Threatened Fabaceae taxa in coastal East Africa: Current and future modelled distributions and conservation priorities

Abstract

• Global climate change causes an increasing threat to coastal species,with the potential extinction of a lot of legume species. • We modelled the distribution of eleven legume taxa at local scales using environmental variables. • The selected legume taxa ecological niches are influenced mainly by mean diurnal range temperature, precipitation of the coldest quarter, and elevation. • Irrespective of the climate change scenario, B. mombassae, C. lukei , and S. speciosa were observed to be most vulnerable to climate change. Predicting the responses of threatened tropical plant species to global climate change has been considered to be critical for assessing changes in species distribution and evaluating their conservation status. In reflecting on the vast species richness, East Africa has long been recognised as a hotspot of biodiversity, but very little is known about the vulnerability of the endemic plant diversity to anthropogenic introduced climate changes. This study evaluated the potential impacts of global climate change on plant species ranges in coastal East Africa by predicting the extent and direction of projected changes in climatic suitability. Specifically, we employed species distribution modelling in MaxEnt to identify species experiencing the highest threat of range declines. To do so, we evaluated climatic suitability for eleven legume species using one global climate model and two greenhouse gas emissions scenarios for present and future climates. The findings indicated that the mean AUC and TSS values of the focal taxa ranged from 0.818 to 0.992 and from 0.780 to 0.851, respectively, indicating that the MaxEnt model's prediction accuracy was good or exceptional. Occupancy and abundance of nine species were positively associated with low elevations, high relative humidity, and warmer temperatures in the coastal regions. Regardless of species, precipitation of the warmest quarter and mean temperature of the wettest quarter exhibited a minor impact on the distribution. Furthermore, the probable distribution regions of these species ranged from 77,270 km 2 to 282,297 km 2 . To our knowledge, this study is the first to appraise the distribution of threatened species within Fabaceae in coastal East Africa. The current findings provide a critical assessment framework for the conservation and management of Fabaceae in the region.