Carbon, nitrogen and phosphorus ecological stoichiometric ratios among live plant-litter-soil systems in estuarine wetland Carbon, nitrogen and phosphorus stoichiometric characteristics during the decomposition of Spartina alterniflora and Cyperus malaccensis var. brevifolius litters Soil carbon, nitrogen and phosphorus ecological stoichiometry of Phragmites australis wetlands in different reaches in Minjiang River estuary Stoichiometry of carbon dioxide and methane emissions in Minjiang River estuarine tidal wetland