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Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
Ns 5 lecture 2 and 3 energy flows and productivity 2010
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Ns 5 lecture 2 and 3 energy flows and productivity 2010

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  1. + THE FLOW OF ENERGY IN ECOSYSTEMS Lecture 2 NS 5 (1st AY 2010-2011)*Parungao
  2. +
  3. + ENERGY: defined in physics as the capacity to do work   inetic K Energy - the energy of movement   otential P Energy - stored energy   nergy E is measured in units called Joules (J)   ne J = about 1/4 calorie O   ne calorie is the amount of energy O needed to raise the temperature of 1 gram of water by 1o C (Celsius)
  4. + ENERGY: defined in physics as the capacity to do work   IRST F LAW OF THERMODYNAMICS: Energy cannot be created or destroyed; it can only change in form   ECOND S LAW OF THERMODYNAMICS: All systems in the universe tend to go from a state of order to a state of chaos (ENTROPY)   ntropy is energy that is unavailable to E do work
  5. + ENERGY IN BIOLOGICAL SYSTEMS   Sun: provides all the earth's energy in the form of LIGHT   Autotroph/Producers: an organism that captures energy and stores it in the chemical bonds of organic molecules that it manufactures from inorganic molecules   Heterotroph/Consumers or Decomposers: an organism that eats other organisms to obtain energy
  6. + AUTOTROPHS AND THEIR ROLE IN ENERGY FLOWS   PHOTOSYNTHESIS: most common means by which autotrophs make organic molecules (sugar   Overall, the chemical reaction of photosynthesis is as follows: Light energy + plant enzymes 6CO2 + 12H2O ---> C6H12O6 + 6O2 + 6H2O   CARBOHYDRATE: storage form for energy in plants for body structure and energy storage   Why do plants make sugar, is it for you? NO
  7. + PRODUCTIVITY IN ECOSYSTEMS: OVERVIEW   s A plants collect solar energy and store it as sugar, they are also BURN that sugar and USE the energy to run their own chemical reactions   lants p usually have some energy left over after photosynthesis: BIOMASS (dry weight) of the plant; it's what the heterotrophs eat, stealing the plant's hard-won energy!
  8. + PRODUCTIVITY IN ECOSYSTEMS: OVERVIEW  GROSS PRIMARY PRODUCTION (GPP): The total amount of light energy converted by producers into chemical energy (organic molecules, such as sugars)  NET PRIMARY PRODUCTION (NPP): Not all of this is stored as plant biomass; left over after the plants have used the sugars they've made for themselves  NPP = GPP – respiration  The productivity of various ecosystems can be calculated by measuring the biomass of vegetation per unit area per unit of time. (WE WILL DISCUSS THIS LATER)
  9. + THE 10% RULE IN ENERGY FLOWS   About 90% of the energy of one trophic level is LOST AS ENTROPY when it is eaten by the next higher trophic level   EXAMPLE: It takes 1,000,000J of sunlight for a plant to store 10,000J worth of biomass. If grasshoppers (primary consumers) eat those 10,000J of plant biomass, they will convert it into only 1000J of grasshopper biomass. If field mice eat 1000J of grasshopper biomass, they will convert it into only 100J of field mouse biomass. If foxes eat 100J of field mouse biomass, they will be able to convert only 10J into fox biomass   It's this PYRAMID OF PRODUCTIVITY that shows us why environmentalists urge us to "eat low on the food chain."   The higher you go in trophic levels, the more energy is wasted at lower levels.
  10. + IMAGINE THIS…   To make 1 kg of human biomass, it takes 10kg of grain   But if you eat beef, it takes 10kg of beef to make 1 kg of human, and 100kg of grain to make that 10kg of beef!   So if you skip the cow step, you can feed more people!   FOOD WEB: reflect its energy transfers, with producers, consumers and decomposers all contributing to the flow of energy and nutrients through the system
  11. + TROPHIC LEVELS   TROPHIC LEVELS: organisms at different levels of feeding   primary (1o)producers - organisms that can perform photosynthesis   primary (1o)consumers - organisms that eat primary producers   secondary (2o)consumers - organisms that eat primary consumers   tertiary (3o)consumers - organisms that eat secondary consumers   quaternary (4o)consumers - organisms that eat tertiary   And so on…..   DECOMPOSERS: are a special type of consumer that can eat dead, organic matter (detritus, carrion) and convert it back into its inorganic components
  12. + FOOD CHAIN
  13. + FOOD WEB
  14. + Food Web reflects the flow of ENERGY and NUTRIENTS through ecosystems   Wealso can categorize animals on the basis of the exact type of food they eat   carnivore - animal that eats meat   herbivore - animal that eats plant matter   omnivore - animal that eats a variety of things (plant and animal)   detritivore - eats dead, organic matter (detritus), but does not decompose it   insectivore - eats insects   frugivore - eats fruits   WHAT “VORE ARE YOU?
  15. + ENERGY BUDGET FOR PRODUCERS   Producers are able to capture solar energy and convert to chemical bond energy.   Much of that energy they used for cellular respiration.   Some of that energy is consumed by herbivores.   Some becomes part of dead tissue and is passed on to decomposers.   Some is stored as growth and reproduction
  16. + ECOLOGICAL carnivores PYRAMID herbivores producers   The standing crop, productivity, number of organisms, etc. of an ecosystem can be conveniently depicted using “pyramids”, where the size of each compartment represents the amount of the item in each trophic level of a food chain   Note that the complexities of the interactions in a food web are not shown in a pyramid; but, pyramids are often useful conceptual devices--they give one a sense of the overall form of the trophic structure of an ecosystem   Apyramid of energy depicts the energy flow, or productivity, of each trophic level   Apyramid of numbers indicates the number of individuals in each trophic level   Apyramid of standing crop indicates how much biomass is present in each trophic level at any one time.
