Energy Flow In Ecosystems Big Idea: What happens to energy stored in Body tissues when one organism eats another?
Food Chains & Food Webs • How does energy flow through ecosystems? • A 1-way stream, from primary producers to consumers • Food Chains • A series of steps in which organisms transfer energy by eating and being eaten
Food Chains & Food Webs • Food Webs • A network of feeding relationships; shows all the feeding relationships within an ecosystem
Food Chains & Food Webs • Food Webs – • Very complicated • Notebook Time: • Describe the ecosystem that is your backyard • Draw a food web of that ecosystem • Be as specific as possible • Draw a food chain from within your food web • What role do decomposers & detritivores play in food webs?
Food Chains & Food Webs • Disturbances • In your groups, answer the following questions using the food web below: • What effect would an insecticide have on the food web? • Would this have an effect on the populations of non-insect eating animals? • What populations would increase? • What populations would decrease? • Would this change any animals eating habits? Which ones & how?
Trophic Levels & Ecological Pyramids • Trophic Level • Each step in a food chain • Ecological Pyramids • Show relative amount of energy or matter contained within each trophic level in a given food chain or food web • There are 3 different types of Ecological Pyramids • Pyramids of Energy • Pyramids of Biomass • Pyramids of numbers
Ecological Pyramids • Pyramids of Energy • Show relative amounts of energy available at each trophic level • Typically • 1/10 or 10% of available energy within one trophic level is passed on to the next level • In other words: • 1/10 of the solar energy captured and stored in leaves of grasses ends up stored in the tissues of cows
Ecological Pyramids • Pyramid of Biomass & Numbers • Biomass – • Total amount of living tissue within a given trophic level • Pyramid of Biomass • Illustrates the relative amount of living organic matter available at each trophic level of an ecosystem
Ecological Pyramids • Pyramid of Biomass & Numbers • Pyramid of Numbers • Shows the relative number of individual organisms at each trophic level in an ecosystem
Cycles of Matter • How does matter move through the biosphere? • Biogeochemical cycles • Elements pass from one organism to another and among parts of the biosphere in closed loops • These loops are powered by the flow of energy. • 4 Processes involved with biogeochemical cycles • Biological Processes • Any and all activities performed by living organisms • Geological Processes • Volcanic eruptions, erosion, plate tectonics • Chemical & Physical Processes • Formation of clouds, flow of running water, lightning • Human Activity • Deforestation, burning of fossil fuels, use of fertilizers
Water Cycle Water moves continuously between, oceans, the atmosphere, land and the organisms in them. • Transpiration • Evaporation of water from leaves of the plants • Evaporation • Loss of water from surface of bodies of water • Condensation • When water vapor cools & becomes liquid • Precipitation • When water falls out of the atmosphere
Nutrient Cycles • 3 main Nutrient Cycles • Carbon • Nitrogen • Phosphorus
Nutrient Cycles • Carbon Cycle • Found in several large reservoirs in biosphere • Atmosphere = CO2 • Oceans = Dissolved CO2 • Land = in organisms, soil & rocks • Underground = • Coal, Petroleum & Calcium Carbonate • In Life = base of all organic molecules
Nutrient Cycles • Nitrogen Cycle • Required to build proteins, DNA, RNA • Atmospheric Nitrogen • N2 = Non-usable form for most organisms • Needs to be “fixed” • Nitrogen Fixation • Process of N2 being converted into ammonia, nitrates & nitrites by bacteria • Relatively small amounts of N2 can be fixed by Lightning • Denitrification • When N2 is released by soil bacteria who use nitrates for energy • Fertilizer • Huge human influence in adding excess Nitrates & Nitrites into aquatic ecosystems • Can cause algal blooms
Nutrient Cycles • Phosphorus Cycle • Essential for creation of DNA, RNA • Not very abundant in biosphere • Remains mostly on land in rock, soil, & sediments • As rock & sediments wear down, P is released to environment.
Nutrient Cycles • Nutrient Limitation • Limiting Nutrient • The nutrient whose supply limits productivity • In Soil • Typically Limiting Nutrients are: • Ca, Mg, S, Fe, Mn, P, Fixed N, • In Ocean • Typically Limiting Nutrients are: • Fixed N