| Bockstael N, R Costanza, I Strand, et al. 1995. Ecological economic modeling and valuation of ecosystems. Ecological Economics, 14: 143-159.Boody G, B Vondracek, D A Andow, et al. 2005. Multifunctional agriculture in the United States. Bioscience, 55(1):27-38.Costanza R, R d'Arge, R de Groot, et al. 1997. The value of the world's ecosystem services and natural capital. Nature, 387(6630): 253-260.de Groot R S. 1987. Environmental functions as a unifying concept for ecology and economics. Environmentalist, 7:105-109.Holder J, P R Ehrlich. 1974. Human population and global environment. American Scientist, 62: 282-297.Holmund C, M Hammer. 1999. Ecosystem services generated by fish population. Ecological Economics, 29: 253-268.Mu X L. 2010. A study on compensation system for agricultural land acquisition. Wuhan: Huazhong Agricultural University. (in Chinese)Naylor R, P Ehrlich. 1997. Natural pest control services and agriculture. In: Daily G C (Ed.). Nature's Services: Societal Dependence on Natural Ecosystems. Washington: Island Press, 151-174.Penning de Vries F W T, F Agus, J Kerr. 1998. Soil erosion at multiple scale. Wallingford, UK: CBAI Publishing.Pretty J N, C Brett, D Gee, et al. 2000. An assessment of the total external costs of UK agriculture. Agricultural Systems, 65:113-136.Tilman D, K Cassman, P Matson, et al. 2002. Agricultural sustainability and the costs and benefits of intensive production practices. Nature, 418: 671-677.Vocke G F, E O Heady (Ed.). 1992. Economic models of agricultural land conservation and environmental improvement. Ames, Iowa: Iowa State University Press.Westman W. 1977. How much are nature's services worth. Science, 197(4307): 960-964.Xie G D, Lu C X, Leng Y F, et al. 2003. Ecological assets valuation of the Tibetan Plateau. Journal of Natural Resources, 18(2):189-196. (in Chinese)Zhang W, T H Richetts, C Kremen, et al. 2007. Ecosystem services and disservices to agriculture. Ecological Economics, 64(2): 253-260.