APES notes Chapter 6

APES notes Chapter 6 - APES notes Chapter 6 Two world views...

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APES notes Chapter 6 Two world views o One view says the earth has too many people collectively degrading the earth’s natural capital o Another view says that technological advances have allowed us to overcome the environmental resistance that all populations face and to increase the earth’s carrying capacity for our species Three major factors that account for recent population growth o Humans developed the ability to expand into diverse new habitats and different climate zones o The emergence of early and modern agriculture allowed more people to be fed for each unit of land area farmed o The development of sanitation systems, antibiotics and vaccines helped control infectious disease agents As a result death rates dropped sharply below birth rates and population size grew rapidly To survive and provide resources for growing number of people, humans have modified, cultivated, built on, or degraded a large and increasing portion of the earth’s natural systems Thomas Malthus o Humans grow at an exponential rate but food does not o Proven wrong because new technologies have helped produce more food with the same amount of land or resources Ways humans have altered the rest of nature to meet their needs o Reduction of biodiversity o Increasing use of the earth’s net primary productivity o Increasing genetic resistance of pest species and disease-causing bacteria o Elimination of many natural predators o Introduction of potentially harmful species into communities o Using some renewable resources faster than they can be replenished o Interfering with the earth’s chemical cycling and energy flow processes o Relying mostly on polluting and climate-changing fossil fuels Developing countries have a higher population growth rate than developed countries Cultural carrying capacity o The limit on population growth that would allow most people in an area or the world to live in reasonable comfort and freedom without impairing the ability of the planet to sustain future generations Human populations grow or decline through the interplay of three factors o Births (fertility) o Deaths (mortality) o Migration
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To calculate population change of an area subtract the number of people leaving a population from the number entering it Crude birth rate o The number of live births per 1000 people in a population in a give year Crude death rate o The number of deaths per 1000 people in a population in a given year Fertility rate o The number of children born to a woman during her lifetime o Replacement-level fertility rate Affects a country’s population size and growth rate The average number of children that couples in a population must bear to replace themselves. The number needed is 2.1 in developed countries and 2.5 in
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This note was uploaded on 02/17/2012 for the course 375 101 taught by Professor Strom during the Spring '08 term at Rutgers.

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APES notes Chapter 6 - APES notes Chapter 6 Two world views...

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