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Ecology The scientific study of interactions among organisms and their environment Includes: Biotic factors (Living organisms) Abiotic factors (Non-living factors) Ecological Hierarchy (BECPO) organism population community ecosystem biosphere BECPO Terms (from smallest to largest): Organism/ Individual Refers to one individual organism Population Refers to all members of one specific species inhabiting a given location (many individuals) Community Refers to all interacting populations in a given location BECPO Terms (from smallest to largest): Ecosystem Refers to the community (biotic) and the physical environment (abiotic) functioning together as an independent, self-sustaining, relatively stable system Biosphere Refers to the portion of the earth where life exists (composed of numerous complex ecosystems) BECPO Terms (from smallest to largest): Ecosystem Refers to the community (biotic) and the physical environment (abiotic) functioning together as an independent, self-sustaining, relatively stable system Biosphere Refers to the portion of the earth where life exists (composed of numerous complex ecosystems) What is meant by “self-sustaining?” Self-sustaining ecosystems Requirements: Constant Source Energy source is constant and individuals are capable of incorporating this energy into of Energy organic molecules, and this energy can be transferred to other individuals Cycling of Materials Materials are continuously cycled between individuals and their environment Essential questions What limits the production in ecosystems? How do nutrients move in the ecosystem? How does energy move through the ecosystem? Ecosystem inputs constant energy flows input of through energy nutrients cycle Matter cannot Don’t forget laws of or bethe created Physics! destroyed nutrients can only cycle biosphere inputs energy nutrients Energy flows through ecosystems sun secondary consumers (carnivores) primary consumers (herbivores) producers (plants) loss of energy loss of energy Generalized Nutrient cycling consumers producers consumers decomposers nutrients nutrients ENTER FOOD CHAIN made available = made available to producers to producers Decomposition connects all trophic levels abiotic abiotic reservoir reservoir (All non-living material) geologic processes return to abiotic reservoir Food chains Trophic levels feeding relationships start with energy from the sun captured by plants 1st sun top carnivore/ Apex predator Level 3 Secondary consumer carnivore Level 2 Primary consumer heterotrophs herbivore level of all food chains food chains usually go Level 1 Producer up only 4 or 5 levels inefficiency of energy transfer Level 4 Tertiary consumer all levels connect to decomposers autotrophs Decomposers Bacteria Fungi sun Inefficiency of energy transfer Loss of energy between levels of food chain To where is the energy lost? The cost of living! 10% growth only this energy moves on to the next level in the food chain energy energy lost lost to to metabolism daily living 40% cellular respiration 50% waste (feces) sun Ecological pyramid Loss of energy between levels of food chain can feed fewer animals in each level Food webs Food chains are linked together into food webs Who eats whom? A species may weave into web at more than one level Example: omnivores eat both consumers & producers bears humans eating meat? eating plants? Nutrients: provide source of energy for each trophic level secondary consumers (carnivores) primary consumers (herbivores) producers (plants) Humans in food chains Dynamics of energy through ecosystems have important implications for human populations how much energy does it take to feed a human? if we are meat eaters? if we are vegetarian? What is your ecological footprint?! Carbon cycle CO2 in atmosphere Diffusion Respiration abiotic reservoir: CO2 in atmosphere enter food chain: Combustion of fuels = photosynthesis carbon fixation in Industry and home Calvin cycle Photosynthesis recycle: return to abiotic: respiration Plants combustion Animals Dissolved CO2 Bicarbonates Photosynthesis Animals Plants and algae Carbonates in sediment Deposition of dead material Deposition of dead material Fossil fuels (oil, gas, coal) Nitrogen cycle Carnivores abiotic reservoir: Nitrogen in atmosphere enter food chain: nitrogen fixation by soil & aquatic bacteria Herbivores recycle: decomposing & nitrifying bacteria return to abiotic: denitrifying bacteria Birds Plankton with nitrogen-fixing bacteria Atmospheric nitrogen Plants Death, excretion, feces Fish excretion Decomposing bacteria amino acids Ammonifying bacteria loss to deep sediments Nitrogen-fixing bacteria (plant roots) Nitrogen-fixing bacteria (soil) Nitrifying bacteria soil nitrates Denitrifying bacteria Phosphorus cycle Plants Land animals Soluble soil phosphate Loss in drainage fungi) Rocks and minerals Decomposers Phosphates (bacteria & fungi) in solution Animal tissue and feces abiotic reservoir: rocks, minerals, soil enter food chain: erosion releases soluble phosphate uptake by plants recycle: decomposing bacteria Animal tissue & fungi Urine and feces return to abiotic: loss toDecomposers ocean (bacteria and sediment Aquatic animals Plants and algae Precipitates Loss to deep sediment abiotic reservoir: surface & atmospheric water enter food chain: precipitation & plant uptake Solar energy recycle: transpiration return to abiotic: Evaporation evaporation & runoff Water cycle Transpiration Water vapor Precipitation Oceans Runoff Lakes Percolation in soil Groundwater Aquifer Transpiration Breaking the water cycle Deforestation breaks the water cycle groundwater is not transpired to the atmosphere, so precipitation is not created forest desert desertification Studying ecosystems Hubbard Brook Experimental Forest 7800 acres 38 acre deforestation Effects of deforestation 40% increase in runoff loss of water loss into surface water 80 nitrate levels in runoff Concentration of nitrate (mg/l ) 60x loss in nitrogen 10x loss in calcium 40 loss out of ecosystem! 4 Deforestation 2 Why is 0 nitrogen 1965 so important? 1966 1967 Year 1968 Ecological Relationships Types: Competition Refers to when two or more organisms rely on the same environmental resource(s) Predation Refers to the behavior of one animal preying upon (feeding on) another Symbiosis Refers to the close relationship of two dissimilar organisms Symbiotic Relationships Types of Symbiosis: Mutualism A symbiotic relationship where both organisms benefit Commensalism A symbiotic relationship where one organism benefits, and the other is neither benefited nor harmed Parasitism A symbiotic relationship in which one organism benefits, and the other is harmed