Factors affecting woody carbon stock in Sirso moist evergreen Afromontane forest, southern Ethiopia: implications for climate change mitigation

Abstract

Among the many other factors that would be taken as one of the most important options for climate change mitigation is forest wood carbon stock. Hence, the aim of this study was to examine the carbon stock potential of woody species and how it varies by community types and topographic aspects, along altitudinal and slope gradients in Sirso moist evergreen Afromontane vegetation ecosystem of southern Ethiopia. To collect data, a systematic sampling procedure was employed. Five transects were laid out across altitudinal gradients which aligned parallel at 2 km intervals, and 50 sample plots (20 m × 20 m) were laid along transects at 100 m altitudinal interval. Carbon stock was estimated based on the equations and conversion factors formulated for tropical forest carbon stock measurement. The results showed that the total carbon stock of woody species in Sirso moist evergreen Afromontane forest was 384.44 ton/ha. The carbon stock of woody species varied among community types, along altitudinal and slope gradients, while topographic aspect had no significant effect. The carbon stock was higher for the community type of Dracaena fragrans–Rytigynia neglecta, for mid-altitude (1934–2319 m.a.s.l.), and upper slope class (58–75%). Schefflera abyssinica, Syzygium guineense, and Ficus sur contributed 49% of the total carbon stock. Our study suggests that selecting a certain forest as the mitigation option for climate change needs to consider the determinants including vegetation composition and topographic features such as altitude and slope gradients.