淡竹对石灰岩山地水分脉动的适应机制

Water wide fluctuation in limestone soil is the limiting factor to plant growth, thus it constrains the vegetation restoration in limestone area. To date, the traditional drought resistance studies do not solve the problem. Based on the characteristic of strong water pulse in limestone soil as well as that in arid area, this study uses the resource pulse theory to explore the water adaptation mechanism of natural dominant plants growing in limestone habitat. Phyllostachys glauca, a dominant species in the limestone mountain in northwest of Jiangxi Province, has strong adaptive ability to cope with the limestone water pulse and distributes throughout hills. According to our previous foundation, we propose the hypothesis that Ph. glauca has an auto-adaptation mechanism to adapt the water pulse: quickly absorbing and storing water during water pulse phase, then reducing the expenditure and exploiting new way to absorb water from air during water interpulse phase. To verify the hypothesis, we design the research schemes of in situ experiments and control experiments. Employing the experimental techniques including stable isotope, fluorescence microscopy technology, minirhizotron, the following contents are planned to carry out: 1) in water pulse phase, the modifications in morphology, structure and physiology of roots to adapt quick water-absorbing; the dynamics of storing water in stem, and the adaptive alterations in structure and physiology for water storing; 2) in water interpulse phase, the changes in morphology, structure and physiology of leaves and roots to adapt water-saving; the transport process of the water absorbed from air by leaves, and the adaptive alterations in structure and physiology for water-absorbing; 3) synthesizing the auto-adaptation strategies and the adjustment behaviors of the two coupling phase, water pulse phase and water interpulse phase. This study aims to reveal the adaptation mechanism of Ph. glauca to water pulse, to construct new study model of ‘water pulse-plant adaptation’ in limestone mountain to propose scientific suggestions for vegetation restoration in this area.

南方石灰岩山地水分渗漏快，脉动（波动）强，是制约植被恢复的瓶颈，亦是传统抗旱研究未解的难题。基于其水分脉动特性与干旱区相似，本项目拟借鉴阐释干旱区植物水分适应机制的资源脉动理论，探寻天然植物对石灰岩山地水分脉动的适应策略。淡竹是赣西北石灰岩山地的天然优势种，前期研究表明其对水分脉动可能存在快吸多贮，节流开源的适应行为。为此，项目结合原位观测和控制试验，采用稳定同位素、荧光显微、微根管等技术，重点研究淡竹：1）水分脉动期，根系形态、结构和生理特征对水分快速吸收的适应变化；茎秆贮水过程及其结构和生理的适应调整；2）水分脉动间期，根、叶为降低水分消耗而进行形态、结构和生理的适应修饰；叶片吸收空气水分的转运途径及其结构特化的开源适应；3）综合分析各种适应策略运用与水分脉动的耦合。研究旨在揭示淡竹对水分脉动的适应机制，进而构建石灰岩山地“水分脉动—植物适应”研究新模式，为该地区植被恢复提供理论依据。

南方石灰岩山地水分渗漏快，脉动（波动）强，是制约植被恢复的瓶颈，亦是传统抗旱研究未解的难题。基于其水分脉动特性与干旱区相似，拟借鉴阐释干旱区植物水分适应机制的资源脉动理论，探寻天然植物对石灰岩山地水分脉动的适应策略。本项目以赣西北石灰岩山地优势种淡竹为研究对象，以水竹、油茶、山胡椒和白栎等作为对照，以采用原位观测和控制试验，运用稳定同位素、荧光显微、活体光合等技术开展了植物对水分脉动期和脉动间期在形态、结构、生理等方面的适应研究，揭示了淡竹对水分脉动的适应机制，构建了“水分脉动—植物适应”研究模式。取得研究成果有：（1）淡竹对石灰岩山地生境水分脉动的快吸、多贮、节流和开源自适应机制：在水分脉动期，淡竹通过根系快速捕获和吸收水分，提高水力导度，较多利用即时降水，并在植物体贮存部分水供脉动间期使用；在水分脉动间期，淡竹降低水分消耗提高水分利用效率，在长脉动间期降低水势从土壤中吸收水分，在重度干旱时通过叶片吸收空气中的雾水以缓解旱害。研究明晰了石灰岩山地植物水分脉动期和脉动间期的水分适应行为及其与水分脉动的耦合关系；（2）综合分析植物器官在水分脉动期和脉动间期前后两阶段的适应策略及其与水分脉动的耦合关系，以淡竹为例构建了优势物种与非优势物种对照、水分脉动特征与植物适应特征耦合的石灰岩山地“水分脉动—植物适应”的研究模式。研究结果为喀斯特地区植物适应机制的阐释和喀斯特植被恢复提供了理论依据。