Carbon Stock potential across the age of exclosure of Woodland in Dire Dawa, Eastern Ethiopia

Abstract Exclosure is feasible to rehabilitate the degraded lands in terms of cost and time of recovery and offers valuable benefits to the community. However, the effectiveness and performance of established exclosures to restore biomass and soil organic carbon stock with their age difference were not determined, and little attention was paid to exclosures in the study area. So that the main aim of this study was to assess the effect of exclosure age on biomass and soil organic carbon stock of degraded woodlands in the Dire Dawa administration. Exclosure of ages 4, 6, 8, and 10 years were selected based on their accessibility and year of establishment. 24 sample plots were taken to collect vegetation and soil samples. Nested plots with a size of 50 m x 50 m, 20 m x 20 m, and 5 m x 5 m were laid systematically to measure trees with a diameter at breast height of 1.37 cm, and also 1 m x 1 m was used for soil sampling. Aboveground carbon stocks were estimated using the allometric equation, while soil organic carbon was analyzed using the Walkley-Black method. Means variation among the exclosure ages tested using one-way ANOVA at p < 0.05. The results showed that the highest mean of aboveground biomass was 2.93 ± 1 .35 ton ha⁻¹, below ground ( 1.65 ± 0.87 ton ha⁻¹), and soil carbon stock (30.09 ± 0.014 ton ha⁻¹) recorded in exclosure of age 10 compared to the mean of biomass and soil carbon stock estimated in exclosure ages 8, 6, and 4. The long period of protection, sustainable land management, and succession are among the reasons for variation in biomass, soil carbon, and the direct relationship between age and total biomass. Therefore, the age of exclosure can affect biomass and soil organic carbon. Supporting exclosure sites with the management plan could enhance the potential of carbon stock aboveground, belowground, and in soil , which could mitigate climate change.