基于根系-河水/地下水动态响应的旱区河岸林系统韧性研究

根系是植物应对水分胁迫的调节器。旱区植物能根据水分条件的变化来优化调整和重塑根系形态，从而保证获取稳定的水源。揭示旱区植物根系自调节机制是理解旱区陆地生态系统韧性和稳定性的关键，也是提升生态系统响应未来环境变化预估能力的基础。本项目拟以干旱区典型河岸带植物（胡杨、柽柳）根系动态为核心，结合根系与环境要素全球数据库和文献资料，通过荟萃分析与数据挖掘等方法，识别不同气候、土壤质地、河流水文情势、地下水位埋深下的根系分布特征，揭示根系分布形态的相似性及区域间的差异性，构建根系随环境变化的数学模型。在此基础上，以黑河下游和塔河下游胡杨和柽柳林地定点观测试验为依托，开展不同水文梯度下的“河流-地下水-植被系统”断面观测与模拟，解析胡杨和柽柳根系对河水/地下水变化的响应策略与重塑能力。研究成果将有助于深化理解旱区陆地生态系统与水文系统之间的协变机制，为我国干旱区生态建设和水资源配置提供科学依据。

The root system is a regulator for plants to cope with water stress. Plants in dryland are able to optimally adjust and reshape root morphology according to changes in water conditions to ensure stable water availability. Revealing the self-regulating mechanism of plant roots is the key for understanding the resilience and stability of dryland ecosystems, and it also provides the basis for improving the ability to predict the response of ecosystem to future environmental changes. This project mainly focus on the root dynamics of two typical riparian plants in arid areas (Populus euphratica and Tamarix spp.). Through meta-analysis and data mining on the plant root dataset and published literature, the objectives of this project are: 1) to clarify the root distribution characteristics under different climates, soil textures, river hydrological regimes, groundwater table depth; 2) to reveal the similarity of root distribution patterns and inter-regional difference, 3) to derive a mathematical model of root system changes with the environment. Furthermore, based on in suit measurements of Populus euphratica and Tamarix spp. in the lower reaches of Heihe and Tarim rivers, cross-sectional observation and simulation of the "river-groundwater-vegetation system" under hydrological gradients are planned to carry out. Strategies and reshape ability of the roots of Populus euphratica and Tamarix spp. in response to river/groundwater changes will be clarified. The results are expected to deepen our understanding of the co-evolutional mechanism between terrestrial ecosystems and hydrological systems in arid regions, and provide a scientific basis for ecological construction and water resource allocation in arid regions of China.