Will Dalbergia species survive climate change? Predicting the potential future distribution of threatened species in Madagascar

Abstract

Many species of Dalbergia, the source of highly prized rosewood, are threatened with extinction, a situation compounded by climate change. Accurate estimates of how suitable habitat will be impacted by global change are needed to inform their sustainable management. We selected five commercially exploited species endemic to humid eastern Madagascar (D. baronii, D. louvelii, D. maritima, D. normandii, and D. orientalis) to explore the potential value of species distribution modeling for understanding factors influencing their current distributions and estimating future patterns of suitable habitat, using MaxEnt and locality information for 715 taxonomically and spatially validated occurrences. Eight bioclimatic variables were used for modeling; projections were made under three scenarios for climate change and two for CO2 emissions. The distribution of each of the five species is primarily influenced by precipitation seasonality. Their potential geographical range is predicted to decrease by 2100 (-5% to -33%) under the optimistic CO2 scenario (RCP 2.6) except for a slight expansion of D. normandii (+2%), and by -14% to -58% under the pessimistic scenario (RCP 8.5). Our results show that suitable habitat will likely decrease with climate change, even within protected areas. They provide valuable information for future application of IUCN Red List criterion A to exploited species with fragmented distributions, targeting ex-situ conservation and management, and guiding restoration, reforestation, and other actions to establish and reinforce Dalbergia populations in areas where they are more likely to persist during climate change over the present century and beyond.

Keywords

• Conservation biology
• Palisander
• Rosewood
• Forest habitat
• Biodiversity loss