Modern pollen deposits in coastal mangrove swamps from northern Hainan Island, China

Pollen analyses of surface sediment samples collected from the coastal mangrove swamps of Dongzhai and Qinglan, situated in northern Hainan Island, China, were undertaken in order to reveal the relationship between modem pollen deposits and their source plants, and to provide a basis for reconstructing the Holocene history of mangrove ecosystem dynamics. Six transects (Transects 1-6) from the Dongzhai and Qinglan mangrove swamps were established to examine local plant zonation pattern along intertidal zones. Four transects (Transects 1, 2, 5, and 6) were sampled for pollen analysis. Surface pollen spectra show close linkage between pollen and local vegetation. Mangrove pollen taxa are roughly arranged by vegetation zones along the intertidal flat. Notably, Rhizophora, Ceriops, Bruguiera, and Avicennia are well represented and localized. Nevertheless, our results also suggest that other common mangroves are poorly represented by their pollen in the surface sediments, including species of Excoecaria, Aegiceras, Clerodendrum, Kandelia, Xylocarpus, and Scyphiphora. Exotic palynomorphs are also present in most of the samples; however, the dominant types are from local mangrove sources. We conclude that mangrove pollen has a local and limited distribution. Our results provide a basis for interpreting paleoecological analyses of below-surface pollen samples from the same mangrove swamps, and are crucial for further paleoecological and paleoenvironmental studies in tropical marshes.