SUCCESSION OF THE ARTIFICIAL GRASSLANDS IN THE MOUNTAIN GRASSLAND AREA OF GANNAN DISTRICT GANSU
甘南山地草原人工草场的演替

Two artificial grasslands of Elymus nutans, one seeded in 1985 and one in 1979, were chosen for our study. Two surveys were made in both 1986 and 1988. Results of our analysis show that (1) There is a continuous shift in community composition toward the original vegetation; (2) Succession rate in the early stages of succession is much faster than in the later ones; (3) Simpson's diversity and homogeneity increase with time, but community dominance decreases; (4) Quality of grassland can be quantaititively measured by the index proposed in this paper, and it tends to decrease after succession begins, and then recovers in final stage.