Transcript Chapter 6
Chapter 6 Humans in the Biosphere 6-1 A Changing Landscape The “natural” Earth has been changed dramatically…because of humans! Ex: Polynesia -> Hawaii Some settlers were self sufficient Others took advantage Earth as an island… Limited resources for survival Natural ecological processes sustain these resources Human Impacts Hunting/gathering Agriculture We learned how to utilize environment Industry and urban development may cause extinction or migration Pollution, waste disposal, loss of natural habitats We are part of the food webs and nutrient cycles in our ecosystems The Green Revolution Development of highly productive crop strains and use of modern agriculture technique to increase crops More food! Better nutrition! Problems? more crops = more insects = more pesticides = possible contamination 6-2 Renewable and Nonrenewable Resources Tragedy of the commons: any resource that is free and accessible to all may eventually be destroyed No responsibility or protection Ex: cattle and grass fields Classifying Resources Renewable: can regenerate (if alive) or be replenished by a cycle (nonliving) Ex: water Nonrenewable: cannot be replenished by natural processes Ex: oil Must be taken in context! 1 tree = renewable/ a forest = nonrenewable Sustainable Development A way of using natural resources to provide for human needs without depleting them or causing environmental harm Research based Ex: insects as pest control 6-3 Biodiversity Sum of all the genetically based organisms in the biosphere Ecosystem diversity: habitats, communities and ecological processes Species diversity: # of different species Genetic diversity: sum of all genetic information in all organisms Threats to Biodiversity Habitat alteration Demand for wildlife products Pollution Biological magnification: when concentration of harmful substances increases in higher trophic levels Ex: DDT pesticide Introduced species Can be on purpose or by accident Invasive species: new organisms end up in a place they are not native to Usually increase in population (no predators) Effect the ecosystem Ex: zebra mussels Conservation Wise management of natural resources including preservation of habitats/wildlife Uses info about relationships, genetics, geography, etc. Ex: captive breeding, national parks Challenges: must maximize benefits and minimize cost Ex: fishing regulations = loss in jobs 6-4 Charting a Course for the Future Human population still growing… Small steps are key to big changes Areas of concern: Ozone absorbs UV light loss of layer = sunburn, cancers, immune system malfunctions, etc. Global depletion climate change increase in greenhouse gases causing flooding, drought