Ch. 55 Ecosystems And Restoration Ecology. AP Biology

Transcription

1 Ch. 55 Ecosystems And Restoration Ecology

2 Studying organisms in their environment organism population community ecosystem biosphere

3 Essential questions What limits the production in ecosystems? How do nutrients move in the ecosystem? How does energy move through the ecosystem?

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

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

6 Food chains Trophic levels feeding relationships start with energy from the sun captured by plants 1 st level of all food chains food chains usually go up only 4 or 5 levels inefficiency of energy transfer all levels connect to decomposers Level 4 Tertiary consumer top carnivore Level 3 Secondary consumer Level 2 Primary consumer Level 1 Producer Decomposers carnivore heterotrophs herbivore autotrophs Bacteria sun Fungi

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

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

9 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? What is your ecological footprint?!

10 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?

11 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

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

13 Ecosystem Energy Budgets The extent of photosynthetic production sets the spending limit for an ecosystem s energy budget 2011 Pearson Education, Inc.

14 The Global Energy Budget The amount of solar radiation reaching Earth s surface limits the photosynthetic output of ecosystems Only a small fraction of solar energy actually strikes photosynthetic organisms, and even less is of a usable wavelength 2011 Pearson Education, Inc.

15 Gross and Net Production Total primary production is known as the ecosystem s gross primary production (GPP) GPP is measured as the conversion of chemical energy from photosynthesis per unit time Net primary production (NPP) is GPP minus energy used by primary producers for respiration NPP is expressed as Energy per unit area per unit time (J/m 2 yr), or 2011 Pearson Education, Inc. Biomass added per unit area per unit time (g/m 2 yr)

16 NPP is the amount of new biomass added in a given time period Only NPP is available to consumers Standing crop is the total biomass of photosynthetic autotrophs at a given time Ecosystems vary greatly in NPP and contribution to the total NPP on Earth 2011 Pearson Education, Inc.

17 Percent reflectance Figure 55.5 TECHNIQUE 80 Snow Vegetation Clouds Soil 20 0 Liquid water ,000 1,200 Visible Wavelength (nm) Near-infrared

18 Tropical rain forests, estuaries, and coral reefs are among the most productive ecosystems per unit area Marine ecosystems are relatively unproductive per unit area but contribute much to global net primary production because of their volume 2011 Pearson Education, Inc.

19 Figure 55.6 Net primary production (kg carbon/m 2 yr)

20 Net ecosystem production (NEP) is a measure of the total biomass accumulation during a given period NEP is gross primary production minus the total respiration of all organisms (producers and consumers) in an ecosystem NEP is estimated by comparing the net flux of CO 2 and O 2 in an ecosystem, two molecules connected by photosynthesis The release of O 2 by a system is an indication that it is also storing CO Pearson Education, Inc.

21 Energy transfer between trophic levels is typically only 10% efficient Secondary production of an ecosystem is the amount of chemical energy in food converted to new biomass during a given period of time 2011 Pearson Education, Inc.

22 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 Production efficiency Net secondary production 100% Assimilation of primary production 2011 Pearson Education, Inc.

23 Figure Plant material eaten by caterpillar 200 J Feces 100 J 33 J 67 J Cellular respiration Not assimilated Growth (new biomass; secondary production) Assimilated

24 Figure 55.10a

25 Birds and mammals have efficiencies in the range of 1 3% because of the high cost of endothermy Fishes have production efficiencies of around 10% Insects and microorganisms have efficiencies of 40% or more 2011 Pearson Education, Inc.

26 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%, with a range of 5% to 20% Trophic efficiency is multiplied over the length of a food chain 2011 Pearson Education, Inc.

27 Approximately 0.1% of chemical energy fixed by photosynthesis reaches a tertiary consumer A pyramid of net production represents the loss of energy with each transfer in a food chain 2011 Pearson Education, Inc.

28 Figure Tertiary consumers Secondary consumers 10 J 100 J Primary consumers Primary producers 10,000 J 1,000 J 1,000,000 J of sunlight

29 In a biomass pyramid, each tier represents the dry mass of all organisms in one trophic level Most biomass pyramids show a sharp decrease at successively higher trophic levels 2011 Pearson Education, Inc.

30 Figure Trophic level Dry mass (g/m 2 ) Tertiary consumers Secondary consumers Primary consumers Primary producers (a) Most ecosystems (data from a Florida bog) Trophic level Primary consumers (zooplankton) Primary producers (phytoplankton) Dry mass (g/m 2 ) 21 4 (b) Some aquatic ecosystems (data from the English Channel)

31 Certain aquatic ecosystems have inverted biomass pyramids: producers (phytoplankton) are consumed so quickly that they are outweighed by primary consumers Turnover time is the ratio of the standing crop biomass to production 2011 Pearson Education, Inc.

