Ecosystems

Studying organisms in their environment biosphere ecosystem community population organism

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 nutrients cycle inputs energy nutrients biosphere energy flows through constant input of energy nutrients cycle Matter cannot be created or destroyed Don’t forget the laws of Physics! nutrients can only cycle inputs energy nutrients

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

Food chains Trophic levels sun feeding relationships Tertiary consumer 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 inefficiency of energy transfer all levels connect to decomposers top carnivore Level 3 Secondary consumer carnivore Level 2 Primary consumer heterotrophs herbivore Level 1 Producer autotrophs Fungi Decomposers Bacteria

Inefficiency of energy transfer 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 energy lost to daily living only this energy moves on to the next level in the food chain 33% cellular respiration 50% waste (feces)

Ecological pyramid sun Loss of energy between levels of food chain can feed fewer animals in each level 1 100 100,000 1,000,000,000

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?

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?

Energy in an Ecosystem Summarize how energy is cycled through an ecosystem

Ecosystem inputs nutrients cycle inputs energy nutrients biosphere energy flows through nutrients cycle inputs energy nutrients

Generalized Nutrient cycling consumers consumers consumers producers decomposers decomposers nutrients ENTER FOOD CHAIN = made available to producers nutrients made available to producers return to abiotic reservoir Decomposition connects all trophic levels abiotic reservoir abiotic reservoir geologic processes geologic processes

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

Nitrogen cycle Atmospheric nitrogen Carnivores Herbivores Birds Plants 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 Nitrogen-fixing bacteria (plant roots) Decomposing bacteria amino acids excretion Ammonifying bacteria Nitrogen-fixing bacteria (soil) loss to deep sediments Nitrifying bacteria Denitrifying bacteria soil nitrates

Phosphorus cycle 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 Land animals Plants Animal tissue and feces Urine Soluble soil phosphate Decomposers (bacteria and fungi) Loss in drainage Rocks and minerals Phosphates in solution Decomposers (bacteria & fungi) Animal tissue and feces Aquatic animals Plants and algae Precipitates Loss to deep sediment

Water cycle Solar energy Transpiration Evaporation Precipitation 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

Remember 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

Effects of deforestation 40% increase in runoff loss of water 60x loss in nitrogen 10x loss in calcium loss into surface water 80 nitrate levels in runoff 40 loss out of ecosystem! of nitrate (mg/l ) Concentration 4 Deforestation 2 Why is nitrogen so important? 1965 1966 1967 1968 Year

Learning Check Differentiate between the nitrogen, water, carbon and phosphorus cycles Sources of each? Outputs of each?

Disoolved Oxygen and Productivity How do you determine how well an ecosystem is functioning? Measure the productivity of the organisms Lab Bench

Productivity Primary productivity Gross productivity Net productivity rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem. Gross productivity the entire photosynthetic production of organic compounds in an ecosystem. Net productivity the organic materials that remain after photosynthetic organisms in the ecosystem have used some of these compounds for their cellular energy needs (cellular respiration).

Lab 12: Dissolved Oxygen measured in 3 ways: primary productivity amount of CO2 used rate of sugar (biomass) formation rate of O2 production

Productivity Since oxygen is one of the most easily measured products of both photosynthesis and respiration, a good way to gauge primary productivity in an aquatic ecosystem is to measure dissolved oxygen.

Lab 12: Dissolved Oxygen Description measure primary productivity by measuring O2 production factors that affect amount of dissolved O2 temperature as water temperature, its ability to hold O2 decreases photosynthetic activity in bright light, aquatic plants produce more O2 decomposition activity as organic matter decays, microbial respiration consumes O2 mixing & turbulence wave action, waterfalls & rapids aerate H2O & O2 salinity as water becomes more salty, its ability to hold O2 decreases

Lab 12: Dissolved Oxygen