Soil properties and ecosystem respiration characterization of mudflat in Lake Dongting during drawdown period

Abstract

于2015年1月洞庭湖枯水期，针对不同出露时间下的洲滩，调查其土壤理化性质，并利用LI-8100便携式二氧化碳气体分析仪监测其生态系统呼吸.结果表明：在洞庭湖枯水期，洲滩出露后，洲滩土壤有机质、硝态氮、铵态氮和全氮含量随出露时间增长而先升高后降低.土壤溶解性有机碳含量是影响洞庭湖枯水期洲滩生态系统呼吸强度的最重要影响因子.溶解性有机碳含量随出露时间增长而提高，洲滩生态系统呼吸强度随之提高，并在洲滩出露约60天后达到最高值.出露洲滩生态系统呼吸通量均值为0.72±0.55 μmol/（m²·s），超过杨树林地、芦苇地和农田地，成为洞庭湖区冬季CO₂排放最活跃的区域.;Soil properties from mudflat at different exposure duration level were investigated during the drawdown period of Lake Dongting in January 2015. The ecosystem respiration was also measured using LI-8100 soil CO₂ flux system. After mudflat's exposing to the air, soil organic matters, soil nitrate nitrogen, soil ammonium nitrogen and soil total nitrogen contents increased at early time, then decreased. Dissolved organic carbon was the most important driving factor for the ecosystem respiration from mudflat during the drawdown period of Lake Dongting. The dissolved organic carbon value was monotonic increasing with the time of mudflat exposing to the air increasing, which strengthens ecosystem respiration from mudflat. The ecosystem respiration flux achieved peak value about 60 days after exposing to the air. The mean ecosystem respiration flux from mudflat was 0.72±0.55 μmol/(m²·s), exceeding the fluxes from poplars, reeds and farmlands. The exposed mudflat became the mainly active CO₂ releasing area in Lake Dongting during the drawdown period.