  17. + INVERTED PYRAMIDS POSSIBLE?   A pyramid of standing crop (or of numbers) may be inverted, i.e., a higher trophic level may have a larger standing crop than a lower trophic level   Thiscan occur if the lower trophic level has a high rate of turnover of small individuals (and high rate of productivity), such that the First and Second Laws of Thermodynamics are not violated. biomass of carnivores biomass of herbivores biomass of producers
  18. + ANALYSIS OF ECOSYSTEM PRODUCTIVITY
  19. + IMPORTANT TERMS IN MEASURING PRODUCTIVITY: BIOMASS  total weight of organic matter, both living and dead, present on a unit area of the ecosystem at any given time  refer specifically to the plant (phytomass) or animal (zoomass) part of the biomass  measurable plant biomass includes undecomposed litter which may be harbouring litter fauna
  20. + IMPORTANT TERMS IN MEASURING PRODUCTIVITY: PRIMARY PRODUCTION  the total organic matter produced as a result of photosynthesis and nutrient uptake from the soil  referred to as gross primary production when all organic matter including that used in metabolism is taken into consideration
  21. + IMPORTANT TERMS IN MEASURING PRODUCTIVITY: ECONOMIC, AGRONOMIC AND BIOLOGICAL PRODUCTIVITY  In forestry and agriculture, only the economic parts of plants or crops are harvested  Productivitycalculated from the economic harvest alone is referred to as economic productivity (Ovington, 1965) and agronomic productivity (Pearson, 1965)
  22. + METHODS USED IN MEASURING RPODUCTIVITY
  23. + DIRECT METHODS   The direct method is based on biomass determined by harvesting and weighing of all organic matter present in a unit area of the ecosystem   techniques based on various growth parameters   (a) total net production and current shoot production   (b) shoot production and stem wood increment   (c) stem wood increment and estimated volume increment   Pearson (1965) estimated annual production in a different way using partially empirical formulae based on tree dimensions such as radius of trunk at base, height of tree, depth of tree canopy and the numerical density of the species studied
  24. + INDIRECT METHODS  Inview of the difficulties encountered in measuring productivity in complex multistrata perennial ecosystems, a number of indirect methods have been and are still being developed to measure productivity 1. The gaseous exchange method: using rate of   gas exchange as a measure of photosynthesis  2. Theuse of leaf area as an index of productivity: the leaf area available for absorbing the incident light will, to a certain extent, determine the rate of photosynthesis
  25. + INDIRECT METHODS  3. The use of chlorophyll content as an index of productivity: highly significant correlation exists between chlorophyll and dry matter production  4. Useof a fraction of total production: total production has been estimated from production of only a part or parts of trees, e.g. estimating roots from the values of top growth, or total production from quantity of leaf litter  5. Useof albedo as an index of productivity: albedo (i.e. the ratio of the amount of light reflected from the landscape to the total amount falling upon it) as an index of production; relationship existed between visible albedo and chlorophyll content
  26. + MEASUREMENT VIA DISSOLVED OXYGEN   Oxygen is critical to the maintenance of life processes of nearly all organisms   Its concentration and distribution in the aquatic environment are directly dependent upon chemical and physical factors and are greatly affected by biological processes   Therefore, themeasurement of dissolved oxygen in the water can be a very important indicator of water quality   Chemical and physical factors--such as salinity, pH, currents, and especially temperature, can affect dissolved oxygen concentration and distribution   Salinity, usually expressed in parts per thousand (PPT), is the content of dissolved salts in the water   Generally, as temperature and salinity increase, the solubility of oxygen in water decreases.
  27. + WHY OXYGEN?   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   We cannot measure gross productivity directly because respiration, which uses up oxygen and organic compounds, is always occurring simultaneously with photosynthesis — but we can measure it indirectly   We can measure net productivity directly by measuring oxygen production in the light, when photosynthesis is occurring   We can also measure respiration without photosynthesis by measuring O2 consumption in the dark, when photosynthesis does not occur.
  28. + Since net productivity = gross productivity – respiration, we can calculate gross productivity
  29. + THE WINKLER TEST   used to determine the level of dissolved oxygen in water samples   used to estimate the biological activity in the water sample   Anexcess of Manganese(II) salt, iodide (I-) and hydroxide (OH-) ions are added to a water sample causing a white precipitate of Mn(OH)2 to form   Thisprecipitate is then oxidized by the dissolved oxygen in the water sample into a brown Manganese precipitate   In the next step, a strong acid (either hydrochloric acid or sulphuric acid) is added to acidify the solution   Thebrown precipitate then convert the iodide ion (I-) to Iodine   The amount of dissolved oxygen is directly proportional to the titration of Iodine with a thiosulphate solution
  30. + An excess of Manganese(II) THE SET-UP   salt, iodide (I-) and hydroxide (OH-) ions are added to a water sample causing a white precipitate of Mn(OH)2 to form   This precipitate is then oxidized by the dissolved oxygen in the water sample into a brown Manganese precipitate   In the next step, a strong acid (either hydrochloric acid or sulphuric acid) is added to acidify the solution   The brown precipitate then convert the iodide ion (I-) to Iodine   The amount of dissolved oxygen is directly proportional to the titration of Iodine with a thiosulphate solution
  31. FOR YOUR ASSIGNMENT: + SUBMIT NEXT MEETING… AND STUDY FOR A QUIZ ON PRODUCTIVITY Page 10 of Activity Book (answer and detach). Use Back Page if necessary..

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