Carbon stock variation along altitudinal and slope gradients in gara–muktar forest, west hararghe zone, Eastern Ethiopia

Abstract

Forests play vital role in combating climate change through carbon sequestration in the atmosphere and serving as a carbon sink. The species composition and carbon stock were studied along environmental gradients using systematic sampling method. Data were collected in the 36 quadrant plots of 20 x 20m each distributed along transect lines. Diameter at breast ≥5cm and total height measured for each tree in the main plot. Above and below ground biomass was estimated using allometric equation, while the litter carbon was estimated by taking 50% of dry biomass as carbon. Soil sample was collected using auguring method and carbon was analyzed following Walkley-Black method, while bulk density analyzed using oven dried method. The data was analyzed was performed using one way ANOVA of R software. The carbon stocks in aboveground, belowground, litter biomass and soil organic carbon showed distinct variation along environmental gradients. The aboveground and below ground carbon stock was showed a decreasing trend along with increasing altitude, while soil organic carbon and liter carbon showed increasing trend along with increasing in altitude. The mean above and below ground carbon stocks were 156.60 t C ha-1 and 31.32 t C ha-1 respectively whereas, litter carbon and soil organic carbon stocks were 2.72 t C ha-1 and 125.86 t C ha-1 respectively. The total carbon stock density of Gara- Mukitar forest was found to be 316.6±67.15 t C ha-1. Similarly 49.5% of carbon was contained in the above ground biomass, 9.9% in below ground biomass, 0.9% in litter carbon and 39.8% in soil organic carbon (0-30 cm depth), respectively. The analysis of carbon stock variation of different carbon pools along altitude of the forest showed a significant variation, whereas the above and belowground carbon stock variation with slope gradient was also significant except soil organic carbon and liter carbon. In conclusion Gara-muktar forest is a reservoir of high carbon, since it has a good capacity to sink carbon from the atmosphere having positive role in reduction of greenhouse gases. Therefore, proper community based forest management options should be implemented for its continuity.