荒漠植物水分-养分利用耦合机制：叶功能性状对生境变化的响应

In order to adapt to the extreme environments, such as drought and saline-alkaline environment, desert plant had evolved unique water-nutrient utilization strategies and adaptation mechanisms that differ from other ecosystems, as symbol of the desert plants adapt to sensitive environment, leaf and its functional traits have be paid widely attention. Currently, research on coupling relationship with leaf traits change and its physiological ecology of desert plants are still scarce. In this project, we will choose the desert in Central Junggar Basin as the study area, and select the dominant species in typical habitats as the study objects, which are Karelinia caspia (salt habitat) and Alhagi sparsifolia (dry habitat), quantitatively analyze the leaf functional traits variation, plant water and nutrient use characteristics change, establish model that reflect relationship among them and clear spatio-temporal variation thresholds of leaf water and nutrient, explore the influence factor causing variation and its internal mechanism, fully reveals the physiological and ecological mechanisms for leaf water-nutrient utilization of desert plant and its coupling relationship change with habitat and seasonal variation change, exploring the adaptive strategy and difference of drought-resistant and salt-tolerant plants. The results are designed to improve the water-nutrient use tradeoff mechanism of desert plants in arid area, providing a scientific basis for the conservation and utilization of desert plant, and ecosystem restoration and reconstruction in arid areas.

干旱荒漠植物为适应干旱、盐碱等极端环境，形成了不同于其他生态系统的独特水分-养分利用策略和适应机制，叶片及其功能性状作为荒漠植物适应敏感环境的标志受到广泛关注，目前关于荒漠植物叶片性状变化与生理生态的内部耦合关系研究仍很缺乏。本项目以准噶尔盆地中部荒漠为研究区，选取典型生境内的优势物种花花柴（盐生境）和骆驼刺（旱生境）为研究对象，定量分析叶片功能性状变异、植物水分、养分利用特征变化，建立三者关系模型明确叶片水分-养分时空变异阈值，探讨引起变异的影响因子及内在机理，全面揭示荒漠植物叶片水分-养分利用及其耦合关系随生境和季节变化的生理生态学机制，探索耐旱和耐盐植物的环境适应策略和差异。研究结果旨在完善干旱区荒漠植物水分-养分利用权衡机制，为干旱区植物保护与利用及生态系统恢复重建提供科学依据。

本项目以准噶尔盆地中部荒漠为研究区，选取典型生境内的优势物种花花柴（盐生境）和骆驼刺（旱生境）为研究对象，定量分析叶片功能性状变异、植物和土壤的水分-养分特征变化，明确叶片水分-养分时空变异阈值，探讨其影响因子及内在机理，探索耐旱和耐盐植物的环境适应特征和差异。重要结果如下：.（1）花花柴叶片含水量随盐分增加呈先降后升趋势；骆驼刺叶片含水量随水分增加而增加。盐分含量过高或过低均会影响土壤有机碳含量积累；水分含量低会影响其积累。花花柴有机碳含量表现为叶<茎<根，骆驼刺为叶<根<茎；二者全氮为叶<根<茎，花花柴（56.27%）叶片N再吸收率显著高于骆驼刺（30.42%）；花花柴全磷为叶>根>茎，骆驼刺则为地上>地下部分，花花柴（46.61%）叶片P再吸收率显著高于骆驼刺（35.78%）。.（2）花花柴和骆驼刺δ13C为叶<根<茎，花花柴δ15N为叶<茎<根，骆驼刺则为叶<根<茎。随着盐渍化程度加深和水分增加，二者WUE均先增加后降低；随季节变化花花柴WUE降低，骆驼刺WUE均增加。.（3）骆驼刺和花花柴叶脉参数随盐分增加改变，花花柴叶脉密度逐渐提高，说明花花柴在盐胁迫下适应性强于骆驼刺。随干旱程度增大，骆驼刺叶脉参数呈先增加后减小趋势。.（4）干旱处理会显著降低骆驼刺Fm和NPQ（P<0.05），降低Fv/Fm；盐处理下花花柴Fv/Fm、Fv/Fo与对照组差异显著（P<0.05），说明盐旱处理会改变叶片表观电子传递效率及内在光合能力。低浓度氮沉降有利于骆驼刺叶绿素合成，而高浓度沉降则降低其值；随氮沉降时间延长，植物生长受到胁迫明显。.（5）花花柴WUE和全氮、同位素氮呈显著正相关（P<0.05），与有机碳和同位素碳呈极显著负相关（P<0.01）。同位素氮和全磷呈极显著负相关（P<0.01）。当同位素氮为-25.935g/kg，WUE最小（4.286）；当有机碳为0.488g/kg，同位素氮最大（1.461）。.（6）骆驼刺WUE和全氮呈显著正相关（P<0.05），与有机碳呈极显著负相关（P<0.01）。而骆驼刺WUE和全氮则呈显著负相关（P<0.05）。当全氮为23.838g/kg，WUE最小（5.610）；当同位素碳为-24.989g/kg，WUE最大（10.825）。.（7）最优方程表明旱生境中叶片湿度对叶功能性状影响较大，盐旱生境中WUE均是叶周长的主要影响因子。