鄱阳湖洪泛湿地生态系统在调节长江流域水文、维系生物多样性等方面具有不可替代的作用,但受气候变化与人类活动复合影响导致湿地水质退化、植被群落结构劣化等问题凸显,亟待开展系统性研究。基于综合水质指数、Pinkas相对重要性指数等方法,在典型洪泛湿地选取6个监测点位,系统分析湿地生态时空分异特征。研究表明:①水质时空分异显著,水质污染物时间上呈现“丰水期稀释-枯水期富集”、空间上呈现“中部劣、上下部优”规律,整体水质均达到“好”程度;土地利用格局变化引发枯水期水质劣化、西部农田扩张与水质劣变区空间耦合。②2024年植被覆盖度较2023年增长38%,但高密度植被区消失,中值区缩减12.7%,底栖动物物种受到人类活动与水文期的复合影响。③鄱阳湖洪泛湿地存在水质污染失衡、生物群落结构退化与生态功能衰减、土地利用冲突与生态功能失衡3个问题。

[Objective] The Poyang Lake floodplain wetland ecosystem plays an irreplaceable role in regulating the hydrology of the Yangtze River Basin and maintaining biodiversity. However, due to the combined effects of climate change and human activities, problems such as water quality deterioration and vegetation community degradation have become increasingly prominent, highlighting the urgent need for systematic investigation. This study aims to address two core scientific questions by constructing a multi-element collaborative analytical framework: (1) to reveal the spatiotemporal change patterns and driving mechanisms of wetland water quality under the dual stress of climate change and human activities; (2) to analyze the combined impact of hydrological regime shifts and land use pattern changes on vegetation community structure and benthic species communities. [Methods] This study integrated multi-source data fusion and spatiotemporal coupling analysis techniques. Six typical monitoring sites were selected, covering three types of habitats: dish-shaped lake areas, tailing areas, and flood detention areas. Water quality parameters (e.g., DO and TP, six indicators in total) and benthic species data were obtained through continuous observations during three hydrological periods (normal, flood, and dry seasons) in 2024. Remote sensing image interpretation was used to obtain land use changes and vegetation conditions. Based on water quality index (WQI), Pinkas’ index of relative importance (IRI), and other methods, the spatiotemporal change characteristics of the wetland ecosystems were systematically analyzed. [Results] (1) The WQI of the Poyang Lake floodplain wetlands was influenced by both temporal and spatial scales. Temporally, it exhibited a migration pattern of pollutants characterized by “dilution in the flood season and enrichment in the dry season”. Spatially, it exhibited a gradient pattern of “poorer conditions in the upper and middle reaches and better conditions in the lower reaches”, with the best water quality observed in the dish-shaped lake areas, while the overall wetland water quality reached the “good” level (60<WQI≤80). Changes in land use patterns led to water quality deterioration during the dry season, and the expansion of farmland in the western region was spatially coupled with areas of water quality deterioration. (2) The vegetation community structure of the Poyang Lake floodplain wetlands deteriorated from 2023 to 2024. The high-density vegetation coverage area (NDVI≥0.7) nearly disappeared in 2024, and the area of the medium-density zone (0.2≤NDVI<0.5) decreased by 12.7%. Vegetation degradation was significant, while overall vegetation coverage increased by 38%. The benthic species communities were significantly influenced by hydrological conditions. Except during the dry season, there were notable interannual variations in the dominant benthic species. Spatially, it was affected by human activities, with community distribution in areas of frequent human activities being lower than that in natural ecological areas. [Conclusion] This study identifies three types of ecological problems in the Poyang Lake floodplain wetlands. The first is the “water quality imbalance under the combined effects of hydrological regimes and human activities”, characterized by significant seasonal variations in pollutants, following a pattern of “dilution in the flood season and enrichment in the dry season”. The second is “degradation of biological community structure and decline in ecological functions”, characterized by deterioration of vegetation community structure, disappearance of high-density areas, reduction of medium-density areas, and lower biomass of benthic species in areas with frequent human activities compared with natural ecological areas. The third is “conflict between land use and ecological functions”, characterized by adverse changes in land cover, forming a positive feedback chain of “farmland encroachment-non-point source pollution-vegetation degradation”. A coordinated governance system of “hydrological regulation-ecological restoration-social participation” is proposed to address these three types of problems. In future, the monitoring scope can be further expanded, and long-term research on the response of wetland ecology to climate change can be strengthened to provide more comprehensive scientific support for sustainable wetland management in the context of the Yangtze River protection strategy.