Abstract: An investigation was made on the plant communities of artificial grasslands established for different years in headwater region of Yangtze River and Y
ellow River, and the related soil physical and chemical properties and soil microbial physiological groups were analyzed. With the increase of establishment years, most of plant communities on the grasslands showed a “V” type change trend in their quantities, i.e., high-low-high, but the forbs biomass had a “Λ” type change trend and the sedge biomass increased gradually. Soil nutrients presented a “V” type but soil bulk density presented a “Λ” type change trend, while soil pH presented a decreasing trend. Most of soil microbial physiological groups and microbial biomass carbon showed a “V” type change trend, phosphorusdissolving bacteria showed a “Λ” type change trend, denitrifying bacteria decreased gradually, while cellulosedecomposing bacteria showed an increasing trend. The numbers of soil microbes had a close relationship with tested soil factors, and the soil microbial physiological groups were directly or indirectly affected by the soil factors. All the results indicated that the establishment of artificial grassland and the positive succession of vegetation could effectively improve soil physical and chemical properties, which benefit for the beneficial microbes to settle down and propagation, while proliferation of the nonbeneficial microbes was inhibited.

Key words: headwater region of Yangtze River and Yellow River, artificial grassland, soil physical-chemical properties, physiological groups of microbe, biodiversity, use value, ecosystem function, service value evaluation.