Population Population Ecology Is concerned with changes in population size and the factors that...

PopulationPopulation

Population EcologyPopulation EcologyIs concerned with changes in population Is concerned with changes in population

size and the factors that regulate size and the factors that regulate populations over timepopulations over time

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•The Spread of Shakespeare’s Starlings– The European Starling

• Has become an abundant and destructive pest in North America

Europeanstarling

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Multiple factors may limit population growthMultiple factors may limit population growth• As a population’s density increasesAs a population’s density increases

Factors such as limited food supply and Factors such as limited food supply and increased disease or predation may increase the increased disease or predation may increase the death rate, decrease the birth rate, or bothdeath rate, decrease the birth rate, or both

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Density of females

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Figure 36.5A 33

The Plague

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Figure 36.9A

The human The human population population has been has been growing growing almost almost exponentially exponentially for centuries, for centuries, standing now standing now at about 7 at about 7 billionbillion

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Baby BoomBaby Boom

The baby boom was in the 1950s when the The baby boom was in the 1950s when the American birthrate skyrocketed. American birthrate skyrocketed.

When the so-called baby boomers were in When the so-called baby boomers were in their 20s, they were young and vibrant, their 20s, they were young and vibrant, and they added to American productivity.and they added to American productivity.

Today, however, the boomers are aging. Today, however, the boomers are aging. Their children worry that elderly boomers Their children worry that elderly boomers will drain resources, not to mention will drain resources, not to mention national attention, from younger adults.national attention, from younger adults.

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Human Population GrowthHuman Population Growth

The world population increases the The world population increases the equivalent of a medium-sized city equivalent of a medium-sized city (200,000) every day and the (200,000) every day and the equivalent of a country the size of equivalent of a country the size of Germany (80 million) every year.Germany (80 million) every year.

Most of the growth is coming from Most of the growth is coming from less-developed countries.less-developed countries.

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Right now, there are about 7 billion Right now, there are about 7 billion people on the planet, but in the next people on the planet, but in the next 100 years, there will be about 11 100 years, there will be about 11 billion.billion.

All populations need nutrientsAll populations need nutrients,, space space, , water, and energy.water, and energy.

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Resources Are Needed

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This means that in about 50 years, This means that in about 50 years, the world will need double the the world will need double the amount of food, jobs, water, energy, amount of food, jobs, water, energy, and so on to maintain the same and so on to maintain the same standard of living.standard of living.

Right now, half of our world’s Right now, half of our world’s population do not have electricity or population do not have electricity or indoor water and cannot read even indoor water and cannot read even enough to sign their name.enough to sign their name.

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We are adding a billion more people to the We are adding a billion more people to the planet much faster than we used to. planet much faster than we used to.

We got our first billion in 1800; the second We got our first billion in 1800; the second billion arrived in 1930; the third billion in billion arrived in 1930; the third billion in 1960; and today there are 7 billion. 1960; and today there are 7 billion.

Only if the growth rate continues to Only if the growth rate continues to decline can there be decline can there be zero population zero population growth when births equal deathsgrowth when births equal deaths and and the population size remains steady.the population size remains steady.

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The More-Developed Versus The More-Developed Versus Less-Developed CountriesLess-Developed Countries

The MDCs of North America, Canada, The MDCs of North America, Canada, England, and Europe, have a England, and Europe, have a population growth under control and population growth under control and the people enjoy a good standard of the people enjoy a good standard of living. living.

The LDCs of South America The LDCs of South America (Argentina, Brazil, Chile), Africa, and (Argentina, Brazil, Chile), Africa, and Asia, have population growth out of Asia, have population growth out of control and the majority of people control and the majority of people live in poverty.live in poverty.

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The term “third-world countries”The term “third-world countries” is is an old term used to mean the less-an old term used to mean the less-developed countries. developed countries.

This term was introduced by those This term was introduced by those who thought of the United States and who thought of the United States and Europe as the first world and the Europe as the first world and the former USSR as the second world.former USSR as the second world.

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The MDCs doubled their populations between The MDCs doubled their populations between 1850 and 1950 because of a decline in the death 1850 and 1950 because of a decline in the death rate and modern medicines. rate and modern medicines.

The populations of a few of the MDCs, Italy, The populations of a few of the MDCs, Italy, Denmark, Hungary, Sweden are actually Denmark, Hungary, Sweden are actually decreasing in size. decreasing in size.

