Holocene vegetation and climate reconstructions from pollen records in the Mu Us Sandy Land, China

Abstract

Knowledge of changes in vegetation and climate during the Holocene is important for improved assessments of future climate change and for mitigating climate warming. Owing to the relative difficulty in obtaining high-resolution sedimentary records and identifying pollen, few paleovegetation reconstructions are available from the Mu Us Sandy Land, China. This study analyzes a naturally-exposed fluvio-lacustrine section in the hinterland of the Mu Us Sandy Land. Based on a chronological framework constructed by AMS 14C, a pollen-based random forest model was used to quantitatively reconstruct changes in Holocene climate and normalized difference vegetation index (NDVI) changes. The relationships between NDVI, pollen and precipitation, as well as pollen assemblage characteristics were combined to reconstruct the evolution of the Holocene vegetation in the Mu Us Sandy Land. Our results show that the climate was cold and humid, and the dominant vegetation type was Ephedra shrub-encroached steppe between 11.2 and 8.3 ka BP; the climate reached an optimum, and vegetation evolved into Artemisia–Taraxacum-type–Thalictrum steppe from 8.3 to 2.6 ka BP; and finally, the climate gradually deteriorated and vegetation became an Artemisia–Chenopodiaceae steppe after 2.6 ka BP. In comparisons with other climate records, we found that the Mu Us Sandy Land climate optimum occurred synchronously at 8.3–2.6 ka BP, and the pattern of climate change is closely consistent with the East Asian summer monsoon. We suggest that millennial-scale Holocene climatic change in this region was mainly driven by the influences of high-latitude ice volume and summer solar radiation on the East Asian summer monsoon.