A study on modern pollen rain and pollen morphology in the tropical western Malay Peninsula and its implications for paleoenvironmental reconstructions in the Sunda region

Abstract

The tropical Southeast Asia area is rich in plant diversity, and the current environment conditions, especially the vegetation, were formed through a series of complicated processes, both geological and biological, in the past. One of the most powerful tools to reveal these processes is pollen analysis. However, so far, it is still poorly understood in the modern pollen rain, hindering further palynological exploration of ecological and environmental evolutions in the region. Here we analyzed 84 surface pollen samples from the western Malay Peninsula and illustrated a high level of pollen and spore diversity by photographic images of 328 types. The results also revealed that all the regional vegetation types are distinguished by a few major characteristic pollen and spore types in the assemblages. For montane rainforests, Podocarpaceae, Ericaceae, cf. Distichostemon, Borreria, Myrica, Rapanea, Ophioglossaceae and Ilex type1 are characteristic. For lowland dipterocarp rainforests, Bursaraceae, Sapotaceae, Mallotus/Macaranga, Eugeissona, Anacardiaceae, Asystasia, Ilex type2/3, Hamamelidaceae, Dicranopteris, etc. are good indicators. The coastal rainforests are distinguished by relatively abundant Casuarina, cf. Pittosporum, Styracaceae, Ulmus, Alstonia and Schoutenia, and the mangrove forest by abundant Rhizophora, Sonneratiaceae, Xylocarpus and Lygodiaceae. Detrended Correspondence Analysis (DCA) of pollen percentages shows strong correlations of plant communities with the distribution elevation and the substrate gradients. Our results demonstrate the potential for detailed paleoecological reconstructions of both montane and lowland communities in the study region, and also suggest a pollen sorting of marine samples after a long-distance transport to the deposition sites.