Demissew, Sebsebe (Professor)Seta, Talemos2018-07-192023-11-092018-07-192023-11-092017-06http://etd.aau.edu.et/handle/123456789/9364The Afromontane forests of Ethiopia have been under a serious degradation threat. Understanding forest structure, floristic compositions and their important roles in providing ecosystem functions like climate change mitigation through carbon sequestration and nutrient flow dynamics are important in targeting sustainable forest management strategies. Therefore, the major objectives of this study were to determine; i/ forest structure, plant community composition in relation to environmental factors and carbon stocks of Biteyu forest and ii/ quantifying forest structure, carbon stocks, litterfall and leaf litter decomposition dynamics, and nutrient release patterns from the Boter- Becho forest. Systematic sampling technique was employed for vegetation and environmental data collection. Thirty plots of 900 m2 and 71 plots of the same quadrat size were selected from the Biteyu and Boter-Becho forests, respectively. Total carbon stocks (t ha-1) were estimated from aboveground biomass, belowground bimass, soil and forest litter carbon pools. The appropriate allometric models were applied for aboveground and belowground biomass estimations. To determine litterfall dynamics in Boter-Becho forest, two sites of the forest namely, low disturbed (LD) and high disturbed (HD) were selected subjectively using field observations. A total of 20 litter traps, ten for each site were deployed. Two hundred forty collections were made from 4th March 2014 to 3rd February 2015, and monthly collections were oven dried at 80 0C for 24 hrs to constant weight. Similarly, the decomposition rate of leaf litter in Boter-Becho forest was investigated using the first order negative exponential decay equation. Different data analyses techniques were employed using R statistical software. The findings showed 190 plant species distributed among 154 genera and 73 families in Biteyu forest. Moreover, altitude and slope strongly affect the community structure of Biteyu forest. The estimates of total carbon stock in Biteyu and Boter-Becho forests was 166 ± 16.4 and 393 ± 24 t ha- ,1 respectively. On the other hand, the amount of total litterfall estimated in Boter-Becho forest was 8.7 t ha- l yr-1. At the end of one year, 66.02% and 66.72% of the leaf litter was decomposed in LD and HD sites, respectively. Consequently, the annual decomposition rate constant measured for Boter-Becho forest was 1.405 year-1(the average of the two sites). With regard to carbon and nutrient release in the Boter-Becho forest, there was no significant difference (P > 0.05) in their mean concentration remaining except K between two sites. Similarly, no strong relationships were observed between initial leaf litter chemistry and C, N, P concentration (P > 0.05) released during the decomposition in both sites. There was high anthropogenic effect and high dependence of the local community in Biteyu forest so that forest conservation and restoration measures should be sought. Moreover, the variation in rainfall and temperature are responsible for controlling litterfall production, rate of litter decomposition, C and nutrient release pattern in the Boter-Becho forest. Therefore, the interventions, which reduce the climate change effect, would be very important in the maintenance of forest ecosystem functioning. Key-words/phrases: Biteyu-forest, Boter-Becho forest, Carbon stocks, forest disturbance, leaf litter decomposition, Litterfall, Nutrient ReleaseenBiteyu-forestBoter-Becho forestCarbon stocksForest disturbanceleaf litter decompositionLitterfall, Nutrient ReleaseThesis