I. Human Population Growth
II. Human Use of Resources and Pollution
III. Biodiversity
IV. Working Toward a Sustainable Society
I. Human Population Growth
A. Current world population: Approx. 7 billion people.
- Exponential Growth: Increase of growth by a great deal.
- Growth Rate: Determined by considering the difference between the number of persons born per year and the number who die per year. Rates are recorded per 1000 people.
- Biotic Potential: Maximum growth rate under ideal conditions.
- Growth declines due to factors such as food and space.
- Carrying Capacity: Maximum population that the environment can support for an indefinite period.
B. MDCs Versus the LDCs
1b. MDCs: More Developed Countries: (countries like N American and Europe.) MDCs are those in which populatin growth is modest and the people enjoy a good standard of living.
- 1850-1950: Big population increases due to development of modern medicine and improvements in public health and socioeconomic conditions. Since then, the decline in death rate was folllowed by a decline in birthrate, so there has only been modest growth since 1950.
- Population by 2050 is expected to be about 1.2 billion.
2b. LDCs: Less-developed countries: (Africa, Asia)
- Death rate declined steeply w/ modern medicine, but birthrate remained high.
- Women in sub-Saharan Africa average 5 children each.
- Population by 2050 is expected to be about 8 billion.
- Asia is the "worst", in that they are expected to experience acute water scarcity, loss of biodiversity, and more urban pollution. 12 of 15 most polluted cities are located in Asia.
(Insert World Map / Population Density picture / mapsofworld.com / http://mapsofworld.com/world-population-density.htm)
C. Comparing Age Structure: Populations have 3 age groups: pre-reproductve, reproductive, and postreproductive.
- Replacement Reproduction: The idea of couples limiting themselves to 2 children equalling zero population grwoth.
- Untrue, beccause since more young women are entering the reproductive years than older women leaving them, the population continues to increase. (Mader 512-513)
II. Human Use of Resources and Pollution
A. Resources used the most by humans: land, water, food, energy, and minerals.
1a. Nonrenewable Resources: Limited in supply. Land, fossil fuels, and minerals is finite and can be exhausted.
- Renewable Resources: Capable of being naturally replenished. Water, certain forms of energy, plants, animals, etc. can be replenished.
B. Pollution: Side effect of resource consumption. Any alteration of the environment in an undesirable way.
- Often caused by human activity. Effect is proportional to the size of the population.
1b. Land: Worldwide, there are approx. 83 persons per square mile of all available land.
- Land is alse required for agriculature, power plants, highways, other buildings (hospitals), etc., in addition to homes.
2b. Beaches and Human Habitation: Approx 40% of world population lives within 60 miles of a coastline, and is expected to increase.
- Causes beach erosion, loss of habitat for marine organisms, and loss of buffer zone for storms.
- Particularly susceptible to pollution.
3b. Semiarid Lands and Human Habitation: 40% of Earth's lands are deserts.
- Desertification: The conversion of semiarid land to desertlike conditions.
- Begins w/ overgrazing of land. Soil can't hold rainwater, so it runs off instead of nourishing life. Any vegetation is removed by humans, and results in a lifeless desert.
(Insert Desertification Risk picture / www.sou.edu http://www.sou.edu/Geography/JONES/GEOG111.112/atlas/atlas.htm)
4b. Tropical Rain Forest and Human Habitation:
- Deforestation: Removal of trees.
- People are settling tropical rain forests, like the Amazon. This land then becomes subject to desertification.
- Land quickly loses its fertility because most of the nutrients are in trees or other vegetation.
- Loss of biodiversity.
C. Water: Worldwide, 70% of all freshwater is used to irrigate crops.
- In MDCs, more water is usde for bathing, flushing toilets, and watering lawns than for drinking and cooking.
- humans increase the supply of freshwater by damming rivers and withdrawing water from aquifers.
