Presentation on theme: "Ecosystems: What Are They and How Do They Work?"— Presentation transcript:
1 Ecosystems: What Are They and How Do They Work? Chapter 3Ecosystems: What Are They and How Do They Work?
2 Chapter Overview Questions What is ecology?What basic processes keep us and other organisms alive?What are the major components of an ecosystem?What happens to energy in an ecosystem?What happens to matter in an ecosystem?How do scientists study ecosystems?
3 Core Case Study: Tropical Rain Forests Are Disappearing 3
4 Core Case Study: Tropical Rain Forests Are Disappearing Cover about 2% of the earth’s land surfaceContain about 50% of the world’s known terrestrial plant and animal speciesDisruption will have three major harmful effectsReduce biodiversityAccelerate global warmingChange regional weather patterns4
5 Natural Capital Degradation: Satellite Image of the Loss of Tropical Rain Forest Santa Cruz, Bolivia 197520035
6 THE NATURE OF ECOLOGY Ecology is a study of connections in nature. How organisms interact with one another and with their nonliving environment.Put another way: Biotic & Abiotic InteractionsNext
7 Biosphere Ecosystems Realm of ecology Communities Populations UniverseGalaxiesBiosphereSolar systemsPlanetsEarthBiosphereEcosystemsEcosystemsCommunitiesPopulationsRealm of ecologyOrganismsCommunitiesOrgan systemsOrgansFigure 3.2Natural capital: levels of organization of matter in nature. Ecology focuses on five of these levels.TissuesCellsPopulationsProtoplasmMoleculesAtomsOrganismsSubatomic ParticlesFig. 3-2, p. 51
8 Organisms and SpeciesOrganisms, the different forms of life on earth, can be classified into different species based on certain characteristics.Next
9 Other animals 281,000 Known species 1,800,000 Insects 751,000 Fungi 69,000Prokaryotes4,800Figure 3.3Natural capital: breakdown of the earth’s 1.4 million known species. Scientists estimate that there are 4 million to 100 million species.Plants248,400Protists57,700
10 Have You Thanked the Insects Today? Many plant species depend on insects for pollination.Insect can control other pest insects by eating themFigure 3-1
11 Core Case Study: Have You Thanked the Insects Today? “…if all insects disappeared, humanity probably could not last more than a few months” [E.O. Wilson, Biodiversity expert].Insect’s role in nature is part of the larger biological community in which they live.
12 E.O. WilsonWorld’s foremost authority on biodiversity
13 Case Study: Which Species Run the World? Multitudes of tiny microbes such as bacteria, protozoa, fungi, and yeast help keep us alive.Harmful microbes are the minority.Soil bacteria convert nitrogen gas to a usable form for plants.They help produce foods (bread, cheese, yogurt, beer, wine).90% of all living mass. (!)Helps purify water, provide oxygen, breakdown waste.Lives beneficially in your body (intestines, nose).
14 Populations, Communities, and Ecosystems Members of a species interact in groups called populations.Populations of different species living and interacting in an area form a community.A community interacting with its physical environment of matter and energy is an ecosystem.
15 PopulationsA population is a group of interacting individuals of the same species occupying a specific area.The space an individual or population normally occupies is its habitat.Monarch ButterfliesFigure 3-4
16 Populations Genetic diversity In most natural populations individuals vary slightly in their genetic makeup.Variation among one speciesof Caribbean snail!Figure 3-5
17 THE EARTH’S LIFE SUPPORT SYSTEMS The biosphere consists of several physical layers that contain:sphere?AirWaterSoilMineralsLifeFigure 3-6
18 (living and dead organisms) (crust, top of upper mantle) OceanicCrustContinentalCrustAtmosphereVegetationand animalsBiosphereLithosphereSoilUpper mantleCrustRockAsthenosphereLower mantleCoreMantleFigure 3.6Natural capital: general structure of the earth.Crust (soil and rock)Biosphere(living and dead organisms)Hydrosphere (water)Lithosphere(crust, top of upper mantle)Atmosphere (air)Fig. 3-6, p. 54
19 What Supports the Biosphere? AtmosphereMembrane of air around the planet.Troposphere: lowest layer; we live in this!Stratosphere: miles upLower portion contains stratospheric ozone to filter out most of the sun’s harmful UV radiation.HydrosphereAll the earth’s water: liquid, ice, water vaporLithosphereThe earth’s crust and upper mantle.
