Holocene lake level, vegetation, and climate at the East Asian summer monsoon margin: A record from the Lake Wulanhushao basin, southern Inner Mongolia

Abstract

Abstract Understanding the impact of Holocene climate variations in arid northern China will provide important insights into a better prediction of future water availability in this region. In this study, we present paleoenvironment data from the lacustrine-aeolian deposit sections and a lake sediment core from the Lake Wulanhushao basin, southern Inner Mongolia. Optically Stimulated Luminescence dating and elevation measurements on the outcrop sections provide an estimation of lake-level changes for the past 10.1 kyr. For the sediment core, multi-proxy analyses of pollen, grain size, loss-on-ignition, element, and chroma were undertaken. The pollen result indicates a tendency of moisture increase from 10.6 to 9.1\xa0cal kyr B.P., providing moderate conditions for the gradual expansion of trees in the mountains. The highest moisture availability was reached from 9.1 to 5.6\xa0cal kyr B.P. leading to the maximal arboreal extent. After then, aridification in the region was evidenced by the declined trees and the increase of desert components. Comparing with the pollen result, non-pollen proxies from the lake sediment core and the outcrop sections indicate a slightly different climate pattern. That is, the initiation of Holocene climate optimum in the lake catchment, suggested by a high lake level, increased biological production, and an enhanced chemical weathering occurred about 1.5 kyr earlier than the arboreal expansion in the distal mountains. While the climate patterns were more or less consistent as inferred from the lacustrine pollen records at the East Asian Summer Monsoon margin, catchment-specific responses to regional climate variations might explain this perplexing discrepancy between pollen and non-pollen proxies. Our study emphasizes the importance of multi-proxy analyses from various perspectives when investigating the local and regional responses to Holocene climate variations.