1c. Dams: Worlwide, 45,000 dams catch 14% of all precipitation runoff, provide water for up to 40% of irrigated land, and provide approx. 65 countries w/ more than 1/2 of their electricity.
- Lots of water loss due to evaporatin and seepage into underlying rock beds.
- Salt left behind by evap. and runoff increases alinity and can make a river's water unusable.
- Hold back less h2n w/ sediment buildup.
2c. Aquifers: Reservoirs found just below or as much as 1km below surface.
- Causes ground-water depletion.
- Consequences: Causing land subsidence, a settling of soil as it dries out. Causes surface of ground to drop. Subsidence causes damage to canals, buildings, and underground pipes.
- Can cause sinkholes: Underground collapsing of cavern when water no longer holds up roof.
- Saltwater Intrusion: As water is withdrawn, water table can lower to the point that seawater backs up into streams and aquifers, which reduces supply of freshwater.
3c. Conservation of Water:
- By 2025, approx. 2/3 of world's population may be living in countries facing seriuos water shortages.
- Possible solutions: Planting drought and salt-tolerant crops, using drip irrigation, re-use of water, and adopting conservation measures. (Mader 514-515)
D. Food: Comes from growing crops, raising animals, and fishing the seas.
1d. Harmful practices of farming methods:
- Monoculture: planting of only a few genetic varieties means a single type of parasite can cause total devestation.
- Heavy use of ferilizers, pesticides, and herbicides. (Causing water pollution, decreased soil fertility, development of cancer.)
- Agricultural runoff: Causes chemicals to enter our water supply.
- Generous irrigation: Too much water is extracted from aquifers.
- Excessive fuel consumption.
2d. Soil Loss and Degredation: Land that is good for farming and grazing animals is being degraded worlwide.
- Soil erosion causes loss of topsoil, causing desertification. Farmland is unproductive.
- U.S. and Canada have the highest rates of soil erosion in the world.
- Salinization: Accumulation of mineral salts due to evaporation of excess irrigation water. Makes land unsuitable for growing crops.
3d. Green Revolutions: Dramatic increase in yield of crops in LDSs due to introduction of new varieites of crops. Still require high levels of fertilizer, water, and pesticides, so they cause the same problem as modern farming methods.
4d. Genetic Engineering: Can produce transgenic plants resistant to insects and herbicides. Soil erosion is minimized.
5d. Domestic Livestock: 2/3 of cropland is devoted to producing livestock feed. Therefore, raising livestock accouts for much of the pollution associated with farming.
- Problems: waste, water use for washing livestock, etc. (Mader 516-519)
E. Energy:
1e. Nonrenewable Sources: Nuclear power (approx. 6% of world's energy supply) and fossil fuels (approx. 75%).
- Nuclear power: Not used very much because of nuclear power dangers and radioactive wastes.
- Fossil Fuels: Oil, natural gas, and coal. Derived from compressed remains of ploants and animal that died many thousands of years ago. U.S. is only 5% of world's population, yet it uses more than half of the fossil fuel energy supply! Pollutants are released into the air as it burns.
2e. Fossil Fuels and Global Climate Change:
- Burning of fossil fuels and burning of forests has caused increase in carbon dioxide in the atmosphere.
- Human activities cause emission of other gases, too, such as methane. These are greenhouse gases, because they allow solar radiation to pass through but hinder the escape of infrared heat back into space.
- Global Warming: Earth may warm to temps never before experienced by living things. If this happens, glaciers will melt, sea levels will rise, and coastal cities could be threatened. Would endanger coral reefs, present assmeblage of species in ecosystems will be disrupted as species migrate north for cooler weather. Loss of species unable to migrate.
(Insert Global Warming picture / global.mitsubishielectric.com / http://global.mitsubishielectric.com/bu/solar/environment/main.html)
3e. Renewable Energy Sources: Hydropower, geothermal, wind, and solar.
- Hydropower: Converts energy of falling water into electricity. Approx. 10% of electric power generated in US, and almost 98% of total renewable energy used.