In contrast, there is no leveling off and no end in In contrast, there is no leveling off and no end in sight to U.S. population growth. sight to U.S. population growth.

Although the death rate began to decline steeply Although the death rate began to decline steeply in the LDCs following World War II with the in the LDCs following World War II with the importation of modern medicine from the MDCs, importation of modern medicine from the MDCs, the birthrate remained high. the birthrate remained high.

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Comparing Age StructureComparing Age Structure

One way of characterizing population is by One way of characterizing population is by age groups. age groups.

If there are more young women entering If there are more young women entering the reproductive years than there are the reproductive years than there are older women leaving them, there will still older women leaving them, there will still be an increase in population. be an increase in population.

Most LDCs have a large proportion of Most LDCs have a large proportion of young women under the age of 15. young women under the age of 15.

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Possible SolutionsPossible Solutions

1. Establish and/or strengthen family1. Establish and/or strengthen family planning programs. planning programs. 2. Use social progress to reduce the2. Use social progress to reduce the desire for large families by providingdesire for large families by providing education, raising the status ofeducation, raising the status of women, and reducing child mortality rate.women, and reducing child mortality rate.3. Delay the onset of childbearing by3. Delay the onset of childbearing by five years and wider spacing of births.five years and wider spacing of births.

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The Human Population and PollutionThe Human Population and Pollution

Intact ecosystems naturally prevent soil Intact ecosystems naturally prevent soil erosion, dispose of environmental wastes, erosion, dispose of environmental wastes, provide fresh water, regulate climate. provide fresh water, regulate climate.

But as the human population increases in But as the human population increases in size, more ecosystems are impacted by size, more ecosystems are impacted by humans. humans.

Ecosystems are no longer able to process Ecosystems are no longer able to process and rid the biosphere of wastes and leads and rid the biosphere of wastes and leads to problems for all living things, and also to problems for all living things, and also problems in the air, in the water, and on problems in the air, in the water, and on land.land.

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The Human Population and PollutionThe Human Population and Pollution

Air pollutants in particular are Air pollutants in particular are involved in causing major involved in causing major environmental effects, including environmental effects, including global warming, acid rain, and ozone global warming, acid rain, and ozone depletion. depletion.

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FOSSIL FUELSFOSSIL FUELS

Problems with the use of fossil fuels such as Problems with the use of fossil fuels such as coal and oil and gas include the fact that coal and oil and gas include the fact that they are nonrenewable, they pollute the they are nonrenewable, they pollute the environment when they are burned, oil and environment when they are burned, oil and gas wells pollute the environment by gas wells pollute the environment by emitting greenhouse gases, and they are emitting greenhouse gases, and they are contributing to the problem of global contributing to the problem of global warming. warming.

The trend for the future is the use of The trend for the future is the use of hydrogen for energy. hydrogen for energy.

Hydrogen-based fuel cells are in use now in some Hydrogen-based fuel cells are in use now in some cities to power vehicles, can be produced locally cities to power vehicles, can be produced locally all over the world, and will reduce global warming all over the world, and will reduce global warming and air pollution.and air pollution.

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POLLUTIONPOLLUTION

Pollution is any undesirable change in the Pollution is any undesirable change in the environment that can be harmful to environment that can be harmful to humans and other life, and does not humans and other life, and does not normally occur.normally occur.

Natural ecosystems are stable in the sense Natural ecosystems are stable in the sense that they take care of themselves and are that they take care of themselves and are balanced in the interaction of the species balanced in the interaction of the species in them. in them.

There is just enough food and energy to There is just enough food and energy to support the populations in them.support the populations in them.

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POLLUTIONPOLLUTION

Human-impacted ecosystems essentially Human-impacted ecosystems essentially have two added parts: the have two added parts: the country, country, where where agriculture and animal husbandry are agriculture and animal husbandry are found, and the found, and the city, city, where most people where most people live and where industry is carried on. live and where industry is carried on.

These two systems require two major These two systems require two major inputs: inputs: fuel energy fuel energy and and raw materials raw materials (e.g., metals, wood, synthetic materials). (e.g., metals, wood, synthetic materials).

The use of these necessarily results in The use of these necessarily results in waste waste and and pollution.pollution.

