Evaluating current and future potential distribution of epiphytic orchids in the Congo Basin with ecological niche models

The Congo Basin Forest harbors a rich diversity of epiphytic communities, with the Orchidaceae alone making up more than 50% of all epiphytes in the region. Despite the huge diversity of epiphytes, many species, including epiphytic orchids, are at risk to a diverse array of threats. Climate change for instance poses severe threats to epiphytic orchids due to elevated temperatures, prolonged periods of droughts, as well as reduced rainfall across the Congo Basin Forest. In this study, we used ecological niche modeling and GIS techniques to identify spatial patterns of species richness, potential future climate refugia, and novel climatic suitability areas, by estimating future potential climatic suitability for epiphytic orchids in 2021-2040. We also evaluated the overlap of hotspots of climatic suitability for epiphytic orchids with the current network of protected areas in the Congo Basin. Using two Global Circulation Models and moderate and high greenhouse gasses emission scenarios, our results showed that, of the 16 species studied, nine species of epiphytic orchids would lose more than 30% of their current potentially suitable range. Additionally, spatial distribution of epiphytic orchids showed less than 5% overlap of potentially suitable climatic hotspots with the network of protected areas in the Congo Basin. Outside of protected areas our models forecasted stable areas buffering climatic changes (“slow lanes” or climate refugia) and as well novel climatic suitability areas across the biogeographic extent of Africa. Climate refugia and novel areas of climatic suitability may be crucial for long-term persistence and thriving of epiphytic orchids. These findings provide the first estimation to the potential distribution of epiphytic orchids in the Congo Basin and serve as a first step towards a regional effort to protect the biodiversity of the Guineo-Congolian landscape.

Ecological Niche Modeling, Species Distribution, GIS, Epiphytic Orchids, Orchidaceae