32 Dynamics of energy flow in ecosystems have important implications for the human population Eating meat is a relatively inefficient way of tapping photosynthetic production Worldwide agriculture could feed many more people if humans ate only plant material 2011 Pearson Education, Inc.

33 Biological and geochemical processes cycle nutrients and water in ecosystems Life depends on recycling chemical elements Nutrient cycles in ecosystems involve biotic and abiotic components and are often called biogeochemical cycles 2011 Pearson Education, Inc.

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

35 Carbon cycle CO 2 in atmosphere Diffusion Respiration abiotic reservoir: CO 2 in atmosphere enter food chain: Combustion photosynthesis of fuels = carbon fixation in Industry and home Calvin cycle Photosynthesis recycle: return to abiotic: Plants respiration Animals combustion Dissolved CO 2 Bicarbonates Photosynthesis Animals Plants and algae Deposition of dead material Carbonates in sediment Deposition of dead material Fossil fuels (oil, gas, coal)

36 Nitrogen cycle abiotic reservoir: N in atmosphere enter food chain: Carnivores nitrogen fixation by soil & aquatic bacteria recycle: decomposing & Herbivores nitrifying bacteria return to abiotic: denitrifying bacteria Atmospheric nitrogen Birds Plankton with nitrogen-fixing bacteria Fish loss to deep sediments excretion Death, excretion, feces Decomposing bacteria amino acids Ammonifying bacteria Nitrifying bacteria soil nitrates Plants Nitrogen-fixing bacteria (plant roots) Nitrogen-fixing bacteria (soil) Denitrifying bacteria

37 Phosphorus cycle Loss in drainage Plants Decomposers (bacteria & fungi) Phosphates in solution Land animals Soluble soil phosphate abiotic reservoir: rocks, minerals, soil enter food chain: erosion releases soluble phosphate uptake by plants recycle: decomposing bacteria Animal & fungi tissue Urine and feces return to abiotic: loss to Decomposers ocean sediment (bacteria and fungi) Rocks and minerals Animal tissue and feces Aquatic animals Plants and algae Precipitates Loss to deep sediment

38 Water cycle Water vapor Transpiration Precipitation Evaporation abiotic reservoir: surface & atmospheric water enter food chain: precipitation & plant uptake recycle: Solar energy transpiration return to abiotic: evaporation & runoff Runoff Oceans Lakes Percolation in soil Groundwater Aquifer

39 Transpiration Remember transpiration?

40 Breaking the water cycle Deforestation breaks the water cycle groundwater is not transpired to the atmosphere, so precipitation is not created forest desert desertification

41 Repairing the damage The Greenbelt Movement planting trees in Kenya restoring a sustainable ecosystem establishing democracy empowering women Wangari Maathai Nobel Peace prize 2004

42 Studying ecosystems Hubbard Brook Experimental Forest 38 acre deforestation 7800 acres

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

44 Bioremediation Bioremediation is the use of organisms to detoxify ecosystems The organisms most often used are prokaryotes, fungi, or plants These organisms can take up, and sometimes metabolize, toxic molecules For example, the bacterium Shewanella oneidensis can metabolize uranium and other elements to insoluble forms that are less likely to leach into streams and groundwater 2011 Pearson Education, Inc.

45 Concentration of soluble uranium ( M) Figure Days after adding ethanol 400

46 Figure 55.18a

47 Biological Augmentation Biological augmentation uses organisms to add essential materials to a degraded ecosystem For example, nitrogen-fixing plants can increase the available nitrogen in soil For example, adding mycorrhizal fungi can help plants to access nutrients from soil 2011 Pearson Education, Inc.

48 Restoration Projects Worldwide The newness and complexity of restoration ecology require that ecologists consider alternative solutions and adjust approaches based on experience 2011 Pearson Education, Inc.

49 Figure 55.19a Equator

50 Figure 55.19b Kissimmee River, Florida

51 Figure 55.19c Truckee River, Nevada

52 Figure 55.19d Tropical dry forest, Costa Rica

53 Figure 55.19e Rhine River, Europe

54 Figure 55.19f Succulent Karoo, South Africa

55 Figure 55.19g Coastal Japan

56 Figure 55.19h Maungatautari, New Zealand

57 Figure 55.UN01 Heat Sun Key Chemical cycling Energy flow Primary producers Primary consumers Detritus Secondary and tertiary consumers Microorganisms and other detritivores

58 Figure 55.UN02 Reservoir A Organic materials available as nutrients: Living organisms, detritus Reservoir D Inorganic materials unavailable as nutrients: Minerals in rocks Fossilization Respiration, decomposition, excretion Assimilation, photosynthesis Weathering, erosion Formation of sedimentary rock Reservoir B Organic materials unavailable as nutrients: Peat, coal, oil Burning of fossil fuels Reservoir C Inorganic materials available as nutrients: Atmosphere, water, soil

59 Figure 55.UN03

60 Figure 55.UN04

61 Any Questions?? We re working on a lot of them!