Vegetation significance of broadleaved woody phytoliths in the mid-subtropical zone of China

Abstract To evaluate the reliability of broadleaved phytoliths for distinguishing different forest types in the mid-subtropical zone of China, we analyzed the phytolith assemblages of 50 broadleaved woody plants and 31 surface soil samples from three forest vegetation types (evergreen broadleaved forest, evergreen/deciduous broadleaved mixed forest, deciduous broadleaved forest). The results showed that the phytolith production and phytolith morphology of different broadleaved woody plants were significantly different. Evergreen broadleaved and deciduous broadleaved woody plants could be clearly distinguished according to their phytolith assemblages, providing a reliable basis for reconstructing forest vegetation. Eight broadleaved woody phytolith morphotypes were identified in the surface soil of the different forest types, accounting for ~ 5% of total phytoliths, and the broadleaved woody phytolith assemblages in the surface soil under different forest types were also different. We propose a phytolith index (B/S, defined as the ratio of broadleaved woody phytoliths to Gramineae short-cell phytoliths) to semi-quantitatively distinguish different forest types. B/S values in the surface soils of the different forest types are as follows. Evergreen broadleaved forest: < 0.03; evergreen/deciduous broadleaved mixed forest: 0.03–0.04; deciduous broadleaved forest > 0.04. Overall, our results support the use of broadleaved woody phytoliths and their indices in the surface soil of the mid-subtropical zone of China to distinguish different forest types, and they provide a useful reference for phytolith-based forest vegetation reconstruction in this region.