Understanding Ecosystems: Energy Flow and Nutrient Cycling

1. Ecosystems

2. Studying organisms in their environment biosphere ecosystem community population organism

3. Essential Questions • What limits the production in ecosystems? • How do nutrients move in the ecosystem? • How does energy move through the ecosystem?

4. Ecosystem • All the organisms in a community plus abiotic factors • ecosystems are transformers of energy& processors of matter • Ecosystems are self-sustaining • Sunlight is needed only • capture energy • transfer energy • cycle nutrients

5. Ecosystem inputs biosphere constant inputof energy energy flowsthrough nutrients cycle Don’t forgetthe laws of Physics! Matter cannot be created ordestroyed nutrients can only cycle Inputs: • energy • nutrients

6. Decompositionconnects all trophic levels Generalized Nutrient cycling consumers consumers producers consumers decomposers decomposers nutrientsENTER FOOD CHAIN= made availableto producers nutrientsmade availableto producers return toabioticreservoir abioticreservoir abioticreservoir geologicprocesses geologicprocesses

7. CO2 in atmosphere Combustion of fuels Industry and home Photosynthesis Diffusion Respiration Plants Animals Dissolved CO2 Bicarbonates Photosynthesis Deposition of dead material Animals Plants and algae Fossil fuels (oil, gas, coal) Deposition of dead material Carbonates in sediment • abiotic reservoir: • CO2 in atmosphere • enter food chain: • photosynthesis = carbon fixation in Calvin cycle • Recycle: • decomposition • return to abiotic: • respiration • Combustion of fossil fuels Carbon cycle

8. abiotic reservoir: • N in atmosphere • enter food chain: • nitrogen fixation by soil & aquatic bacteria • recycle: • decomposing & nitrifying bacteria • return to abiotic: • denitrifying bacteria Nitrogen cycle Atmospheric nitrogen Carnivores Herbivores Birds Plants Plankton with nitrogen-fixing bacteria Death, excretion, feces Nitrogen-fixing bacteria (plant roots) Fish Decomposing bacteria amino acids excretion Nitrogen-fixing bacteria (soil) Ammonifying bacteria loss to deep sediments Nitrifying bacteria Denitrifying bacteria soil nitrates

9. 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 Aquifer Groundwater

10. Ecosystem inputs biosphere energy flowsthrough nutrients cycle inputs • energy • nutrients

11. loss of energy loss of energy Energy flows through ecosystems sun secondary consumers (carnivores) primary consumers (herbivores) producers (plants)

12. sun Food chains Level 4 Tertiary consumer top carnivore • Trophic levels • feeding relationships • start with energy from the sun • captured by plants • 1st level of all food chains • food chains usually go up only 4 or 5 levels • Due to inefficiency of energy transfer • all levels connect to decomposers Level 3 Secondary consumer carnivore Level 2 Primary consumer heterotrophs herbivore Level 1 Producer autotrophs Fungi Decomposers Bacteria

13. energy lost todaily living energy lost todaily living sun Inefficiency of energy transfer • Loss of energy between levels of food chain • To where is the energy lost? The cost of living! 17% growth only this energymoves on to the next level in the food chain 33% cellular respiration 50% waste (feces)

14. sun Ecological pyramid • Loss of energy between levels of food chain • can feed fewer animals in each level • Few organisms at the top due to energy loss

15. 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? Vegetarians? What is yourecological footprint?!

16. Food webs • Food chains are linked together into food webs • Who eats whom? • a species may weave into web at more than one level • bears • humans • eating meat? • eating plants?