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Loss of mountain forests accelerating worldwide

Over 85 percent of the Earth’s mammal, bird, and amphibian species live in mountain forests. Unfortunately, these forests are disappearing at an alarming rate.

According to a new study led by the University of Leeds in the UK and the Southern University of Science and Technology in China, 78.1 million hectares (7.1 percent) of mountain forests have been lost since the beginning of the new millennium. This is an area larger than the size of Texas. Most of this loss has occurred in tropical biodiversity hotspots, thus significantly threatening a variety of already endangered animal species. 

Forested mountain areas were previously protected from deforestation by their rugged location. But as lowland regions became depleted or subject to protection at the beginning of the 21st centuries, mountain forests became increasingly exploited.

To clarify the current situation, the experts tracked changes in mountain forests on an annual basis from 2001 to 2018, measuring both losses and gains in tree cover, estimating the rate at which change was occurring, comparing different elevations and types of forests (such as boreal, tropical, or temperate), and exploring the impacts of forest loss on biodiversity.

“Knowledge of the dynamics of forest loss along elevation gradients worldwide is crucial for understanding how and where the amount of forested area available for forest species will change as they shift in response to warming,” the authors explained.

The investigation revealed that logging was the main driver of forest loss (42 percent), followed by wildfires (29 percent), shifting or “slash-and-burn” cultivation (15 percent), and permanent or semi-permanent agricultural practices (10 percent). However, the importance of these factors was found to differ from region to region. The most significant losses occurred in Asia, South America, Africa, Europe, and Australia, with North America and Oceania appearing to fare slightly better.

Unfortunately, the rate of mountain forest loss appears to be accelerating, with the annual rate of loss rising by 50 percent from the 21st century’s first to second decade (which witnessed about 5.2 million hectares annual losses). This acceleration is likely driven by the rapid agricultural expansion into highland regions in mainland Southeast Asia, as well as by increased logging due to either depletion or protection of lowland forests.

Although tropical forests experienced the greatest loss (42 percent of the global total), they also had a faster rate of regrowth compared to temperate and boreal mountain forests. While protected areas experienced less forest loss than unprotected ones, this may not be sufficient to protect endangered species.

“Regarding sensitive species in biodiversity hotspots, the critical issue extends beyond simply preventing forest loss. We must also maintain the integrity of forests in large enough zones to allow natural movements and sufficient space for ranging species,” the authors wrote.

The researchers concluded by highlighting the importance of reaching a balance between the protection of forests and human livelihoods. “Any new measures to protect mountain forests should be adapted to local conditions and contexts and need to reconcile the need for enhanced forest protection with ensuring food production and human wellbeing.”

The study is published in the journal One Earth.  

By Andrei Ionescu, Staff Writer

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