陆生植物氮同位素组成与气候环境变化研究进展

Progress of Research on Relationships between Terrestrial Plant Nitrogen Isotope Composition and Climate Environment Change

近年来,由于植物氮同位素组成(δ15N)记载了气候环境变化的信息,因而被广泛应用于全球变化研究中,成为古气候环境再造和了解现代气候环境变化信息的有力工具。然而,人们对气候环境引起的δ15N变化及其指示的气候环境意义并不完全清楚,这就有可能限制植物δ15N在古气候环境变化等领域研究中的应用。在概述植物氮同位素分馏和植物不同氮源的氮同位素分布的基础上,分析了温度、降水、大气CO2浓度和海拔高度等气候环境因子对陆生植物δ15N的影响以及它们的关系。指出了目前研究中存在的问题及其研究前景,认为在全球变化研究中利用植物氮同位素技术不仅可以重建古气候环境(如重建大气CO2浓度变化),揭示历史时期温度、降水的变化,而且还可以在一定的时间和空间上综合反映生态系统氮循环的特征。

Recently, since stable nitrogen composition （δ15N） in plants records abundant climate and environment information （such as information on temperature, humidity, precipitation and environment isotopes composition） , it has been widely used in paleoctimate studies and becomes a powerful tool for understanding paleoenvironment reconstruction and modern climate change. However, some potential uncertainties have always involved in the reconstruction of paleoclimate and paleoenvironment. Among them, the most dominant uncertainty is due to our poor understanding of the relationship between nitrogen isotope ratios of plants and climatic factors, particularly the relationships among nitrogen isotope ratios, temperature and precipitation. Based on summarizing plant δ15NN fractionation and nitrogen isotope distribution of different N sources, the effects of environmental factors, e. g. , temper- ature, precipitation, atmospheric CO2 concentration, and altitude on terrestrial plant δ15N and their mechanism were analyzed in this paper. Furthermore, the existing and disputed problems in nitrogen isotope study were discussed, and the future trends of nitrogen isotope technique in global change research were prospected. It is pointed out that the technology of nitrogen isotope in plants could not only be used to rebuild paleoclimate （ such as reconstructing the sequences of atmospheric CO2 concentration changes） , revealing the trends of climate changes, but also in a certain time and space to reflect comprehensively the characteristics of nitrogen cycling in ecosystem. This will make more readers have a more profound understanding of the field and eventually broaden the development of the field.