基于生态系统稳态转换机制的湖泊生态需水阈值研究

In recent years, more and more researchers have focused on the importance of environmental flows the ecosystem health of lakes, and numerous methodologies have been developed for determining the environmental flows within these systems. However, most of the current studies have been confined to the relationship between environmental flows and specific target species, and it is still difficult to define environmental flows for ecosystem-level protection. In this study, we propose a combined framework to overcome these shortcomings in traditional studies. Firstly, time series data and sediment records will be integrated to investigate the evolution of lake ecosystems and processes of regime shifts. Then, a coupled model with the hydrodynamic module and the food web module will be established, which can be used to facilitate the selection of key indicators of the ecosystem structure and function stability, and quantify the instable mechanism and “tipping point” of lake ecosystems under anthropogenic impacts. The outcome of this study is expected to expand the evolution theory on eco-hydrological processes, provide new thoughts on the complex system simulation of lake eco-hydrology, and consequently make contribution to bridging the gap between environmental flows supplement and protection or restoration of lakes at the ecosystem level, which has both important theoretical and practical significance.

保障湖泊生态需水是维系湖泊生态系统健康的有效措施，也是调控和恢复湖泊生态系统的关键。当前生态需水研究缺乏对生态系统整体演变规律、突变特征的考虑，其生态需水评估结果难以满足生态系统整体层面的保护需求。本研究拟将湖泊沉积记录分析和生态系统动态模拟相结合，通过沉积物中硅藻和孢粉信息反演湖泊中浮游和大型水生植物群落的演变趋势，识别湖泊草-藻稳态的转换特征及其关键驱动因子；针对导致生态系统稳态转换的主要驱动因素，构建包含关键过程的水动力与水生态耦合模型；建立水文情势多要素与生态系统多因子之间的响应关系，并通过突变检验法揭示水文情势变异条件下的生态系统失稳机制及突变过程，明确维持生态系统结构和功能稳定的湖泊生态需水阈值。本研究将为生态需水评估提供可靠的理论依据，为从整体层面保护和修复湖泊生态系统提供科学依据，具有重要的理论和现实意义。

保障湖泊生态需水是维系湖泊生态系统健康的有效措施，也是调控和恢复湖泊生态系统的关键。当前生态需水研究缺乏对生态系统整体演变规律、突变特征的考虑，其生态需水评估结果难以满足生态系统整体层面的保护需求。本项目以白洋淀浅水湖泊生态系统为研究对象，将湖泊沉积记录分析和生态系统动态模拟相结合，以沉积物中硅藻和孢粉信息反演湖泊中浮游和大型水生植物群落的演变趋势，通过突变检验法揭示了水文情势变异条件下的生态系统失稳机制及突变过程；针对导致生态系统突变的主要驱动因素，构建了包含关键过程的水动力与水生态耦合模型，阐明水文情势要素与生态系统状态之间的响应关系，提出了维持生态系统结构和功能稳定的湖泊生态需水量。研究结果表明白洋淀大型水生植物丰度在1960-1964发生显著突变。其中挺水植物、沉水植物的平均丰度在60年代后呈显著下降趋势，湿生植物和盘星藻的丰度在60年代后呈显著上升趋势。在突变发生前的1-16年植物丰度序列出现方差增大、自相关系数和偏度显著降低趋势。方差、偏度和自相关的变化趋势表明突变前生态系统出现频繁波动现象；EFDC-AQUATOX耦合模型对21个水质-水量协同情景的模拟结果表明，为保持白洋淀生态系统不发生明显退化，年均生态流量应大于2m3/s，水质满足IV类地表水标准；为保持生态系统处于理想状态，不同水文年3-5月生态流量应保持在9-13.5m3/s，其他月生态流量5-9.5m3/s，水质满足III类地表水标准。本研究将为生态需水评估提供可靠的理论依据，为从整体层面保护和修复湖泊生态系统提供科学依据，具有重要的理论和现实意义。