15N自然丰度法在陆地生态系统氮循环研究中的应用

随着氮沉降的不断增加以及人们对全球变化问题的日益关注, 稳定同位素技术在全球变化研究中得到广泛的应用。因为植物和土壤的氮同位素组成记录了氮循环影响因子的综合作用, 并且具有测量简单以及不受取样时间和空间限制的优点, 所以氮同位素自然丰度法被用于氮循环的研究中。该文从氮循环过程中植物和土壤的氮分馏入手, 总结国内外相关文献, 阐述了植物和土壤氮自然丰度在预测生态系统氮饱和和氮循环长期变化趋势中的应用; 总结了利用树轮δ ¹⁵N法研究氮循环过程中应该注意的事项以及目前尚未解决的问题。

Use of 15N natural abundance in nitrogen cycling of terrestrial ecosystems

Stable isotope technique has been widely used in ecology research with the increasing concern on global change.Our objectives are to better understand the impacts of nitrogen addition and other environment changes on the nitrogen cycling of terrestrial ecosystem,predict the consequent changes in environmental conditions,and provide a reference for policy making to help ensure the sustainable development of terrestrial ecosystems.Based on the relationship between nitrogen (N) isotope composition (δ15N) in ecosystem N status and soil N cycle,we summa-rized the effects and mechanisms of N input and other environment changes on δ15N of plant and soil.Most stud-ies show significant positive relationships between N input and δ15N values of plant and soil.Higher N input in-creases soil N availability,which leads to 15N enrichment in soil because of mass discrimination during soil N cycling processes.Foliar δ15N also will be higher as plants take up the relatively 15N-enriched soil available N.15N natural abundance can be a useful tool for assessing nitrogen saturation and N cycling.