The study area—Sangong River watershed (87°47′ to 88°17′ E,43°09′ to 45°29′ N)—is located on the north side of the Tianshan Mountains, Xinjiang, China (see Fig. 1). As a typical arid region that has an inland arid climate but relatively high moisture in the mountainous regions, the Tianshan Mountains consist of plain desert grassland [ meter above sea level (m a.s.l.)], low-mountain dry grassland (700 to 1,650 m a.s.l.), mid-mountain forest meadow belt (1,650 to 2,700 m a.s.l.), alpine/subalpine shrub and/or meadow (2,700 to 3,500 m a.s.l.), and alpine exposed rock or snow–ice belt (over 3,500 m a.s.l.).20 The mid-mountain forest belt (1,650 to 2,700 m a.s.l.) is covered by a mountainous coniferous forest, mainly Schrenkiana on the north side of the mountain, and by mountainous meadow with vegetation coverage of 70% to 95% on the south side of the mountain. The areas with an elevation of 2,700 to 3,500 m are alpine and subalpine shrub or meadow belt with vegetation coverage of 30 to 80%. Considering the data availability and the objective of this study, a case study covering approximately in the mid-mountain forest meadow belt and alpine/subalpine shrub and/or meadow was selected [Fig. 1(b)]. According to the Tian Chi weather station, at an elevation of 1,942 m, the study area has an annual precipitation of 525 mm, annual temperature of 2.2°C, and average annual potential evaporation of 1,339 mm. The alpine tree line in the study area is a transition from closed forest (i.e., Picea Schrenkiana, hereafter, Schrenkiana), sparse forest, Juniperus Sabina (hereafter, Sabina), and subalpine meadow. The elevation range in this case study is approximately 2,300 to 3,300 m.