Abstract: By using static chamber/gas chromatography, the CO₂ fluxes in a Carex cinerascen-dominated wetland in the Poyang Lake Nanji Wetland National Nature Reserve were measured in non-flooded period (from September 2009 to April 2010). Two treatments were installed, i.e., soil-plant system (TC) and aboveground plant removal (TJ), representing ecosystem respiration and soil respiration, respectively. There was an obvious seasonal variation in the ecosystem respiration and soil respiration. The respiration rate in treatment TC ranged from 89.57 to 1243.99 mg CO₂·m^-2·h^-1, and that in TJ was from 75.30 to 960.94 mg CO₂·m^-2·h^-1. Soil respiration  accounted for 39%-84% of ecosystem respiration, with an average of 64%. Soil temperature was the main factor controlling the ecosystem respiration and soil respiration, explaining more than 80% of the respiration variance. The temperature coefficient (Q₁₀), an index of temperature sensitivity for respiration, was 3.31 for ecosystem respiration and 2.75 for soil respiration. The Q₁₀ value was higher in winter than in autumn and spring. No significant correlation was observed between soil moisture and CO₂ fluxes. In non-flooded period, the C. cinerascens-dominated wetland acted as a carbon sink of atmospheric CO₂, with a carbon uptake of 1717.72 g C·m^-2.

Key words: Poyang Lake, wetland, ecosystem respiration, soil respiration, Q₁₀