2.1. Study area and experimental design
This study was conducted in Ganchaitan, close to Haibei station (101°19′E, 37°37′N, 3100 m), and included two neighboring sites (i.e., shrubs and grassland) in the northeastern Qinghai-Tibet Plateau, located in Qinghai Province, China, (Figure 1). The region is in a semiarid, cold, high-altitude climate zone(Dai et al., 2019b). The mean annual precipitation is approximately 562 mm. Almost 80% of the annual precipitation falls during the growing season (i.e., from May to September). The mean annual air temperature is approximately -1.7℃, with the maximum temperature occurring in July (9.8 ℃) and the minimum temperature occurring in January (-14.80℃) (Dai, et al., 2021). Alpine shrubs and meadows are the dominant vegetation types at the study sites. The dominant primary vegetation is the shrub P. fruticose ; herbs include Elymus nutans, Poaprsten, Kobresia humilis, Double-stigma Bulrush, and Polygonum vivipsrum . The characteristics of the community were investigated and shown in Table 1.
Table1 Community characteristics of grassland and shrub sites.