ESTIMATING WATERSHED-SCALE FOREST BIOMASS AND ANNUAL SUSTAINABLE SUPPLY OF BIOFUEL FOR THE LOCAL COMMUNITIES OF TIGRAY, NORTHERN ETHIOPIA

Abstract

Estimating forest biomass is an important component of planning and decision-making in the course of forest management. The main objective of this study was to estimate watershed-scale forest biomass and analyse the supply and biofuel demand of the local communities. This study was conducted in Hawza and Gemad watersheds located in Kilte-awlaelo district in the eastern zone of Tigray, northern Ethiopia. We used both destructive and non-destructive sampling methods to collect biomass data from the two watersheds located in the district. To develop regression functions, tree parameters such as diameter at stump height, diameter at breast height, crown diameter and total height of individual trees were measured. We used a locally developed biomass model as well as recommended pre-developed biomass and yield models to estimate watershed-scale aboveground biomass. In this study, a locally developed model with log transformed diameter at stump height was the best estimator of aboveground biomass with co-efficient of determination, R2 = 0.96, 0.91 and 0.92 for total tree, stem and branch component models, respectively. Our study shows that with the estimated annual biofuel demand of 10986.36 tons and the estimated annual sustainable supply of only 3725.85 tons, the local communities living in the two watersheds experienced a deficit of about three times the sustainable biofuel supply. Based on our study, the biomass from the two watersheds are not satisfying the biofuel and fuelwood consumptions of the local communities. Therefore, we recommend private plantations of high biomass generating tree species and other feasible energy alternatives that might increase the existing energy supply of the local communities.