Spatial distribution and environmental significance of phytoliths in the surface soil of the Xilingol Grassland in Inner Mongolia, China

Abstract

Reconstruction of grassland ecosystems and their vegetation succession is an important issue in palaeoenvironmental research. Phytoliths and pollen are two common proxies for palaeovegetation reconstruction, and their importance can be evaluated based on investigations of the relationships between modern vegetation and phytolith/pollen assemblages in surface-soil samples. The correlations between phytolith assemblages and environmental variables were analysed based on 34 surface-soil samples from the Xilingol Grassland, Inner Mongolia, North China, and a palynological analysis was carried out on the same samples, enabling a comparison between their sensitivity to vegetation and climate change. The results show that the phytolith assemblages mainly consist of blocky and rondel phytoliths, while other short-cell phytolith types, such as saddle and bilobate types, are scarce. The pollen assemblages were characterised by a high abundance of Artemisia and Amaranthaceae. Canonical correspondence analysis (CCA) indicated that the most important environmental factors affecting the distribution of phytoliths are altitude and latitude, while the mean warmest monthly temperature (MWMT) and altitude were the most significant environmental factors affecting the distribution of the pollen assemblages. CCA of the phytoliths and pollen assemblages separated both samples into two groups: broadleaf forest/scrub and steppe/meadow groups, but it appeared that phytoliths were more sensitive in arid grasslands. This case study could be used as a baseline for interpreting fossil phytolith/pollen assemblages from the grasslands of Inner Mongolia and indicates that multiproxy analysis of the same samples can provide reliable information on palaeovegetation and palaeoclimate reconstruction.