numDF: numerator degrees of freedom. denDF: denominator degrees of freedom. Linear mixed-effects models were conducted separately for each species for each phenological observation. Warming (W), year (Y) and their interaction (W * Y) were considered as fixed factors, while plot nested within block was considered as a random factor. Asterisks indicate significant differences at P < 0.05 (*),P < 0.01 (**) and P < 0.001 (***). Sk:Stipa krylovii . Pc: Poa crymophila . Kc: Koeleria cristata . Mr: Medicago ruthenica . Kh: Kobresia humilis . As: Artemisia scoparia . Ha: Heteropappus altaicus . Gs:Gentiana squarrosa .