鄱阳湖水文水动力过程与生态演替相互作用机理多尺度研究

In recent years, influenced by natural and human activities, significant changes have taken place in Poyang Lake’s hydrological regime and ecological environment, and the relevant scientific issues have been becoming domestic research hotspot in the field of water environment and water ecology. The project focuses on the degradation of the lake ecological system driving by Poyang Lake adverse hydrological situation changes, analyzing the Poyang lake’s time-space change rules in hydrology and hydrodynamics due to the influence of natural and human activities, discriminating the main meteorological factors of the effect in hydrological regime situation changes, studying on the structural characteristic of ecosystem succession and feedback mechanism with the change of hydrological regime from the perspective of macro system dynamics in Poyang Lake and the interaction mechanism between wetland vegetation and lake hydrodynamic, nutrient salt conditions, also the influence of the pivotal organisms by the microenvironment change on the mesoscopic in ecological dynamics model. Thus a platform model will be built to reflect the Poyang lake ecosystem succession simulation system, revealing the mechanism of lake wetland ecosystem succession on account of large lakes changes in hydrological process from the different levels of the macroscopic and mesoscopic system, clarifying the hydrological and hydrodynamic drive mechanism in the phenomenon of Poyang lake wetland ecosystem degradation. The research is not only beneficial to solve the Poyang Lake water environment worsening and ecosystem degradation problem，but also to enrich and perfect the lake water ecological maintenance and repair theory further, promote the development of ecological hydrology and hydraulics.

近年来，受自然和人类活动的影响，鄱阳湖水文情势和生态环境发生了明显的变化，其相关科学问题成为目前国内水环境与水生态领域的研究热点。针对鄱阳湖不利水文情势变化驱动下的湖泊生态系统退化问题，分析自然和人类活动影响下的鄱阳湖水文水动力时空变化规律，辨析影响水文情势变化的主控气象因子，宏观上从系统动力学角度研究水文情势变化下鄱阳湖生态系统演替的结构特征及反馈机制，细观上以生态动力学模型研究湿地植被与湖泊水动力和营养盐条件的交互作用机理以及微生境变化对关键生物类群的影响，构建反映鄱阳湖生态系统演替的模拟系统平台，从宏观、细观不同层次系统揭示大型湖泊水文过程变化对湖泊湿地生态系统演替的作用机理，阐明鄱阳湖湿地生态系统退化现象的水文、水动力学驱动机制。项目的研究不仅有利于解决鄱阳湖面临的水环境恶化和生态系统退化的问题，而且将进一步丰富和完善湖泊水生态维护和修复理论，推动生态水文学、生态水力学的发展。

本项目以变化环境下的湖泊水文生态过程研究为基础，以生态因子对水动力因子胁迫响应规律为主线，以水文过程与生态演替的交互作用机理为核心，以维持湖区可持续发展和生态系统健康为目标，在多学科协作攻关的基础上，采取资料分析、现场观测、数值模拟、室内和野外实验相结合的方法开展了研究。所取得的成果包括（1）揭示了水动力与水环境变化下鄱阳湖湿地植被演替机理。水动力与水环境变化下，鄱阳湖湿地植被呈现总体退化趋势；湿地植被沿高程形成地带分布特征，湿地植被对淹水时长的响应总体符合“钟形曲线”；植被的生存策略是决定其适应能力和生态阈值的主要原因，优势湿地植被均存在适宜、最适和限制阈值。（2）解析了植被影响下的湿地水流结构与溶质运移规律。湿地中存在的植被通过改变水流的流速分布来改变溶质的输移过程，而湿地中的吸收边界是通过改变溶质质量对溶质在空间的分布；植被摩阻抑制溶质云团的扩散，边界吸收强度抑制溶质云团的扩散范围，而整体溶质浓度分布呈现更为均匀的状态；提出了悬沙浓度垂向离散模型，采用随机位移法求解模型获得了植被水流中悬沙浓度的垂向分布。（3）揭示了大型底栖生物的水生生物生境变化驱动机理。与水文过程变化显著相关的水深、浊度、可溶解性有机碳、氮磷营养盐等是影响鄱阳湖生物群落演替和生物多样性结构的重要因素，对于湖泊生态系统重要生物类群及其生态功能具有重要影响。水文剧烈变化下，蝶形湖和出露区微生物群落的结构、功能具有显著差异，碟形湖微生物较高的共生关系和生物多样性，对于区域生态系统结构稳定性的维持具有重要作用。研究成果在植被、水流、泥沙、污染物交互作用机理方面有理论上的创新，揭示了水文情势变化下生物群落的短期适应机制，为了解气候变化和人为活动影响下鄱阳湖生态系统的演变规律提供了重要的科学依据，进一步丰富和完善了湖泊水生态维护和修复理论，推动生态水文学、生态水力学的发展。