rotational and non-rotational tree plantations and trees in urban areas are included as trees. TTC covers 4.35 billion hectares of land in the tropics and is currently available for the year 2020.
Tree Cover Loss and Deforestation
Tree cover loss is not always deforestation, which typically refers to human-caused, permanent removal of natural forest cover. Tree cover loss is defined as the complete removal of tree cover for any reason. It includes both human-caused loss and natural disturbances, and loss that is permanent or temporary. Examples of tree cover loss that may not meet the definition of deforestation include loss from logging within production forests, fire, disease or storm damage.
This report uses tree cover loss dataHansen et al. 2013, https://doi.org/10.1126/science.1244693 to measure the complete removal of tree cover at a 30-m pixel scale because it can be measured consistently across the globe, but it also attempts to estimate forest loss (within primary forests) and deforestation where data allow.
Tree Cover Gain and Restoration
Tree cover gain is defined in this report as areas that had tree cover at least five meters tall in 2020 but not in 2000 at a 30-m pixel scale. Tree cover gain is more difficult to detect from satellite imagery over short intervals due to the gradual process of tree growth compared to tree removal. As such, the tree cover gain dataPotapov et al. 2022, https://doi.org/10.3389/frsen.2022.856903 used in this report are only available as a cumulative estimate from 2000 to 2020. Annual data and updates for this data set will eventually be available.
Tree cover gain does not perfectly represent “forest landscape restoration,” a key goal of international commitments such as the Bonn Challenge and the New York Declaration on Forests, for several reasons:
-
The data aggregate many different causes of tree cover gain, including dynamics that may not always count towards restoration commitments (e.g., regrowth in tree plantations, regeneration after natural disturbances, etc.). In the future, once annual gain data are available, we anticipate that some of these dynamics could be distinguished by determining areas that have faced cycles of loss and gain. Ideally, a method similar to the Curtis et al. (2018)Curtis et al. 2018, https://doi.org/10.1126/science model for determining drivers of tree cover loss could be developed to distinguish the various drivers and dynamics of tree cover gain.
-
The tree cover gain data do not cover other forms of restoration, such as enhancement of forest quality or planting of sparse trees in agricultural landscapes. Forthcoming annual height data has the potential to be used to determine areas that are becoming taller and denser over time, as a proxy for improving forest quality. Detecting sparse trees, on the other hand, likely requires higher-resolution imagery than that used in this dataset. The new Trees in Mosaic Landscapes data, which is an AI-derived map based on 10-m resolution Sentinel imagery, is more adept at picking up sparse tree cover outside of forests. Additionally, other tools such as Collect Earth allow local experts to interpret freely available high-resolution images within sample plots to detect individual trees outside forests and changes over time (see the Trees outside Forests Indicator).
-
Most restoration initiatives have objectives beyond increasing forest cover that are not accounted for in current tree cover gain data, including carbon removal from the atmosphere, increased biodiversity habitat and connectivity, water filtration and flow regulation, improved soil fertility, and income generation from fuelwood sales or agroforestry activities. Although there is guidance on how to monitor these objectives at the landscape scale,Buckingham et al. 2019, https://www.wri.org/publication/restoration-monitoring-guide doing so at a global level remains difficult.
Glossary
Definitions for basic forest-related concepts and terms are often varied and controversial. For consistency and clarity, the Global Forest Review (GFR) uses the following definitions across the report:
agroforestry: A diversified set of agricultural or agropastoral production systems that integrate trees in the agricultural landscape.
biodiversity intactness: The proportion and abundance of a location's original forest community (number of species and individuals) that remain.
biodiversity significance: The importance of an area for the persistence of forest-dependent species based on range rarity.
boundary plantings: Trees planted along boundaries or property lines to mark them well.
carbon dioxide equivalent: Carbon dioxide equivalent (CO2e) is a measure used to aggregate emissions from various greenhouse gases (GHGs) on the basis of their 100-year global warming potentials by equating non-CO2 GHGs to the equivalent amount of CO2.
