The World’s Last Intact Forests Are Becoming Increasingly Fragmented
Susan Minnemayer and Lars Laestadius contributed to a previous version of this article.
Intact forest landscapes, or vast stretches of unbroken forested wilderness, are some of the most important ecosystems in the world. Their intactness makes them uniquely valuable to nature. They regulate temperature and rainfall across continents, provide homes to Indigenous Peoples, have some of the highest biodiversity rates in the world and store huge amounts of carbon, among other benefits.
But they’re also under threat.
According to the latest data on Global Forest Watch, the extent of world’s intact forest landscapes decreased by 12% (155 million hectares) between 2000 and 2020. This is an area larger than twice the size of Chile.
Furthermore, the global rate at which intact forest landscapes are decreasing is speeding up, from an average of 7.1 million hectares per year from 2000-2013 to an average of 9 million hectares per year from 2013-2020.
New roads developed for industrial timber and oil and gas extraction, agricultural expansion and fires are the main causes of reduction in the extent of intact forest landscapes. If the trend doesn’t reverse, the world could lose much of its unbroken forest tracts this century, posing problems for nature, the climate and human well-being.
Intact forest landscapes are patches of forests and natural treeless ecosystems that show no signs of significant human activity or habitat fragmentation (as detected by satellite imagery) and are large enough to maintain all native biodiversity. Some forms of low-intensity or historic human disturbances, such as scattered, small-scale shifting cultivation and low-intensity selective logging may be included in an intact forest landscape if the disturbance is too small to be detected by satellites.
In order to ensure that areas designated as intact forest landscapes are large enough to provide refuge for wide-ranging species, researchers used three criteria in addition to the requirement of no visible, significant human-caused disturbances: 1) minimum area of 50,000 hectares; 2) minimum patch width of 10 km; and 3) minimum corridor/appendage width of 2 km.
A portion of an intact forest landscape, or in some cases an entire patch, may no longer be considered an intact forest landscape if these criteria are no longer met due to human-caused alteration or fragmentation. For example, if a road is built across an intact forest landscape patch that causes the remaining patches to no longer meet the criteria, the entire patch would no longer be considered an intact forest landscape. As a result, that intact forest landscape area is lost and the total global area decreases. For each update of the global intact forest landscape map, researchers only assess areas currently designated as intact forest landscapes. Therefore, this methodology does not take into account forest regeneration and assumes that once lost, intactness cannot be regained.
Where and Why Are Intact Forests Becoming Fragmented?
Countries with the largest remaining areas of intact forest landscapes are found primarily in boreal and tropical regions. These areas also experienced the largest reduction in intact forest landscape area over the past two decades. Only small areas of intact forest landscapes remain in temperate regions due to extensive commercial logging and agricultural activities prior to the year 2000.
Timber harvesting and agricultural expansion were the leading drivers of reduction of intact forest landscapes in the tropics, while timber harvesting was the leading cause in the southern boreal and temperate zones. In the northern boreal region, human-caused fires were the leading driver of intact forest landscape reduction.
As of 2020, Canada, Russia and Brazil had the largest area of remaining intact forest landscapes, making up over 65% of the global total. However, these countries also experienced the largest reduction from 2000-2020.
Russia experienced the largest reduction in intact forest landscape area between 2000 to 2020, losing 40.9 million hectares due largely to oil and gas extraction, industrial logging, gold mining and extensive human-caused fires linked to these activities.
In Brazil, which experienced the second-highest reduction, agricultural and pasture expansion was responsible. In Canada, human-caused fires adjacent to logging, mining and infrastructure were the leading driver.
Romania had the largest percent decline, losing all of its intact forest landscape area by 2013, followed by Paraguay, where the intact forest landscape area decreased by 81% by 2020. The Solomon Islands, Laos, Central African Republic, Nicaragua and Equatorial Guinea lost over half of their intact forest landscape area by 2020.
However, not all countries experienced a decline in intact forest landscape extent. Although they contain a relatively small area, Cuba and Japan had almost no change in their extent of intact forest landscapes from 2000-2020.
The Problem with Losing Forest Intactness
Intact forest landscapes are unique and irreplaceable. With many forests around the world being degraded and lost, intact forest landscapes offer important areas of high forest integrity. Intactness cannot easily be regained — once altered, complex assemblages of biodiversity would be extremely challenging to restore.
For example, extending new roads into remote forest areas facilitates human access, which can lead to cascading changes: wildlife habitat loss, unregulated hunting, increased human settlement and population density, forest clearing from logging, forest loss from agricultural expansion, fires, and other changes that degrade forests and may eventually convert vast forest areas to other land uses.
