CO_2和N浓度变化对树木生理的影响

Impacts of elevated CO_2 and nitrogen addition on physiological responses of trees

综述了国内外有关CO_2浓度升高与N添加对树木生理影响的研究进展。主要包括CO_2浓度升高、N添加以及C-N交互作用对树木的光合作用、水分利用效率、呼吸作用以及植物的生长等方面的影响。分析表明,环境CO_2浓度升高短期会促进树木的光合作用与生长,但长期可能会产生"光合适应"。高浓度CO_2可提高水分利用效率,但对树木的呼吸作用存在不确定性。适量的N添加一般会促进树木的光合作用、呼吸作用与生长,但对树木水分利用效率和生物量分配的影响存在不确定性。当N添加过量时会对树木产生不利影响。C-N交互对树木生理特征的作用显著,即N添加可提高高浓度CO_2对树木光合速率和生长的促进程度。因此,大气CO_2浓度升高与N添加的交互作用对树木将产生重要影响。以后相关研究需进一步从多方面、多角度及长时间尺度探讨二者的交互作用对树木影响的生理机制,以期为预测森林应对全球变化下多环境因子改变的能力提供科学依据。

This paper conducts a survey of the research worldwide focusing on the impacts of elevated C02and nitrogen addi-tion on physiological responses of trees, including photosynthesis, water use efficiency, respiration and growth. The results show that elevated C02 increased photosynthesis rates and growth in the short term, but may lead to photosynthetic acclima-tion in the long term. Additionally, elevated C02 enhanced water use efficiency, but its？ effect on respiration rates is still un-clear. Moderate nitrogen addition often increased rates of photosynthesis and respiration and growth, but its ＊ impacts on wa-ter use efficiency and biomass allocation pattern remained unclear. However,excessive nitrogen has negative effects on trees.The degree of C02 impacts on plant photosynthesis and growth was elevated by nitrogen addition, indicating the significant interactive effects of C02 and N. Thus,C -N interaction had substantial impacts on trees. Future studies are needed to un-cover the physiological basis of how C - N interaction would impact plants from broader views and longer time periods, provi-ding insights into predicting the capacity of forests to cope with multiple environmental factors in future climates.