Phytolith characteristics and preservation in trees from coniferous and broad-leaved mixed forest in an eastern mountainous area of Northeast China

Research on phytolith morphology and the preservation of phytoliths in soils provides the theoretical basis for reconstructing shifts in forest-grassland ecotones and the evolution of plant communities. Based initially on anatomical origin, then shape and finally texture, phytoliths in broad-leaved trees were divided into six major types, 10 types and 33 sub-types, respectively; and correspondingly phytoliths in coniferous trees were divided into seven major types, 9 types and 20 sub-types. Results of detrended correspondence analysis showed that broad-leaved trees were characterized by epidermal phytoliths, hair, hair base, sclereid, elongate attenuate, stomate and tracheids; while the main coniferous phytoliths were elongate, tabular, blocky and margin-cuneiform. In Pinaceae, Larix closely corresponded to elongate and margin-cuneiform; Picea and Abies to blocky scrobiculate, stomate and tracheids; while Pinus corresponded well with epidermal, blocky and tabular. Only five kinds of broad-leaved phytoliths and seven kinds of coniferous phytoliths appeared in soils. The preservation degree of different phytolith types was determined by comparing the contents of the same phytoliths in plants and soils. Evidence showed that coniferous phytoliths were better preserved than broad-leaved ones. Among coniferous phytoliths, the cubic, tabular echinate and elongate cavate phytoliths were better preserved than other types. Among broad-leaved phytoliths, sclereid and blocky facetate showed the best preservation. Overall, this research will support the more accurate use of tree phytoliths in interpreting paleo-environments and paleo-vegetation.