Preliminary assessment on above ground carbon stock of agroforestry and monoculture crop systems in peatlands

Abstract

Peatlands can be used for crop cultivation with various combination patterns both agroforestry and monoculture systems. Utilization of these lands not only produces high economic value products, but also contributes in providing environmental services, including carbon sequestration. This study aims to measure aboveground carbon stock of agroforestry and agricultural monoculture systems in Rasau Jaya, Kubu Raya Regency, West Kalimantan Province. The agroforestry system observed is divided based on the level of peat depth, which are 0-2 m and 3-4 m. The pattern of agroforestry at a depth of 0-2 m is a combination of timber and non timber tree species and agricultural crops, while the pattern of agroforestry at a depth of 3-4 m is a combination of timber and non-timber tree species and plantation crops. Timber tree species are Pulai (Alstonia pneumatohara) and Gerunggang (Cratoxylon arborescens Bl); the non-timber tree species is jelutung (Dyera costulata); and plantation crop species are Jengkol (Archidendron pauciflorum) and Pinang (Areca catechu); and the agricultural crops are peanuts, cayenne pepper, tomatoes, bitter melon and eggplant. Observations were also conductedon the agricultural monoculture pattern, including the eggplant, chili, bitter melon and tomato. The components of measured carbon stocks are plant biomass (trees and lower plants), wooden necromasses, non-woody necromasses, and wild plant biomass. The measurement results show a shallow peat agroforestry system (0-2 m) with a combination of one year old trees and agricultural crops contributing to carbon stock of 0.8 tons/ha. Deep peat agroforestry systems (3-4m) with a combination of timber trees, non-timber trees and plantation crops contribute to carbon stocks of 3 tons/ha. While the monoculture system of agricultural crops produce an average carbon stock of 1.1 tons/ha. Contribution of tree component in the agroforestry system are still relatively small, which is 2.6% of total carbon stock. However, it is estimated that the carbon stocks will continue to increase with increasing age.