研究了 2 3种固氮与非固氮树种叶部N、P含量的季节变化、输出率以及叶片衰老过程中N、P的输出过程 .结果表明 ,供试树种叶部N、P含量均存在着明显的季节变化 ,平均变化率为 2 1～ 2 3% ,最大变化率出现在叶片衰老期 .在衰老期内不同树种表现出不同的N、P动态特征 .固氮树种表现出低输出率 ,落叶中N含量是非固氮树种的 1 .6～ 3.7倍 .固氮树种生长季叶部N含量在 2 .5%左右 . The leaf area N and P contents of 23 kinds of nitrogen-fixing and non-nitrogen-fixing tree species were studied in terms of seasonal variation, output rate and N, P export during the leaf senescing process.The results showed that there were obvious N , The average rate of change was from 21% to 23%, and the maximum rate of change appeared in the leaf senescence stage.The different tree species showed different N and P dynamic characteristics during the senescence period.The nitrogen-fixing species showed the low output rate, The content of N is 1.6 ~ 3.7 times that of the non-nitrogen-fixing species, and the content of N in the leaf of the nitrogen-fixing species is about 2.5%.