小降水事件作为荒漠生态系统主要降水类型，是一年生草本植物在干旱多变环境下生长和繁殖的可靠水分来源，其强度和格局变化会对一年生草本植物繁殖物候产生重要影响。目前荒漠植物繁殖物候与降水关系的研究多集中于多年生植物，对于一年生草本植物繁殖物候与小降水事件关系的研究还相对有限。在全球气候变化背景下，如何准确量化小降水事件格局和强度变化对一年生草本植物繁殖物候的影响以及引起其繁殖适应能力的变化，仍需要进一步探索。本项目以河西走廊荒漠典型一年生草本植物为研究对象，通过野外典型群落自然观测和控制实验，结合结构等式和表型最优化模型的理论分析方法，揭示一年生草本植物繁殖物候对小降水事件的响应规律；阐明繁殖物候变化的内在机制(繁殖物候可塑性或权衡策略)；解析其对间断且不可预知的干旱区小降水事件的繁殖适应对策。研究结果将为河西荒漠地区植被保护和恢复提供科学依据。

As the main precipitation type, small precipitation events are essential drivers for annual herb plant growth and reproduction in water-limited arid desert ecosystems. The changes in precipitation pattern and intensity would have important impacts on their reproductive phenology. In recent years we have mainly studied the relationship between precipitation and the reproductive phenology of perennial plants. Further study will be needed about how small precipitation events affect annual plant reproductive phenology. Under the background of global climate and precipitation change, our knowledge of the influence of small precipitation events and their changes on reproductive phenology and reproduction remains limited in Hexi desert area. In this study, we selected three annual dominant herb plants as the research subject in a typical arid desert in Hexi Corridor in Gansu province. By means of field investigations, manipulation experiments, and two theoretical analyses, we address the main scientific questions: (1) the responses of reproductive phenology of the three annual herb plants to small precipitation events; (2) what triggers off such reproductive phonological changes and the possible mechanisms underlying these changes；(3) the reproductive adapting strategies in the non-continuous and uncertain precipitation environment. These findings may provide scientific guidance for the conservation and restoration in Hexi desert area.