Indicators of Forest Extent

Primary Forest Loss

Last Updated on April 4, 2024

This indicator aims to monitor the total area of primary forest lost or removed globally each year. Primary forests are mature natural forests that have not been disturbed in recent history.

Primary forests have only been mapped comprehensively in the humid tropics. Therefore, this indicator uses maps of intact forest landscapes as a proxy for primary forest loss in the temperate and boreal ecozones. Intact forest landscapes are a subset of primary forests. To be considered intact, a forest must be both undisturbed by human activity and larger than 50,000 hectares.

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How much primary forest loss occurred in humid tropical forests?

The humid tropics have lost 76.3 million hectares (Mha) of primary forests since the turn of the century, representing 7.4 percent of their extent in 2001. Just three countries—Brazil, the Democratic Republic of the Congo, and Indonesia—accounted for 63 percent of this loss. Roughly 56 percent of this loss was related to conversion for commodity production (industrial-scale agriculture, mining, oil and gas, etc.), with an additional 37 percent related to shifting agriculture. Tropical primary forest loss spiked in 2016 and 2017 due to fires in Brazil, Indonesia, and elsewhere. These fires were mostly ignited by people, usually as a technique to clear land for agriculture, but they were exacerbated by drought conditions. 

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The Importance of Primary Forests

Primary forests typically store more carbon than other forests and are often irreplaceable when it comes to biodiversity. Any loss of primary forest indicates a long-term change to the ecosystem—even if forest regrowth ensues, the recovering secondary forest is unlikely to match the carbon and biodiversity values of a primary forest for several decades or longer.

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The extent of humid tropical primary forest in 2001

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Tropical primary forest loss, 2002-2023

 

How much tree cover loss occurred within temperate and boreal intact forests?

Although no comprehensive spatial data exists for primary forests in temperate and boreal ecozones, loss occurring within intact forest landscapes can be used to approximate where these important forests are most at risk. Russia and Canada experienced the highest levels of tree cover loss in intact forest landscapes in temperate and boreal ecozones, primarily due to logging and fire. Russia lost 23 Mha of tree cover in intact forests between 2001 and 2023, and Canada lost 23.3 Mha. 

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Areas of tree cover loss from logging in intact boreal forests in Russia since 2000

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Limitations and Future Prospects

Primary forest extent data are currently available only for humid tropical forests and thus exclude old-growth forests in dry tropical forests (e.g., western Madagascar) and in temperate and boreal forests. Intact forest landscapes have been mapped globally but only cover a subset of all primary forests, excluding forest landscapes smaller than 50,000 ha.

Differentiating primary forests from managed, seminatural forests in temperate and boreal forests is challenging using remote sensing techniques because these forests tend to have similar visual qualities in satellite imagery. At this time, no near-term prospects for comprehensively mapping primary forests in these regions have been identified.