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Cuyahoga RiverCuyahoga River

A river in northeast Ohio, USA, into which A river in northeast Ohio, USA, into which industries around Cleveland dumped oily wastes, industries around Cleveland dumped oily wastes, and which has literally caught fire on numerous and which has literally caught fire on numerous occasions. occasions.

The most serious fire occurred on 23 June 1969, The most serious fire occurred on 23 June 1969, and that event triggered a series of important and that event triggered a series of important pollution control initiatives including the Clean pollution control initiatives including the Clean Water Act (1972) and the Great Lakes water Water Act (1972) and the Great Lakes water quality agreement, and the creation of federal quality agreement, and the creation of federal and state environmental protection agencies.and state environmental protection agencies.

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Cuyahoga River Fire, 1969Cuyahoga River Fire, 1969

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The CountryThe Country The country areas are where our food is grown, The country areas are where our food is grown,

but it has an impact on our ecosystem.but it has an impact on our ecosystem.1.1. Heavy use of fertilizers and pesticides contribute Heavy use of fertilizers and pesticides contribute

to water pollution, and pesticides kill off beneficial to water pollution, and pesticides kill off beneficial soil organisms. soil organisms.

2.2. Generous irrigation by river water will dump a Generous irrigation by river water will dump a heavy concentration of salt back into the river. heavy concentration of salt back into the river. The salt content of the Rio Grande River in the The salt content of the Rio Grande River in the Southwest is so high that the government has Southwest is so high that the government has built a treatment plant to remove the salt. built a treatment plant to remove the salt.

3.3. Excessive fuel consumption for water pumps and Excessive fuel consumption for water pumps and large farming machines. large farming machines.

4.4. Loss of land quality. Evaporation of excess water Loss of land quality. Evaporation of excess water can leave behind excess salt, making it can leave behind excess salt, making it unsuitable for the growth of more crops. unsuitable for the growth of more crops.

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The CityThe City Industries increase the amount of Industries increase the amount of

carbon dioxide in the atmosphere. carbon dioxide in the atmosphere. The city is dependent on the country to The city is dependent on the country to

meet its needs. For example, each person meet its needs. For example, each person in the city requires several acres of land in the city requires several acres of land from the country for food production. from the country for food production.

As the population increases, the amount of As the population increases, the amount of farmland goes down when it needs to go farmland goes down when it needs to go up.up.

Cities currently rely mainly on coal and oil Cities currently rely mainly on coal and oil for fuel. for fuel.

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The CityThe City The city wastes fuel in many ways.The city wastes fuel in many ways. An office building with lights always An office building with lights always

on and windows that cannot be on and windows that cannot be opened.opened.

People who drive cars long dis tances People who drive cars long dis tances instead of carpooling or taking public instead of carpooling or taking public transportation and who drive short transportation and who drive short distances instead of walking or bicy distances instead of walking or bicy cling. cling.

Materials are not always recycled.Materials are not always recycled. Note that having an air conditioner on Note that having an air conditioner on

during a hot day is NOT an example of during a hot day is NOT an example of wasting fuel.wasting fuel.

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PollutionPollution

Burning fossil fuels causes air and Burning fossil fuels causes air and water pollution. water pollution.

Chemical and solid wastes cause Chemical and solid wastes cause pollution, both during its production pollution, both during its production and when it is discarded. and when it is discarded.

Humans themselves produce much Humans themselves produce much sewage that is discharged into sewage that is discharged into bodies of water, often after only bodies of water, often after only minimal treatment.minimal treatment.

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The SolutionThe Solution

In human-impacted ecosystems, fuel combustion In human-impacted ecosystems, fuel combustion by products, sewage, fertilizers, pesticides, and by products, sewage, fertilizers, pesticides, and solid wastes all are added to the environment in solid wastes all are added to the environment in the hope that natural cycles will cleanse the the hope that natural cycles will cleanse the ecosystem of these pollutants. ecosystem of these pollutants.

However, we have exploited natural ecosystems However, we have exploited natural ecosystems to the extent that the environment is overloaded.to the extent that the environment is overloaded.

We have an ever-increasing number of people We have an ever-increasing number of people want to maintain a standard of living that want to maintain a standard of living that requires many goods and services. requires many goods and services.

But we can help this if we achieve zero population But we can help this if we achieve zero population growth and if we conserve energy and raw growth and if we conserve energy and raw materials. materials.

