Abstract: Land use has significant effects on the products and services provided by ecosystem, through its interaction with ecosystem processes and services. Taking Shapingba County in Chongqing as an example, and by the Costanza method and ecological sensitivity analysis, this paper analyzed the effects of land use change on ecological service value. The results indicated that from 1992 to 2002, the ecological service value of this County was from ＄ 1.74×10⁷ to ＄16.8×10⁷, i.e.,＄ 0.54×10⁵ was lost. Accordingly, each hectare land suffered an average loss of ＄13.62. The ecological service value coefficient assigned to different categories of land use had little effects on the total ecological service value, and the total change of ecological service value was inelastic. The summation of the ecological service value coefficients assigned to cultivated land, forestland and garden land was very close to regional actualities. But, the ecological service value coefficient assigned to the waters was higher than the actual value, while rectifying 30 percent of the previous coefficient by 5 667 ＄·hm^-2·yr^-1 would be very close to the actual one. Applying Costanza method to estimate the change of regional ecological service value was practicable, and would make a reference for the evaluation of land use benefits and the organization of land use planning.

Key words: Wheat, Low P stress, Morphology of roots, Phosphorus efficiency