deforestation: The change from forest to another land cover or land use, such as forest to plantation or forest to urban area.
forest: Tree cover greater than 30 percent tree canopy density and greater than 5 meters in height as mapped at a 30-meter Landsat pixel scale.
forest concession: A legal agreement allowing an entity the right to manage a public forest for production purposes.
forest degradation: The reduction in a forest’s ability to perform ecosystem services, such as carbon storage and water regulation, due to natural and anthropogenic changes.
forest disturbance: A discrete event that changes the structure of a forest ecosystem.
forest fragmentation: The breaking of large, contiguous forests into smaller pieces, with other land cover types interspersed.
Forest Landscape Restoration: The ongoing process of restoring landscapes to regain ecological functionality and enhance human well-being across deforested or degraded forest landscapes.
forest management plan: A plan that documents the stewardship and use of forests and other wooded land to meet environmental, economic, social, and cultural objectives. Such plans are typically implemented by companies in forest concessions.
global land squeeze: Pressure on finite land resources to produce food, feed and fuel for a growing human population while also sustaining biodiversity and providing ecosystem services.
hectare: One hectare equals 100 square meters, 2.47 acres, or 0.01 square kilometers and is about the size of a rugby field. A football pitch is slightly smaller than a hectare (pitches are between 0.62 and 0.82 hectares).
intact forest: A forest that contains no signs of human activity or habitat fragmentation as determined by remote sensing images and is large enough to maintain all native biological biodiversity.
land and environmental defenders: People who peacefully promote and protect rights related to land and/or the environment.
loss driver: The direct cause of forest disturbance.
low tree canopy density: Less than 30 percent tree canopy density.
managed forest concession: Areas where governments have given rights to private companies to harvest timber and other wood products from natural forests on public lands.
managed natural forest: Naturally regenerated forests with signs of management, including logging, clear cuts, etc.
megacity: A city with more than 10 million people.
open canopy systems: Individual tree crowns that do not overlap to form a continuous canopy layer.
persistent loss and gain: Forests that have experienced one loss or one gain event from 2001 to 2016.
plantations: An area in which trees have been planted, generally for commercial purposes.
planted forest: Stand of planted trees — other than tree crops — grown for wood and wood fiber production or for ecosystem protection against wind and/or soil erosion.
planted trees: Stand of trees established through planting, including both planted forests and tree crops.
primary forest: Old-growth forests that are typically high in carbon stock and rich in biodiversity. The GFR uses a humid tropical primary rainforest data set, representing forests in the humid tropics that have not been cleared in recent years.
production forest: A forest where the primary management objective is to produce timber, pulp, fuelwood, and/or nonwood forest products.
restoration: Interventions that aim to improve ecological functionality and enhance human well-being in degraded landscapes. Landscapes may be forested or non-forested.
shifting agriculture: Temporary loss or permanent deforestation due to small- and medium-scale agriculture.
tree cover: All vegetation greater than five meters in height and may take the form of natural forests or plantations across a range of canopy densities. Unless otherwise specified, the GFR uses greater than 30 percent tree canopy density for calculations.
tree cover gain: The establishment of tree canopy in an area that previously had no tree cover. Tree cover gain may indicate a number of potential activities, including natural forest growth or the crop rotation cycle of tree plantations. As such, tree cover gain does not equate to restoration.
tree cover loss: The removal or mortality of tree cover, which can be due to a variety of factors, including mechanical harvesting, fire, disease, or storm damage. As such, loss does not equate to deforestation.
tree crops: Stand of perennial trees that produce agricultural products, such as rubber, oil palm, coffee, coconut, cocoa and orchards.
trees outside forests: Trees found in urban areas, alongside roads, or within agricultural land are often referred to as Trees Outside Forests (TOF).
unmanaged natural forest: Naturally regenerated forests without any signs of management, including primary forest.
