Study on Biomass Dynamics of Phragmites australis and Spartina alterniflora in the Wetlands of Minjiang River Estuary

Two populations,Phragmites australis and Spartina alterniflora growing in the wetlands of Minjiang River Estuary,were studied,in terms of their structural and biomass characteristics.The major findings were:for both,there was a significantly negative correlation between plant height and density;for Phragmites australis,the highest aboveground biomass was 1 524.8±78.85 g·m-2,appearing in summer season,but for Spartina alterniflora the value would be 3 037.2±248.78 g·m-2,and the season was autumn instead of summer;the aboveground biomass of Spartina alterniflora was significantly greater than that of Phragmites australis(P0.05),but for withering biomass,no significant difference existed(P0.05);for both,the belowground biomass decreased with depth(0～15 cm15～30 cm30～60 cm);for Phragmites australis,the biomass in summer season was greatly higher than in other seasons,but for Spartina alterniflora,the peak season was winter,with its biomass gradually decreasing to the lowest point in summer;for both plants,the total biomass accumulation dynamics showed a single peak pattern within a year;and,the total biomass of Spartina alterniflora was higher,but not at significant level,than that of Phragmites australis.Finally,it was predicted that the total biomass of Spartina alterniflora,which was identified as a kind of invasive species for the study area,would continue to increase over time in the future.