Long term evaluation of green vegetation cover dynamic in the Atacora Mountain chain (Togo) and its relation to carbon sequestration in West Africa

The research was done in the Atacora Mountain chain in Togo which tended to assess the change of vegetation cover during a 24-year period. It also aims to evaluate the dynamic of the net primary productivity (NPP) of the living plants over the same period. The Landsat imagery covering three different periods (1987, 2000, and 2011) was pre-processed to correct atmospheric and radiometric parameters as well as gapfilling the 2011 SCL-off images. Then, the vegetation indices such as NDVI (normalized difference vegetation index), SR (simple ratio vegetation index), SAVI (soil-adjusted vegetation index), and CASA (carnegie- ames- stanford approach)model for NPP were applied on these images after masking the study area. The results showed a quiet decrease in the vegetation cover. The vegetation loss was more significant from 2000 to 2011 than from 1987 to 2000, and anthropogenic activities can be deemed as the main cause of the vegetation loss. The biomass assessment by NPP computation also showed a decrease over the time. Similar to the change of the vegetation cover, the ecosystem net productivity was very low in 2011 compared to 2000 and 1987. It seems that the general health condition of the vegetation, including its potentiality in carbon sinking, was negatively affected in this area, which has already been under threatened. A perpetual monitoring of these ecosystems by means of efficient techniques could enhance the sustainable management tools of in the framework of reducing emissions from deforestation and forest degradation (REDD).