Freshwater Swamp Forest Trees of Bangladesh Face Extinction Risk from Climate Change

Global climate change is impacting the distribution and abundance of species acting as a major cause of species extinction. It is rapid in freshwater swamp forest ecosystems, since they support disproportionate levels of biodiversity compared to their spatial coverage. The natural swamp forests of Bangladesh have been especially susceptible to climate change as they are limited in range to a few scattered patches in the north-eastern region. We sought to understand how climate change may impact the swamp forests of Bangladesh by modelling distributional changes in Pongamia pinnata and Barringtonia acutangula species, which dominate or co-dominate most swamp forest ecosystems across Bangladesh. We used the maximum entropy (MaxEnt) modelling tool, combined presence-only data of species and bioclimatic variables for two climate scenarios (RCP6.0 and RCP8.5). We compared current, 2050 and 2070 distributions. Results suggest that plant extractable water holding capacity of soil, annual precipitation, precipitation of warmest quarter and mean annual actual evapotranspiration are the key bioclimatic variables for the distribution of both trees. The MaxEnt models indicate that Pongamia pinnata and Barringtonia acutangula trees of Bangladesh face increasing climate stress and may become extinction under both mid-range and extreme climate scenarios.