Fig. 2.

Time series variation of aboveground biomass in Damxung (a) alpine grasslands. Mean richness, mean dominance, species synchrony, and stability of aboveground biomass in Damxung (b-e) nitrogen (N) and phosphorous (P) enrichment were calculated. In Damxung nutrient enrichment experiment, N and P addition were performed in a winter grazing alpine grassland. LN, HN, P, LNP, and HNP represent low N (5 g N m⁻² yr⁻¹), high N (10 g N m⁻² yr⁻¹), constant P (5 g P m⁻² yr⁻¹), low N combined with P ((5 g N + 5 g P) m⁻² yr⁻¹), and high N combined with P ((10 g N + 5 g P) m⁻² yr⁻¹), respectively. In the control treatment (C), neither N nor P was added. Symbols with different letters represent significant differences among the treatments at the P < 0.05 level (based on Tukey's test). The nutrient treatments were carried out starting in 2008. We used data collected in P treatment ranging from 2013 to 2018, in other five treatments ranging from 2010 to 2018.