10Viney P A,William H S,Jan W E.Effects of agriculture upon the quali ty and climates:research.Policy and regulations[J].Environmental sci ence&technology,2009,6(15):4234-4240.
6Baily R G, Collins F, Zoltai S C. Ecological regionalization in Canada and the United States[J]. C, eoforum, 1985,6(3) :265-275.
7Omernik J M. Ecoregions of the conterminous United States (Map supplements) [J]. Annals of the Association of American Geo-graphers,1987,77(1):l18-125.
8Elder J. The big picture: Sierra club critical ecoregions program [J]. Sierra, 1994,79 (2) : 52-57.
9Olsen D M, Dinerstein E. The Global 2000: A representation approach to conserving the Earth's most biologically valuable ecoregions[J]. Conservation Biology, 1998,12 (3) : 502-515.
