Climate change leads to the loss of caatinga mammals – 10/20/2023 – Environment

The climate change scenario predicted for the caatinga is catastrophic for the majority of terrestrial mammal species that inhabit the region.

In a study published this Tuesday (17) in the journal Global Change Biology, researchers from Unicamp (State University of Campinas) and the federal universities of Paraíba (UFPB) and Minas Gerais (UFMG) predict the loss of 91.6% of communities of these animals in the biome, with 87% of species losing habitat by 2060.

“This is the optimistic scenario, in which humanity complies with the Paris Agreement, reduces greenhouse gas emissions and reduces the rate of warming predicted for the coming decades”, explains Mário Ribeiro de Moura, researcher at the Institute of Biology ( IB) from Unicamp supported by Fapesp and coordinator of the study.

The team of researchers crossed the most recent predictions of future temperatures released by the Intergovernmental Panel on Climate Change (IPCC), of the UN (United Nations), with databases of the occurrence of mammal species in the caatinga.

Different statistical models were used to capture the species’ physiological tolerances to the current climate. These models were then explored in future climate scenarios, yielding similar results.

By 2060, according to the IPCC, average temperatures are expected to rise by 2.7°C in the north of South America, with an increase of 21 consecutive dry days in the dry season.

Since it takes thousands or millions of years for animals to adapt to such drastic changes, the models indicate that only a few species would find more climatically suitable areas in the future, including armadillos, agoutis and deer, all of which are large. However, primate species, for example, would lose suitable areas.

Small mammals, whose adult individuals weigh less than one kilogram, will be most affected. These animals constitute 54% of the mammals in the caatinga. In total, 12 species (12.8%) would completely lose their habitats by 2060, in the most optimistic scenario. According to the most pessimistic model, however, there would be 28 species (30%) without suitable areas by 2100.

Among small rodents and marsupials, animals such as the cuíca (Gracilinanus agilis), the tree rat (Rhipidomys mastacalis) and the thorn rat (Trinomys albispinus) will be some of the most affected.

“For 70% of mammal communities, there will be homogenization, with a few generalist species replacing rare and specialist ones. This leads to the loss of ecological functions, such as seed dispersal, and the entire ecosystem becomes less resilient”, says Moura.

In previous work, Moura and other co-authors also used statistical models and databases to predict how caatinga plants would be affected by climate change.

Among the results, a homogenization of 40% of plant communities is also expected, with the replacement of tree species by grasses, for example.

Transition zone

Moura explains that, although mammals can change behaviors to escape higher temperatures, the period of the day with milder weather can be used by many species at the same time. This can lead to greater competition for resources, which can also affect survival chances.

In all scenarios, the most affected part of the biome will be to the east. In this area there is a transition with the Atlantic Forest. One of the consequences of the greater humidity brought from the coast is that more species live there.

“This is also the part of the caatinga where the largest cities in the region are located. Deforestation, hunting and other historical practices contribute to making the situation even more complicated there, which can amplify the effects of climate change”, assesses the researcher.

Therefore, the authors argue that the success of socio-environmental policies and long-term conservation planning depends on taking into account predictions about biodiversity.

In addition to the project coordinated by Moura, the work received funding through a Research Grant granted to Mathias Mistretta Pires, professor at IB-Unicamp and co-author of the article.

The article “Climate change should drive mammal defaunation in tropical dry forests” can be read here (in English).