人 文 地 理(3轮)13.1.ppt

第十三章 人文地理学所面临的问题Human Actions and Environmental Impacts 1. Physical Environments and Cultural Impacts Environment is an overworked word that means the totality f things that in any way affect an organism. Humans exist within a natural environment—the sum of the physical world—that they have modified by their individual and collective actions. Those actions include clearing forests, plowing grasslands, building dams, and constructing cities. On the natural environment, then, we have erected our cultural environment,modifying, altering, or destroying the conditions of nature that existed before human impact was expressed. 第十三章 人文地理学所面临的问题Human Actions and Environmental Impacts 2. Climates , Biomes, and Change The pattern of global climates that these physical controls established was, at the same time, a pattern of biomes. Biomes are major communities of plants and animals occupying extensive areas of the earth’s surface in response to climatic conditions. 第十三章 人文地理学所面临的问题Human Actions and Environmental Impacts The fears those pressures generated began to be replaced, in the 1980s,(1)a global warning caused by the”greenhouse” effect, (2) acid rain, and(3) ozone depletion. These, too, are threats ascribed to human introduction into the atmosphere of kinds and amounts of materials that natural systems apparently cannot handle or recycle. Present evidence and projections suggest that they may well alter the composition of the atmosphere and the pattern of climates. 第十三章 人文地理学所面临的问题Human Actions and Environmental Impacts 3. Land Use and Land Cover 1) Tropical Deforestation Now it is the tropical rain forest—also known as the tropical moist forest—biome that is feeling the pressure of growing population numbers, the need for more agricultural land, expanded demand for fuel and commercial wood, and a midlatitude market for beef that can be satisfied profitably by replacing tropical forest with cleared grazing land. About 45% of their original expanse has already been cl