Combretum-Terminalia vegetation accumulates more carbon stocks in the soil than the biomass along the elevation ranges of dryland ecosystem in Southern Ethiopia

Dry land ecosystems including Combretum-Terminalia vegetation cover a wider area in the tropics. These resources are believed to greatly contribute for climate change mitigation in dry land ecosystems. Therefore, the objective of this study was to investigate biomass and soil carbon stocks of Combretum-Terminalia vegetation along the elevation ranges. A total of 60 nested sample plots of 20 m x 20 m were laid systematically along lower, middle and higher elevation ranges, representing 20 plots for each elevation. Within each nested sample plot inventory of woody species, litter and soil samples (0-15, 15-30 cm layers) were collected. The total carbon stocks (biomass plus soil) significantly (p < 0.05) differed among the three studied elevation ranges. The biomass carbon stocks were not significantly different between middle and higher elevations but both of them significantly (p < 0.05) differed from lower elevation, and also showed a decreasing trend from lower to higher elevations. However, inconsistence trends were observed for soil organic carbon and litter along the elevation ranges. It was concluded that woodland ecosystem has a potential to accumulate higher carbon stocks in the soil than the biomass and significantly vary along elevations.