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 4Ecosystems: What Are They and How Do They Work?
2 ECOLOGYEcology is the study of the connection between organisms and their living and non-living environments.The average number of organisms that can be sustained in an ecosystem is known as carrying capacity.Food, water, and shelter are known as limiting factors.Ecology is the study of the interaction or connection between organisms and their living and non-living environments.
3 F O C U S E D on in L G Y L E V S of O R G A N I Z T Biosphere EcosystemsCommunitiesPopulationsOrganisms
4 Population Species Community Biome Biosphere Ecosystem Look at the hierarchy here. Species is the lowest on this hierarchy. This lists from the smallest “unit” to the largest, the Biosphere.BiosphereEcosystemSpecies is the lowest on this hierarchy and Biosphere is the largest.
5 Which of these graphs shows a stable population? homeostasis
6 What are the major parts of the Earth’s life-support systems What are the major parts of the Earth’s life-support systems? The Spheres of Life.Atmosphere – thin envelope or membrane of air around the planettroposphere – inner layer of the atmosphere (extends 11 miles above sea level)stratosphere – next layer, 11 to 30 miles above Earth’s surface, lower portion contains the ozone layerHydrosphere – consists of the Earth’s waterLithosphere – Earth’s crust and upper mantle; contains nonrenewable fossil fuels and minerals, and renewable soil chemicals (nutrients) needed for plant lifeBiosphere – portion of the Earth in which living (biotic) organisms exist and interact with one another and with their nonliving (abiotic) environment
7 Atmosphere (troposphere, stratosphere) Oceanic crustContinental crustVegetationand animalsBiosphereLithosphereUpper mantleSoilCrustAsthenosphereRockLower mantlecoreWhat are the major parts of the Earth’s life-support systems? The Spheres of Life.Atmosphere – thin envelope or membrane of air around the planettroposphere – inner layer of the atmosphere (extends 11 miles above sea level); contains most of Earth’s airstratosphere – next layer, 11 to 30 miles above Earth’s surface, lower portion contains the ozone layer for filtering out the sun’s UV raysHydrosphere – consists of the Earth’s waterLithosphere – Earth’s crust and upper mantle; contains nonrenewable fossil fuels and minerals, and renewable soil chemicals (nutrients) needed for plant lifeBiosphere – portion of the Earth in which living (biotic) organisms exist and interact with one another and with their nonliving (abiotic) environmentMantleCrust(soil and rock)Biosphere(Living and deadorganisms)Atmosphere (troposphere, stratosphere)(air)Lithosphere(crust, top of upper mantle)Hydrosphere(water)
8 Solar Capital Solar Energy in = Energy out radiation Reflected by atmosphere (34%)UV radiationRadiated byatmosphereas heat (66%)Lower stratosphere(ozone layer)VisiblelightGreenhouseeffectAbsorbedby ozoneTroposphereHeatAbsorbedby the earthSolar Capital: flow of energy to and from the Earth.Heat radiatedby the earthEarth
9 ECOLOGYAbiotic – All of the non-living elements in an ecosystem like air, water, and temperature.Biotic – All of the living elements in an ecosystem.
11 Abiotic Factors in Terrestrial and Aquatic Ecosystems • Sunlight• Temperature• Precipitation• Wind• Latitude (distance from equator)• Altitude (distance above sea level)• Fire frequency• Soil• Light penetration• Water currents• Dissolved nutrient concentrations (especially N and P)• Suspended solids• SalinityAbiotic factors in terrestrial and aquatic ecosystems
13 ToleranceRange of Tolerance: range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally.Law of Tolerance: the existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by the species.
14 Abundance of organisms Population SizeLowHighTemperatureZone ofintolerancephysiological stressOptimum rangeNoorganismsFewLower limitof toleranceAbundance of organismsUpper limitRange of tolerance for a population of organisms, such as fish,to an abiotic environmental factor—in this case, temperature.
15 EcologyBiodiversity is the number and variety of organisms found within a certain region.Extinction is when a species is no longer in existence.Endangered means a species is in danger of extinction throughout all of a significant portion of its range.
16 ECOLOGYFood Chain – A chain illustrating the organisms and their food source.Grass grasshopper bird
17 A food chain illustrates the transfer of energy from one trophic level to the next.
19 ECOLOGYFood Web – multiple chains assembled into one large web.
20 that shows the relationship between the organisms in ECOLOGYEcological PyramidA food chainthat shows the relationship between the organisms ineach trophic level.
