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Ecosystems & Restoration Ecology

Ecosystems & Restoration Ecology

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Ecosystems & Restoration Ecology

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  1. Ecosystems & Restoration Ecology Campbell & Reece Chapter 55

  2. Ecosystems no matter what size; 2 processes occurring: energy flow chemical cycling

  3. Conservation of Energy • 1st Law of Thermodynamics: • nrg can neither be created or destroyed, only transferred or transformed • 2nd Law of Thermodynamics: • every exchange of nrg increase the entropy of the universe • lost nrg: heat

  4. Conservation of Mass • matter can neither be created or destroyed • elements not significantly gained or lost on a global scale but can be gained or lost from a particular ecosystem • in nature most gains & losses to ecosystems small compared to amt cycled but balance between inputs & outputs determines if given ecosystem is a source or a sink for a given element

  5. Energy, Mass, & Trophic Levels • trophic levels are based on their main source of nutrition & nrg • Primary Producers ultimately support all other levels • biosphere‘s main autotrophs: • plants • algae • photosynthetic prokaryotes

  6. Definitions Detritus: nonliving organic material Detritivores: decompsers

  7. Global Energy Budget • every day Earth’s atmosphere bombarded by ~ 10²² joules of solar radiation • (or enough nrg to supply demands of Earth’s human population for ~25 yrs using 2009 levels) • most incoming solar radiation is absorbed, scattered or reflected by clouds & dust in the atmosphere • amt that actually reaches Earth’s surface limits the possible photosynthetic output of ecosystems

  8. Gross & Net Production GPP: gross primary production = amt nrg from light (or chemicals in chemoautotrophic systems) converted to the chemical nrg of organic molecules per unit time NPP: net primary production = GPP – nrg used by primary producers for their own respiration (Ra) NPP = GPP – Ra NPP =/= total biomass of photosynthetic autotrophs present; NPP = amt new biomass added in given period of time

  9. Primary Production amt of light nrg chemical nrg by autotrophs in an ecosystem during given time GPP: total nrg assimilated by an ecosystem in given time NPP: nrg accumulated in autotroph biomass,

  10. Net Ecosystem Production • total biomass accumulation of an ecosystem = • GPP – total ecosystem respiration • satellites used to study global patterns of primary production • show ecosystems vary considerably • tropical rainforest highest • coral reefs & estuaries high but global total is low because only cover ~1/10th what rainforest do

  11. Primary Production in Aquatic Ecosystems limited by light & available nutrients

  12. Primary Production in Terrestrial Ecosystems • globally limited by: • temperature • moisture • locallylimited by: • a particular soil nutrient

  13. Limiting Nutrient is the element that must be added for production to increase in marine ecosystems it is most often N or P

  14. Secondary Production amt of chemical nrg in consumers’ food that is converted to their own new biomass during a given period of time vast majority of an ecosystem’s production is eventually consumed by detritivores

  15. Energy partitioning w/in a Link of the Food-Chain

  16. Production Efficiency • efficiency with which food nrg is converted to biomass @ each link in a food chain • another way: • Production Efficiency is the % of nrg stored in assimilated food not used for respiration

  17. 10% Efficiency in Energy Transfers • Production efficiency = • Net secondary production x 100 Assimilation of primary production

  18. Trophic Efficiency • % of production transferred from 1 trophic level to the next • ~ 5% – 20% with 10% being typical • Pyramids of nrg & biomass reflect low trophicefficiency • aquatic ecosystems can have inverted biomass pyramids: producers grow, reproduce & are consumed so quickly there is no time to develop a large population

  19. Biogeochemical Cycles • photosynthetic organisms essentially have unlimited supply of solar nrg but have limiting amts of chem elements • atoms taken in by organism either  assimilated or wastes • organism dies: atoms replenish pool of inorganic nutrients  used by other organisms • this cycling of nutrients involving biotic & abiotic components called: biogeochemical cycles

  20. Water Cycle: Biological Importance • water: • essential to all organisms • availability influences rates of ecosystem processes • especially 1° production & decomposition in terrestrial biomes

  21. Water Cycle: Forms Available to Life most water used in its liquid phase seasonal freezing limits soil water’s availability to terrestrial organisms

  22. Water Cycle: Reservoirs

  23. Water Cycle: Key Processes main processes driving water cycle: evaporation of liquid water by solar radiation condensation of water vapor Precipitation Transpiration Runoff : surface or percolation  groundwater

  24. Carbon Cycle: Biological Importance C forms framework of organic molecules essential to all living organisms

  25. Carbon Cycle: Forma Available to Life photosynthetic organisms utilize CO2 converting inorganic C  organic C

  26. Carbon Cycle: Reservoirs fossil fuels sediments of aquatic ecosystems soils plant & animal biomass atmosphere (CO2)

  27. Carbon Cycle: Key Processes removing CO2 from atmosphere: photosynthesis returning CO2 to atmosphere: cellular respiration burning of fossil fuels & wood volcanic eruptions

  28. Nitrogen Cycle: Biological Importance N part of a.a., proteins, & nucleic acids

  29. Nitrogen: Forms Available to Life plants can assimilate 2 forms of N: ammonium: nitrate

  30. Nitrogen: Forms Available to Life bacteria can use both these & nitrite, NO2-

  31. Nitrogen: Forms Available to Life animals can only use organic forms of N

  32. Nitrogen Cycle: Reservoirs • main reservoir of N is the atmosphere (80% free N gas) • others: • soil • sediments of rivers, lakes, oceans • biomass

  33. Nitrogen Cycle: Key Processes • Nitrogen Fixation: • N2 forms that can be used to synthesize organic N cpds • natural methods: • certain bacteria or lightening • man activities: • industrial production of fertilizers • legume crops

  34. Nitrogen Cycle: Key Processes • Denitrification: • certain bacteria in soil • organic N  N2 gas (reduction of N2 )

  35. The Phosphorus Cycle

  36. Phosphorus Cycle: Biological Importance • P is major component of • Nucleic Acids • Phospholipids • ATP

  37. Phosphorus Cycle: Forms Available to Life plants absorb phosphate ion  organic molecules