Abstract: Constructing allometric equation is a common method for non-destructive estimation of plant above-ground biomass (AGB). Cyperus malaccensis is a common emergent macrophyte in the estuarine tidal wetlands of Fujian and Guangdong, the allometric equation of which has not been reported. In this study, we monthly measured plant height, base diameter, fresh and dry mass of C. malaccensis shoots in the Minjiang River estuary. Based on these indicators, the allometric equations of dry and fresh mass of both the green and dead standing AGBs of C. malaccensis individuals were established with different accuracy and practicability. The dry and fresh mass (g) models are y=exp(0.14x²+0.32x-4.28) and y=exp(0.08x²+0.58x-2.56), respectively, while the dry mass (g) model of dead standing plant is y=exp(1.48x-6.76) (x is the natural logarithm of plant height (cm)). Based on the AGB models of individual plant, we established the rapid green plant AGB estimation models per unit area. The modeling method proposed here is valuable for the AGB modeling of other salt marsh plants in estuaries and coastal areas. The models built in our study can provide technical support for the estimation of AGB and blue carbon sink of the coastal C. malaccensis marshes.

Key words: emergent macrophyte, allometric equation, carbon sink, coastal wetland, Minjiang River estuary.