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Ecosystems Essential Questions: What limits the production in ecosystems? How do nutrients move in the ecosystem? How does energy move through the ecosystem? Ecosystem All the organisms in a community plus abiotic factors ecosystems are transformers of energy & processors of matter Ecosystems are self-sustaining what is needed? capture energy transfer energy cycle nutrients 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 Food chains Trophic levels feeding relationships start with energy from the sun captured by plants 1st sun top carnivore 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 Energy flows through food chains sun Energy is incorporated into a community by what group? secondary consumers (carnivores) primary consumers (herbivores) producers (plants) loss of energy loss of energy Inefficiency of energy transfer Loss of energy between levels of food sun chain To where is the energy lost? The cost of living! 17% growth only this energy moves on to the next level in the food chain energy lost to daily living 33% cellular respiration 50% waste (feces) sun Ecological pyramid Loss of energy between levels of food chain can feed fewer animals in each level Average of 10% energy available for next level Notice only 1% of sunlight energy converted by plants Humans in food chains Energy dynamics of ecosystems have important implications for human populations How much energy is available if we are: carnivores? vegetarians? Seems to be easier/cheaper to support a large population on grain than on beef! Productivity Primary productivity: Term for the rate which producers photosynthesize organic compounds in an ecosystem. Gross primary productivity: total amount of photosynthetic biomass production in an ecosystem Net Primary Productivity = GPP – respiration cost Ecosystems with greater productivity have more sunlight, water and nutrients. What you need to be able to do: Using the laws of conservation of matter and energy to do some basic accounting and determine different aspects of energy and matter usage in a community. Remember: Inputs have to equal outputs Sample problem #1 Total energy output? .75 kcal How much is used to build biomass or Secondary Production? .05 kcal What % is not being efficiently used for biomass? 93% Sample problem #2 A caterpillar consumes 100 kcal of energy. It uses 35 kcal for cell respiration, and loses 50 kcal as waste. Determine the trophic efficiency for its creation of new biomass. Total energy consumed = 100 kcal Lost and Respired: 35 + 50 = 85 kcal Total energy for growth: 15 kcal Efficiency (%) = 15/100 = .15 or 15% 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 return to abiotic reservoir abiotic reservoir geologic processes Carbon cycle CO2 in atmosphere Combustion of fuels Industry and home Diffusion Respiration Photosynthesis Plants Animals Dissolved CO2 Bicarbonates Photosynthesis Animals Plants and algae Carbonates in sediment abiotic reservoir: CO2 in atmosphere enter food chain: photosynthesis = carbon fixation in Calvin cycle recycle: return to abiotic: respiration combustion Deposition of dead material Deposition of dead material Fossil fuels (oil, gas, coal) Nitrogen cycle abiotic reservoir: N in atmosphere enter food chain: nitrogen fixation by soil & aquatic bacteria recycle: decomposing & nitrifying bacteria return to abiotic: denitrifying bacteria Atmospheric nitrogen Carnivores Herbivores Birds Plankton with nitrogen-fixing bacteria 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 abiotic reservoir: rocks, minerals, soil enter food chain: erosion releases soluble phosphate uptake by plants recycle: decomposing bacteria & fungi return to abiotic: loss to ocean sediment Phosphorus cycle Plants Land animals Animal tissue Urine and feces Soluble soil phosphate Decomposers (bacteria and fungi) Loss in drainage Rocks and minerals Decomposers Phosphates (bacteria & fungi) in solution Animal tissue and feces Aquatic animals Plants and algae Precipitates Loss to deep sediment abiotic reservoir: surface & atmospheric water enter food chain: precipitation & plant uptake recycle: transpiration return to abiotic: evaporation & runoff Water cycle Solar energy Transpiration Water vapor Evaporation Precipitation Oceans Runoff Lakes Percolation in soil Groundwater Aquifer Transpiration Why does water flow into, up and out of a plant? We will discuss process in detail soon! Breaking the water cycle Deforestation breaks the water cycle groundwater is not transpired to the atmosphere, so precipitation is not created forest desert desertification 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