长白山林线植物对UV-B辐射的响应与适应机理

地表紫外线-B(UV-B)辐射增强，是全球环境变化中最为引人注目的热点问题之一。增强的UV-B辐射能直接损伤植物DNA和光系统，甚至改变植物碳平衡及其地理分布格局。然而，在具有强辐射特征的高山地区，UV-B辐射却不被认为是一个限制性因子。近年来分子生物学技术在高山生态上应用的发现，对以往研究结论的可信性提出了质疑。因此，弄清高山林线植物对UV-B胁迫的分子响应与适应机理，是理解和预测高山植物分布受限的前提。本研究以长白山林线岳桦及冻原植被为研究对象，通过野外及同质园控制实验，明确UV-B对岳桦DNA及光系统的损伤程度；系统地研究岳桦对UV-B的防御机理和碳平衡的反馈调节，进而分析UV-B与高山胁迫因子的复合效应，探讨高山植物对UV-B的适应策略；结合冻原植被的长期监测，阐明UV-B在群落水平上的影响，从而有助于理解和预测臭氧层衰减下山地生态系统的动态变化，为山地植被恢复提供理论支持。

Increase in the ground ultraviolet-B (UV-B) radiation is one of the most compelling hot issues in global environmental change. Enhanced UV-B could directly damage plant DNA and photosystem and even change plant carbon balance and its geographical distribution. In general, however, UV-B radiation is not considered as a limiting factor for plants in alpine areas where UV-B intensity is much pronounced. Recently, the application and discovery of molecular biology techniques in alpine ecology have challenged the knowledge derived from past related studies. Therefore, understanding the molecular responses and adaptation mechanisms of alpine treeline plants to UV-B stress is the key to understanding and predicting the distribution of alpine plants. In the present study, we will focus on UV-B effects on alpine treeline species (Betula ermanii) and tundra vegetation on Changbai Mountain, through various manipulation and simulation experiments in the field and common garden. This study will evaluate UV-B damage levels on DNA and photosystem of B.ermanii plants along elevations, and then systematically explore their defense mechanism of UV-B and the feedback regulation of carbon balance. The interaction effects of UV-B and alpine stress factors will be further analyzed to examine the adaptation strategies of alpine plants to UV-B under the climatic change. Combined with the long-term monitoring of the tundra vegetation, the influence of UV-B on the community level is clarified, which helps to understand and predict the dynamic changes of mountain ecosystems under the depletion of ozone layer, and provides theoretical support for the mountain vegetation restoration.