两种白刺叶片及沙堆土壤化学计量学特征的比较

在植物叶片氮、磷化学计量学研究中,氮磷比常作为判断土壤养分限制性的指标,其适用范围从海洋、湖泊等水生生态系统扩展到陆地生态系统。以生长在民勤绿洲的毛瓣白刺(Nitraria praevisa)和唐古特白刺(N. tangutorun)为研究对象,分别测定叶片N、P含量以及沙堆各层土壤有机质、N、P含量,以探讨两种白刺叶片及其沙堆土壤化学计量学特征的关系。研究结果表明:①白刺叶片的N、P含量之间存在显著的正相关关系；②两种白刺沙堆各项土壤养分指标差异极显著(P<0.01)；③毛瓣白刺沙堆土壤的N含量在0～20 cm土层存在富集现象,唐古特白刺沙堆土壤的有机质、N、P含量在20～40 cm土层存在富集现象；④在水分为最主要的限制性因子的荒漠生态系统中,能否以叶片N∶P作为判定营养元素限制性的标准,值得进一步探讨。

Stoichiometric Analysis of Leaves of Two Types of Nitraria and the Sited Nebkhas Soil

N∶P concentration ratio is often used as an index of soil nutrients limitation in research of ecological stoichiometry of nitrogen (N) and phosphorus (P) concentrations in leaf tissue, and the research area relates the sea, lake ecosystems, and the land surface ecosystem. This paper analyzed the N and P concentrations in leaf tissues of two dominant species, Nitraria praevisa and N. tangutorun, in the arid Minqin oasis, Gansu, China, and N, P and organic matter (SOM) concentrations at 0—60 cm nebkhas soil layers of the two species inhabit. Results indicate that: (1) there is a significant positive relationship between the N and P concentrations in leaf tissues of the two species; (2) N, P and SOM concentrations differ significantly between the two types of nebkhas (P<0.01); and (3) N is concentrated at the soil layer of 0—20 cm for the N. praevisa nebkhas, and N, P and SOM at the soil layer of 20—40 cm for the N. tangutorun nebkhas. A further study is necessary to reveal whether or not N∶P concentrations ratio can be used as an index of soil nutrients limitation in the extreme arid desert environments.