Intact forests also offer a unique opportunity to mitigate two of the greatest environmental challenges Earth faces: climate change and species extinction.
Multiple measures of forest health
Various methodologies exist for designating forests that have significant ecological value. These include High Conservation Value (HCV) Forests, High Carbon Stock Forests and Forest Landscape Integrity, in addition to intact forest landscapes. Although these designations can all be used to identify forests that are important to protect, they differ with respect to their specific definitions, requirements and methodologies, and they each have strengths and limitations depending on the context and purpose for which they are used.
In some cases, these measures can be complementary. For example, the Forest Landscape Integrity Index measures the degree to which a forest’s structure, composition and function are free from modification by humans, and can show forest degradation on a spectrum. This can provide information about the variation in integrity outside the most intact areas. Meanwhile, intact forest landscapes are a binary classification, and the forests found within them have high integrity values.
Intact forest landscapes are critical for sequestering and storing carbon. Forests within remaining intact forest landscapes had an average annual net sink of -2 gigatonnes CO2e per year from 2001-2021, making up over one-quarter of the average annual global net carbon sink from forests. On average, tropical intact forests store triple the amount of above-ground carbon of non-intact tropical forests.
Meanwhile, northern boreal forests have huge soil carbon stores. While they store less above-ground carbon than their tropical counterparts, boreal intact forests occupy a vast area, making up 38% of global intact forest landscapes in 2020. These intact forest landscapes play an important role in the protection of permafrost, which is critical to preventing the release of climate-warming carbon and methane locked in soils.
Additionally, scientists estimate that tropical forests contain over half of the world’s terrestrial vertebrate species, despite occupying less than one-fifth of global land area. Many of these species depend on intact forests for their survival.
How Can We Protect Intact Forest Landscapes?
The importance of intact forest landscapes is being increasingly recognized in conservation and climate policy. The International Union for the Conservation of Nature (IUCN), for example, recognizes the value of intact forest landscapes and the need to conserve them in their policy on primary forests, recommending that stakeholders take steps to mitigate threats to intact forests and identify appropriate management options. IUCN policies, which are adopted through multi-stakeholder processes among IUCN member organizations including civil society and governments, guide global conservation priorities. This recognition can help elevate the importance of intact forest landscapes in national and international policy.
Additionally, climate finance is becoming more accessible to countries with large areas of intact forest and low deforestation rates, such as through crediting for the protection of forests in these jurisdictions as part of the Architecture for REDD+ Transactions (ART) Environmental Excellence Standard. Increasing flows of climate finance can support countries in their efforts to preserve intact forests.
For international agreements and national forest commitments that aim to halt forest loss — including the New York Declaration on Forests, the UN Sustainable Development Goals, the Glasgow Leaders Declaration on Forests and Land Use and the Convention on Biological Diversity’s (CBD) Post-2020 Biodiversity Framework — intact forest landscapes offer a measurable benchmark toward goals. They are also important areas to prioritize in order to achieve many of these international targets.
Research shows that designating intact forest landscapes as protected areas has proven effective at limiting their fragmentation, but only 36% of remaining intact forests are under some form of legal protection. Countries should consider intact forest landscapes high-priority candidates when they revise or expand existing protected areas, such as through efforts to meet the CBD’s Post-2020 Biodiversity Framework target to conserve and equitably manage 30% of global land by 2030.
Moreover, research shows that the rate of intact forest loss is lower in areas that overlap with Indigenous Peoples’ lands — over one-third of intact forest landscapes globally — highlighting local communities’ critical role in managing these forests. Recognizing Indigenous Peoples’ land tenure rights and supporting their efforts to sustainably manage their lands can help avoid further fragmentation of intact forest landscapes.
The latest intact forest landscape boundaries are now available on Global Forest Watch, along with tools and data to monitor how forest change is affecting them.
The authors would like to acknowledge members of the IFL mapping team who contributed to the intact forest landscape data update, including Svetlana Turubanova (University of Maryland), and Anna Komarova, Igor Glushkov and Ilona Zhuravleva (Greenpeace).
 Fire-related disturbances are considered a factor that can lead to a reduction in intact forest landscape area only when they are likely to be caused by humans, rather than natural causes (such as lightning strikes). The intact forest landscape methodology differentiates natural fires from human-caused fires by assuming that burned areas that are adjacent to areas with human access (e.g., near infrastructure, logging sites or agricultural areas) are likely to be caused by humans.