Agroforestry System and Their Carbon Stock in Terai and Mid-Hill Regions of Central Nepal

Abstract

Trees and forests play a critical role in human livelihood as well as in ecosystem functioning. Agricultural emissions from crop and livestock production grew from 4.7 billion tons of CO eq. per year in 2001 to over 5.3 billion tons in 2011 due to agriculture fermentation. Compensation in loss of biodiversity, concern of food security, improvement in the living standard by generating income and the global issue of climate change related with carbon sequestration can be addressed with the scientific knowledge of agroforestry system. It can directly store carbon in tree components and potentially slows down the deforestation rate by reducing the need to clear forest land for agriculture. In the country like Nepal which is very suitable for agriculture, the agroforestry practice can be highly demanding for the overall growth of the nation. The study was carried out in Terai and mid-hill physiographic region. This study focuses mostly on the species grown in the home garden for the various purposes and to determine the total carbon stock of these two regions. The plot of 20×20m 2 was set up and the trees inside the plot were listed, counted and the various parameters like dbh, angle of elevation and distance between the observer and tree were measured for biomass carbon stock. The study was conducted in 30 home-gardens from Terai and 50 from midhill. Total 171 species were

recorded in the study. Shannon's index was 1.247 in Terai and 1.216 in mid-hill. Simpson's index was 0.0915 in Terai and 0.087 in mid-hill. The total mean tree trunk volume was found to be 17.46 m 3 /ha. The average total biomass was significantly greater in Terai (21.314 t/ha) than in mid-hill (11.203 t/ha). The mean of total biomass carbon stock was found to be 10.255 tons C / ha and 5.24 tons C / ha for Terai and mid-hill respectively. The soil was collected from 0-20 cm depth. 80 soil samples were air dried and brought to laboratory for further analysis of soil carbon stock. The study found the soil bulk density to be 1.38 g/cm 3 in Terai and 1.076 g/cm in midhill region. The soil carbon stock was found to be 61.17 t C ha -1 in Terai and 67.608 t C ha -1 in mid-hill. The biomass carbon stock and soil carbon stock were summed up to obtain the total carbon stock. However, the study found no significant difference in the total carbon stock between the two regions i.e. 71.433 t C/ha in Terai and 72.856 t C/ha in mid-hill. 2 3 Though agroforestry does not contribute as much as the forest, however, it can store enough significant amount of carbon when designed in a proper way. Thus, agroforestry system can be proved to be one of the best alternatives to cope with the alarming problem of biodiversity loss, food security and climate change. Starting from a small area around the home, it can create its impact to the global scale.

Keywords: Species diversity, Uses, Biomass carbon stock, Soil carbon stock.