Most people point to deforestation — the clearing or burning of forests to make way for a different land-use, such as agriculture — as the greatest threat facing the world’s forests. But there’s another issue that’s just as important: forest integrity.
Forest integrity refers to the health of the forest that remains standing, including its ability to store carbon, protect biodiversity and provide social and economic benefits. Though equally important, forest integrity is harder to measure than deforestation.
The Forest Landscape Integrity Index on Global Forest Watch tracks forest integrity globally for the first time and shows that less than half of the world’s remaining forests have high integrity.
Here, we explain what forest integrity is and examine the health of the world’s remaining forests.
Forest integrity is the degree to which a forest’s structure, composition and function are free from modification by humans. It exists as a spectrum, with very high-integrity forests on one end and very low-integrity, severely degraded forests on the other.
Minimal human influence is associated with high forest integrity; as more and more human activities affect a forest — such as logging, human-caused fires or farming — integrity declines. A high-integrity forest usually provides more environmental benefits than a forest of lower integrity.
High-integrity forests are also typically more resilient to the effects of climate change, such as the warmer, drier conditions that can lead to forest fires.
What are the biggest threats to forest integrity?
Forests can be degraded directly by a wide range of human activities, including intensive logging, human-caused fires and over-hunting.
They can also be degraded in less visible ways by fragmentation, and by the “edge effects” that spill over from adjacent human activities such as infrastructure development, farming and urbanization.
A forest edge is more exposed and accessible than its interior, leaving it more susceptible to human activities like wood fuel extraction, hunting, livestock grazing, burning and the spread of invasive species, and more vulnerable to conditions such as direct sunlight, high winds, heatwaves and droughts.
The Forest Landscape Integrity Index estimates the loss of integrity in a given area of forest by combining observed reductions in forest connectivity with proxy data on the intensity of human activities known to degrade forests. Some of these activities are observed directly as part of the analysis, specifically infrastructure, agriculture and recent deforestation. The associated edge effects cannot readily be observed, so they are estimated using models based on field studies.
Where are the world’s remaining high-integrity forests?
The Forest Landscape Integrity Index examines forest integrity along a spectrum and categorizes forests as high, medium or low integrity. According to the data, only 40.5% of the world’s remaining forests still have high integrity. And even within this category, most forests have experienced at least a small degree of human modification.
High-integrity forests are concentrated mainly in the boreal forests of northern Russia, Canada and Alaska, as well as across the tropics in parts of the Amazon, the humid forests of Central Africa and the island of New Guinea.
Some smaller but still highly important patches also survive in other regions, including Mesoamerica, Madagascar, West Africa, Sumatra, Borneo and mainland Southeast Asia. Effective protected area management, action by Indigenous peoples and local communities, difficult terrain and remote locations that deter industrial activity all contribute to forest integrity remaining high in these places.
Where is forest integrity at risk?
Hardly any forest on Earth is wholly free of human influence. The index shows that 31% of all forests worldwide experience easily observed direct pressures from infrastructure, agriculture or recent tree cover loss, while a further 60% experience some degree of human impact through edge effects and fragmentation. Over 25% are classified as low integrity.
As a result of a history of adverse human modification, low-integrity forests are now prevalent in many regions, including west and central Europe, the southeastern United States, mainland Southeast Asia, the Andes, West Africa, much of China and India, and the Atlantic Forests of Brazil. These low-integrity forests may be dominated by planted trees, including monoculture stands and agroforestry.
But it’s not just the vast expanse of low integrity forests that warrant concern. Many large areas with high-integrity forests are also experiencing high rates of tree cover loss and degradation, particularly in Brazil and the Democratic Republic of the Congo.
In 2020 alone, these two countries lost 1.7 million hectares and 0.5 million hectares of primary forest, respectively. High-integrity forests are not necessarily legally protected from development; they can be highly threatened by encroaching human activities. Less than half of forests in every biome have high integrity, and of these, only a quarter are located in legally protected areas.
Governments and other actors must protect and monitor the world’s remaining high-integrity and medium-integrity forests, and protect and restore areas of low integrity.
Why does forest integrity get less attention than deforestation?
Deforestation is easier to measure than integrity. While there have been substantial improvements in our ability to monitor forest loss and gain in the past decade, consistent monitoring of forest integrity has proven more elusive until now.
In recent years, pioneering maps of intact forest landscapes and wilderness areas have identified tracts of high integrity, but because they use a binary classification, they cannot tell us about the variation in integrity outside the most intact areas.
Technical challenges and lack of data have historically made it difficult to monitor the nuances of forest integrity, especially since activities like selective logging are difficult to detect in satellite imagery, and the forest canopy obscures many activities that are harmful to forests.
The Forest Landscape Integrity Index accounts for this nuance at a global scale for the first time by estimating integrity along a spectrum. We can expect further advances in mapping and monitoring forest integrity as datasets and processing capabilities continue to improve.
What can we do to protect high-integrity forests and restore other forests?
While policy targets for deforestation are usually precise and ambitious, targets for degradation and forest integrity are often vague or absent entirely. The new data provide a transparent and credible tool that policymakers and other decision-makers can use to set quantified targets, create evidence-based plans, enhance monitoring, and retain and restore the ecological integrity of forests.
For example, governments could create and report on measurable, time-bound goals for maintaining or enhancing forest integrity within treaties such as the post-2020 Global Biodiversity Framework, countries’ Nationally Determined Contributions under the Paris Agreement and several UN Sustainable Development Goals.
Setting such policy goals can encourage governments and other stakeholders to invest in better forest management and restoration. They can formally recognize high-integrity forests, prioritize them in spatial planning, and place them under effective management schemes, such as through designated protected areas or Indigenous control.
Decision-makers can also identify low- and medium-integrity areas and target them for more sustainable management and/or restoration.
In parallel, corporate zero-deforestation commitments must go further to incorporate and monitor forest integrity in businesses’ supply chains. Zero-deforestation commitments do not address the problem of declining forest integrity so long as it falls short of outright deforestation.
Keeping healthy, high-integrity forests functioning at their full potential can be a key part of the solution to global climate, biodiversity, inequality and health crises. We’ll lose many of these important ecosystem services if only degraded, low-integrity forests are left standing. Keeping global commitments such as the recent Glasgow Leaders’ Declaration on Forests within reach means we need to incorporate both deforestation and integrity into policy planning.
