芦苇和香蒲地上部N和P积累动态及适宜收获时期分析

通过野外采样和室内分析相结合的方法,对5月至11月芦苇〔Phragmites australis(Cav.)Trin.ex Steud.〕和香蒲(Typha orientalis Presl)地上部生物量以及N和P的含量和积累量的动态变化进行了分析,并对生物量、N和P含量及N和P积累量间的相关性进行了研究;在此基础上,确定芦苇和香蒲的适宜收获时期。结果表明:在整个生长过程中,芦苇和香蒲地上部生物量随生长时间延长呈典型的单峰型曲线,最高值分别出现在9月份和10月份,且芦苇地上部生物量极显著高于香蒲(P<0.01)。芦苇和香蒲地上部N含量呈先升高后降低的趋势、P含量呈逐渐降低的趋势,香蒲地上部N和P含量均极显著高于芦苇地上部。芦苇地上部N和P积累量在8月份达到最高,香蒲地上部N和P积累量在9月份达到最高。芦苇和香蒲地上部C/N、C/P和N/P比在不同月份差异较大,C/N和N/P比呈波动趋势,C/P比则总体呈逐渐升高的趋势。总体来看,芦苇和香蒲的生长在生长初期和中期受N限制、在生长末期受P限制。相关性分析结果表明:芦苇和香蒲地上部的N含量与P含量、N积累量与P积累量间均呈极显著正相关;N和P积累量与其生物量呈显著正相关(P<0.05),但与N和P含量的相关性不显著(P>0.05)。综合分析结果表明:芦苇和香蒲的适宜收获时期分别为8月份和9月份。

Analyses on accumulation dynamics of N and P in above-ground part and appropriate harvest period of Phragmites australis and Typha orientalis

By combining methods of field investigation and laboratory analysis, dynamic changes of biomass, contents and accumulations of N and P of above-ground part of Phragmites australis （Cav.） Trin. ex Steud. and Typha orientalis Presl from May to November were analyzed, and correlations among biomass, N and P contents, and N and P accumulations were researched. On this basis, appropriate harvest period of two plants was also determined. The results show that during the whole growth process, biomass of above-ground part of two plants appears a typical single-peak curve with prolonging of growth time, their maximum biomass appears in September and October, respectively, and biomass of above- ground part of P. australis is obviously significantly higher than that of T. orientalis （P〈0.01）. N content in above-ground part of P. australis and T. orientalis appears a trend of first increasing and then decreasing, while P content appears a trend of gradually decreasing. Contents of N and P in above-ground part of T. orientalis are obviously significantly higher than those of P. australis. Accumulations of N and P in above-ground part of P. australis are the highest in August, and those of T. orientalis are the highest in September. There are larger differences in ratios of C/N, C/P and N/P of above-ground part of P. australis and T. orientalis among different months, ratios of C/N and N/P appear fluctuating trends, and ratio of C/P appears a trend of gradually increasing. On the whole, growth of P. australis and T.orientalis in the early and middle periods of growth process is limited by N, and that in the end period is limited by P. The result of correlation analysis shows that there are obviously significant positive correlations between contents of N and P, and between accumulations of N and P in above-ground part of two plants, and there are also significantly positive correlations of N and P accumulations with biomass （P〈0.05）, but correlations of N and P accumulations with N and P contents are not significant （P〉 0.05 ）. The result of comprehensive analysis shows that appropriate harvest period of P. australis and T. orientalis is August and September, respectively.