Forest carbon stock variation with altitude in bolale natural forest, Western Ethiopia

Abstract

This study was initiated to assess forest carbon stock variation with altitude. A systematic sampling technique was used to select sample plots. A total of 36 (12 plots from each altitude class) square plots with size of 20 m × 20 m were obtained. Diameter at breast height (DBH) and height of individual trees of DBH > 5 cm were measured from all the selected sample plots. A total of 216 soil samples, 108 for analysis of soil organic carbon (SOC) fraction (% C), and 108 for bulk density determination (BD), were collected. Altitude had a significant effect on above and belowground tree biomass, and litter carbon stock, but not on deadwood, and soil organic carbon stock. The aboveground and belowground biomass and litter carbon were higher at lower altitudes, which were attributed to higher biomass production due to higher photosynthesis and higher net primary production. Soil organic carbon varied significantly with depth. A higher soil organic carbon stock was observed at the upper soil depth (0–10 cm). At lower soil depths, carbon stocks were smaller due to less plant residue and less biological activity in the deeper soil. In general, the study found that carbon density is high at lower altitudes and lower at higher altitudes. Therefore, altitude should be given due consideration for forest development and management for climate change mitigation. The result suggests that different governmental and nongovernmental organizations have to give due attention for forest conservation to reduce the CO2 emmission.