Abstract
Exclosure is one option of in degraded lands to promoting to restore above and belowground biomass productivity and soil carbon contents in Ethiopia especially in Tigray. The study was conducted to assess the total amount of carbon stocks of above ground, belowground, and soil organic carbon stock in the exclosure and adjacent open grazing land and soil depth layers.
The systematic sampling method was used for collecting the biophysical and soil data for estimating total carbon stocks. To collected field data inventory of diameter at breast or stump height of ≥2.5cm along the two land uses employed 51 plots (41 plots from exclosure and 10 from open free grazing land) a size of 100m2. The 204 soil samples were taken from two soil layers of 0-15cm and 15-30cm depth to determine soil carbon stock of the two land uses. The soil organic carbon was analyzed in a laboratory using the Walkley-Black method. Above-ground biomass or carbon stocks were estimated using the allometric equation of (Mengesteab Hailu et al., 2018) that is develops in the Tigray semi-arid exclosure area. The belowground biomass was estimated using 27% root shoot ratio method. One way analyses of variance (ANOVA) with Tukey’s post hoc test were conducted to test the effect of land uses and soil depth on carbon stock density. The total mean carbon stock result of the Gundi-etki study area was 20.48±0.72 and 15.38±0.94 tons of carbon per hectare respectively in exclosure and free grazing land and had a significant difference at (p=0.007). The soil has a higher carbon stock proportion (83.42%) and followed aboveground (13.05%) and belowground (3.52%). The topsoil layer had significantly higher total mean soil carbon stock at a 95% confidence interval (p=0.008) than the lower soil depth of the study area. Conclusion; exclosure had four times significantly higher ecosystem carbon stocks than adjacent open free grazing land. The topsoil layer is having significantly higher soil carbon stock than the lower soil depth layer. Recommendation; exclosure had a positive value for improved above ground, below ground, and soil carbon stock; it should be necessary to expand to other nonexclosure areas. It should be necessarily establishment area exclosure widely in semi-arid areas of Tigray region and specific study Woreda Ahferom to increases vegetation biomass, carbon stocks restoration potentials, and minimizing soil organic carbon stock or soil organic matter depletion.
Keywords: carbon stock, Exclosure, free grazing land, soil depth, soil organic carbon.