{"Glossary":{"51":{"name":"agricultural tree crops","description":"Trees cultivated for their food, cultural, or economic values. These include oil palm, rubber, cocoa, cashew, mango, oranges (citrus), plantain, banana, and coconut.\r\n"},"141":{"name":"agroforestry","description":"A diversified set of agricultural or agropastoral production systems that integrate trees in the agricultural landscape.\r\n"},"101":{"name":"albedo","description":"The ability of surfaces to reflect sunlight.\u0026nbsp;Light-colored surfaces return a large part of the sunrays back to the atmosphere (high albedo). Dark surfaces absorb the rays from the sun (low albedo).\r\n"},"94":{"name":"biodiversity intactness","description":"The proportion and abundance of a location\u0027s original forest community (number of species and individuals) that remain.\u0026nbsp;\r\n"},"95":{"name":"biodiversity significance","description":"The importance of an area for the persistence of forest-dependent species based on range rarity.\r\n"},"142":{"name":"boundary plantings","description":"Trees planted along boundaries or property lines to mark them well.\r\n"},"98":{"name":"carbon dioxide equivalent (CO2e)","description":"Carbon dioxide equivalent (CO2e) is a measure used to aggregate emissions from various greenhouse gases (GHGs) on the basis of their 100-year global warming potentials by equating non-CO2 GHGs to the equivalent amount of CO2.\r\n"},"99":{"name":"CO2e","description":"Carbon dioxide equivalent (CO2e) is a measure used to aggregate emissions from various greenhouse gases (GHGs) on the basis of their 100-year global warming potentials by equating non-CO2 GHGs to the equivalent amount of CO2.\r\n"},"1":{"name":"deforestation","description":"The change from forest to another land cover or land use, such as forest to plantation or forest to urban area.\r\n"},"77":{"name":"deforested","description":"The change from forest to another land cover or land use, such as forest to plantation or forest to urban area.\r\n"},"76":{"name":"degradation","description":"The reduction in a forest\u2019s ability to perform ecosystem services, such as carbon storage and water regulation, due to natural and anthropogenic changes.\r\n"},"75":{"name":"degraded","description":"The reduction in a forest\u2019s ability to perform ecosystem services, such as carbon storage and water regulation, due to natural and anthropogenic changes.\r\n"},"79":{"name":"disturbances","description":"A discrete event that changes the structure of a forest ecosystem.\r\n"},"68":{"name":"disturbed","description":"A discrete event that changes the structure of a forest ecosystem.\r\n"},"65":{"name":"driver of tree cover loss","description":"The direct cause of forest disturbance.\r\n"},"70":{"name":"drivers of loss","description":"The direct cause of forest disturbance.\r\n"},"81":{"name":"drivers of tree cover loss","description":"The direct cause of forest disturbance.\r\n"},"102":{"name":"evapotranspiration","description":"When solar energy hitting a forest converts liquid water into water vapor (carrying energy as latent heat) through evaporation and transpiration.\r\n"},"2":{"name":"forest","description":"Forests include tree cover greater than 30 percent tree canopy density and greater than 5 meters in height as mapped at a 30-meter Landsat pixel scale.\r\n"},"3":{"name":"forest concession","description":"A legal agreement allowing an entity the right to manage a public forest for production purposes.\r\n"},"90":{"name":"forest concessions","description":"A legal agreement allowing an entity the right to manage a public forest for production purposes.\r\n"},"53":{"name":"forest degradation","description":"The reduction in a forest\u2019s ability to perform ecosystem services, such as carbon storage and water regulation, due to natural and anthropogenic changes.\r\n"},"54":{"name":"forest disturbance","description":"A discrete event that changes the structure of a forest ecosystem.\r\n"},"100":{"name":"forest disturbances","description":"A discrete event that changes the structure of a forest ecosystem.\r\n"},"5":{"name":"forest fragmentation","description":"The breaking of large, contiguous forests into smaller pieces, with other land cover types interspersed.\r\n"},"6":{"name":"forest management plan","description":"A plan that documents the stewardship and use of forests and other wooded land to meet environmental, economic, social, and cultural objectives. Such plans are typically implemented by companies in forest concessions.