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Sơ đồ metapopulation một. Các khu vực bị cô lập trong trắng là những bị chiếm đóng bởi các cá nhân của các loài trong câu hỏi. Metapopulation được kết nối với mức độ khác nhau bằng cách di chuyển (mũi tên). | The Spatial Nature of Conservation and Development 5 Fig. 1.1 Diagram of a metapopulation. The isolated areas in white are those occupied by individuals of the species in question. The metapopulation is connected to varying degrees by migration arrows . Some subpopulations will function as sources births exceeding deaths while others will function as sinks deaths exceeding births . The fate of the population as a whole depends upon the structure and dynamics of the metapopulation. Humans Economy Ecology and the Need to Consider Resource Management in Land Use Planning Humans rely on the landscape for most of their economic activities. These activities include mining agriculture forestry livestock and urbanization. The extent of the surface of the planet under some form of development is substantial table 1.1 . Land use categories are cropland rangeland and forests or woodland. The other major land use category mining is not included. Mining is of great economic importance but the amount of land altered by mining activities is generally very small amounting to only about 0.25 percent of the land area in the United States for example Hodges 1995 . Estimates for the period 1989-1991 are that 37 percent of the total land area of the planet is either in cropland or permanent pasture WR1 1994 . Europe is the most extensively altered geographi- 6 Thomas E. Lacher Jr. Table 1.1 Land Use Activities by Region for 1983 in Millions of Hectares modified from Wolf 1986 Region Cropland Rangeland Forests and Woodland North America 236 265 591 Central America South America 175 550 999 Europe Soviet Union a 373 459 1 075 Africa 183 778 688 Oceania 47 459 116 Asia Mideast 456 645 561 Total 1 470 3 156 4 030 aIncludes all of the former Soviet Union. Table 1.2 Percents of Total Areas Under Various Land Use Activities Country Total Area Domesticated Crops Crops Pasture Pasture Forest Forest Developed countries United States 916 660 47 187 776 20 239 172 26 287 400 31 Canada 922 097 8 45
