干旱半干旱草地生态系统与土壤水分关系研究进展

研究干旱半干旱草地生态系统与土壤水分关系和相互作用机理对于揭示草地生态系统稳定性及其水土关键要素的变化过程具有重要意义。从不同界面、不同尺度综述了草地生态系统对土壤水分的影响及草地生态系统的响应与适应机制,总结了草地生态系统与土壤水分关系模型研究的相关进展,并分析了气候变化对草地生态系统和土壤水分关系的影响。草地生态系统通过影响水文过程和生态过程来影响土壤水分,土壤水分在植物生长发育、形态、生理生态过程、种间关系、群落组成和结构以及草地生态系统功能等方面对草地生态系统产生影响;充分揭示草地生态系统-土壤水分相互作用机理是模型研究的关键;气候变化对草地生态系统植物与土壤水分关系具有重要影响。今后应加强以下研究:1)开展草地不同优势种和植物功能型与土壤水分关系的研究,找出能反映植物对土壤水分响应的性状指标,阈值响应点及适应机制;2)注重对不同时间和空间尺度上的转换和比较;3)加强个体、群体和生态系统尺度草地植物生长模型的研究及其与土壤-植被-大气水分传输模型的耦合;4)加强草地生态系统与土壤水分关系对气候变化响应的研究。

The relationship between grassland ecosystem and soil water in arid and semi-arid areas: a review

In arid and semi-arid areas, the interactions and relationships between grassland ecosystem and soil water are important for revealing the role of grasslands in regulating water balance and for predicting future grasslands in line with climate change and other important scientific issues. We reviewed the effects of grasslands on soil moisture, as well as the responses and adaptation mechanisms of grasslands to soil moisture, from different interfaces and on different scales. Further, we analyzed the modeling methods used to simulate the relationships between grasslands and soil moisture. The effects of climate change on the relationships between grasslands and soil moisture were also summarized, since this is currently a topic of high interest. The grasslands affect soil moisture by influencing both hydrological and ecological processes. Various vegetation factors influenced soil moisture on different spatial scales and different interfaces. Soil moisture directly affects individual plant morphology characteristics, especially the leaf, stomata, and roots, leading to changes in plant physiological and ecological processes such as photosynthesis, transpiration, and soil water absorption. Furthermore, soil moisture also changes the interspecific relationships between grass species, as well as the grassland community composition and structure, which ultimately affects the functions of the grassland ecosystem. The complexity of plant water transport in the soil-plant-atmosphere continuum (SPAC) system increases the difficulty of modeling research. A full understanding of the mechanisms involved in the interaction between vegetation and soil water is key to solving the problem. Revealing the responses of relationships between plants and soil water to climate change is conducive for the accurate prediction of the impact of climate change on grassland ecosystems in arid and semiarid regions. Based on the analysis of the present research, studies on the interactions between grasslands and soil water have mainly focused on the analysis of a one-way effect, and there are deficiencies in the coupling effects and feedback between grasslands and soil water. Finally, the following further studies are proposed: 1) investigating the relationship between soil water and the dominant species and plant functional types of the grasslands, especially the mechanisms of the interactions, the threshold response, and adaptation mechanisms of different species, and the plant traits indicators that can reflect the plant responses to soil moisture; 2) investigating the conversion and comparison of different temporal and spatial scales, and the study of grassland-soil water relationships on community, landscape, ecosystem, regional, and global scales; 3) investigating plant models on individual, community, and ecosystem scales, and their coupling with water transfer models among soil-vegetation-atmosphere systems for good prediction of future changes and plant distributions of grassland, and better modeling of soil moisture; and 4) investigating the effects of climate change on the relationships and feedback between grassland and soil water, especially the plant physiological and ecology characteristics related to soil moisture.