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Conservation Can Be Achieved Conservation Can Be Achieved

Wise use of only what is actually Wise use of only what is actually neededneeded

Recycling of iron, copper, lead, and Recycling of iron, copper, lead, and aluminumaluminum

Use renewable energy resourcesUse renewable energy resources Development of more efficient ways Development of more efficient ways

to utilize all forms of energyto utilize all forms of energy

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Working With NatureWorking With Nature

Some farmers have adopted organic Some farmers have adopted organic farming methods and do not use farming methods and do not use fertilizers or pesticides. fertilizers or pesticides.

Instead, they use special planting Instead, they use special planting techniques to control weeds, crop techniques to control weeds, crop rotation to combat major pests, and rotation to combat major pests, and the growth of legumes (a type of the growth of legumes (a type of bean that makes nitrogen) to supply bean that makes nitrogen) to supply nitrogen fertility to the soil. nitrogen fertility to the soil.

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Working With NatureWorking With Nature Some farmers use natural predators and Some farmers use natural predators and

parasites instead of pesticides to control parasites instead of pesticides to control insects.insects.

Organic farms require only about two-fifths Organic farms require only about two-fifths as much fossil energy. as much fossil energy.

There is one-third less soil erosion. There is one-third less soil erosion. It is important to consider that ecosystems It is important to consider that ecosystems

should be developed and managed with care should be developed and managed with care so that their integral nature is preserved. so that their integral nature is preserved.

This is often called “working with nature” This is often called “working with nature” rather than against nature. rather than against nature.

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Pollution of OceansPollution of Oceans

Pesticides and other chemicals get Pesticides and other chemicals get into the ground and water supply, into the ground and water supply, and new plants absorb them, animals and new plants absorb them, animals eat the plants, and humans eat the eat the plants, and humans eat the plants and the animals. plants and the animals.

In that way, our bodies pick up these In that way, our bodies pick up these toxins.toxins.

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The oceans are the final receptors for The oceans are the final receptors for water pollutantswater pollutants carried by rivers. carried by rivers.

Waste products that are dumped into Waste products that are dumped into areas that drain into the ocean can also be areas that drain into the ocean can also be washed back to shores. washed back to shores.

The plastic piece that holds a six-pack of The plastic piece that holds a six-pack of cans gets tangled in birds, fishes, and cans gets tangled in birds, fishes, and marine mammals, causing their death.marine mammals, causing their death.

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Oil spills in the ocean kill plankton, Oil spills in the ocean kill plankton, fish, and shellfish, as well as birds fish, and shellfish, as well as birds and marine mammals. and marine mammals.

The largest tanker spill in U.S. The largest tanker spill in U.S. territorial waters occurred on March territorial waters occurred on March 24, 1989, when the tanker 24, 1989, when the tanker Exxon Exxon Valdez Valdez struck a reef in Alaska and struck a reef in Alaska and leaked 44 million liters of crude oil. leaked 44 million liters of crude oil.

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The water here is so clear it looks The water here is so clear it looks like the boat is hovering above itlike the boat is hovering above it

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VideoVideo

Overpopulating Mother Earth 14 mins14 mins

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EstuariesEstuaries

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Cyanide Fishing and Coral ReefsCyanide Fishing and Coral ReefsDiscussionDiscussion

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Pesticide: An Asset and a Liability: Pesticide: An Asset and a Liability: DiscussionDiscussion

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Smog Can KillSmog Can Kill : Discussion : Discussion

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Population VideosPopulation Videos

Population and Pollution in China, 2 mins, 2 mins Seven Billion and Counting, 4 minsSeven Billion and Counting, 4 mins China’s Population Problems, 7 minsChina’s Population Problems, 7 mins Overpopulation, 7 minsOverpopulation, 7 mins

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Pollution VideosPollution Videos

Land, Air, and Water Pollution, 7 minsLand, Air, and Water Pollution, 7 mins Air Pollution, 5 minsAir Pollution, 5 mins Ocean Plastic Pollution, 11 minsOcean Plastic Pollution, 11 mins Ocean Pollution, 27 minsOcean Pollution, 27 mins Pollution in China, part 1, 14 minsPollution in China, part 1, 14 mins Pollution in China, part 2, 14 minsPollution in China, part 2, 14 mins

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