Environmental Niche Models Reveal Receding Refugia for Philippine Endemic and Threatened Melastome Trees under Accelerated Climate Change

Abstract

Home to exceedingly diverse and highly endemic flora in the Malesian region, the Philippines is highly vulnerable to species loss due to climate change. The lack of baseline ecological and biogeographic information in the country, which are requisites to effective conservation, compounds this problem. To address this, we used maximum entropy modeling to predict suitable habitats of four Philippine endemic trees – Astronia cumingiana, and three threatened species, Astrocalyx calycina, Beccarianthus ickisii, and B. pulcherrimus (Astronieae: Melastomataceae) – under current climate conditions. We then predicted changes in their habitats for the years 2041–2060 and 2061–2080 under two future climate scenarios. We also assessed the level of protection that the species receive using the current protected area boundaries. Our models showed potentially suitable habitats for all species outside of their observed occurrence under the present climate, but their niches are generally predicted to shrink and ascend to higher altitudes when projected under future climate scenarios. The overlaps of their suitable niches outside protected area boundaries also increase southward, with Mindanao island possibly harboring the greatest number of unprotected Astronieae species. Our findings contribute to the emerging field of environmental niche modeling in the country and support the need to re-envision the country’s protected area system to move towards climate-smart local conservation strategies.