ABSTRACT Climate change is the most serious global problem due to the abundance of carbon dioxide in the atmosphere. This study was conducted in Weira-Amba and Bededo Forests, with the objectives of estimating of the carbon stock and its variation along the environmental gradients and species diversity. A systematic sampling method was used to conduct the vegetation sampling. In order to collect vegetation data a total of 30 sample plots were used, in each plot with the size of 50m x 50m nested plot design were used, with at an interval of 50 m between plots and were laid along the established transects at 100m apart. The Shannon-Wiener diversity index showed that both forests were natural regenerations and plantations. So, their evenness were almost equal, no difference between them. But according to diversity Weira-Amba forest was more diverse with (Hʹ) 2.424 than Bededo forest. The major tree species for carbon stock sinkers at Weira-Amba forest was Acacia Senegal 35.986 %, Eucalyptus camaldulensis 20.471 % and Olea europaea 15.886 % whereas, at Bededo forest Cupressus lusitanica and Eucalyptus globules by accounted 66.344 and 32.288 % respectively. Related to Aspect at Weira-Amba forest higher mean values of above and below ground biomass have got on North-West aspects, whereas in Bededo forest higher mean values of above and below ground biomass were recorded on Southwest and South aspects. The highest total mean carbon stock density at Weira-Amba forest got from medium elevation and at the Bededo forest at upper elevations 184.15 and 226.47 tons of carbon ha-1 were recorded respectively. Mean carbon stocks of the aboveground and below ground carbon in the Weira-Amba forest was a statistically significant difference in elevation (P < 0.05) p=0.043 also in aspect gradient p=0.015. But in Bededo forest there was no significant difference between them. Generally the elevation difference, species type, and aspect gradient were factors that affect the different carbon pools of the forest. From the point of view of managing forests for climate change mitigation, the result suggested that the forest should be conserved and protected in a sustainable way for further carbon sinks. Keywords: Aspect, carbon stock, elevation and species diversity