20 What Sustains Life on Earth? Solar energy, the cycling of matter, and gravity sustain the earth’s life.Figure 3-7
21 Carbon cycle Phosphorus cycle Nitrogen cycle Water cycle Oxygen cycle BiosphereCarboncyclePhosphoruscycleNitrogencycleWatercycleOxygencycleFigure 3.7Natural capital: life on the earth depends on the flow of energy (wavy arrows) from the sun through the biosphere and back into space, the cycling of crucial elements (solid arrows around ovals), and gravity, which keeps atmospheric gases from escaping into space and helps recycle nutrients through air, water, soil, and organisms. This simplified model depicts only a few of the many cycling elements.Heat in the environmentHeatHeatHeatFig. 3-7, p. 55
22 What Happens to Solar Energy Reaching the Earth? Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth.Figure 3-8
23 1 billionth of total solar energy reaches the earth! radiationEnergy in = Energy outReflected byatmosphere (34% )Radiated byatmosphere as heat (66%)UV radiationLower Stratosphere(ozone layer)Absorbedby ozoneVisibleLightGreenhouseeffectTroposphereHeatFigure 3.8Solar capital: flow of energy to and from the earth.Absorbedby the earthHeat radiatedby the earthFig. 3-8, p. 55
24 ECOSYSTEM COMPONENTSLife exists on land systems called biomes and in freshwater aquatic and marine aquatic life zones.Figure 3-9
25 39th parallel transect across the USA Average annual precipitation 100–125 cm (40–50 in.)75–100 cm (30–40 in.)50–75 cm (20–30 in.)4,600 m (15,000 ft.)25–50 cm (10–20 in.)3,000 m (10,000 ft.)below 25 cm (0–10 in.)1,500 m (5,000 ft.)CoastalmountainrangesSierraNevadaMountainsGreatAmericanDesertRockyMountainsGreatPlainsMississippiRiver ValleyAppalachianMountainsFigure 3.9Natural capital: major biomes found along the 39th parallel across the United States. The differences reflect changes in climate, mainly differences in average annual precipitation and temperature.Coastal chaparraland scrubConiferous forestDesertConiferous forestPrairie grasslandDeciduous forestFig. 3-9, p. 56
26 Nonliving and Living Components of Ecosystems Ecosystems consist of nonliving (abiotic) and living (biotic) components.Figure 3-10
27 Falling leaves and twigs Soluble mineral nutrients Oxygen (O2)SunProducerCarbon dioxide (CO2)Secondary consumer(fox)Primaryconsumer(rabbit)PrecipitationProducersFalling leaves and twigsFigure 3.10Natural capital: major components of an ecosystem in a field.Soil decomposersWaterSoluble mineral nutrientsFig. 3-10, p. 57
28 Factors That Limit Population Growth Availability of matter and energy resources can limit the number of organisms in a population.Figure 3-11
29 Lower limit of tolerance Upper limit of tolerance NoorganismsFeworganismsFeworganismsNoorganismsAbundance of organismsPopulation sizeFigure 3.11Natural capital: range of tolerance for a population of organisms, such as fish, to an abiotic environmental factor—in this case, temperature. These restrictions keep particular species from taking over an ecosystem by keeping their population size in check.Zone ofintoleranceZone ofphysiological stressOptimum rangeZone ofphysiological stressZone ofintoleranceLowTemperatureHighFig. 3-11, p. 58
30 Limiting Factor Principal Too much or too little of any one abiotic factor can limit or prevent the growth of a population, even if all other limiting factors are at or near the optimum rangeFigure 3-11
31 Factors That Limit Population Growth The physical and chemical conditions of the environment can limit the distribution of a species.Figure 3-12
32 Sugar MapleWhy does the sugar mapleonly grow in this range?CLIMATE is the most important factor that determines what biome grows in a particular area.Figure 3.12The physical conditions of the environment can limit the distribution of a species. The green area shows the current range of sugar maple trees in eastern North America. (Data from U.S. Department of Agriculture)Fig. 3-12, p. 58
34 Producers: Basic Source of All Food Most producers capture sunlight to produce carbohydrates by photosynthesis:Producers form the base of all food chains on earth, so the limiting factors that act upon producers are critical in determining what grows in a particular area.
