Phytolith analyses of tropical plants and topsoil from western Peninsular Malaysia and their implications for paleoenvironmental reconstruction

The underrepresentation of many important rainforest species in pollen records still hinders accurate paleovegetation reconstructions in tropical Southeast Asia. In this study, we conducted a modern phytolith study of 141 plant and 15 surface soil samples around the forests of Jerai Hill in western Peninsular Malaysia to evaluate the potential of phytolith assemblages as a proxy for indicating tropical vegetation types. In the plant samples, including many Dipterocarpaceae species, tracheary annulate/helical phytoliths occur most commonly, followed by silicified epidermis, silicified stomata, elongate entire, sclereid, trichomes, irregular. A few diagnostic phytoliths with unique morphological features are found in dicotyledonous trees, palms, and ferns, such as spheroid ornate (sph_orn) and spheroid echinate (sph_ech). In contrast, the phytolith assemblage of surface sediment is dominated by sph_orn, sph_ech, and spheroid psilate. This suggests that similar to pollen, the contribution from dominating forest vegetation rich in Dipterocarpaceae species is obscure in phytolith deposits. However, phytolith analysis highlights the representation of monocotyledons and a few dicotyledonous trees. The more sensitive indication of Poaceae short-cell phytoliths than pollen for parent plants implies that their ratio to forest indicator phytoliths might be a valuable proxy of landscape openness. Additionally, the statistical analysis confirms that phytolith assemblages in the heath forest are slightly different from those in the lowland dipterocarp forest, exhibiting their potential to indicate various vegetation types.