CARBON STOCK QUANTIFICATION AND TREE DIVERSITY ASSESMENT OF HOMEGARDENS IN RANGPUR DISTRICT

Abstract

Homegarden systems are suggested to hold a large potential for carbon (C) sequestration, especially for climate change mitigation and adaptation under changing environment. This is due to their multifunctional ecosystem services while decreasing pressure on natural forests and hence saving and storing carbon. In this research total above and bellow ground carbon stock, tree species diversity and soil organic carbon were quantified in homegarden around four villages of two Upazila of Rangpur district in northern part of Bangladesh. A total 64 homegardens were sampled on size, diameter at breast height of trees, tree height and tree species diversity. Using allometric equations, assuming C as 50% of biomass a total mean above and bellow ground biomass carbon stocks (AGB+BGB) was found 53.53Mg ha -1 . Mean carbon stock per unit area was higher in small homegarden (69.15 Mg ha -1 ) compared to medium (47.96 Mg ha -1 ) and large (39.93 Mg ha -1 ) homegarden. In total 1671 trees were sampled and 32 different tree species were identified and recorded. The Shannon Wiener index was used to evaluate the tree diversity per homegarden and it ranged from 1.00 to 2.2 with a mean value of 1.64. For determination of soil organic carbon (SOC), soil sample were collected from two depths (5-10 cm and 20-25cm) at two different sampling sites of sampled homegardens. The average value of SOC was found 49.24 Mg ha -1 where small size homegarden had high tree density contain highest amount of SOC (63.62 Mg ha -1 ) per unit area compared to medium (42.80 Mg ha ) and large (38.50 Mg ha -1 ) size homegardens. These results imply that homegarden can serve as an important ecological tool in terms of carbon sequestration, conservation of tree species diversity and storage of soil organic carbon. However specific homegarden management plan for increased carbon sequestration potentiality and conservation of homegarden species diversity through scientific management should be encouraged for further investigation in this region. This result also useful for whether homegarden should be considered to be included in the UN-REDD+ National Program as an activity to enhance natural forest cover within Bangladesh.