Seasonal changes of potassium, calcium, and magnesium and their accumulation in different phenotype Suaeda salsa communities in a tidal flat of the Yellow River estuary.

The seasonal changes of potassium (K),calcium (Ca),and magnesium (Mg) and their accumulation in different phenotypes of Suaeda salsa in the intertidal zone of the Yellow River estuary were studied from May to November 2008.The biomass of different organs of S.salsa in the middle (JP1) and low (JP2) tidal flats showed significant seasonal dynamics,and the values of JP1 were generally greater than those of JP2,according to a parabola model.The amounts of JP1 and JP2 bulk litter increased during the growing season,and could be described by an exponential growth model.The changing patterns of K,Ca,and Mg content in different parts of JP1 and JP2 were different:Changes of K content almost accorded with parabola or linear models,while changes of Ca and Mg contents generally accorded with Gauss curves.The K,Ca,and Mg contents in different parts of JP1 and JP2 at different time periods were significantly different,and the values in the root,leaf and litter of JP1 were much greater than those of JP2,while the Ca,Mg contents in the stem of JP2 were much greater than those of JP1.In addition,the correlations,storage,and accumulation rates of K,Ca,and Mg in different plant parts were also significantly different.In general,the stem and leaf were the main K storage sites,providing 43.02%±20.80% of total storage in JP1 and 48.03%±4.31% in JP2.The leaf was the main storage site for Ca and Mg,providing 40.38%±18.34% and 50.58%±20.73% of the total storage in JP1 and 62.96%±10.56% and 58.02%±10.62% in JP2.Further studies indicated that the differences of biomass,nutrient (K,Ca,Mg) content,storage and accumulation rate in different plant parts between JP1 and JP2 were mainly due to their ecological characteristics,nutrient function of the different organs,and the water or salinity status in the S.salsa habitat.