强干扰下白洋淀湖沼湿地生态响应与适宜水位研究

气候变化和高强度人类活动干扰下，白洋淀面临着生态需水短缺和生态系统退化等生态环境问题。本项目强调自然水位升降节律对维持湖沼湿地生态系统健康的关键作用，针对湖沼湿地生态水位功能性机理研究中的难点与不足，着重突破湖沼湿地生态系统结构与功能对水位变化响应机制的关键科学问题，以“水文胁迫-生态响应-系统模拟-适宜水位”为主要研究思路，分析自然状态以及极端旱涝与生态补水等强干扰下水位波动强度与频率特征，研究植被组成、分布与碳收支动态对水位变化的响应规律，改进湿地植被分布演替与碳收支的生态水文模型，剖析不同水位梯度下植被分布、净初级生产力、碳排放、碳固定之间的动态响应关系，构建碳收支各功能分项对水位变化的响应函数，界定系统响应的平衡点和转换阈值，建立维持湖沼湿地生态系统功能稳定的生态水位阈值。从内涵和机制上丰富湖泊湿地生态水位核算的理论与方法，为白洋淀生态系统的保护与恢复提供理论指导与技术保障。

Influenced by intense disturbances from climate change and anthropogenic activities, Baiyangdian wetland faces up to a series of ecological environment problems, e.g, shortage of ecological water and ecosystem degradation. This project highlights that naturally hydrological regime is emphasized for the crucial role in maintaining ecological integrity of wetland. Focused on the ecological water level assessed by the wetland function indictors, the scientific issues aimed to the response of wetland structure and function to water level fluctuation. According to the thought “hydrological stress, ecological response and simulation, assessment of suitable ecological water level” and using methods of in-situ monitoring, experiment and modeling, objectives of this project are: (i) to study fluctuation of water level, such as intensity and frequency, to explore the water level different response to extreme hydrological events (e.g., flood and draught) and ecological water transfer, to analyze the ecological response to fluctuation of water levels; (ii) to set up a wetland ecohydrological model considering vegetation distribution and carbon flux measurements, carbon pool measurements, and manipulative experiments, to simulate response of vegetation distribution, net primary productivity, carbon flux, and carbon sequestration in different water levels; and (iii) to develop a key ecological function to water levels, and assess the suitable water level thresholds and suitable water level curve. Results of this project will enrich and develop the theory of ecological water level for wetland, also will help to protect and restore the ecosystem of Baiyangdian wetland.