A família Orchidaceae e as mudanças climáticas da Mata Atlântica
Messias, Patrícia Aparecida
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The Atlantic Forest, located in Brazil, has one of the highest levels of biodiversity and endemism on the planet, mainly due to the variety of vegetation types associated with the various types of soil, topography and climate. These vegetation types have delicate balance and currently suffer strong pressure from fragmentation. In the future, it is also likely to be impacted by climate change. To predict the effects of these changes in the distributions of living organisms, models that simulate climatic conditions projected for the future have been used. The Orchidaceae family stands out as a representative group within the Atlantic Forest formations, with 63% of endemic species, especially for Coastal Plain Forest (CPF) and Rainforest (RF). Most species of this family are epiphytic plants, identified as most sensitive to changes in the environment. This study evaluated the effects of future climate change in the Atlantic Forest formations based on orchid species. By using the algorithm MaxEnt, eight bioclimatic variables in models 17, simulated to be the potential distribution in the current scenario and two future climate scenarios (RCP 4.5 - optimistic and RCP 8.5 scenario - pessimistic). We selected 31 endemic species of RF and three species of CPF. The forecasts indicate area loss of future potential distribution for both areas of study. The reduction will be potentially higher in the RF, with 29.92% to 34.32% and RCP 4.5 to RCP 8.5 and lower in CPF, 8.35% for the RCP 4.5 scenario and 10.68% for RCP 8.5. Regarding the loss of species, loss of CPF reached 100% in certain localities, and 67.74% loss of species for RF. Forecasts suggest gains of new areas in the Northeast of the country for CPF, and RF in the Southern and Southeastern regions. It is noteworthy that such areas have favorable climatic conditions for survival of the species, but cannot be colonized. The areas that will maintain current climatic conditions will be the Northeastern region for CPF and mountainous regions on the coast of Santa Catarina, Paraná, São Paulo and Rio de Janeiro states for RF. In general, loss of vegetation types of the study area is characterized by a narrowing of the potential distribution. The RF was highlighted with higher values of area loss, mainly due to the dependence of moisture. For CPF, species' resistance to sunlight, low water requirement, or other physiological traits may explain its prediction of low values of area loss. As a measure for future protection of vegetation types, one must pay attention to protected areas, as these areas maintain climatic conditions and, possibly, maintain species and vegetation type, through the creation of Conservation Units and compliance with current legislation on deforestation.