Tropical mountain forests contribute greatly to carbon sequestration and reduction of carbon levels in the atmosphere. In order to achieve the “Reducing Emission from forest deforestation and degradation” (REDD +) objectives, reliable information on carbon sequestration of all forest management areas is required. So, this study aims to determine the amount of above ground carbon bound in trees and how carbon sequestration capacity of trees varies with altitudinal change in the Magamba Nature Forest Reserve. A random stratified coordinate by elevation method was used, measuring approximately 2636 tree of 5<diameter at breast height (DBH) distributed across 29 plots with a total area of 2.03ha. The effect of altitude was tested using ANOVA and Pearson correlation test. The results show that there is a significant (p<0.05) positive correlation between aboveground carbon sequestered and elevation, and that there was significant difference (p<0.02) in the amount of aboveground carbon stored between low elevation (147.5 tones ha^-1) mid elevation (244.86 tonnes ha^-1) and high elevation (245.4 tones ha^-1). The lower amount of carbon at low elevation may be due to anthropogenic activities including logging and fuel production, since it is easier to reach lower altitude than higher altitude forest zone. To improve carbon sequestration capacity of tropical Mountain protected forests, participatory protective measure at lower elevation zones are of importance. These should even be included in management plans, detailing the involvement of adjacent community.