- Geothermal Energy: Uranium, thorium, radium, and plutonium undergo radioactive decay below Earth's surface and heat the surrounding rocks. When they are in contact w/ water, it heats water. Can be piped up to surface for use.
- Wind Power: Space needed for wind farms that produce electricity is comparable to amount of land required by a coal-fired power plant or solar energy system. Expected to increase use in future.
(Insert Wind Farm picture / www.ronsaari.com / http://www.ronsaari.com/stockImages/windmills/WindFarmPalmSpringsCA.php)
- Energy and the Solar-Hydrogen Revolution: Solar energy must be collected, converted, and stored. Can be used for passive-solar heating of houses, and heat can be sotred in water tanks, rocks, bricks, etc.
- Photovoltaic (solar) cell: A wafer of electron-emitting metal is in contact with another metal that collects the eletrons and passes them along into wires in a steady stream. These cells can be placed on roofs to generate electricity. Can be used to create hydrogen fuel, to be used in future cars. (Mader 520-522)
F. Minerals: Nonrenewable raw materials in Earth's crust that can be extracted. Includes fossil fuels, nonmetallic raw materials, such as sand, gravel, and phophate; and metals, such as aluminum copper, iron, lead, and gold.
- Heavy metals are dangerous to humans: lead, mercury, arsenic, cadmium, tin, chromium, zinc, and copper. Used in electronics, medicines, paints, etc. Inhibit vital enzymes in body.
- Strip / surface mining: One of greatest threats to maintenance of ecosystem and biodiversity. Rain washes toxic waste deposits into streams and rivers.
1f. Hazardous Wastes: Nine most common: heavy metals, synthetic organic compounds, benzene, polychlorinated biphenyls, and chloroform.
- Chlorofluorocarbons: Type of halogenated hydrocarbon in which both chlorine and flourine atoms replace some of the hydrogen atoms. Thin ozone shield, which is essentail for protection of utraviolet radiation.
- Biological Magnification: Wastes that enter and accumulate in the fat or organisms, ans since they are not excreted, they become more and more concentrated as they pass along a food chain. (Mader 522-523)
III. Biodiversity
A. Biodiversity is the variety of life on Earth, described in terms of the number of different species.
- We are in biodiversity crisis: Number of extinctions expected to occur in the near future is unparallel in the history of the Earth.
B. Loss of Biodiversity is due to all of the following:
- Habitat Loss: Human occupation and expansion.
- Alien Species (Exotics): Nonnative members of an ecosystem. Humans introduce them to ecosystems due to colonization, horticulture, and agriculture, and accidental transport. Some are invasive, and crowd out native species.
- Pollution: Acid deposition (weakens trees), global warming (loss of habitat, etc.), ozone depletion (CFCs), and synthetic organic chemicals.
- Overexploitation: Too many individuals are taken from a wild population so it is reduced in number. ie. exotic pets. (Poaching, overfishing, etc.)
- Disease: Exposure to domestic animals and their pathogens occur when humans encroach on wildlife habitats.
(Insert Biodiversity Loss picture / www.greenfacts.org http://www.greenfacts.org/en/desertification/l-3/7-climate-change-biodiversity-loss.htm)
C. Direct Value of Biodiversity: Direct value of wildlife is related to their medicianl value, agricultural value,and consumptive use value.
1c. Medicinal Value: Potent medicines are dervied from plants, fungus, some animals (ie horseshoe crab) and certain types of bacteria.
2c. Agricultural Value: Crops are dervied from wild plants that have been modified to be high producers. Biological pest control, bees pollinating plants, etc/
3c. Consumptive Use Value: Catching of fishes, crustatceans, and mammals. Products sold in marketplaces. Trees for wood, etc.
D. Indirect Value of Biodiversity: Services that are pervasive and not easily discernable.
- Waste Disposal: Decomposers break down dead organic matter and other types of wastes to inorganic nutrients that are used by the producers within ecosystems. If not for this service, Earth would be covered in waste. Some biological communities can break down and immobilize pollutants.
