Abstract: Understory vegetation is an important component of forest ecosystems, which plays an important role in ecosystem nutrient cycling. The effects of understory removal on soil microbial biomass, activities of enzymes catalyzing organic carbon (C), nitrogen (N), and phosphorus (P), and available N and P concentrations were examined in a nutrientpoor Pinus sylvestris var. mongolica plantation in Horqin Sandy Land. Understory removal significantly decreased microbial biomass C and P, available P concentrations, as well as all measured enzyme activities in summer (August), but only decreased N-acetylβ-Dglucosidase activity and did not influence microbial biomass, available nutrient concentrations and activities of other enzymes in spring (May). These results suggested that preservation of understory vegetation could effectively improve soil microbial activity and accelerate mineralization of organic C, N and P, and thus maintain the nutrient supply in this nutrientpoor pine plantation.

Key words: remote sensing based ecological index (RSEI), Shanghai, impervious surface, remote sensing, New York