35 Producers: Basic Source of All Food Photosynthesis: source of ALMOST ALL foodexceptionChemosynthesis:“Sea Vent Community”- Some organisms such as deep ocean bacteria draw energy from hydrothermal vents and produce carbohydrates from the chemical energy in hydrogen sulfide (H2S) gas .Some chemosynthetic bacteria are found in hot springs and geysers (as found in Yellowstone National Park)
36 Sea Vent Community Found in deep sea hydrothermal vents
37 Sea Vent Community Found in deep sea hydrothermal vents
39 Photosynthesis: A Closer Look Chlorophyll molecules in the chloroplasts of plant cells absorb solar energy.This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars and oxygen.Figure 3-A
40 Sun Chloroplast in leaf cell Chlorophyll H2O Light-dependent Reaction Figure 3.ASimplified overview of photosynthesis. In this process, chlorophyll molecules in the chloroplasts of plant cells absorb solar energy. This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars, such as glucose, and oxygen.H2OLight-dependentReactionO2Energy storageand release(ATP/ADP)GlucoseLight-independentreactionCO2Sunlight6CO2 + 6 H2OC6H12O6 + 6 O2Fig. 3-A, p. 59
41 Consumers: Eating and Recycling to Survive Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains.HerbivoresPrimary consumers that eat producersCarnivoresSecondary consumers: Carnivores that eat primary consumersTertiary and higher level consumers: Carnivores that eat carnivores.OmnivoresFeed on both plant and animals.
42 Decomposers and Detritovores Detritovores: Insects or other scavengers that feed on wastes or dead bodies.Decomposers: Recycle nutrients in ecosystems.Figure 3-13
43 Termite and carpenter ant work Bark beetle engraving ScavengersDecomposersTermite and carpenter ant workBark beetle engravingCarpenter ant galleriesLong-horned beetle holesDry rot fungusWood reduced to powderFigure 3.13Natural capital: various scavengers (detritivores) and decomposers (mostly fungi and bacteria) can “feed on” or digest parts of a log and eventually convert its complex organic chemicals into simpler inorganic nutrients that can be taken up by producers.MushroomTime progressionPowder broken down by decomposers into plant nutrients in soilFig. 3-13, p. 61
44 Aerobic and Anaerobic Respiration: Getting Energy for Survival Organisms break down carbohydrates and other organic compounds in their cells to obtain the energy they need.This is usually done through aerobic respiration.The opposite of photosynthesis
45 Aerobic and Anaerobic Respiration: Getting Energy for Survival Anaerobic respiration or fermentation:Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen.The end products vary based on the chemical reaction:Methane gas- methanogens in our intestinesEthyl alcohol- yeast that make alcoholAcetic acid- bacteria that make vinegarHydrogen sulfide- bacteria in the salt marsh
46 Two Secrets of Survival: Energy Flow and Matter Recycle An ecosystem survives by a combination of energy flow and matter recycling.Figure 3-14
47 Abiotic chemicals (carbon dioxide, Heat oxygen, nitrogen, Solar Heat minerals)HeatSolarenergyHeatHeatProducers(plants)Decomposers(bacteria, fungi)Figure 3.14Natural capital: the main structural components of an ecosystem (energy, chemicals, and organisms). Matter recycling and the flow of energy—first from the sun, then through organisms, and finally into the environment as low-quality heat—links these components.Consumers(herbivores,carnivores)HeatHeatFig. 3-14, p. 61
49 ENERGY FLOW IN ECOSYSTEMS Food chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem.Next
50 (decomposers and detritus feeders) First TrophicLevelSecond TrophicLevelThird TrophicLevelFourth TrophicLevelProducers(plants)Primary consumers(herbivores)Secondary consumers(carnivores)Tertiary consumers(top carnivores)HeatHeatHeatSolar energyHeatHeatFigure 3.17Natural capital: a food chain. The arrows show how chemical energy in food flows through various trophic levels in energy transfers; most of the energy is degraded to heat, in accordance with the second law of thermodynamics.HeatHeatDetritivores(decomposers and detritus feeders)HeatFig. 3-17, p. 64
51 Food WebsTrophic levels are interconnected within a more complicated food web.Next
52 Humans Blue whale Sperm whale Crabeater seal Elephant seal Killer whaleLeopardsealAdeliepenguinsEmperorpenguinSquidFigure 3.18Natural capital: a greatly simplified food web in the Antarctic. Many more participants in the web, including an array of decomposer organisms, are not depicted here.PetrelFishCarnivorous planktonKrillHerbivorousplanktonPhytoplanktonFig. 3-18, p. 65
53 Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs In accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.
