长白山原始红松阔叶林及其次生林细根分解动态和氮元素的变化

该文采用网袋分解法对长白山不同演替状态的原始红松阔叶林、白桦山杨成熟林和白桦山杨幼林中优势树种的细根分解动态及其氮元素的变化进行了研究.研究表明:在3块样地中，细根分解初期速率较快，然后趋于缓慢.在原始红松阔叶林中，水曲柳细根的分解最快，红松次之，而紫椴细根的分解最慢.在白桦山杨成熟林和幼林中，山杨的细根分解均比白桦细根快.细根的分解不仅受其本身化学性质的影响，而且也受到周围环境的影响.在原始红松阔叶林的演替过程中，细根分解过程中会释放或富集氮元素.温度较低和降雨较少的春秋季节，细根分解过程中主要表现为释放氮元素，而温度较高和降雨较多的夏季，则表现为富集氮元素. 

Fine root decomposition and nitrogen mineralisation of the primitive Korean pine and broadleaved forests as well as its secondary forests in the Changbaishan Mountains, northeastern China.

Decomposition of fine root of the primitive Pinus koraiensis and broadleaved forests as well as its secondary Betula platyphylla and Populus davidiana forests was studied from May to October 2002 to examine the decomposition dynamic and nitrogen mineralization using litter bags.The experiments involved three forest sites during different forest succession of the primitive Korean pine and broadleaved forests,80 years and 20 years old secondary Betula platyphylla and Populus davidiana forests,respectively.In the three sample plots,the decomposition speed was fast at initial stage,and then it was slowing down gradually.In the primitive forests,the fastest decomposition rate of fine root was Fraxinus mandshurica,followed by Pinus koraiensis,and the slowest one was Tilia amurensis.In two secondary forests,fine root decomposition rate of P.davidiana was faster than that of Betula platyphylla.The fine root decomposition was affected not only by the chemical properties of tree species but also by stand environment.In the three plots,N would release or concentrate during the fine root decomposition.In spring and autumn,N would release because of the lower air temperature and the less rainfall.In summer,N would concentrate because of the higher air temperature and more rainfall.