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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"},"153":{"name":"climate domain","description":"Major ecosystem regions, summarized as boreal, temperate, tropical and subtropical.\u0026nbsp;"},"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 cause of tree cover loss, such as agriculture or urban development. There are direct drivers, which are the immediate cause of the loss, and indirect drivers, which are the secondary cause of loss (i.e., land speculation)."},"70":{"name":"drivers of loss","description":"The cause of tree cover loss, such as agriculture or urban development. There are direct drivers, which are the immediate cause of the loss, and indirect drivers, which are the secondary cause of loss (i.e., land speculation)."},"81":{"name":"drivers of tree cover loss","description":"The cause of tree cover loss, such as agriculture or urban development. There are direct drivers, which are the immediate cause of the loss, and indirect drivers, which are the secondary cause of loss (i.e., land speculation)."},"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"},"154":{"name":"fastwood monoculture","description":"Stands of single species planted trees that grow quickly.\u0026nbsp;"},"53":{"name":"forest degradation","description":"The reduction in a forest\u2019s quality and ability to perform ecosystem services, such as carbon storage and water regulation, due to natural and anthropogenic changes."},"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"},"155":{"name":"Forest Landscape Restoration","description":"The ongoing process of restoring landscapes to regain ecological functionality and enhance human well-being across deforested or degraded forest landscapes."},"156":{"name":"forest moratorium","description":"A temporary restriction on activities that cause forest loss or degradation."},"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.\r\n"},"66":{"name":"hectares","description":"One hectare equals 100 square meters, 2.47 acres, or 0.01 square kilometers."},"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"},"161":{"name":"logging concession","description":"A legal agreement allowing an entity the right to manage a public forest for production purposes, including for timber and other wood products."},"157":{"name":"logging concessions","description":"A legal agreement allowing an entity the right to manage a public forest for production purposes, including for timber and other wood products."},"160":{"name":"Logging concessions","description":"A legal agreement allowing an entity the right to manage a public forest for production purposes, including for timber and other wood products."},"9":{"name":"loss driver","description":"The cause of tree cover loss, such as agriculture or urban development. There are direct drivers, which are the immediate cause of the loss, and indirect drivers, which are the secondary cause of loss (i.e., land speculation).\r\n"},"10":{"name":"low tree canopy density","description":"Less than 30 percent tree canopy density.\r\n"},"104":{"name":"managed natural forests","description":"Naturally regenerated forests with signs of management, including logging and clear cuts.Lesiv et al. 2022, https:\/\/doi.org\/10.1038\/s41597-022-01332-3"},"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."},"86":{"name":"natural","description":"A forest that that grows with limited or no human intervention. Natural forests can be managed or unmanaged (see separate definitions).\u0026nbsp;"},"12":{"name":"natural forest","description":"A forest that that grows with limited or no human intervention. Natural forests can be managed or unmanaged (see separate definitions). \r\n"},"63":{"name":"natural forests","description":"A forest that that grows with limited or no human intervention. Natural forests can be managed or unmanaged (see separate definitions).\u0026nbsp;"},"144":{"name":"open canopy systems","description":"Individual tree crowns that do not overlap to form a continuous canopy layer.\r\n"},"88":{"name":"planted","description":"Stands of trees established through planting, including both planted forest and tree crops."},"14":{"name":"planted forest","description":"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":"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":"Stands of trees established through planting, including both planted forest and tree crops."},"149":{"name":"Planted trees","description":"Stands 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"},"159":{"name":"restoration","description":"Interventions that aim to improve ecological functionality and enhance human well-being in degraded landscapes. Landscapes may be forested or non-forested."},"87":{"name":"seminatural","description":"Forest with predominantly native trees that have not been planted. Trees are established through silvicultural practices, including natural regeneration or selective thinning.FAO"},"59":{"name":"seminatural forests","description":"Forest with predominantly native trees that have not been planted. Trees are established through silvicultural practices, including natural regeneration or selective thinning.FAO"},"96":{"name":"shifting agriculture","description":"Agricultural practices where forests are cleared, used for agricultural production for a few years, and then temporarily abandoned to allow trees to regrow and soil to recover.\u0026nbsp;"},"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":"The percent of ground area covered by the leafy tops of trees. 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.\u0026nbsp;\u0026nbsp;"},"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"},"163":{"name":"tree cover loss due to fire","description":"The mortality of tree cover where forest fires were the direct cause of loss.\u0026nbsp;"},"164":{"name":"tree cover loss due to fires","description":"The mortality of tree cover where forest fires were the direct cause of loss.\u0026nbsp;"},"162":{"name":"tree cover loss from fires","description":"The mortality of tree cover where forest fires were the direct cause of loss.\u0026nbsp;"},"150":{"name":"tree crops","description":"Stand of perennial trees that produce agricultural products, such as rubber, oil palm, coffee, coconut, cocoa and orchards."},"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":"A forest that grows without human intervention and has no signs of management, including primary forest.Lesiv et al. 2022, https:\/\/doi.org\/10.1038\/s41597-022-01332-3"},"105":{"name":"unmanaged natural forests","description":"A forest that grows without human intervention and has no signs of management, including primary forest.Lesiv et al. 2022, https:\/\/doi.org\/10.1038\/s41597-022-01332-3"},"158":{"name":"tree cover loss from fire","description":"The mortality of tree cover where forest fires were the direct cause of loss.\u0026nbsp;"}}}

Citation

“Primary Forest Loss Indicator.” Global Forest Review, updated April 4, 2024. Washington, DC: World Resources Institute. Available online at https://research.wri.org/gfr/forest-extent-indicators/primary-forest-loss.