An Assessment of Carbon Stock in Eucalyptus Forest with Variation in Stand Age in Rawatamai Afforestation Project Area, Jhapa, Nepal

The research was focused to quantify and compare variation of carbon stock (above and below ground) with various age stands in planted living biomass of Eucalyptus forest. Four sample plots were established in each hector for single aged plantation area. Concentric circular plots were established to measure forest biomass. Eucalyptus plants of different stand age up to pole were measured establishing circle of radius 5.64 m. For determining soil carbon content, 3 soil samples (0-10 cm, 11-20 cm and 21-30 cm) up to a depth of 30 cm were collected randomly and made composite mixing soil from each sample plots in same proportion. Collected soil sample were tested in laboratory to determine the carbon content. The data obtained from lab were analyzed with the carbon stock calculation formula proposed by Pukkala (1990) and Walkley (1958). It was carried out to assess and quantify the soil and vegetation carbon stock as well as carbon stock variation in soil and vegetation in Eucalyptus forest with variation in stand age. Random sampling was used for the estimation of above ground and below ground biomass. The biomass carbon content was taken 47% of the dry biomass as followed by Total stem volume was calculated using equation developed by Chave et. al. (2005). Root carbon was calculated as 12.5% of above ground carbon. The average bulk density of Ratuwamai Afforestation Project (RAP) was found to be 1.44 gm./cu.cm. Similarly the average soil organic carbon percent of RAP was found to be 1.19. And the average soil organic carbon percent in 0-10 cm, 11-20 cm & 21-30 cm was 1.61, 1.19 & 0.91 respectively. The total amount of soil organic carbon up to 30 cm depth in RAP was 35.97 t/ha. The carbon stock in Eucalyptus was increased with the increase in stand age. The soil carbon was fluctuated with age as well as with the presence & absence of the vegetation. Keywords: Forest Biomass, Root Carbon, Bulk density, Soil Organic Carbon, Vegetatio