54 Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next.Figure 3-19
55 Heat Heat Tertiary consumers Decomposers (human) Heat 10 Secondary (perch)Heat100Primaryconsumers(zooplankton)Figure 3.19Natural capital: generalized pyramid of energy flow showing the decrease in usable energy available at each succeeding trophic level in a food chain or web. In nature, ecological efficiency varies from 2% to 40%, with 10% efficiency being common. This model assumes a 10% ecological efficiency (90% loss in usable energy to the environment, in the form of low-quality heat) with each transfer from one trophic level to another. QUESTION: Why is it a scientific error to call this a pyramid of energy?1,000Heat10,000Usable energyAvailable atEach tropic level(in kilocalories)Producers(phytoplankton)Fig. 3-19, p. 66
56 Productivity of Producers: The Rate Is Crucial Gross primary production (GPP)Rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass.Figure 3-20
57 Gross primary productivity (grams of carbon per square meter) Figure 3.20Natural capital: gross primary productivity across the continental United States based on remote satellite data. The differences roughly correlate with variations in moisture and soil types. (NASA’s Earth Observatory)Gross primary productivity(grams of carbon per square meter)Fig. 3-20, p. 66
58 Net Primary Production (NPP) NPP = GPP – RRate at which producers use photosynthesis to store energy minus the rate at which they (the producers) use some of this energy through respiration (R).Figure 3-21
59 and unavailable to consumers Respiration SunPhotosynthesisEnergy lostand unavailable to consumersRespirationGross primary productionNet primary production (energy available to consumers)Figure 3.21Natural capital: distinction between gross primary productivity and net primary productivity. A plant uses some of its gross primary productivity to survive through respiration. The remaining energy is available to consumers.Growth and reproductionFig. 3-21, p. 66
60 What are nature’s three most productive and three least productive systems? Figure 3-22
61 Average net primary productivity (kcal/m2 /yr) Terrestrial EcosystemsSwamps and marshesTropical rain forestTemperate forestNorth. coniferous forestSavannaAgricultural landWoodland and shrublandTemperate grasslandTundra (arctic and alpine)Desert scrubExtreme desertAquatic EcosystemsEstuariesFigure 3.22Natural capital: estimated annual average net primary productivity per unit of area in major life zones and ecosystems, expressed as kilocalories of energy produced per square meter per year (kcal/m2/yr). QUESTION: What are nature’s three most productive and three least productive systems? (Data from Communities and Ecosystems, 2nd ed., by R. H. Whittaker, New York: Macmillan)Lakes and streamsContinental shelfOpen oceanAverage net primary productivity (kcal/m2 /yr)Fig. 3-22, p. 67
62 MATTER CYCLING IN ECOSYSTEMS Nutrient Cycles: Global RecyclingGlobal Cycles recycle nutrients through the earth’s air, land, water, and living organisms.C, H2O, S, N, PBiogeochemical cycles move these substances through air, water, soil, rock and living organisms.
63 Characterizing Biogeochemical Cycles Where is Most of the Matter? Biogeochemical cycles are characterized by where the major reservoir of that compound or element is storedWater- On average, a water molecule stays in the ocean for 3,000 years, while it stays in the atmosphere only 9 days.Carbon- Most carbon is stored as dissolved carbonic acid in the oceanNitrogen- atmosphericPhosphorous- sedimentary
64 The Hydrologic Cycle Condensation Transpiration Evaporation Rain cloudsTranspirationEvaporationPrecipitation to landTranspiration from plantsPrecipitationPrecipitationEvaporation from landEvaporation from oceanSurface runoff (rapid)RunoffPrecipitation to oceanInfiltrationSurface runoff (rapid)Figure 3.26Natural capital: simplified model of the hydrologic cycle.Percolation: Groundwater movement (slow)Ocean storageFig. 3-26, p. 72
65 Water’s Unique Properties There are strong forces of attraction between molecules of water (allows transpiration)Water exists as a liquid over a wide temperature range.Liquid water changes temperature slowly.It takes a large amount of energy for water to evaporate.Liquid water can dissolve a variety of compounds.Water expands when it freezes.
66 Effects of Human Activities on Water Cycle We alter the water cycle by:Withdrawing large amounts of freshwater.Clearing vegetation and eroding soils.Polluting surface and underground water.Contributing to climate change.
