Net Primary Productivity And Nitrogen And Phosphrous Dynamics Of Dominant Plants In The Wetland Of Minjiang River Estuary

In this paper, the structure characteristics and biomass of an invasive plant, Spartina alterniflora, and indigenous plants, Phragmites australis and Cyperus malaccensis Lam.var. brevifolius Bocklr, were compared in the wetland of Minjiang River estuary. The concentration and accumulation of the N,P elements in net primary productivity(NPP) of three commuities were measured, and the soil factors affecting the NPP of wetlands plants were also discussed.The research result indicated that: there was a significant negative correlation between the height and density in three commuities (P<0.01). The concentration and accumulation of the N,P elements and biomass structure were difference in different season. Seasonal dynamic of biomass and accumulation of the N,P elements in three commuities had single peak. NPP of P. australis, C. malaccensis and S. alterniflora was rearched 1056.75gC·m^-2·a^-1,1035.13gC·m^-2·a^-1 and 1401.40gC·m^-2·a^-1, respectively. NPP of S. alterniflora was higher than that of P. australis and C. malaccensis, and it has the trend of expansion. All of the three plants NPP were nitrogen-limited, and there was a significant correlation between accumulation of the N element and biomass in three plants (P<0.05). The soil factors which affect NPP were different. By the grey correlative analysis of all environmental factors, Eh and temperature in the soil were the primary factors which affect the NPP of P. australis and C. malaccensis, but for S. alterniflora, salinity and pH in the soil were the primary factors. The concentration and accumulation of N element in three commuities were significantly higher than P element (P<0.01). The highest accumulation of N and P elements of S. alterniflora were 33.01-55.43 g·m^-2 and 4.29-5.46 g·m^-2 . Clearly, removals of S. alterniflora through harvesting can be an effective management protocols to reduce nutrients from the site.