Linkage between C_4 vegetation expansion and dune stabilization in the deserts of NE China during the late Quaternary

摘要

Knowledge of the role of C-4 vegetation expansion in regulating dune stabilization during the late Quaternary is important for understanding the evolution of the environment and climate in the climatically-sensitive margin of the East Asian summer monsoon. However, due to the lack of both reliable vegetation records and chronological control during episodes of dune activity, the relationship between C-4 vegetation expansion and dune stabilization in the deserts of NE China during the late Quaternary remains unclear. Here, we present a new regional compilation of late Quaternary stable carbon isotopic data from organic matter, together with dated records from sub-aerial sedimentary deposits in the region. Our compilation of vegetation development and dune activity in these deserts suggests that C-4 vegetation expansion, with a main contribution from Chenopodiaceae, and a secondary contribution from Poaceae and Cyperaceae, may have played a critical role in dune semi-stabilization with a northwestward trend, from similar to 13 to 9 ka; and dune stabilization throughout the entire study region, from similar to 9 to 5 ka. In addition, during the late Holocene, intensified millet cultivation (or overgrazing) and/or climatic deterioration at similar to 1.5 ka likely caused an increase in C-4 vegetation abundance in the deserts of NE China, which is associated with a dune mobilization episode. In contrast, after similar to 2.5 ka, decreased vegetation cover and dune mobilization in the Mu Us and Hobq deserts were likely caused by poor land-use practices and historically documented droughts. Overall, C-4 vegetation expansion was the main cause of dune stabilization in these deserts during the late Quaternary.