Regular Article J F E S Journal of Forest and Environmental Science pISSN: 2288-9744, eISSN: 2288-9752 Journal of Forest and Environmental Science Vol. 36, No. 1, pp. 25-36, March, 2020 https://doi.org/10.7747/JFES.2020.36.1.25 J For Environ Sci 36(1), 25-36 25 Acacia Dominated Area Exclosures Enhance the Carbon Sequestration Potential of Degraded Dryland Forest Ecosystems Zenebu Halefom 1 , Fassil Kebede 2 , Ibrahim Fitwi 3 , Zenebe Abraha 3 , Girmay Gebresamuel 3 and Emiru Birhane 3,4, * 1 Mekelle Zone Bureau of Agriculture, Mining and Energy, Mekelle 38, Ethiopia 2 Gonder University, College of Agriculture and Veterinery, Gonder 196, Ethiopia 3 Mekelle University, College of Dryland Agriculture and Natural Resources, Mekelle 231, Ethiopia 4 Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Ås 5003, Norway Abstract Area exclosure is a widely practiced intervention of restoring degraded lands though its impact in sequestering terrestrial and soil carbon is scanty. The study was initiated to investigate the effect of exclosure of different ages on carbon sequestration potential of restoring degraded dryland ecosystems in eastern Tigray, northern Ethiopia. Twelve plots each divided into three layers were randomly selected from 5, 10 and 15 years old exclosures and paired adjacent open grazing land. Tree and shrub biomasses were determined using destructive sampling while herb layer biomass was determined using total harvest. The average total biomass obtained were 13.6, 24.8, 27.1, and 55.5 Mg ha -1 for open grazing, 5 years, 10 years, and 15 years exclosures respectively. The carbon content of plant species ranged between 48 to 53 percent of a dry biomass. The total carbon stored in the 5 years, 10 years and 15 years age exclosures were 39 Mg C ha -1 , 46.3 Mg C ha -1 , and 64.6 Mg C ha -1 respectively while in the open grazing land the value was 24.7 Mg C ha -1 . Carbon stock is age dependent and increases with age. The difference in total carbon content between exclosures and open grazing land varied between 14.3-40 Mg C ha -1 . Although it is difficult to extrapolate this result for a longer future, the average annual carbon being sequestered in the oldest exclosure was about 2.7 Mg C ha -1 yr -1 . In view of improving degraded area and sequestering carbon, area exclosures are promising options. Key Words: area exclosure, biomass, carbon sequestration, vegetation, northern Ethiopia Received: January 4, 2018. Revised: December 13, 2019. Accepted: December 15, 2019. Corresponding author: Emiru Birhane Mekelle University, College of Dryland Agriculture and Natural Resources, Mekelle 231, Ethiopia Tel: 251344409018, Fax: 251344409304, E-mail: emiru.birhane@mu.edu.et Introduction Ethiopian population relies heavily on wood and biomass fuel for household energy (Badege and Abdu 2003). Scarcity of firewood has become acute in many parts of the country causing a continuous rise in prices, and thus in- creasing the economic burden on the household budget. This forced the people to clear forest for domestic use. Also animal dung and crop residues are increasingly being used for household fuel rather than being added to the soil to im- prove soil fertility. Associated with the environmental changes that resulted from deforestation and poor land management, there has been loss of carbon to the atmos- phere which contributed to the climate change (Itana et al. 2011). Soils of the world are potentially sources and sinks for atmospheric carbon depending on the management of