Distribution and sources of modern pollen in a shallow lake, eastern China: Revealing their relationships with land cover and aquatic plants.

Pollen sources and deposition processes in shallow lakes in densely populated plain areas are complicated, more modern studies are needed to establish the relationship between pollen and vegetation, so as to provide accurate indicators for environmental reconstruction. In this study, 23 surface sediments were collected from Changdang Lake in the Taihu Lake basin (covering inlets, outlets, and open water areas) for discussing the indicative significance of pollen on regional land cover and aquatic plants in the lake. The results show that the terrestrial pollen assemblages in surface sediments can reflect the main vegetation types in the watershed. However, there are significant differences in the source and input mode of the major pollen taxa. All life forms of aquatic plants show a good spatial correspondence with pollen signals, and these signals have good potential for the reconstruction of lake environment. The pollen concentration increases from inlets to outlets, mainly affected by the hydrologic dynamics inside lake. The variations of T/A ratio (the ratio of terrestrial pollen to aquatic pollen proportions) indicate that the central lacustrine sediments are more suitable for reconstructing past watershed vegetation and climate changes. The anthropogenic P/V ratio (pollen proportions/corresponding land cover proportions) maintains a stable value (~0.5) in eastern China, and proves that the pollen of cultivated plants and anthropochores can be used to assess the extent of human impacts on natural landscapes.