[Seasonal changes of potassium, calcium and magnesium contents and accumulation in Calamagrostis angustifolia in Sanjiang Plain].

From May to October 2004, the seasonal changes of K, Ca, and Mg contents and accumulation in Calamagrostis angustifolia, the dominant species in the typical meadow and marsh meadow communities of Sanjiang Plain, were studied. There was a greater difference in the seasonal changes of K, Ca, and Mg contents in different parts of typical meadow C. angustifolia (TMC) and marsh meadow C. angustifolia (MMC). The K content in aboveground parts of the two communities had an overall decreasing trend, according with linear model K = A + B(t), the Ca content had a smaller change in stem but an overall increasing trend in leaf and vagina, being accorded with parabola model Ca = A +B1t + B2t2 and exponential growth model Ca = Aexp(t/B1) + B2, respectively, while the Mg content had the greatest change in stem but changed relatively smoothly in leaf and vagina. The differences of K, Ca, and Mg contents in different parts of TMC and MMC were obvious. The K content in aboveground parts of TMC was generally higher than that of MMC, while the Ca and Mg contents in the root and vagina of MMC were higher than those of TMC. The K, Ca, and Mg storage and accumulation in different parts of TMC and MMC also differed. Root had the greatest K, Ca, and Mg storage, occupying 63.82 +/- 23.19%, 78.68 +/- 15.44%, and 76.48 +/- 19.06% of the total storage in TMC and 85.23 +/- 9.20%, 93.51 +/- 3.46%, and 92.39 +/- 3.22% in MMC, respectively. The aboveground parts of TMC had a higher storage of K, Ca and Mg than those of MMC, while the root was in adverse. Such a difference was mainly due to ecological characteristics of C. angustifolia and its habitat conditions.