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Introduction to Environmental Studies Ecology the study of how plants, animals, and microbes interact with each other and with their physical environment Environmental Science the study of how humans impact natural ecosystems
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The First Principle of Ecology: everything is connected to everything else What are the implications of this principle?
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History of Environmentalism Thoreau and Emerson John Muir Gifford Pinchot Theodore Roosevelt Rachel Carson 1960’s Earth Day
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Most famous for his book, Walden, which details simple living in Nature A. Ralph Waldo Emerson B.John Muir C. Aldo Leopold D.Henry David Thoreau E. Gifford Pinchot
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In the late 1800’s, he started the Sierra Club, an environmental organization still going strong today A. Ralph Waldo Emerson B.John Muir C. Aldo Leopold D.Henry David Thoreau E. Gifford Pinchot
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In the book Silent Spring, this author and scientists warned of the dangers of pesticides A.Aldo Leopold B.Gifford Pinchot C.Thoreau D. Rachel Carson E. Robert Underwood Johnson
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Creator of the U.S. Forest Service A. Theodore Roosevelt B. Franklin Roosevelt C. Aldo Leopold D. Ronald Reagan E. Henry David Thoreau
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Changing Worldviews Expansionist Worldview natural resources are unlimited and for our use Ecological Worldviews –Conservation wise use and management of natural resources today will insure use for future generations –Preservation minimal use of nature – nature should not be thought of as just here to serve humans – nature deserves to exist for its own sake
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Deep Ecology
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Sustainable development – a pattern of resource use that aims to meet human needs while preserving the environment so that these needs will always be met in the future
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Principles of Ecology To understand environmental issues and foster sustainable development, humans should take lessons form how ecosystems function …
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Ecosystem – a group of plants, animals, and microbes interacting with each other and the physical environment in a sustainable way
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ecosystem size … very small … a small pond … your back yard
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or very large …
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biomes – large terrestrial ecosystems biosphere – the earth’s “super- ecosystem” … includes all life forms and the physical environments supporting life
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ecotone – transitional region between adjacent ecosystems
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Categories of Organisms (common to every ecosystem)
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autotrophs – (producers) “self- feeding” – typically, green plants
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heterotrophs – consumers and detritivores and decomposers types of consumers …
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herbivores (primary consumers)
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carnivores (secondary or tertiary consumers)
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omnivores (primary, secondary or tertiary, depending on the meal)
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decomposers (bacteria and fungi) break down organic material recycling nutrients in the process
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detritivores and scavengers – exploit the available energy in recently dead organisms
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Feeding Relationships
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food chains show the direction of energy flow between organisms in an ecosystem
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food web a more comprehensive model showing all feeding pathways
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trophic levels – steps on a food chain biomass – total mass of biological material (living) – usually refers to specific trophic level
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Fig. 3-18, p. 49 Secondary consumers (perch) 10 100 1,000 10,000 Usable energy available at each tropic level (in kilocalories) Heat Producers (phytoplankton) Tertiary consumers (human) Primary consumers (zooplankton) Pyramid of Energy Flow Decomposers
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biomass pyramid – shows the relative proportions of biomass at each trophic level in the most efficient ecosystems, there is only about 10% of food energy available for the next higher trophic level – what happened to the other 90%? food chains in most terrestrial ecosystems rarely go higher than four trophic levels
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Fig. 9-16, p. 197 DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in water 0.000003 ppm, or 3 ppt DDT in zooplankton 0.04 ppm Biomagnification of DDT
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Toxins in Food Chains bioaccumulation: the storing of toxins in an organism over time biomagnification: an increase in the concentration of toxins as you move higher in a food chain
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Non-feeding Ecological Relationships symbiosis – a close physical relationship between two different species
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commensalism – one organism benefits while the other is unaffected
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mutualism – beneficial to both organisms
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competition intraspecific – competition between members of the same species – a major force in Natural Selection interspecific – competition for limited resources between different species
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Abiotic factors – physical and chemical environmental conditions that determine the types of plants and animals in an ecosystem … examples? optimum conditions – for every abiotic factor there exists a certain level at which a species does best limiting factor – an environmental factor that restricts the success of a species
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range of tolerance – acceptable range of environmental conditions for each species
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Lower limit of tolerance Upper limit of tolerance TemperatureLowHigh Abundance of organisms Few organisms Few organisms No organisms No organisms Zone of intolerance Zone of physiological stress Zone of intolerance Zone of physiological stress Optimum range Population Size Fig. 3-11, p. 43 Range of Tolerance
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habitat and niche – the place where organism is found and the role it plays
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Ecosystem Sustainability Energy – life depends on producer’s ability to convert solar energy to chemical energy in the form of organic molecules that consumers can utilize
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cellular respiration – the breakdown of glucose to release energy for cell activity energy flows “one way” through an ecosystem, it can not be recycled
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Solar energy Chemical energy (photosynthesis) Chemical energy (food) Mechanical energy (moving, thinking, living) Waste heat Waste heat Waste heat Waste heat Fig. 2-11, p. 32 Second Law of Thermodynamics
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continuity of life depends upon an unending supply of nutrients CHONPS – the “elements of life” Nutrient Cycling carbon cycle nitrogen cycle
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Ecological Succession Succession- a series of regular predictable changes occurring to an ecosystem after a disturbance climax community- the end result of succession characteristics- stable, sustainable primary succession- begins with soil formation, occurs after major disturbance secondary succession- more common, faster
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Seven Major Terrestrial Biomes
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Fig. 5-8, p. 84 Precipitation and Temperature Affects Biome Type Polar Subpolar Tropical Chaparral Grassland Desert Scrubland Savanna Dry Cold Tundra Coniferous forest Decreasing Temperate precipitation Decreasing Deciduous forest Tropical seasonal forest Wet Hot Rain forest temperature
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climatographs – a graph showing average precipitation and temperature for a given region net primary productivity – the amount of energy available for consumers resulting from photosynthesis how is NPP related to temperature and precipitation?
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Fig. 3-20, p. 50 Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland and shrubland Temperate grassland Tundra (arctic and alpine) Desert scrub Extreme desert Aquatic Ecosystems Estuaries Lakes and streams Continental shelf Open ocean Terrestrial Ecosystems 800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600 Average net primary productivity (kcal/m 2 /yr) Net Primary Productivity in Major Life Zones and Ecosystems
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