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 Core Case Study: 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
3 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.
4 THE NATURE OF ECOLOGY Ecology is a study of connections in nature. How organisms interact with one another and with their nonliving environment.Figure 3-2
5 EcologyEcology: the study of the relationships between organisms & the abiotic (nonliving) and biotic (living) environment.The physical conditions influence the habitat in which an organism lives. These include:substratehumiditysunlighttemperaturesalinitypH (acidity)exposurealtitudedepthEach abiotic (or physical) factor may be well suited to the organism or it may present it with problems to overcome.O2NutrientsCO2Relationships involve interactions with the physical world as well as interrelationships with other species and individuals of the same species.
6 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
7 Biological Complexity Living organisms can be studied at different levels of complexity.From least to most complex, these levels are (in an ecological context):IndividualPopulationCommunityEcosystemBiomeBiosphereBiosphereBiomeEcosystemCommunityPopulationIndividual
8 Organisms and SpeciesOrganisms, the different forms of life on earth, can be classified into different species based on certain characteristics.Figure 3-3
9 Other animals 281,000 Known species 1,412,000 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.Plants248,400Protists57,700Fig. 3-3, p. 52
10 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).
11 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.
12 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.Figure 3-4
13 Populations Genetic diversity In most natural populations individuals vary slightly in their genetic makeup.Figure 3-5
14 The population of all species living & interacting in an area. CommunityThe population of all species living & interacting in an area.
15 EcosystemsEcosystems consist of nonliving (abiotic) and living (biotic) components.Figure 3-10
16 The BiosphereThe biosphere is the region within which all living things are found on Earth, extending from the bottom of the oceans to the upper atmosphere.The biosphere is but one of the four separate components of the geochemical model along with the lithosphere, hydrosphere, and atmosphere.The Gaia Hypothesis maintains that the Earth is a single self-regulating complex evolving system. An example being the exchange of elements between oceans and land.
17 THE EARTH’S LIFE SUPPORT SYSTEMS The biosphere consists of several physical layers that contain:AirWaterSoilMineralsLifeFigure 3-6
18 Biosphere Atmosphere Stratosphere Hydrosphere Lithosphere Membrane of air around the planet.StratosphereLower portion contains 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.
19 (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
20 HabitatAn organism’s habitat is the physical place or environment in which it lives.Organisms show a preference for a particular habitat type, but some are more specific in their requirements than others.Most frogs, like this leopard frog, live in or near fresh water, but a few can survive in arid habitats.Lichens, fungi & algae or bacteria, are found on rocks, trees, and bare ground.
22 MacronutrientsChemicals organisms need in large numbers to live, grow, and reproduce.Ex. carbon, oxygen, hydrogen, nitrogen, calcium, and iron.
23 MicronutrientsThese are needed in small or even trace amounts.Ex. sodium, zinc copper, chlorine, and iodine.
24 Presence of other organisms Ecological NicheThe ecological niche describes the functional position of an organism in its environment.A niche comprises:the habitat in which the organism lives.the organism’s activity pattern: the periods of time during which it is active.the resources it obtains from the habitat.AdaptationsHabitatActivitypatternsPresence of other organismsPhysicalconditions
25 The Fundamental NicheThe fundamental niche of an organism is described by the full range of environmental conditions (biological and physical) under which the organism can exist.The realized niche of the organism is the niche that is actually occupied. It is narrower than the fundamental niche.This contraction of the realized niche is a result of pressure from, and interactions with, other organisms.
26 Factors That Limit Population Growth Availability of matter and energy resources can limit the number of organisms in a population.Figure 3-11
27 Law of ToleranceThe law of tolerance states that “For each abiotic factor, an organism has a range of tolerances within which it can survive.”Tolerance rangeOptimum rangeNumber of organismsUnavailable nicheMarginal nichePreferred nicheMarginal nicheUnavailable nicheExamples of abiotic factors that influence size of the realized nicheToo acidicpHToo alkalineToo coldTemperatureToo hot
28 Factors That Limit Population Growth The physical conditions of the environment can limit the distribution of a species.Figure 3-12
29 Population Growth Cycle Limited ResourcesA population can grow until competition for limited resources increases & the carrying capacity (C.C.) is reached.
30 Typical Phases 1. The population overshoots the C.C. 2. This is because of a reproductive time lag (the period required for the birth rate to fall & the death rate to rise).3. The population has a dieback or crashes.4. The carrying capacity is reached.
31 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
32 Producers: Basic Source of All Food Most producers capture sunlight to produce carbohydrates by photosynthesis:
33 Producers: Basic Source of All Food Chemosynthesis:Some organisms such as deep ocean bacteria draw energy from hydrothermal vents and produce carbohydrates from hydrogen sulfide (H2S) gas .
34 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
35 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
36 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 producersCarnivoresPrimary consumers eat primary consumersThird and higher level consumers: carnivores that eat carnivores.OmnivoresFeed on both plant and animals.
