Ecosystem Energy Flow- Productivity Studying organisms in their environment
population
biosphere 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
constantenergy flows input ofthrough energy nutrients cycle
MatterDon’t forget cannot bethe created laws of or destroyedPhysics!
nutrients inputs can only . energy biospherecycle . nutrients Generalized Nutrient consumers cycling
consumersproducers
decomposers nutrients ENTER FOODnutrients CHAIN = mademade available available to producersto producers return to Decomposition abiotic reservoir connects all abiotic trophic levels reservoir
geologic processes Carbon cycle
CO2 in Combustion of fuels atmosphere Industry and home Photosynthesis Diffusion Respiration
Plants Animals
Dissolved CO2
abiotic reservoir:
. CO2 in atmosphere Bicarbonates enter food chain: . photosynthesis = Photosynthesis carbon fixation in Calvin cycle Deposition recycle: of dead Animals . return to abiotic: material Plants and algae . respiration . combustion Fossil fuels Deposition of (oil, gas, coal) Carbonates in sediment dead material abiotic reservoir: . N in atmosphere enter food chain: Nitrogen cycle . nitrogen fixation by soil & aquatic bacteria recycle: . decomposing & nitrifying bacteria return to abiotic: . denitrifying bacteria Atmospheric Carnivores nitrogen
Herbivores
Birds Plankton with Plants nitrogen-fixing bacteria Death, excretion, feces Fish Nitrogen-fixing Decomposing bacteria bacteria (plant roots) excretion amino acids Ammonifying bacteria Nitrogen-fixing bacteria loss to deep sediments (soil) Nitrifying bacteria Denitrifying soil nitrates bacteria abiotic reservoir: . rocks, minerals, soil enter food chain: . erosion releases soluble phosphate Phosphorus cycle . uptake by plants recycle: . decomposing bacteria & fungi return to abiotic: . loss to ocean sediment Plants Land animals Animal tissue Urine and feces Soluble soil phosphate Decomposers Loss in (bacteria and drainage fungi) Rocks and minerals Decomposers Phosphates (bacteria & fungi) in solution
Animal tissue and feces Aquatic Plants and animals algae Precipitates
Loss to deep sediment abiotic reservoir: . surface & atmospheric water enter food chain: Water cycle . precipitation & plant uptake recycle: . transpiration return to abiotic: . evaporation & runoff Solar energy Transpiration Water vapor Evaporation
Precipitation
Oceans
Runoff Lakes Percolation in soil Aquifer Groundwater Transpiration
Why does water flow We will discuss into, up process in and out of detail soon! a plant? Energy flows through ecosystems
secondary loss of consumers energy sun (carnivores)
primary consumers Energy is (herbivores) loss of incorporated energy into a community by what group? producers (plants) . Ecosystem dynamics involve two main processes: energy flow (productivity) and chemical cycling (biogeochemical cycles) . Energy flows through ecosystems . Matter cycles within them . Physical laws govern energy flow and chemical cycling in ecosystems
Conservation of Energy (first law of thermodynamics)
Energy enters from solar radiation and is lost as heat
Conservation of matter - Chemical elements are continually recycled within ecosystems . Ecosystems are open systems, absorbing energy and mass and releasing heat and waste products 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 are more stable and diverse than ecosystems with less productivity.
Which ecosystems are most productive? Energy transfer between trophic levels is typically only 10% efficient . Net Primary Production (NPP) is the amount of new biomass added in a given time period . Only NPP is available to consumers . Ecosystems vary greatly in NPP and contribution to the total NPP on Earth
Limited by light, nutrients and other abiotic factors . Secondary is the amount of chemical energy in food converted to new biomass Inefficiency of energy transfer . Loss of energy between levels of food chain
To where is the energy lost? The cost of living!
sun
17% growth
energy lost to only this energy daily living moves on to the 33% next level in cellular the food chain respiration 50% waste (feces) Production Efficiency
. When a caterpillar feeds on a leaf, only about one-sixth of the leaf’s energy is used for secondary production . An organism’s production efficiency is the fraction of energy stored in food that is not used for respiration Figure 55.10
Plant material eaten by caterpillar
200 J
67 J Cellular 100 J respiration Feces 33 J
Not assimilated Growth (new biomass; Assimilated secondary production) Trophic Efficiency and Ecological Pyramids . Trophic efficiency is the percentage of production transferred from one trophic level to the next . It is usually about 10% (“10% Law”), with an actual range of 5% to 20% . Trophic efficiency is multiplied over the length of a food chain sun Ecological pyramid . Loss of energy between levels of food chain
can feed fewer animals in each level
10% energy available for next level
Notice only 1% of sunlight energy converted by plants Interesting Energy production facts:
. Birds and mammals have efficiencies in the range of 13% . Fishes have production efficiencies of around 10% . Insects and microorganisms have efficiencies of 40% or more
. WHY?? Role of Humans in Energy flow and nutrient cycling:
. Dynamics of energy flow in ecosystems have important implications for the human population . Eating meat is a relatively inefficient in terms of utilizing photosynthetic production (and water) . Worldwide agriculture could feed many more people if humans ate only plant material . Fossil fuels used to produce foods Humans in food chains-carbon cycle
. 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? Better harvest? Combustion and water/ ocean pollution Humans and 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 . 60x loss in nitrogen loss of water . 10x loss in calcium
loss into 80 nitrate levels in runoff surface water
40 loss out of 4 ecosystem! Deforestation
2
Concentration of of nitrate (mg/l) Why0 is nitrogen1965 so 1966 1967 1968 important? Year 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 . 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 = 100 kcal
Lost and Respired: 35 + 50 = 85 kcal
Total energy for growth: 15 kcal . Efficiency = part/total = 15/100 = .15 (or 15% transfer or 3/20 as fraction) The “take home” energy defines ecology!