[Biomass structure and nitrogen and phosphorus contents of Calamagrostis angustifolia populations in different communities of Sanjiang Plain].
Calamagrostis angustifolia is the dominant species in the typical meadow and marsh meadow communities of Sanjiang Plain. The study on its biomass structure and the N and P contents in its different organs showed that the biomass of different C. angustifolia organs in the two types of wetland communities was distinctly different, which could be described by Y = A + B1t + B2t2 + B3t3. The biomass of aboveground part and each organ presented single peak changing, with the maximum value of the latter occurred 15 d after. The F/C values were all less than 1, which was bigger in typical meadow than in marsh meadow. The total N and P contents in different organs of aboveground part all descended linearly in growth season, with the order of leaf > vagina> stem. The total N content in the roots of two C. angustifolia types was consistent, while that of total P was quite different. The contents of total N, NH4+ -N and NO3- -N, especially of NH4+ -N and NO3- -N, varied widely in different organs, with NH4+ -N/NO3- -N >1. Root was the important storage of N and P, but the storage of N and P in stem, leaf and vagina fluctuated greatly. The N/P ratios of two C. angustifolia types were all less than 14, which implied that N might be the limiting nutrient of C. angustifolia, and the limitation degree was higher in typical meadow than in marsh meadow.