Impacts of current and future climate trends on the distribution of Combretaceae in Niger

Abstract

Many species are threatened with extinction or have disappeared due to the degradation or disappearance of their habitats because of the effects of climate change. This study focused on modeling the potential distribution of Combretum micranthum G.DON and Combretum glutinosum Per ex DC in Niger. Modeling was carried out using three algorithms: MAXENT, BRT and RF, and the results were tested based on the Operating Characteristic Curve. Points of presence were derived from field surveys and the GBIF database. Environmental variables were downloaded from the WorlClim website. The results show that precipitation in the coldest quarter (BIO12) and mean monthly temperature of daily variation (BIO2) are the bioclimatic variables that most influence the distribution of these species. The mapping of potential areas reveals that species will experience decreases in favorable areas for all the scenarios used, except for RCP8.5_2050, which predicts an increase. This scenario predicts a gain of 41,410.80 km² for Combretum micranthum and 15,573.70 km² for Combretum glutinosum. The greatest loss of favorable area was observed with the RCP8.5_2070 scenario, with a reduction of -111,483.60 km² for Combretum micranthum and 118,307.74 km² for Combretum glutinosum. The results show that these species are threatened by the adverse effects of climate change and can serve as a decisionmaking tool for forest managers in defining their choice of tree species.