Carbon Dioxide Fluxes and Their Environmental Control in a Reclaimed Coastal Wetland in the Yangtze Estuary

摘要: Large areas of natural coastal wetlands have suffered severely from human-driven damages or conversions (e.g., land reclamations), but carbon flux responses in reclaimed are largely unknown. The lack knowledge the environmental control mechanisms fluxes also limits budget management wetlands. net ecosystem exchange (NEE) a wetland at Dongtan Chongming Island Yangtze estuary was monitored throughout 2012 using eddy covariance technique more than 14 years after this dykes to stop tidal flooding. driving biophysical variables NEE were examined. results showed that displayed marked diurnal and seasonal variations. monthly mean functioned as CO2 sink during 9 months year, with maximum value September (−101.2 g C m−2) minimum November (−8.2 g C m−2). annual balance −558.4 g C m−2 year−1. ratio respiration (ER) gross primary production (GPP) 0.57, which suggests 57 % organic assimilated by plants consumed plant soil heterotrophic respiration. Stepwise multiple linear regressions suggested temperature photosynthetically active radiation (PAR) two dominant micrometeorological variations NEE, while moisture (M s) salinity (PSs) played minor roles. For entire PAR daytime significantly correlated, well nighttime NEE. These nonlinear relationships varied seasonally: photosynthetic rate (A max), apparent quantum yield (∂), Q 10 reached their peak values summer (17.09 μmol CO2 m−2 s−1), autumn (0.13 μmol CO2 μmol−1 photon), spring (2.16), respectively. Exceptionally high M s PSs indirectly restricted fixation capacity reducing sensitivity leaf area index (LAI) live aboveground biomass (AGBL) correlated growing season. Although distinctly lower unreclaimed same region, it quite relative many inland freshwater estuarine/coastal located latitudes higher site. Thus, is concluded although reduced reclamation, can still perform an important sink.