37 Decomposers and Detrivores Decomposers: Recycle nutrients in ecosystems.Detrivores: Insects or other scavengers that feed on wastes or dead bodies.Figure 3-13
38 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
39 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
40 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 gasEthyl alcoholAcetic acidHydrogen sulfide
41 Two Secrets of Survival: Energy Flow and Matter Recycle An ecosystem survives by a combination of energy flow and matter recycling.Figure 3-14
42 DecompositionAs plant or animal matter dies it will break down and return the chemicals back to the soil.This happens very quickly in tropical rainforest which results in low-nutrient soils.Grasslands have the deepest and most nutrient rich of all soils
44 Biodiversity Loss and Species Extinction: Remember HIPPO H for habitat destruction and degradationI for invasive speciesP for pollutionP for human population growthO for overexploitation
45 Biodiversity Loss and Species Extinction: Remember HIPPCO H for habitat destruction and degradationI for invasive speciesP for pollutionP for human population growthC for Climate ChangeO for overexploitation
46 Why Should We Care About Biodiversity? Biodiversity provides us with:Natural Resources (food water, wood, energy, and medicines)Natural Services (air and water purification, soil fertility, waste disposal, pest control)Aesthetic pleasure
47 Solutions Goals, strategies and tactics for protecting biodiversity. Figure 3-16
48 ENERGY FLOW IN ECOSYSTEMS Food chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem.Figure 3-17
49 Food WebsTrophic levels are interconnected within a more complicated food web.Figure 3-18
50 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.
51 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
52 10% RuleWe assume that 90% of the energy at each energy level is lost because the organism uses the energy. (heat)It is more efficient to eat lower on the energy pyramid. You get more out of it!This is why top predators are few in number & vulnerable to extinction.
53 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
54 Net Primary Production (NPP) NPP = GPP – RRate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R).Figure 3-21
55 What are nature’s three most productive and three least productive systems? Figure 3-22
56 What Sustains Life on Earth? Solar energy, the cycling of matter, and gravity sustain the earth’s life.Figure 3-7
57 MATTER CYCLING IN ECOSYSTEMS Nutrient Cycles: Global RecyclingGlobal Cycles recycle nutrients through the earth’s air, land, water, and living organisms.Nutrients are the elements and compounds that organisms need to live, grow, and reproduce.Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.
59 Water’ Unique Properties There are strong forces of attraction between molecules of water.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.
60 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.
61 The Carbon Cycle: Part of Nature’s Thermostat Figure 3-27
64 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
65 Carbon CyclingCarbon cycles as gaseous carbon is fixed in the process of photosynthesis and returned to the atmosphere in respiration.Carbon may remain locked up in sinks or reservoirs that are biotic or abiotic for long periods of time, e.g. in the wood of trees, oceans or in fossil fuels such as coal or oil.Indirectly carbon forms carbonate deposits as carbon is removed from the atmosphere. (The carbonate is stored mostly in the marine ecosystem.)Humans have disturbed the balance of the carbon cycle through activities such as combustion and deforestation.Burning fossil fuelsPetroleum & Coal
69 Nitrogen in the Environment Nitrogen cycles between the biotic and abiotic environments. The largest reservoir for nitrogen is the atmosphere and thus it is difficult to fix, bacteria play an important role in this transfer.Nitrogen-fixing bacteria are able to fix atmospheric nitrogen.Nitrifying bacteria convert ammonia to nitrite, and nitrite to nitrate.Denitrifying bacteria return fixed nitrogen to the atmosphere.Atmospheric fixation also occurs as a result of lightning discharges.Humans intervene in the nitrogen cycle by producing and applying nitrogen (nitrates) fertilizers which is the main cause of eutrophication.Lightning can fix atmospheric nitrogenBacteria on the roots of legumes can fix nitrogen
70 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.
71 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
73 Phosphorus CyclingPhosphorus cycling is very slow and tends to be local and stable; in aquatic and terrestrial ecosystems, phosphorous is a sedimentary cycle.Phosphorous is lost from ecosystems through run-off, precipitation, and sedimentation.A very small amount of phosphorus returns to the land as guano (manure of fish-eating birds). Weathering and phosphatizing bacteria return phosphorus to the soil.Often the Limiting factor in the ecosystemThe phosphorous cycle has no real significant gas phase and under many conditions will form stable insoluble compoundsDeposition as guano…Loss via sedimentation…Fertilizer production
74 Effects of Human Activities on the Phosphorous Cycle We remove large amounts of phosphate from the earth to make fertilizer.We reduce phosphorous in tropical soils by clearing forests.We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers contributing to eutrophication
76 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
77 Molecular bridges in proteins Sulfur CyclingSulfur is naturally occurring in rock or mineral forms and is a sedimentary cycle.Sulfur is an essential component of proteins and is important in determining the acidity of precipitation, surface water, and soil.Sulfur circulates through the biosphere as:hydrogen sulfide (H2S), sulfur dioxide (SO2), sulfate (SO42-), and elemental sulfur (S)Sulfur in petrolMolecular bridges in proteinsElemental sulfur
78 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.
79 HOW DO ECOLOGISTS LEARN ABOUT ECOSYSTEMS? Ecologist 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 SystemsRemote SensingEcologists also use controlled indoor and outdoor chambers to study ecosystems
80 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.Figure 3-33
81 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
82 Systems AnalysisEcologists develop mathematical and other models to simulate the behavior of ecosystems.Figure 3-34
83 Identify and inventory variables Obtain baseline data on variables Define objectivesSystemsMeasurementIdentify and inventory variablesObtain baseline data on variablesMake statistical analysis ofrelationships among variablesDataAnalysisDetermine significant interactionsSystemModelingObjectives Construct mathematical modeldescribing interactions amongvariablesFigure 3.34Major stages of systems analysis. (Modified data from Charles Southwick)Run the model on a computer,with values entered for differentVariablesSystemSimulationSystemOptimizationEvaluate best ways to achieveobjectivesFig. 3-34, p. 80
84 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).