ESTIMATION OF ORGANIC CARBON FLUX FROM TWO STREAMS IN TROPICAL PEAT SWAMP FOREST OF RIAU PROVINCE, SUMATRA, INDONESIA

摘要

Organic carbon (C) fluxes (i.e. organic C load and C yields) were estimated in two stream of tropical peat swamp forest (TPSF) within a peatland area of Riau Province, Sumatra, Indonesia. One stream, Meranti Ditch (MD) is an artificial ditch with a small catchment (4.8 km~2) in semi-intact condition. Another stream, Turip River (TR) is a large catchment (458 km~2) covered with TPSF that is largely intact. Due to large content of carbon store in TPSF, it is necessary to know how much organic C fluxes in the stream are released from this type of landscape. By combining the concentration of total organic carbon (TOC) with continuous discharge, organic C load (Gg C yr~(-1)) in TPSF stream water was estimated. Organic C yields (g Cm~2 yr~(-1)) were obtained from C load divided by catchment area. Stream dissolved organic carbon (DOC) constituted the greatest portion (95.0 to 99.8% in concentration) of TOC, with stream TOC concentration in MD range from 85 to 94 mg C l~(-1) which was higher compared to the TR range from 50 to 58 mg C l~(-1). The high concentration in MD is expected as this catchment has been disturbed from several rounds of logging including intensive pattern of ditch dug a decade ago. TOC load of stream water in MD and TR were 0.23 and 14.0 Gg C yr~(-1) respectively. TOC yields or fluxes through the fluvial system ranged from 26.2 g Cm~2 yr~(-1) in TR to 55.5 g Cm~2 yr~(-1) in MD.