Holocene palaeoenvironmental reconstruction based on fossil beetle faunas from the Altai-Xinjiang region, China

This project presents the results of the analysis of fossil beetle assemblages extracted from 71 samples from two peat profiles from the Halashazi Wetland in the southern Altai region of northwest China. The fossil assemblages allowed the reconstruction of local environments of the early (10,424 to 9500 cal. yr BP) and middle Holocene (6374 to 4378 cal. yr BP). In total, 54 Coleoptera taxa representing 44 genera and 14 families have been found, and 37 species have been identified, including a new species, Helophorus sinoglacialis. The majority of the fossil beetle species identified are today part of the Siberian fauna, and indicate cold steppe or tundra ecosystems. Based on the biogeographic affinities of the fossil faunas, it appears that the Altai Mountains served as dispersal corridor for cold-adapted (northern) beetle species during the Holocene.
Quantified temperature estimates were made using the Mutual Climate Range (MCR) method. In addition, indicator beetle species (cold adapted species and bark beetles) have helped to identify both cold and warm intervals, and moisture conditions have been estimated on the basis of water associated species. Generally, the fossil beetle record indicates a cold and wet early Holocene (from ~10,424 to ~ 9500 cal. yr BP) and a relativly cold and dry middle Holocene (from ~6374 to ~ 4378 cal. yr BP) at the Halashazi Wetland.
The appearance of bark beetle fossils (Phloeotribus spinulosus and Trypodendron sp.) clearly demonstrate the presence of trees at or very near the site around 9665, 9570 and 5451 cal. yr BP, whereas the spruce pollen values at the site never exceeded five percent, and there were no spruce macrofossils found in the palaeobotanical study.
Using Quaternary beetles to reconstruct palaeoenvironments is a new research method for this region, and has never before been done in China. The project provides new evidence concerning the environmental history of the study area. This study has helped establish Quaternary beetle research in China, and has contributed to beetle faunal research in Eurasia.