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Part 2- Terr. Ecol
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Ecological Communities
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Ecosystem A community of different species interacting together & with the chemical & physical factors making up its non-living environment.
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Nonliving and Living Components of Ecosystems
Ecosystems consist of nonliving (abiotic) and living (biotic) components. Figure 3-10
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Biosphere Ecosystems Realm of ecology Communities Populations
Universe Galaxies Biosphere Solar systems Planets Earth Biosphere Ecosystems Ecosystems Communities Populations Realm of ecology Organisms Communities Organ systems Organs Figure 3.2 Natural capital: levels of organization of matter in nature. Ecology focuses on five of these levels. Tissues Cells Populations Protoplasm Molecules Atoms Organisms Subatomic Particles Fig. 3-2, p. 51
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Population A group of individual organisms of the same species living w/in a particular area.
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Community The population of all species living & interacting in an area.
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Habitat The place where an organism or a population lives.
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Habitat Needs Cover – shelter; trees, shrubs, etc. Water Nutrients
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Niche The total way of life or role of a species in an ecosystem.
All the physical, chemical, and biological conditions a species needs to live & reproduce in an ecosystem.
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Niche: an individual’s ecological role
Fundamental niche = when an individual fulfills its entire role by using all the available resources Realized niche = the portion of the fundamental niche that is actually filled Due to competition or other species’ interactions
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Consumers: Eating and Recycling to Survive
Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains. Herbivores Primary consumers that eat producers Carnivores Primary consumers eat primary consumers Third and higher level consumers: carnivores that eat carnivores. Omnivores Feed on both plant and animals.
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Energy passes through trophic levels
One of the most important species interactions is who eats whom Matter and energy move through the community Trophic levels = rank in the feeding hierarchy Producers Consumers Detritivores and Decomposers 13
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Producers An organism that uses solar energy (green plant) or chemical energy (some bacteria) to manufacture its food.
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Producers: Basic Source of All Food
Photosynthesis Producers: Basic Source of All Food The process in which glucose is synthesized by plants. Most producers capture sunlight to produce carbohydrates by photosynthesis:
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Productivity The amount of increase in organic matter per unit of time.
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Primary Consumer (herbivore)
An organism that feeds directly on all or parts of plants.
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Secondary Consumer (carnivore)
An organisms that feeds only on primary consumers. Most are animals, but some are plants (Venus fly-trap).
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Tertiary Consumer (carnivore)
Animals that feed on animal-eating animals. Ex. hawks, lions, bass, and sharks.
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Quaternary Consumer (carnivore)
An animal that feeds on tertiary consumers. Ex. humans.
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Decomposer (scavenger, detritivore)
An organism that digests parts of dead organisms, cast-off fragments, and wastes of living organisms. Ex. bacteria and fungi.
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Decomposition As plant or animal matter dies it will break down and return the chemicals back to the soil. This happens very quickly in tropical rainforest which results in low-nutrient soils. Grasslands have the deepest and most nutrient rich of all soils
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Decomposers and Detrivores
Decomposers: Recycle nutrients in ecosystems. Detrivores: Insects or other scavengers that feed on wastes or dead bodies. Figure 3-13
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What Eats What?
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Abiotic chemicals (carbon dioxide, Heat oxygen, nitrogen, Solar Heat
minerals) Heat Solar energy Heat Heat Producers (plants) Decomposers (bacteria, fungi) Figure 3.14 Natural capital: the main structural components of an ecosystem (energy, chemicals, and organisms). Matter recycling and the flow of energy—first from the sun, then through organisms, and finally into the environment as low-quality heat—links these components. Consumers (herbivores, carnivores) Heat Heat Fig. 3-14, p. 61
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Pyramids of energy, biomass, and numbers
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Biomass The organic matter produced by plants; dry weight.
Energy from wood, garbage & agricultural waste. Can be used for electrical energy!
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Structure Shows the decrease in usable energy available at each succeeding trophic level in a food chain or web.
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Relationship Between Biomass and Energy
Biomass is dry weight & represents the chemical energy stored at each energy level. Water is neither a source of energy, nor has any nutritional value.
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10% Rule We assume that 90% of the energy at each energy level is lost because the organism uses the energy. (heat) It is more efficient to eat lower on the energy pyramid. You get more out of it! This is why top predators are few in number & vulnerable to extinction.
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Food webs show relationships and energy flow
Food chain = the relationship of how energy is transferred up the trophic levels Food web = a visual map of feeding relationships and energy flow Includes many different organisms at all the various levels Greatly simplified; leaves out the majority of species 31
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Food Webs/Chains Purpose – determines how energy & nutrients move from one organism to another through the ecosystem Arrows – point from the producer to the consumer
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Food Chains
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(decomposers and detritus feeders)
First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Producers (plants) Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores) Heat Heat Heat Solar energy Heat Heat Figure 3.17 Natural capital: a food chain. The arrows show how chemical energy in food flows through various trophic levels in energy transfers; most of the energy is degraded to heat, in accordance with the second law of thermodynamics. Heat Heat Detritivores (decomposers and detritus feeders) Heat Fig. 3-17, p. 64
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Food Webs
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Trophic Levels Each step in the transfer of energy through a food chain or food web is known as a trophic level. A trophic level is one of the steps in a food chain or food pyramid; examples include producers and primary, secondary, and tertiary consumers.
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Trophic Levels
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Energy Flow in a Ecosystem
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Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs
In accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.
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Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs
Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next. Figure 3-19
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Question of the Day Explain why ecological efficiency only 10%?
90% of available energy is lost at heat or other waste energy as it passes through each trophic level. As a result the amount of energy decreases as it moves up and food web/chain.
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