Pollen distribution in surface sediments of a mangrove system, Yingluo Bay, Guangxi, China

Pollen analysis was carried out on samples of surface sediments from various plant communities of mangrove systems in Yingluo Bay, Guangxi to examine the relationships between vegetation and present-day pollen. High percentages of mangrove types can be indicators of the mangrove vegetation in general, although some terrestrial pollen occur. The exact present-day pollen assemblages can define plant community boundaries on a fine scale, which greatly increases the accuracy in the reconstruction of past environments and sea levels. Several interacting factors determine the degree to which each plant community is reflected by the pollen assemblages. After drawing the scatter diagram and using correlation analysis, cluster analysis, and detrended correspondence analysis, we summarize two groups impacting on pollen abundance. One includes the parameters of plants, in which plant cover is significantly associated with pollen percentages for Rhizophora stylosa and Kandelia candel, plant percentage plays an important role in pollen abundance for Bruguiera gymnorrhiza and Excoecaria agallocha, and tree breast diameter is for Avicennia marina by controlling plant percentage. The other group focuses mainly on the environmental conditions, of which soil types and salinity factors are displayed by the first axis of DCA (altitude); water table depth is shown by the second axis; and tidal hydrodynamics is indicated by the third axis according to the separated samples associated with the communities in each sampling square.