Abstract: A comparative study was made on the superoxide dismutase (SOD) and catalase (CAT) activities of dominant plants growing on two closed municipal solid waste sanitary landfill in Hunan Province. On the 3-year closed landfill under poor ecological condition, the SOD activity of Rumex dentatus, Polygonum lapathifolium and Cyperus glomeratus was 408.35, 298.56 and 219.97 U·mg^-1prot. The CAT activity ofEchinochloa crusgalli, Flos chrysantheni and Aster fastigiatus was 20.72, 18.10 and 16.42 U·mg^-1 prot, respectively, while Coronopus didymus had the lowest (3.54 U·mg^-1prot) CAT activity. Through the comprehensive comparison of the enzyme activity and the sum of R/Q, it was deduced that R. dentatus, P. lapathifolium, E. crusgalli, F. chrysantheni and A. fastigiatus had better resistance against environmental stress, being the dominant plants at the early stage of landfill closure. On the 8year closed landfill, the plants with the highest SOD activity were C. didymus, Medicago minima, Erigeron canadensis, R. dentatus and Carduus crispus, and those with the highest CAT activity were Potentilla  supina, C. crispus, Polypogon fugax, A. fastigiatus and R. dentatus. The sum of R/Q was in the range of 0.17-0.61. C. didymus, Potentilla supina, C. crispus, Polypogon fugax  and  R. dentatus had the stronger adaptability to the environmental stress. Natural succession of dominant plants was observed on the landfills closed for different years, which provided a basis for landfill vegetation restoration.

Key words: Principle grain production area, Agricultural resources and environment, Systematic identification, Macro regulation