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The hydrologic variations of Gaoyou Lake and the basin wide climate changes over the last millennium were interpreted using pollen assemblages and grain size data from sediment cores of Gaoyou Lake,eastern China.The high contents of terrestrial herbs and results from principle component analysis inferred an arid environment during AD 900-1300 years,corresponding to the dry condition of the in Medial Warm Period in China.The following period between AD 1300 and 1650 witnessed more humid climate conditions,as revealed by increased pollen contents of aquatics and fern spores and simultaneous decreased grain size value.A rise of xerophytic herb taxa(especially Artemisia and Chenopodiaceae)pointed to more arid climate from AD1650 to 1850 years,consistent with the Little Ice Age.The modern period(1850 AD onwards)was characterized by moisture condition reflected by the decline of herb contents and particle size value.The course shifts of the Yellow River to the sea at AD1194 and AD1855 were tangibly recorded by the abrupt changes of sediment characteristics as well as contents of alien pollen taxa.Intense human impacts were evidenced by the occurrence of cereal-type pollen and the increased contents of cultivated plants such as Poaceae and Cruciferae.