中文摘要：

顶级群落建群种的N、P化学计量特征对退化草地群落稳定性和生产力维持具有重要意义。本文以松嫩草地顶级群落建群种羊草（Leymus chinensis）为研究对象，分析盐碱退化对羊草N、P化学计量特征的影响。结果表明：松嫩盐碱退化草地羊草相比较于中国北方草地羊草和草地植物具有较低的叶P含量（1．32g·kg-1）、中等的叶N含量（18．90g·kg-1）和略高的N／P（15．83）。叶N含量和N／P与土壤全氮、土壤碱解氮显著正相关；叶P含量与土壤全氮、土壤碱解氮显著负相关，其它因子与叶N、P和N／P相关性不明显。叶P含量与土壤氮的显著相关性和与土壤P含量的背离显示松嫩盐碱退化草地羊草可能存在一定的P限制。

英文摘要：

N and P stoichiometry of constructive species of a climax community has an important influence on the stability and productivity of community. We chose Leymus chinensis, the constructive species of Songnen grassland community to study the effects of grassland degradation on N and P stoichiometry of L. chinensis under saline-alkali stress. There were lower leaf P content（ 1.32 g· kg-1 ） , medium leaf N content（ 18.90 g · kg-1） and slightly higher N/P（ 15.83 ） in degraded L. chinensis grassland compared with the L. chinensis grassland in the north of China. Leaf N and N/P were significantly positively correlated with soil total nitrogen and soil alkaline hydrolysis nitrogen. Leaf P was significantly negatively correlated with soil total nitrogen and soil alkaline hydrolysis nitrogen, but other factors were not significantly correlated with N, P and N/P. Both the significant correlations between leaf P content and soil N content and departure from leaf P content and soil P content common displayed that there might be a limitation of P in Songnen Plain at the saline alkali degradation of L. chinensis grassland.