Mountain forests are being lost faster and endanger biodiversity – Zoo House News
- March 18, 2023
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More than 85% of the world’s bird, mammal and amphibian species live in mountains, particularly in forest habitats, but researchers report in One Earth magazine March 17 that these forests are disappearing at an accelerating rate. Globally, we have lost 78.1 million hectares (7.1%) of mountain forest since 2000—an area larger than the size of Texas. Much of the loss has occurred in tropical biodiversity hotspots, increasing pressure on threatened species.
Although their rugged location once protected montane forests from deforestation, they have been increasingly exploited since the turn of the 21st century as lowland areas are depleted or placed under protection. A team of scientists led by Xinyue He (@xinyue_he), Dominick Spracklen and Joseph Holden of Leeds University in the UK, and Zhenzhong Zeng of Southern University of Science and Technology in China set out to study the extent and global distribution of montane forest Loss.
To this end, the team tracked changes in mountain forests annually from 2001 to 2018. They quantified both losses and gains in tree cover, estimated the speed at which changes are occurring, compared different elevations and types of montane forests – boreal, temperate, tropical – and examined the impact of this forest loss on biodiversity.
“Knowing the dynamics of forest loss along elevational gradients globally is critical to understanding how and where the amount of forested area available to forest species will change as it shifts in response to warming,” write the authors.
Deforestation was the overall largest contributor to montane forest loss (42%), followed by wildfires (29%), relocation or slash-and-burn (15%), and permanent or semi-permanent agriculture (10%). although the importance of these various factors varied from region to region. Significant losses occurred in Asia, South America, Africa, Europe and Australia, but not in North America and Oceania.
Disturbingly, the rate of montane forest loss appears to be accelerating: the annual rate of loss increased by 50% from 2001-2009 to 2010-2018, when we were losing approximately 5.2 million hectares of montane forest per year. The authors write that this acceleration is likely due in large part to rapid agricultural expansion into highland areas of mainland Southeast Asia, as well as increasing deforestation of montane forests, either due to the depletion of lowland forests or because those lowland forests have been protected.
Tropical montane forests experienced the greatest loss – 42% of the global total – and the fastest rate of acceleration, but also had a faster regrowth rate compared to montane forests in temperate and boreal regions. Overall, the researchers observed some sign of tree cover regrowth in 23% of the areas where forest was lost.
Protected areas saw less forest loss than unprotected areas, but the researchers warn that this may not be enough to conserve threatened species. “Regarding sensitive species in biodiversity hotspots, the critical question goes beyond simply preventing forest loss,” the authors write. “We also need to preserve the integrity of forests in zones large enough to allow for natural movement and adequate space for dispersing species.”
The authors also emphasize the importance of considering human livelihoods and well-being when developing forest conservation strategies and measures. “Any new measures to protect mountain forests should be adapted to local conditions and contexts, and balance the need for increased forest protection with ensuring food production and human well-being.”
This research was supported by the Southern University of Science and Technology, the University of Leeds and the National Natural Science Foundation of China.