Research Article
Aklilu Bajigo, Mikrewongel Tad
Abstract
This study was conducted in Gunugo watershed at Wolayitta zone to estimate the amount of carbon stored in traditional agroforestry practices and along different elevation gradients. Dominant agroforestry practices (home garden, parkland and woodlot) were used, and the elevation gradient was stratified in to upper, middle and lower altitudes. With three replications, a total of 27 sampling points were used. A complete measure in home garden, 50 m × 100 m quadrates in parklands, and 10 m × 10 m quadrates for woodlot were used and DBH and height was measured. At every sampling point in a 20 × 20 m plot, soil samples were taken from top and sub soil at each corner and at center. One composite sample was taken from each sampling point at each soil depths, to have a total of 54 soil samples. Then, above ground and below ground tree carbon, total tree biomass carbon, soil organic carbon and total carbon in agroforestry practices and along elevation gradient was determined at p<0.05. From the agroforestry practices, woodlot was significantly higher in above ground tree carbon (106.47 Mg/ha), total tree biomass carbon (133.09 Mg/ha) and total carbon (448 Mg/ha) followed by home gardens and parklands. However, there was no significant difference in soil organic carbon among agroforestry practices even though higher concentration was observed under home garden. Despite no significant differences was seen between elevation gradients for above ground tree carbon, total biomass tree carbon, soil organic carbon and total carbon. It had the order of lower>middle>upper elevation, suggesting that more plantations are needed in upper and middle elevation for better carbon storage. Lower elevation was dominated by high density Eucalyptus woodlot, had better total carbon stock. However, Eucalyptus woodlot would create drought, so that it needs to be replaced by other fast growing trees such as Gravillea Robusta.