\r\n"},"62":{"name":"forests","description":"Forests include tree cover greater than 30 percent tree canopy density and greater than 5 meters in height as mapped at a 30-meter Landsat pixel scale.\r\n"},"69":{"name":"fragmentation","description":"The breaking of large, contiguous forests into smaller pieces, with other land cover types interspersed.\r\n"},"80":{"name":"fragmented","description":"The breaking of large, contiguous forests into smaller pieces, with other land cover types interspersed.\r\n"},"74":{"name":"gain","description":"The establishment of tree canopy in an area that previously had no tree cover. Tree cover gain may indicate a number of potential activities, including natural forest growth or the crop rotation cycle of tree plantations.\r\n"},"143":{"name":"global land squeeze","description":"Pressure on finite land resources to produce food, feed and fuel for a growing human population while also sustaining biodiversity and providing ecosystem services.\r\n"},"7":{"name":"hectare","description":"One hectare equals 100 square meters, 2.47 acres, or 0.01 square kilometers and is about the size of a rugby field. A football pitch is slightly smaller than a hectare (pitches are between 0.62 and 0.82 hectares).\r\n"},"66":{"name":"hectares","description":"One hectare equals 100 square meters, 2.47 acres, or 0.01 square kilometers and is about the size of a rugby field. A football pitch is slightly smaller than a hectare (pitches are between 0.62 and 0.82 hectares).\r\n"},"67":{"name":"intact","description":"A forest that contains no signs of human activity or habitat fragmentation as determined by remote sensing images and is large enough to maintain all native biological biodiversity.\r\n"},"78":{"name":"intact forest","description":"A forest that contains no signs of human activity or habitat fragmentation as determined by remote sensing images and is large enough to maintain all native biological biodiversity.\r\n"},"8":{"name":"intact forests","description":"A forest that contains no signs of human activity or habitat fragmentation as determined by remote sensing images and is large enough to maintain all native biological biodiversity.\r\n"},"55":{"name":"land and environmental defenders","description":"People who peacefully promote and protect rights related to land and\/or the environment.\r\n"},"9":{"name":"loss driver","description":"The direct cause of forest disturbance.\r\n"},"10":{"name":"low tree canopy density","description":"Less than 30 percent tree canopy density.\r\n"},"84":{"name":"managed forest concession","description":"Areas where governments have given rights to private companies to harvest timber and other wood products from natural forests on public lands.\r\n"},"83":{"name":"managed forest concession maps for nine countries","description":"Cameroon, Canada, Central African Republic, Democratic Republic of the Congo, Equatorial Guinea, Gabon, Indonesia, Liberia, and the Republic of the Congo\r\n"},"104":{"name":"managed natural forests","description":"Naturally regenerated forests with signs of management, including logging, clear cuts, etc.\r\n"},"91":{"name":"megacities","description":"A city with more than 10 million people.\r\n"},"57":{"name":"megacity","description":"A city with more than 10 million people."},"56":{"name":"mosaic restoration","description":"Restoration that integrates trees into mixed-use landscapes, such as agricultural lands and settlements, where trees can support people through improved water quality, increased soil fertility, and other ecosystem services. This type of restoration is more likely in deforested or degraded forest landscapes with moderate population density (10\u2013100 people per square kilometer). "},"86":{"name":"natural","description":"A forest that is grown without human intervention.\r\n"},"12":{"name":"natural forest","description":"A forest that is grown without human intervention.\r\n"},"63":{"name":"natural forests","description":"A forest that is grown without human intervention.\r\n"},"144":{"name":"open canopy systems","description":"Individual tree crowns that do not overlap to form a continuous canopy layer.\r\n"},"82":{"name":"persistent gain","description":"Forests that have experienced one gain event from 2001 to 2016.\r\n"},"13":{"name":"persistent loss and gain","description":"Forests that have experienced one loss or one gain event from 2001 to 2016."},"97":{"name":"plantation","description":"An area in which trees have been planted, generally for commercial purposes.\u0026nbsp;\r\n"},"93":{"name":"plantations","description":"An area in which trees have been planted, generally for commercial purposes.