【摘要】 于１９９６年６～１０月生长季内．在长白山北坡自然保护区海拔７４０ｍ的高度．用化学和生化分析方法分析了原始阔叶红松林受到破坏后形成的３０ａ林龄的杨桦林土壤中Ｎ素及有效形态ＮＯ３一Ｎ和Ｎ比一Ｎ含量的动态状况．同时对冠层山杨和白桦及林下更替树种水曲柳、红松、色木和树的幼苗、幼树的Ｎ素营养状况进行了动态研究．目的是揭示杨、桦及林下更替树种幼苗、幼树的Ｎ素营养关系及杨桦林向阔叶红松林演替过程中Ｎ素的机制作用。结果表明：（１）在生长季中．根层土壤ＮＯ３一Ｎ含量和其上层土壤动态趋势一致．在７、８月份其ＮＨ４一Ｎ含量也是如此．它们之间相关性较强；（２）山杨和白桦虽都有较强同化ＮＯ３一Ｎ的能力．对ＮＯ３一Ｎ需求的竞争也不激烈．而根中ＮＨ４--Ｎ含量比ＮＯ３一Ｎ含量高很多、它们对ＮＨ４一Ｎ需求的竞争则比较激烈．且它们在果实成熟期间对ＮＯ３一Ｎ和ＮＨ４一Ｎ的需求都较大：（３）林下更替树种水曲柳、红松、色木、树等的幼苗、幼树对Ｎ素吸收利用和土壤Ｎ素供应的动态状况是一致的．它们之间对Ｎ素需求竞争不激烈．但其与冠层杨、桦对Ｎ素需求的竞争却比较激烈。更多还原

【Abstract】 In the growing season. June to October 1996, in order to find the relationship of nitrogen nutrientand the nitrogen mechanism in the forest succession, chemical and biochemical analysis methods wereused to monitor the dynamic variations of nitrogen nutrient among the dominant tree species Populusdavidiana. Betula’ platyphylla and the regeneration tree species such as Pinus koraiensis. Tilla amurensis.Acer mono and Fraxinus mandshurica in 30-year-old secondary birch forest formed by destroyed broad- leaved Korean pine forest on Changbai Mountains with an elevation of 740 m in Northeast China. Theamounts of total nitrogen. available nitrate (NOs--N) and ammonium (NH.-N) in soil. leaves and rootsof the dominant tree species and regeneration species were studied. The results show that in the growingseason there is similar variation trends of NOs-N content among different layers of the soil. and alsoof NH4- N content in July and August. Comparing Populus davidiana with Betula platyphylla. thereexists competition for NH4-N. but not for NO3- N. The regeneration tree species all adapt to soilnitrogen nutrient conditions and there is no strong competition in nitrogen requirement. while strongcompetition exists in the crown lcyer.更多还原