全球变化对羊草叶脉性状及其与功能性状关系的影响

The effect of leaf veins traits on plant physiological and ecological functions is enormous. Its own changes and its coordinated variation with other leaf functional traits constitute a strategy for plants to cope with global change. The study of veins traits breaks the limitations of the application of functional traits in previous studies and provides theoretical foundation and new ideas for coping with future global changes. In view of the important which is role of veins in plant adaptation and response strategies often neglected, this study focused on the basic idea of the impact of global changes on leaf traits – the coordinated variation of veins traits and other leaf functional traits. We are planning to use the largest area of China's meadow grassland Hulunbuir as the research area, and study the leaf vein traits (leaf veins density, veins input ratio) and leaf functional traits (leaf area, stomatal density, leaf mass per area, total nitrogen content, C/N ratio and carbon isotope ratio) of Leymus chinensis. Using the method of positioning control experiment and by measuring the effects of temperature, water and nitrogen addition and their interactions on the leaf vein traits and the relationship with other leaf traits of Leymus chinensis, we want to identify the response patterns of leaf vein traits and the coordinated variation with other leaf functional traits in the process of global changes, and finally clarify the changes of leaf vein traits in response to global changes and their functional effects, and provide scientific guidance for predicting the changes of ecosystem function under global change.

叶脉性状对植物生理生态功能的影响巨大，其自身的变化以及其与它叶片功能性状的协同变化共同构成了植物应对全球变化的策略。对叶脉性状的研究打破了以往研究中应用功能性状的局限，为应对未来全球变化提供理论依据和新思路。鉴于叶脉性状在植物适应和响应策略中的重要作用但却往往疏于考虑，本研究围绕“全球变化对叶脉性状的影响—叶脉性状与其它叶片功能性状协同变化”这一基本思路，以我国面积最大的草甸草原呼伦贝尔为研究区域，以其主要植物之一羊草的叶脉性状（叶脉密度、叶脉投入比）和叶片功能性状（叶片面积、气孔密度、比叶质量、全氮含量、碳氮比、碳同位素比）为研究对象，运用定位控制实验的方法，通过测度三年温度、水分和氮添加的变化及其互作对羊草叶脉性状以及与其它叶片性状关系的影响，明确植物响应全球变化过程中叶脉性状协同其它叶片性状变化的模式。最终阐明羊草叶脉性状在响应全球变化中的变化规律及其功能作用。

本项目通过测度不同气候条件下呼伦贝尔草甸草原建群植物—羊草的叶片性状的变化，尤其是叶脉性状的变化，明确了增温、增水和氮添加及其互作效应对羊草叶脉性状的影响，及其与其它叶片功能性状之间的关系。增水显著增加了叶脉密度，氮添加显著减少了叶脉密度，增温对叶脉密度的影响不显著。增水与氮添加对叶脉密度具有显著的互作效应，同时增水和氮添加可抵消两者对叶脉密度的相反作用。增温、增水和氮添加对其他叶片性状也具有显著的影响。增温和增水显著增加了叶片的比叶质量，而氮添加显著的减少了叶片正面气孔的长度，并显著增加了叶片正面气孔的宽度。气候变化对叶片正面和反面的气孔密度无显著作用，对叶片反面气孔长度和宽度的影响也不显著。但是不同气候因子之间的互作效应对叶片反面的气孔密度、气孔长度和气孔宽度具有显著作用。增温和增水对叶片的净光合速率、胞间CO2浓度、蒸腾速率和气孔导度均具有显著的降低作用。增温显著降低叶片叶绿素A、叶绿素B和胡萝卜素的含量。增温还能够对叶片中镁、钠、氮、碳同位素和氮同位素具有显著影响。增温、增水和氮添加对土壤中的全钾、全碳、全磷和全氮的影响微弱。羊草的叶片通过结构和生理性状的协同变化来应对短期的气候变化。本项研究深入挖掘了植物响应气候变化的机制，并能够为草地管理提供借鉴。