The exceptional value of intact forest ecosystems, Watson et al. 2018

Forests currently cover a quarter of Earth’s terrestrial surface, although at least 82% of that remaining forest is degraded by human activity. While a handful of international accords rightly encourage forest conservation and reforestation to limit global warming, these agreements fail to prioritize protection specifically of intact forests, or forests that are free from human activities “known to cause physical changes in a forest that lead to declines in ecological function” [Watson 2018: 1].

The authors argue for the protection of all forests, including degraded ones, as well as reforestation, to stem global ecological collapse, while here they particularly emphasize the exceptional value of intact forests. They present these key arguments:

• Carbon sequestration and storage. “Intact forests store more carbon than logged, degraded or planted forests in ecologically comparable locations. Industrial logging and conversion of forest to cropland causes heavy erosion and contributes to the loss of belowground carbon” [Watson 2018: 3].
• Local climate. “Intact tropical forests are critical for rain generation because air that passes over these forests produces at least twice as much rain as air that passes over degraded or non-forest areas” [Watson 2018: 4]. By contrast, deforestation and forest degradation can increase the frequency of hot, dry days, leading to drought.
• Biodiversity. Forested ecosystems support the majority of global terrestrial biodiversity, and “beyond outright forest clearance, forest degradation from logging is the most pervasive threat facing species inhabiting intact forests” [Watson 2018: 4]. “For example, a recent global analysis of nearly 20,000 vertebrate species showed that even minimal initial deforestation within an intact landscape had severe consequences for vertebrate biodiversity in a given region, emphasizing the special value of intact forests in minimizing extinction risk” [Watson 2018: 5].
• Indigenous peoples. “Industrial-scale degradation of intact forest erodes the material basis for the livelihoods of indigenous forest peoples, depleting wildlife and other resources. It also renders traditional resource management strategies ineffective, and undermines the value of traditional knowledge and authority” [Watson 2018: 5], ultimately driving indigenous peoples off their land.
• Human health. “Forested ecosystems are major sources of many medicinal compounds that supply millions of people with medicines worldwide” [Watson 2018: 6]. Forest degradation results in the decline or loss of medically relevant species, while also directly harming human health through increased wildfire severity and spread of disease.
• Forest resilience. Forest degradation reduces the resilience of forests to climate change, leading to even greater ultimate loss of ecosystem function.

The authors warn that intact forests could soon disappear unless action is taken to protect them, which must necessarily start with greater recognition of their value compared to degraded forests.

There are still significant tracts of forest that are free from the damaging impacts of large-scale human activities. These intact forests typically provide more environmental and social values than forests that have been degraded by human activities. Despite these values, it is possible to envisage, within the current century, a world with few or no significant remaining intact forests. Humanity may be left with only degraded, damaged forests, in need of costly and sometimes unfeasible restoration, open to a cascade of further threats and lacking the resilience needed to weather the stresses of climate change. The practical tools required to address this challenge are generally well understood and include well-located and managed protected areas, indigenous territories that exemplify sound stewardship, regulatory controls and responsible behavior by logging, mining, and agricultural companies and consumers, and targeted restoration. Currently these tools are insufficiently applied, and inadequately supported by governance, policy and financial arrangements designed to incentivize conservation. Losing the remaining intact forests would exacerbate climate change effects through huge carbon emissions and the decline of a crucial, under-appreciated carbon sink. It would also result in the extinction of many species, harm communities worldwide by disrupting regional weather and hydrology, and devastate the cultures of many indigenous communities. Increased awareness of the scale and urgency of this problem is a necessary precondition for more effective conservation efforts across a wide range of spatial scales [Watson 2018: 8].