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7-3 How Have We Affected the Word’s Terrestrial Ecosystems?
Concept 7-3 In many areas, human activities are impairing ecological and economic services provided by the earth’s deserts, grasslands, forests, and mountains.
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Humans Have Disturbed Most of the Earth’s Lands
According to the 2005 Millennium Ecosystem Assessment, about _______ of the world’s major terrestrial ecosystems are being degraded or used unsustainably. This percentage is likely to ________ as our human ecological footprint gets bigger. 62% increase
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Deserts We build large desert ___________
Destruction of soil and underground habitats by off-road _____________ Soil ________________ from irrigation… a gradual accumulation of salt in the upper soil layers from repeated irrigation Depletion of ___________________ Land disturbance and pollution from _______________ and mineral extraction cities Deserts vehicles salinization groundwater mining
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Grasslands Conversion to _________________
____________________ by livestock ___________ production in the tundra ________________ in the tundra farmland Overgrazing oil off-roading
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Forests Clearing for ________________ and livestock grazing
Clearing for _____________ development Conversion of diverse forest to tree ___________________ Off-road vehicles Pollution of forest _________________ agriculture Forests timber urban farms/plantations streams
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Mountains Agriculture ________________ ___________________
Hydroelectric _________ and reservoirs Increasing ________________ Air ___________________ blowing in from urban areas Water supplies threatened by glacial _______________ Mountains timber mining dams tourism pollution melting
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Humans Have Disturbed Most of the Earth’s Lands
How long can we continue to use our natural capital unsustainably before we threaten our _________________ and the long-term _______________ of other species? No one knows for sure, but it may be wise to act ___________ than later economies survival sooner Homo sapiens “wise man”
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Sustainability How has life on earth managed to sustain itself for such a long time? By following the three principles of sustainability! Relying on solar energy Maintaining biodiversity and chemical cycling
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Three Big Ideas Differences in ________________, based mostly on long-term differences in average temperature and precipitation, largely determine the types and _________________ of the earth’s deserts, grasslands, and forests. The earth’s terrestrial systems provide important ecological and economic _____________________. climate locations services
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Three Big Ideas Human activities are ____________________ and disrupting many of the ecological and economic services provided by the earth’s terrestrial ecosystems. degrading
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Review Match each example of degradation with the correct biome…
Overgrazing of livestock Depletion of groundwater Water supplies threatened by glacial melting Clearing for timber and urban development grasslands deserts mountains forests
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