Abstract: Based on the natural snow distribution, an experiment comparing three snow regimes of different snow depths and durations at an altitude of 4,100 m in the Minshan Range on the eastern Tibetan Plateau were conducted. These three snow regimes included a shallow and short duration snowpack (SS), a moderate snow depth and medium duration snowpack (MS), as well as a deep and long duration snowpack (DS). The results showed that deep snowcover promoted the biomass, carbon and nitrogen contents accumulation of Polygonum macrophyllum and Carex atrofusca and made the quantity and quality of their litter better. Moreover, the pattern on the accumulation and distribution of carbon and nitrogen in these two plants had some differences. Deep snowcover only promoted the roots growth and the accumulation of carbon and nitrogen contents in P.macrophyllum(forb), whereas it enhanced the aboveground and belowground biomass, carbon and nitrogen contents of C.atrofusca(graminoid). Deep snowcover enhanced the seed biomass, carbon and nitrogen contents of C.atrofusca, which might be a positive effect on seed reproduction ability. Thus, it was speculated that increased snow depth might enhance the competition of C.atrofusca and ultimately lead to the change in primary production and its structure, species component of vegetation community in the alpine meadow in eastern Tibetan Plateau.

Key words: seasonal snowcover, carbon and nitrogen content, non-growing season, Tibetan Plateau