Effect of land use change on carbon stocks in an agricultural region of southern Benin

Abstract

AbstractLand use change is one of the most important determinants of carbon storage and dynamics in ecosystems. Areas in the proximity of metropoles undergo land use changes but are poorly studied for their soil and biomass carbon budget, especially in Africa. Close to Benin's economic capital, the Lama Territory located on the Allada Plateau and is subject to high demographic and urbanization pressures. Carbon (C) stocks in the region are likely to be rapidly changing. This research assessed the land use changes and quantified the spatial distribution and variation of C stocks between 2000 and 2018 on the Ferralsols of the study area. Random forest models using spectral bands of LANDSAT images and some spectral indices as predictors were calibrated to classify the land use. C stocks of four C pools (aboveground, belowground biomass, litter, and soil) were mapped with InVEST (integrated valuation of ecosystem services and tradeoffs) model. Land use change occurred in 61% of the Ferralsol area between 2000 and 2018. The surface of forests and crop‐plantation associations decreased in benefit of tree plantations, adult palm groves, and built‐up areas. With the loss of forest surface and the increasing urbanization, C stocks of the region decreased by −218 Gg C with 4% uncertainty (−175 Gg C in soil pools, and − 125 Gg C in aboveground biomass with both 6% uncertainty) between 2000 and 2018. Results highlight: (i) the need for soil C stock accounting to avoid underestimation of C stocks evolution in a rural region; and (ii) the relevance of tree plantations and deforestation control to maintain the C stocks in tropical areas.