- Provision of freshwater: Water cycle supplies freshwater to terrestrial ecosystems. Provide us w/ fish and other food. "Sponge Effect": Forests soak up water and release it at a regular rate.
- Prevention of Soil Erosion: Intact ecosystems naturally retain soil and prevent soil erosion.
- Biogeochemical Cycles: Biodiversity within ecosystems contributes to the workings of the water, phophorus, nitrogen, carbon, and other biogeochemical cycles, which we depend on for freshwater.
- Regulation of Climate: Trees provide shade and reduce the need for fans and air conditioners. Forests ameliorate the climate because they take up carbon dioxide. Carbon dioxide has a significant impact on global warming, which is increased with deforestation.
- Ecotourism: Relaxing in the wild! :) (Mader 524-530)
IV. Working Toward a Sustainable Society
A. Sustainable Society: One that could always provide the same amount of goods and services for future generations as it does at present. Biodiversity would also be preserved.
1a. Today's Unsustainable Society: Population growth and excessive resource consumption stresses the environment, including worldwide pollution and the extnction of wildlife.
(Insert Species Extinction by State picture / www.unl.edu / http://www.unl.edu/nac/conservation/atlas/Map_Html/Biodiversity/National/Species_Extinctions/Species_extinctions.htm)
2a. Characteristics of a Sustainable Society:
- Makes use of only renewable solar energy.
- Materials cycle through the various populations back to the producer.
- Protection of natural ecosystmes.
- Efficiency (cars, etc.)
3a. Rural Sustainability:
- Emphasis on preservation: ecosystems, agricultural land, groves of fruit trees, etc. Possible steps: plant cover crops, multiuse farming, replenish soil nutrients, low flow or trickle irrigation, increase planting of cultivars, use precision farming, use integrated pest management, etc.
4a. Urban Sustainability:
- Sharing of resources. Possible steps: Energy-efficient transportation system, solar or geothermal energy, utilize green roofs, improve storm-water management, plant native species grasses, create greenbelts, etc.
B. Assessing Economic Well-Being and Quality of Life:
- Gross National Product: Measurement of the flow of money from consumers to businesses, in the form of goods and services purchased. (Total costs of manufacturing, production and srvices in the form of salaries, wages, mortgage and rent, interets and loans, taxes, and profit. Use value, option value, existence value, aesthetic value, cultural value, and scientific and educational value are all factors. (Mader 530-533)
Ok... So I'm not going to lie... I had a REALLY hard time fitting the last part of your powerpoint into chapter 24. I felt like I was reading the wrong chapter, or something. So, I'm including it here in the end:
In a community, relationships among species can be beneficial, damaging or neutral:
Symbiotic: mutually beneficial, both species benefit
Parasitic: one species benefits (“parasite”) and the other is harmed (“host”)
Commensal: One species benefits, the other is unharmed
Mutualism: both species benefit, like symbiosis, but it may appear one species has the advantage, but evolutionarily, over the long-term, both benefit
Predation: Usually considered parasitic, where the predator is the parasite, but can also be seen as mutualistic.
(Frolich PowerPoint Slide 26)
A. Relationships Among Species
- We do still have ecological relationships with “wild” species. Examples:
- Hunt mushrooms
- Create game reserves
- Create national parks
- Household and urban/rural “pests” (e.g. molds, sewer rats)
- Symbiotic micro-organisms (skin and mouth bacteria)
- Disease-causing micro-organisms
(Frolich PowerPoint Slide 26)
B. Our Relationships w/ Domesticated Species
- But mostly we have tight relationships with domesticated species. Basis for ecological relationship:
- Food and agriculture (by far most common—food crops and animals)
- Transportation (“beasts of burden”)
- Care and protection (pets)
- Laboratory study and production
(Frolich PowerPoint Slide 29)
