Abstract
After 500 years of exploitation and destruction, the Brazilian Atlantic Forest has been reduced to less the 8% of its original cover, and climate change may pose a new threat to the remnants of this biodiversity hotspot. In this study we used modelling techniques to determine present and future geographical distribution of 38 species of trees that are typical of the Brazilian Atlantic Forest (Mata Atlântica), considering two global warming scenarios. The optimistic scenario, based in a 0.5% increase in the concentration of CO2 in the atmosphere, predicts an increase of up to 2 °C in the Earth's average temperature; in the pessimistic scenario, based on a 1% increase in the concentration of CO2 in the atmosphere, temperature increase may reach 4 °C. Using these parameters, the occurrence points of the studied species registered in literature, the Genetic Algorithm for Rule-set Predictions/GARP and Maximum entropy modeling of species geographic distributions/MaxEnt we developed models of present and future possible occurrence of each species, considering Earth's mean temperature by 2050 with the optimistic and the pessimistic scenarios of CO2 emission. The results obtained show an alarming reduction in the area of possible occurrence of the species studied, as well as a shift towards southern areas of Brazil. Using GARP, on average, in the optimistic scenario this reduction is of 25% while in the pessimistic scenario it reaches 50%, and the species that will suffer the worst reduction in their possible area of occurrence are: Euterpe edulis, Mollinedia schottiana, Virola bicuhyba, Inga sessilis and Vochysia magnifica. Using MaxEnt, on average, in the optimistic scenario the reduction will be of 20% while in the pessimistic scenario it reaches 30%, and the species that will suffer the worst reduction are: Hyeronima alchorneoides, Schefflera angustissima, Andira fraxinifolia and the species of Myrtaceae studied.
Highlights
The Brazilian Atlantic Forest sensu lato is classified as an area that comprises three types of forests: Ombrophylus Dense forests, Semideciduous and Deciduous Stationary forests from the South and Southern regions, and Ombrophylus Mist forest, known as Araucaria forest from Southern Brazil (Joly et al, 1999; Oliveira Filho and Fontes, 2000)
The main objectives of this paper are: to compare projected Atlantic Forest tree species distribution shifts and/or reductions due to global climate change, to similar data produced by Siqueira and Peterson (2003) for Cerrado trees; and, using the same set of data, compare the projections made using genético para previsões baseadas em regras pré-estabelecidas (GARP) with those made using Maxent
All GARP and Maxent projection models of the present area of occurrence of the 38 species presented a high level of significance (Binomial Test: two proportions, p < 0.05 for all species); showing that the models based only on Guatteria australis A.St.Hil
Summary
The Brazilian Atlantic Forest sensu lato is classified as an area that comprises three types of forests: Ombrophylus Dense forests, Semideciduous and Deciduous Stationary forests from the South and Southern regions, and Ombrophylus Mist forest, known as Araucaria forest from Southern Brazil (Joly et al, 1999; Oliveira Filho and Fontes, 2000). The always green dense forest occurs in an ombrophylus climate without a biologically dry period throughout the year and exceptionally with two months of scarce humidity. Semideciduous and deciduous forests occur in areas with 2 to 5 months of dry season, with the same range of temperatures. The Araucaria forest of Southern Brazil occurs in areas with a subtropical mesotermic climate, with temperature in the range of 12 to 22 °C.
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