Abstract: Five different gramineous mixed pastures planted in 1999 were studied, and pasture productivity and plant community characteristics were recorded during two consecutive years of N fertilization at 75 kg N/ha (N₁), 150 kg N/ha (N₂), 225 kg N/ha (N₃), or 0 kg N/ha (CK). N fertilization enhanced the pasture productivity and height of these alpine pastures, but reduced plant species richness and diversity to some extent. The optimal fertilization rate for these 15 year old pastures was 150 kg N/ha per year, as this application rate improved pasture productivity and maintained the dominance of gramineous species in the plant communities. The nitrogen response differed between years and pasture with a large proportion of Elymus nutans was more responsive to N fertilizer than other pasture types. This experiment also demonstrated that single N fertilizer applications may enhance community stability or productivity of these alpine, perennial, mixed cropping cultivated grasslands.