*2.1. Study Area*

The QLMs represent the largest mountain system in the marginal northeast of the QTP, which crosses Gansu Province and Qinghai Province. The geographical coordinates lie between 93◦25–103◦50E and 35◦52–39◦52N, with a total area of approximately 184,000 km2. The terrain gradually rises from northeast to southwest, and the average elevation exceeds 3500 m (Figure 1). The northern slope of the QLMs contain the headwaters of three inland rivers (Heihe, Shulehe, and Shiyanghe rivers) in China [27]. Qinghai Lake is the largest inland saltwater lake in China and is fed from the south slope of the QLMs. The QLMs belong to the midlatitude northern temperate zone, which has a typical continental plateau climate [28]. Due to the obvious vertical zonality and horizontal zonality, the water and heat conditions in the Qilian Mountains dramatically vary spatially. Precipitation mainly occurs in the summer and decreases from east to west, increasing with altitude, but temperature shows the reverse pattern [25]. The main vegetation types in the region include broadleaf forests, needleleaf forests, shrublands, meadows, grasslands, and deserts, and the natural ecosystems are fragile and sensitive to climate change because of complex topographic and climatic conditions.

**Figure 1.** Geographical location of the Qilian Mountains.
