Figure 1

Study area.

The smaller map on the left is the map of China, illustrating Guizhou Province and Sichuan Province in southwest China. The map on the right illustrates the study area, located in the convergence region of Guizhou and Sichuan provinces, including Yibin (N28°45′17.01″ E104°38′21.56″) and Luzhou (N28°52′28.94″ E105°26′20.32″) in Sichuan Province, and Zunyi (N27°47′43.76″ E106°23′51.55″) in Guizhou Province, as one of the major liquor-producing regions, referred to as “the golden triangular region”. The liquor and tree ring samples in our study were collected in this region. The map was created by the software ArcGIS 10.2 (Version:10.2.0.3348, www.esri.com).