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Up to 66 per cent of key biodiversity areas (KBAs) in tropical forests have recently entered a new phase characterised by novel mean annual temperature regimes, according to a study published in Conservation Letters.
KBAs are sites contributing significantly to the global persistence of biodiversity in terrestrial, freshwater and marine ecosystems. The post-2020 global biodiversity framework, also known as the Kunming-Montreal Global Biodiversity Framework, was adopted in December 2022 with the goal of halting and reversing biodiversity loss by 2030, with a target of conserving at least 30 per cent of land globally. KBAs are specifically identified as a core priority for this effort.
The proportion of KBAs with new temperature regimes was 72 per cent in Africa, 59 per cent in Latin America and 49 per cent in Asia and Oceania, the new paper found.
“Tropical forests are global hotspots of terrestrial biodiversity, providing critical ecosystem services and sustaining the livelihoods of over a billion people worldwide,” the researchers wrote in their study.
The environment beneath the forest canopy is climatically stable, with less temperature variation than in open habitats, according to the research. This results in cooler maximum temperatures, warmer minimum temperatures and lower seasonal and interannual fluctuations.
This means the species in tropical forests have evolved under these stable conditions and may be unable to tolerate significant warming beyond their optimal temperature range, making them vulnerable.
“Beneath the canopy of tropical forests, a wealth of biodiversity exists in a very stable climate,” Brittany Trew, from the Environment and Sustainability Institute on Exeter’s Penryn Campus in Cornwall, said in a statement.
The researchers conducted the first global analysis of changes in below-canopy temperature conditions in tropical KBAs. They found that 2.9 per cent of KBAs in Latin America and 4.9 per cent in Asia and Oceania have recently transitioned to almost entirely novel temperature regimes.
In Latin America, these KBAs were located in Ecuador, Colombia, Venezuela and Panama. In Asia, areas experiencing significant temperature shifts were mainly in Indonesia and the Philippines. Only 0.02 per cent of KBAs in Asia and Oceania remained almost stable, with Northern Australia’s tropical forests experiencing some of the least novel temperature regimes globally, the paper highlighted.
The study also revealed that 34 per cent of tropical forest KBAs are not yet experiencing new temperature regimes, with over half of these areas under some form of protection. In Asia and Oceania, of the 12 per cent of KBAs that have not transitioned to novel temperature regimes, 23 per cent lack protection.
“We need ‘climate-smart’ policies that protect these vital refuges,” Trew added.
The importance of addressing deforestation, habitat degradation and climate change to mitigate biodiversity loss in KBAs affected by rapid local climate change was emphasised by the authors in the paper. They also called for large-scale forest restoration programmes within and outside these areas.
