Anthropogenic hydrological regulation is profoundly altering the structure and function of wetland ecosystems. Due to the scarcity of long-term monitoring records, the responses of wetland ecosystems to anthropogenic hydrological regulation remain unclear. We reconstructed past ecohydrological changes in Dajiuhu Wetland during the last 40 years and explored the driving forces, based on multiproxy records of a 44-cm-length sediment core collected from Wuhaohu Lake of Dajiuhu Wetland in Shennongjia, Hubei. The results showed that the diatom community in Wuhaohu Lake had experienced three major stages, including the dominance of benthic diatoms between 1980 and 2008, the rapid increase in planktonic diatoms between 2008 and 2016, and the dominance of small-sized fragilarioid species after 2016. Results of redundancy analysis showed that change in diatom assemblage was significantly correlated with total organic carbon, total nitrogen and the ratios of Mn to Fe. Diatom floral changes after 2008 indicated the shift of Wuhaohu Lake from an early organic-rich peatland to a shallow lake, mainly in response to an increase in water table driven by damming. From 2016, the increases in benthic and epiphytic diatoms responded to the expansion of aquatic plants and improved light penetration after the relocation of local population. Sedimentary diatom records revealed the process of environmental changes, and hence would provide a scientific basis for the environmental protection of wetlands.
人为水文调控正深刻改变湿地生态系统的结构与功能。由于缺乏长期监测记录,目前针对湿地生态系统如何响应人为水文调控的报道较少。本研究基于神农架大九湖五号湖的一根长44 cm的沉积岩芯多指标记录,重建了近40年来大九湖生态水文变化过程,并探讨其驱动因子。结果表明: 五号湖的硅藻群落经历了3个主要演化阶段: 1980—2008年以底栖硅藻为主,2008—2016年浮游硅藻迅速增加,2016年以来小型脆杆藻占主导。冗余分析表明,硅藻组合变化与总有机碳、总氮和Mn/Fe值显著相关。2008年以来硅藻组合变化反映了五号湖由早期富含有机质的泥炭地向浅水湖泊转变,主要响应筑坝提升水位;2016年以来底栖和附生硅藻增多,响应大九湖移民搬迁后水生植物扩张、水体透明度增加的过程。沉积硅藻记录揭示了大九湖的环境变化过程,为湿地保护提供了科学依据。.
Keywords: Dajiuhu Wetland; biodiversity; diatom; paleolimnology; water-table change.