21 Ecological Pyramid of Numbers The figures represent number of individuals counted at each trophic level.
22 Ecological Pyramid of Biomass The total dry weight of organisms in a particular trophic level is referenced as biomass.BIOMASS=# of organismsxthe weight of an average individualbiomass
23 Ecological Pyramid of Energy Energy in ecosystems flows from producers to consumers.Energy is depicted in kilocalories.Ecological efficiency: % of usableenergy transferred from one trophic level to the next. (Average is about 10%.)Ecological Pyramids of EnergyEnergy in ecosystems flows from producers (photosynthetic organisms) to consumers (herbivores and carnivores). Ecological pyramids of energy usually depict the amount of living material (or its energetic equivalent) that is present in different trophic levels. In this diagram, energy is depicted in kilocalories.Primary producers convert only about 1% of the energy in available sunlight. The average amount of energy that is available to the next trophic level is about 10%. Because so much energy is utilized in building and maintaining organisms, food chains (series of feeding relationships) are usually limited to just three or four steps. Pyramids of energy can not be inverted.
26 Nutrient CyclesCycling of materials between the environment and organisms.Chemical and biological processes.Examples:Water cycleCarbon cycleNitrogen cyclePhosphorus cycleSulfur cycleOxygen cycleBiogeochemical CyclesChemical elements essential to life are available in limited amounts and must be cycled between living organisms and the environment. Because these processes involve both chemical and biological processes, they are called biogeochemical cycles. Elements such as carbon (from carbon dioxide), hydrogen, and nitrogen move between the atmosphere and organisms, while elements such as phosphorus, calcium, potassium, magnesium, sodium, and iron enter into organisms from the soil. The four primary biogeochemical cycles are water, nitrogen, carbon, and phosphorus.
27 Water (Hydrologic) Cycle CondensationRain cloudsPrecipitationTranspirationfrom plantsPrecipitationPrecipitationto oceanTranspirationEvaporationSurface runoff (rapid)EvaporationFromoceanRunoffInfiltration andpercolationSurface runoff(rapid)Groundwater movement (slow)Ocean storageGroundwater movement (slow)
28 Carbon Cycle Carbon Cycle Carbon, in the form of carbon dioxide, comprises about 0.03 percent of the atmosphere. Worldwide circulation of carbon atoms is called the carbon cycle. Since carbon becomes incorporated into molecules used by living organisms during photosynthesis, parts of the carbon cycle closely parallel the flow of energy through the earth’s living systems. Carbon is found in the atmosphere, the oceans, soil, fossil deposits and living organisms. Photosynthetic organisms create carbon-containing molecules (known as “organic” compounds), which are passed to other organisms as depicted in food webs. Each year, about 75 billion metric tons of carbon are trapped in carbon-containing compounds through photosynthesis. Carbon is returned to the environment through respiration (breakdown of sugar or other organic compounds), combustion (burning of organic materials, including fossil fuels), and erosion.
29 Nitrogen Cycle Nitrogen Cycle A major component of the atmosphere, nitrogen is essential for all living things. However, most organisms are unable to use the gaseous forms of nitrogen present in the atmosphere. In order for nitrogen to be usable by most organisms, it must be “fixed,” in other words, combined with oxygen, hydrogen or carbon to form other molecules. Nitrogen fixation can happen during rainstorms, which yields nitrate and ammonium ions. Nitrogen also can be fixed biologically by free-living and symbiotic bacteria. Leguminous plants, for example, host nitrogen-fixing bacteria in root nodules allowing them to capture nitrogen and incorporate it into proteins and other molecules.Unlike other organisms, nitrogen fixing bacteria are able to convert atmospheric nitrogen to ammonia, which then can serve as raw material for the incorporation of nitrogen into other molecules. The other four important steps in the nitrogen cycle are: (1) assimilation (reduction of nitrate ions [NO2-] inside plants to ammonium ions [NH4+], which are used to manufacture proteins and other molecules; this conversion requires energy); (2) ammonification (release of excess nitrogen in the form of ammonia [NH3] and ammonium ions [NH4+] by soil-dwelling bacteria and some fungi during the decomposition of complex organic compounds such as proteins, and nucleic acids); (3) nitrification (the oxidation of ammonium ions or ammonia by free-living, soil dwelling bacteria to nitrates [NO2-]; and (4) denitrification (the conversion of nitrate to gaseous nitrogen [N2 ] by free-living bacteria in soil; this conversion yields energy and occurs in conditions with low levels of oxygen).
30 Nitrogen Cycle Nitrogen Fixation: bacteria convert nitrogen to ammonia Nitrification: bacteria convert ammonia to nitrite and nitrate, which are used by plantsAssimilation: plant roots absorb ammonia and nitrateAmmonification: decomposers convert dead organisms and waste to simpler compoundsDenitrification: bacteria convert ammonia back into nitrite and nitrate, which are released into the air (cycle begins again)
31 Phosphorus Cycle Erosion Phosphate Rock Phosphate Mining Fertilizer containing phosphatesAnimal wasteUplifting into rocksAnimal ExcretionDissolved Phosphates
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