湖泊生态系统往往受营养、水文和气候等诸多环境因子的影响.区分不同环境因子的影响是揭示湖泊生态环境演化机制的关键.本文基于巢湖岩芯210Pb和137Cs测年、硅藻、地球化学指标和粒度分析结果以及流域水文、气候、人口和农业资料,利用冗余分析,定量区分1950年来营养、水文和气侯对硅藻组合演替的影响.1978年前硅藻组合中Aulacoseira granulata占绝对优势,此后耐营养种Cyclostephanos dubius大量出现.2000年以来C.dubius占绝对优势,并伴随Cyclostephanos tholiformis和Stephanodiscus parvus等其它耐营养种增加.结果表明,沉积物TP、TN、年均温、年均风速和水位变幅是影响硅藻组合演替的五个显著变量,它们分别单独解释硅藻组合方差的6.5％、4.7％、4.5％、4.7％和3.0％.这表明近50年来营养是巢湖硅藻组合演替的决定因素,水文过程和气候变化也是硅藻组合演替的重要诱因.%Ecosystem in shallow lakes is generally subjected to the effects of multiple stressors, including nutrient, hydrology and climate. It is important to identify the impacts of multi-stressors for understanding the mechanism of environmental change in the lakes. Based on sedimentary proxies (I. E. ,2l0Pb and I37Cs dating, diatom, geochemical indicators and particle size) from Chaohu sediment core and documentary data (I. E. , hydrology, climate, population and agriculture) in Chaohu basin, this study estimated quantitatively the effects of nutrient, hydrology and climate on diatom succession since 1950 using the redundancy analysis. Before 1978 diatom assemblages were dominated by Aulacoteira granulata, followed by an abrupt increase in eutrophic species (I. E. Cy-clastephanos duirius). Since 2000 diatom assemblages were characterized by C. Dubius, with increases in eutrophic species (e.g. , Cyclostephanos tholiformis and Stephanodiscut parvus). Results showed that sedimentary total phosphorus, total nitrogen, annual mean temperature, annual mean wind speed and annual water level amplitude were five significant variables, explaining solely 6.5% , 4.7% , 4.5% , 4.7% and 3.0% of the variances in diatoms respectively. Therefore, nutrient input was the most important factor on diatom succession. Meanwhile, changes in climate and hydrological conditions also imposed an effect on diatom succession in Lake Chaohu during the last 50 years.
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