67 The Carbon Cycle: Part of Nature’s Thermostat Figure 3-27
68 Effects of Human Activities on Carbon Cycle We alter the carbon cycle by adding excess CO2 to the atmosphere through:Burning fossil fuels.Clearing vegetation faster than it is replaced.Figure 3-28
69 (billion metric tons of carbon equivalent) HighprojectionLowprojection(billion metric tons of carbon equivalent)CO2 emissions from fossil fuelsFigure 3.28Natural capital degradation: human interference in the global carbon cycle from carbon dioxide emissions when fossil fuels are burned and forests are cleared, 1850 to 2006 and projections to 2030 (dashed lines). (Data from UN Environment Programme, British Petroleum, International Energy Agency, and U.S. Department of Energy)YearFig. 3-28, p. 74
70 The Nitrogen Cycle: Bacteria in Action Figure 3-29
72 Effects of Human Activities on the Nitrogen Cycle We alter the nitrogen cycle by:Adding gases that contribute to acid rain.Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone.Contaminating ground water from nitrate ions in inorganic fertilizers.Releasing nitrogen into the troposphere through deforestation.
73 Effects of Human Activities on the Nitrogen Cycle Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined.Figure 3-30
74 Global nitrogen (N) fixation Nitrogen fixation by natural processesGlobal nitrogen (N) fixation(trillion grams)Figure 3.30Natural capital degradation: human interference in the global nitrogen cycle. Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. (Data from UN Environment Programme, UN Food and Agriculture Organization, and U.S. Department of Agriculture)Nitrogen fixation by human processesYearFig. 3-30, p. 76
77 Effects of Human Activities on the Phosphorous Cycle We remove large amounts of phosphate from the earth to make fertilizer.It has been estimated that there is about 50 years of guano and phosphate rock remaining at current rates of removal by humansWe reduce phosphorous in tropical soils by clearing forests.We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.
79 Acidic fog and precipitation WaterSulfurtrioxideSulfuric acidAcidic fog and precipitationAmmoniaAmmoniumsulfateOxygenSulfur dioxideHydrogen sulfidePlantsDimethyl sulfideVolcanoIndustriesAnimalsOceanFigure 3.32Natural capital: simplified model of the sulfur cycle. The movement of sulfur compounds in living organisms is shown in green, blue in aquatic systems, and orange in the atmosphere. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the sulfur cycle?Sulfate saltsMetallicsulfidedepositsDecaying matterSulfurHydrogen sulfideFig. 3-32, p. 78
80 Effects of Human Activities on the Sulfur Cycle We add sulfur dioxide to the atmosphere by:Burning coal and oilRefining sulfur containing petroleum.Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment.
81 The Gaia Hypothesis: Is the Earth Alive? Some have proposed that the earth’s various forms of life control or at least influence its chemical cycles and other earth-sustaining processes.The strong Gaia hypothesis: life controls the earth’s life-sustaining processes.The weak Gaia hypothesis: life influences the earth’s life-sustaining processes.
82 HOW DO ECOLOGISTS LEARN ABOUT ECOSYSTEMS? Field Research- Going “into the field”Measuring and/or observations out in natureUsuallyControlled experiments e.g. Hubbard BrooksRarelyLab ResearchControlled indoor & outdoor chambersSystems Analysis/ModellingFeedback loops mathematically programmed
83 Remote Sensing & GISEcologist go into ecosystems to observe, but also use remote sensors on aircraft and satellites to collect data and analyze geographic data in large databases.Geographic Information Systems (GIS)Remote Sensing
86 The effect of building roads in a rainforest… Remote SensingThe effect of building roads in a rainforest…
87 Geographic Information Systems (GIS) A GIS organizes, stores, and analyzes complex data collected over broad geographic areas.Allows the simultaneous overlay of many layers of data.Next
88 USDA Forest Service Private owner 1 Habitat type Critical nesting site locationsUSDA Forest ServiceUSDAForest ServicePrivateowner 1Private owner 2TopographyHabitat typeForestWetlandFigure 3.33Geographic information systems (GISs) provide the computer technology for organizing, storing, and analyzing complex data collected over broad geographic areas. They enable scientists to overlay many layers of data (such as soils, topography, distribution of endangered populations, and land protection status).LakeGrasslandReal worldFig. 3-33, p. 79
89 Systems AnalysisEcologists develop mathematical and other models to simulate the behavior of ecosystems.Figure 3-34
90 Importance of Baseline Ecological Data We need baseline data on the world’s ecosystems so we can see how they are changing and develop effective strategies for preventing or slowing their degradation.Scientists have less than half of the basic ecological data needed to evaluate the status of ecosystems in the United Sates (Heinz Foundation 2002; Millennium Assessment 2005).
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