Study areas
Lebu Valley (27°49′-28°00′N, 91°41′-91°52′E; Figure 1) is located in the Eastern Himalayas (one of the 34 biodiversity hotspots all over the world. Mittermeier, Turner, Larsen, Brooks, & Gascon, 2011), China. ranging from 2,300 m above sea level (a.s.l.) to 5,000 m a.s.l. The planimetric distance from the bottom of the valley to the summit of Mt. Xiala is about 46 km. There are five vegetation types along the elevational gradient in Lebu: broadleaved deciduous forest (2,300-2,900 m a.s.l.), coniferous and broad-leaf mixed forest (2,900-3,400 m a.s.l.), dark coniferous forest (3,400-3,800 m a.s.l.), alpine shrub and meadows (3,800-4,400 m a.s.l.), and alpine meadow (4,400-5,000 m a.s.l.) (Wang et al., 2020).