\u0026nbsp;\r\n"},"88":{"name":"planted","description":"A forest composed of trees that have been deliberately planted and\/or seeded by humans.\r\n"},"14":{"name":"planted forest","description":"Stand of planted trees \u2014 other than tree crops \u2014 grown for wood and wood fiber production or for ecosystem protection against wind and\/or soil erosion.\r\n"},"73":{"name":"planted forests","description":"Stand of planted trees \u2014 other than tree crops \u2014 grown for wood and wood fiber production or for ecosystem protection against wind and\/or soil erosion."},"148":{"name":"planted trees","description":"Stand of trees established through planting, including both planted forest and tree crops."},"149":{"name":"Planted trees","description":"Stand of trees established through planting, including both planted forest and tree crops."},"15":{"name":"primary forest","description":"Old-growth forests that are typically high in carbon stock and rich in biodiversity. The GFR uses a humid tropical primary rainforest data set, representing forests in the humid tropics that have not been cleared in recent years.\r\n"},"64":{"name":"primary forests","description":"Old-growth forests that are typically high in carbon stock and rich in biodiversity. The GFR uses a humid tropical primary rainforest data set, representing forests in the humid tropics that have not been cleared in recent years.\r\n"},"58":{"name":"production forest","description":"A forest where the primary management objective is to produce timber, pulp, fuelwood, and\/or nonwood forest products."},"89":{"name":"production forests","description":"A forest where the primary management objective is to produce timber, pulp, fuelwood, and\/or nonwood forest products.\r\n"},"87":{"name":"seminatural","description":"A managed forest modified by humans, which can have a different species composition from surrounding natural forests.\r\n"},"59":{"name":"seminatural forests","description":"A managed forest modified by humans, which can have a different species composition from surrounding natural forests. "},"96":{"name":"shifting agriculture","description":"Temporary loss or permanent deforestation due to small- and medium-scale agriculture.\r\n"},"103":{"name":"surface roughness","description":"Surface roughness of forests creates\u0026nbsp;turbulence that slows near-surface winds and cools the land as it lifts heat from low-albedo leaves and moisture from evapotranspiration high into the atmosphere and slows otherwise-drying winds. \r\n"},"17":{"name":"tree cover","description":"All vegetation greater than five meters in height and may take the form of natural forests or plantations across a range of canopy densities. Unless otherwise specified, the GFR uses greater than 30 percent tree canopy density for calculations.\r\n"},"71":{"name":"tree cover canopy density is low","description":"Less than 30 percent tree canopy density.\r\n"},"60":{"name":"tree cover gain","description":"The establishment of tree canopy in an area that previously had no tree cover. Tree cover gain may indicate a number of potential activities, including natural forest growth or the crop rotation cycle of tree plantations.\u0026nbsp;As such, tree cover gain does not equate to restoration.\r\n"},"18":{"name":"tree cover loss","description":"The removal or mortality of tree cover, which can be due to a variety of factors, including mechanical harvesting, fire, disease, or storm damage. As such, loss does not equate to deforestation.\r\n"},"150":{"name":"tree crops","description":"Stand of perennial trees that produce agricultural products, such as rubber, oil palm, coffee, coconut, cocoa and orchards."},"19":{"name":"tree plantation","description":"An agricultural plantation of fast-growing tree species on short rotations for the production of timber, pulp, or fruit.\r\n"},"72":{"name":"tree plantations","description":"An agricultural plantation of fast-growing tree species on short rotations for the production of timber, pulp, or fruit.\r\n"},"85":{"name":"trees outside forests","description":"Trees found in urban areas, alongside roads, or within agricultural land\u0026nbsp;are often referred to as Trees Outside Forests (TOF).\u202f\r\n"},"151":{"name":"unmanaged","description":"Naturally regenerated forests without any signs of management, including primary forest."},"105":{"name":"unmanaged natural forests","description":"Naturally regenerated forests without any signs of management, including primary forest.\r\n"}}}
