Climate change may affect Caatinga biodiversity – 07/10/2023 – Environment

Loss of species, replacement of rare plants by more general ones and homogenization of 40% of the landscape are the main consequences of climate change in the Caatinga, a biome that tends to present an even more arid climate in the future. The prediction is from a study whose results were released in the Journal of Ecology.

Researchers from the State University of Campinas (Unicamp), Federal University of Paraíba (UFPB), Federal University of Pernambuco (UFPE), Federal University of Viçosa (UFV) and the Federal Institute of Goiano (IFG) studied data from scientific collections, herbaria and literature to compile an unprecedented database, with more than 400,000 occurrence records of around 3,000 species of plants in the biome.

In addition to the geographical distribution, information was added on the form of growth of plant species (grasses, herbs, shrubby vegetation, arboreal or succulent plants), climate and soil where they occur. The proportion of tree species in each locality versus non-tree species was also calculated.

Through evaluated and validated models, with different types of statistical algorithms and artificial intelligence, more than a million projections were made with the possible responses of Caatinga species to future climate changes.

“We based our forecasts on the last report of the Intergovernmental Panel on Climate Change (IPCC), from 2021, which contains simulations about the climate on the planet”, explains Mario Ribeiro de Moura, a researcher at Unicamp and author of the work.

“But it is worth remembering that we do not know how humanity will behave from now on, so we consider two scenarios: in the optimistic scenario, technologies capable of reducing greenhouse gas emissions and making the Paris Agreement viable [que prevê limitar o aumento da temperatura média global até 1,5 °C acima dos níveis pré-industriais]; in the pessimist, deforestation rates, the use of fossil fuels and population growth will remain high, without progress in innovation.”

The results of the study, funded by FAPESP through two projects (22/12231-6 and 21/11840-6), indicate that 99% of plant communities in the Caatinga will experience species loss by 2060.

The climate of the future in the region should be even hotter and drier, making it more difficult and impactful for trees, which should be replaced by low-sized vegetation, especially grasses, due to their ease of expansion and growth. As a consequence, the ecosystem services that vegetation provides to populations will also be affected, such as photosynthesis, air renewal and carbon storage – the famous carbon stocks occur in the form of plant biomass, accumulated in trunks, roots and leaves, which naturally it is larger in trees.

These events will be more visible in mountainous areas, such as Chapada Diamantina and Chapada do Araripe, respectively in the south and central-north of the biome. The explanation is simple: as the climate warms up, species from the lowlands move up the mountain to continue inhabiting a climatically more satisfactory region. Those of the highest portions end up extinct.

“For the entire biome, we predicted, in the optimistic scenario, 50 species of extinct plants and, in the pessimistic one, 250”, says Moura. “Both are pretty bad.”

With all this, 40% of the region will suffer a simplification of its composition, with the loss of rare species. “It’s like taking the landscape and hitting it in a blender to homogenize everything.”

mitigation projects

With this data in hand, the researchers’ idea is that the dialogue between different levels of government starts to consider macro-scale conservation planning, with a long-term vision. Creating this type of strategy is important both to mitigate the effects of climate change and to stop other types of human-made impacts, such as deforestation, habitat destruction, and soil degradation and exposure.

“Projects that recover landscape connectivity in areas subject to impacts from climate change, for example, increase the chances that the species that live there will be able to disperse over time to more suitable regions, either by animals or by the wind” , says Moore.

“On the other hand, if we impact the region’s biodiversity too much, through degradation and deforestation of natural vegetation, widespread use of pesticides or hunting, we further compromise the resources we have from now on.”

The article Pervasive impacts of climate change on the woodiness and ecological generalism of dry forest plant assemblies can be read here.