Variations in tree-ring width indices over the past three centuries and their associations with sandy desertification cycles in East Asia

A database of 39 annually resolved, tree-ring width chronologies covering the Mongolian Plateau, northeastern China region, and the Yellow River drainage was established to identify variations in sandy desertification cycles over the past three centuries. Our results show that the arid, semiarid, and semi-humid East Asia experienced multiple sandy desertification cycles over the past 300 years. The Mongolian Plateau experienced sandy desertification from the 1730s to the 1750s and the 1810s to the 1910s. Northeastern China region was subject to sandy desertification from the 1700s to the 1720s, the 1770s to the 1820s, and the 1830s to the 1860s. In the Yellow River drainage, sandy desertification occurred from the 1700s to the 1730s, the 1750s to the 1780s, and the 1810s to the 1850s. The occurrence of sandy desertification was closely related to weakened summer monsoon and enhanced winter monsoon associated with decreases in precipitation and increases in aeolian activity during the Little Ice Age; reversals of sandy desertification resulted mainly from increases in precipitation and decreases in aeolian activity during the Current Warm Period. The sandy desertification cycles we reconstructed have been verified by monitoring results of modern sandy desertification trends and evidence from ancient archives and archaeological records. (C) 2013 Elsevier Ltd. All rights reserved.