Impact of Land-use/cover Change on Tree Species Diversity in Dry Forestland in Southeastern Senegal

Abstract

Given that land use/cover change is one of the major drivers of biodiversity loss, yet this impact remains poorly quantified. This study aims to estimate the impact of land use/cover change on tree diversity in the Missirah Forest in southeastern Senegal over the last 15 years. We classified land use/cover maps in 1990, 2003 and 2014 using Landsat images, and from there we detected land use/cover changes. Using data on the tree vegetation community gathered from plots sampled across the study area, we constructed the species-area-relationship (SAR) for each vegetation type, which created a basis upon which to estimate changes in species richness induced by land use/cover change. After subtracting the 926 species turnover among vegetation types, the results show the overall species richness decreased from 1234 to 1044 species respectively between 1990 and 2014. The gallery forest showed the highest species richness but also the highest decline with a loss of 22% between 1990 and 2014. This highlights the importance of reinforcing the protection of the gallery forest in order to conserve the biodiversity of the whole area. The clear relationships between net changes in species richness and net changes among land-use cover types provide a basis for land change management that promotes biodiversity. This study demonstrates an empirical method with which to estimate net changes in species richness, which is often a challenging task, based on the land-use/cover change data that are easily obtained nowadays.