biopl240_part3divintro07 - 99 of California grassland 91 of...

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Bio Pl 240 Fall 2007 Part III: Biodiversity The topic of Biodiversity is a bit different than the other two topics covered in the class. There is little argument that we are seeing a decline in Biodiversity over recent times. It’s the value of the loss, and what can be realistically done about it that is topic for debate. Introduction A. Human activity and the effect on Biodiversity Humans have taken over, disturbed, or degraded 4—50% of the earth’s surface- conversion of grasslands and forests to crop fields or urban areas, filling in wetlands Half of all wetlands in the world have been lost in the last century Global forest cover has been reduced by 20-50% Estimates are that the global extinction rate is 100-10,000 times higher than it was before human existence Studies in 2000- 34% of fish species, 25% of amphibians, 24% of mammals, 20% of reptiles, 14% of plant species face premature extinction…33% of plant and animal species in the united states 95-98% of virgin forests in the USA have been cleared since 1620; 98% of tallgrass prairie in the Midwest;
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Unformatted text preview: 99% of California grassland, 91% of wetlands, and 85% of redwood forests are gone. B. Factors Which Decrease Biodiversity Environmental Stress Large Environmental Disturbance Extreme Environmental Conditions Resource limitations Invasive, non-native species Geographic Isolation Human Activities related to the above- Habitat loss and degradation; invasive species; hunting, poaching, overfishing; sale of exotic species (animal and plants); pollution; climate change? C. Value of Biodiversity 1. Instrumental Value- usefulness to us a. Utilitarian Uses - Economic Goods- Food, fuel, fiber, medicines, etc. -Ecological Sservices- Nutrient recycling, pollination of crops, soil maintenance, pest control, absorption and detox of pollutants, purification of air and water -Information- genetic information, educational info by studying -Recreation b. Non-Utilitarian Uses- We find value in its existence 2. Intrinsic Value- Inherent value and right to exist beyond usefulness to us....
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biopl240_part3divintro07 - 99 of California grassland 91 of...

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