Variations and impact factors of CO<sub>2</sub> fluxes of <i>Carex cinerascens</i>-dominated and <i>Artemisia selengensis</i>-dominated wetland in Lake Poyang during drawdown periods

Abstract

于2014年10月到2015年5月鄱阳湖退水期，利用密闭箱-气相色谱法对鄱阳湖北部星子县洲滩两种代表性的植被群落——薹草（Carex cinerascens）和藜蒿（Artemisia selengensis）进行CO₂通量的对比观测，结果表明：薹草和藜蒿湿地的生态系统呼吸具有明显季节变化模式，其最小值均出现在冬季，最大值均出现在春季，平均值分别为3291.80和2581.89 mg CO₂/（m²·h），退水期薹草和藜蒿湿地累积的CO₂通量分别为213.71±2.27和176.39±11.48 t CO₂/hm².较高的生物量是薹草湿地CO₂通量高于藜蒿湿地的原因.5 cm土温是影响薹草和藜蒿湿地CO₂通量季节变化最重要的影响因子，藜蒿湿地生态系统呼吸的温度敏感性指数（Q₁₀）高于薹草湿地.水分、植物生物量和湿地CO₂通量之间无显著相关性.;By using static chamber and gas chromatography, the CO₂ fluxes from Carex cinerascens-dominated and Artemisia selengensis-dominated wetland in Xingzi County(in the Northern Lake Poyang)were measured during drawdown periods (from October 2014 to May 2015). Ecosystem respiration of the two wetlands showed an obvious seasonal variations, with the minimum value in winter and the peak value in spring,and the mean CO₂ flux for the Carex cinerascens-dominated and Artemisia selengensis-dominated wetland were 3291.80 and 2581.89 mg CO₂/(m²·h), respectively. The cumulative CO₂ fluxes were 213.71±2.27 and 176.39±11.48 t CO₂/ha for the two wetlands during drawdown periods, respectively. Furthermore, the higher CO₂ flux from Carex cinerascens-dominated wetland resulted from higher biomass. Soil temperature (5 cm) was the key factor controlling the seasonal variations of the CO₂ fluxes. The temperature coefficient (Q₁₀), an index of temperature sensitivity for respiration, was higher in Artemisia selengensis-dominated wetland, comparing to Carex cinerascens-dominated wetland. No significant correlations were found between soil moisture content and vegetation biomass and CO₂ fluxes.