2. Materials and methods
2.1. Research area
China is a vast country located in East Asia; it covers an area of 9.6 million km2 and consists of 34 province-level administrative units. In this study, Mainland China was included in the research scope. Our area of interest is the Yunnan, Guangxi, Guangdong, Fujian, and Hainan provinces in Southern China along Southeast Asia, located approximately between N 18°–30° and E 97°–120° (Figure 1).