Brazil’s semi-arid biome could lose more than 90% of its mammal species by 2060

The predicted effects of climate change on Caatinga, the semi-arid scrub and thorn forest biome of Brazil’s northeastern region, will be catastrophic for most terrestrial mammal species that live there.

A study reported in the journal Biology of global change by Brazilian researchers affiliated with the State University of Campinas (UNICAMP), the Federal University of (UFPB) and the Federal University of Minas Gerais (UFMG), they predict a loss of species for 91, 6% of the species assemblages of the Caatinga and a loss of habitat for 87%. by 2060.

“This is a best-case scenario, which assumes that humanity fulfills the promises made in the Paris Agreement, reduces greenhouse gas emissions and slows the rate of global warming predicted for decades to come,” said Mário Ribeiro de Moura, corresponding author of the study. article and study coordinator.

The researchers crossed data from the latest projections of future temperatures published by the Intergovernmental Panel on Climate Change (IPCC) with data on the occurrence of terrestrial mammals in the Caatinga.

They used several statistical models to capture the species’ physiological tolerance to existing climate and future climate change scenarios.

According to the IPCC, the average temperature in arid areas of South America will increase by up to 2.7°C by 2060, and the dry season will lengthen by up to 21 consecutive dry days.

Since animals take thousands or even millions of years to adapt to such drastic changes, models suggest that only a few species will find areas with suitable climates in the future, including armadillos. , agoutis and deer, all of which are large mammals. On the other hand, primates will lose their habitat.

Small species whose adults weigh less than 1 kg, representing 54% of Caatinga mammals, will lose the most. Twelve species, or 12.8% of the total, will completely lose their habitat by 2060 in the best case and 28 (30%) by 2100 in the worst case.

The hardest hit rodents and marsupials will include the agile slender opossum (Gracilinanus agilis), the long-tailed climbing mouse (Rhipidomys mastacalis), and the white-spined Atlantic thorn rat (Trinomys albispinus).

“Biotic homogenization (in which previously distinct plant communities will gradually become more similar) will occur in 70% of mammal assemblages, with a few generalist species surviving while rarer specialists will lose suitable areas and become locally extinct. This will result in a loss of ecological protection functions such as seed dispersal, and the ecosystem as a whole will become less resilient,” Moura said.

A previous study by Moura and colleagues also used statistical models and databases to predict how plants in the Caatinga will be affected by climate change. The results include a 40% homogenization of plant assemblages, with shrubs and grasses surviving better than trees and other woody species.

Transition zone

Although mammals may change their behavior to escape higher temperatures, many species may use cooler times of the day at the same time, which will lead to greater competition for resources, which will also affect their chances of survival. survival, Moura explained.

The eastern part of the Caatinga, which contains the transition zone to the Atlantic Rainforest biome, will be most affected in all scenarios. More and more species are living there thanks to higher levels of humidity due to evapotranspiration from oceans and forests.

“It is also the part of the Caatinga that has the largest towns. Deforestation, poaching and other long-standing practices contribute to making the situation even more complicated, potentially amplifying the effects of climate change,” said Moura.

In light of all these factors, the article highlights the importance of considering biodiversity forecasts in long-term socio-environmental policies and conservation planning.