Environmental Science, 15e PDF

Environmental Science, 15e MILLER/SPOOLMAN G. TYLER MILLER | SCOTT E. SPOOLMAN 3 Ecosystems: What Are They and How...

Environmental Science, 15e MILLER/SPOOLMAN G. TYLER MILLER | SCOTT E. SPOOLMAN 3 Ecosystems: What Are They and How Do They Work? © 2016 Cengage Learning. All Rights Reserved.  Core Case Study: Tropical Rainforests are Disappearing Cover only 2% of the earth’s surface, but can contain up to half of the world’s terrestrial plant and animal species – Destroyed by logging, crop development, cattle grazing and encroaching civilization Why should you be concerned about the disappearance of tropical rainforests? Can you identify the ecosystem in which you live? © 2016 Cengage Learning. All Rights Reserved.  3.1 How Does the Earth’s Life-Support System Work? Earth’s life-support system has four spherical components that interact with each other Life is sustained by the cycling of nutrients and energy between and through these systems © 2016 Cengage Learning. All Rights Reserved.  Earth’s Life-Support System Has Four Major Components Atmosphere – composed of the troposphere and the stratosphere Hydrosphere – water at or near the earth’s surface (ice, water, and water vapor) Geosphere – composed of a hot core, a thick, mostly rocky mantle and a thin outer crust Biosphere – wherever life is found within the other three spheres © 2016 Cengage Learning. All Rights Reserved.  Natural Capital: Earth’s Four Life-Support Systems © 2016 Cengage Learning. All Rights Reserved.  Three Factors Sustain the Earth’s Life The one-way flow of high-quality energy – Solar energy principle of sustainability – Greenhouse effect The cycling of nutrients – Chemical cycling principle of sustainability Gravity © 2016 Cengage Learning. All Rights Reserved. © 2016 Cengage Learning. All Rights Reserved.  3.2 What Are the Major Components of an Ecosystem? Organisms that: – Produce their own nutrition – Satisfy nutritional requirements by consuming other organisms – Decompose waste and remains of organisms thereby recycling nutrients © 2016 Cengage Learning. All Rights Reserved.  Ecosystems Have Several Important Components Ecology: organisms interact with each other and with their non-living environment Biotic (living) and abiotic (non-living) parts of the environment exhibit sequential levels of organization – Five of these levels: organisms, populations, communities, ecosystems, and the biosphere © 2016 Cengage Learning. All Rights Reserved.  Levels of the Organization of Matter in Nature © 2016 Cengage Learning. All Rights Reserved.  Producers and Consumers Organisms belong to feeding/tropic levels depending on their source of nutrients Producers (autotrophs – plants) use photosynthesis to make nutrients Consumers (heterotrophs) feed on other organisms or their remains – Can be herbivores (plant eaters), carnivores (meat eaters) or omnivores (eat both plants and meat) © 2016 Cengage Learning. All Rights Reserved.  Living (Biotic) and Non-Living (Abiotic) Components © 2016 Cengage Learning. All Rights Reserved.  Natural Capital: The Main Components of a Ecosystem © 2016 Cengage Learning. All Rights Reserved.  3.3 What Happens To Energy in an Ecosystem? Energy flows through ecosystems via movement between trophic levels through food chains and food webs – The quality of energy available to organisms decreases as each successive trophic level is reached, because so much energy (heat) is lost moving from one level to the next © 2016 Cengage Learning. All Rights Reserved.  Energy Flows Through Ecosystems in Food Chains and Food Webs Food chains – A sequence of organisms, each of which serves as a nutritional source for the next (big fish eat little fish) Food webs – A complex network of interconnected food chains Pyramid of energy flow – Energy flow through various trophic levels © 2016 Cengage Learning. All Rights Reserved.  First Second Third Fourth Trophic Trophic Trophic Trophic Level Level Level Level Producers Primary Secondary Tertiary (plants) consumers consumers consumers (herbivores) (carnivores) (top carnivores) Heat Heat Heat Heat Solar energy Heat Heat Heat Decomposers and detritus feeders © 2016 Cengage Learning. All Rights Reserved. Stepped Art © 2016 Cengage Learning. All Rights Reserved.  A Generalized Pyramid of Energy Flow © 2016 Cengage Learning. All Rights Reserved.  Some Ecosystems Produce Plant Matter Faster than Others Do GPP (gross primary productivity) – The rate that an ecosystem’s producers convert energy into biomass NPP (net primary productivity) – The rate that producers use photosynthesis to produce and store chemical energy minus the rate at which they use energy for aerobic respiration © 2016 Cengage Learning. All Rights Reserved.  Some Ecosystems Produce Plant Matter Faster Than Others Do Terrestrial and aquatic ecosystems differ in their NPP (net primary productivity) – Despite low NNP, oceans produce most of the world’s biomass because of their vast size – Tropical rainforests have high NPP – much is lost through natural capital degradation Only plant matter represented by NPP is available as nutrients for consumers © 2016 Cengage Learning. All Rights Reserved.  3.4 What Happens To Matter in an Ecosystem? Matter in the form of nutrients and energy are naturally cycled and recycled through ecosystems and the biosphere – However, these chemical cycles are being altered by human activities © 2016 Cengage Learning. All Rights Reserved.  Nutrients Cycle Within and Among Ecosystems Biogeochemical cycling, driven by incoming solar radiation and earth’s gravity continually, moves nutrients and energy through air, water, soils, rocks, and living organisms – Supports the chemical cycling principle of sustainability © 2016 Cengage Learning. All Rights Reserved.  The Water Cycle – Evaporation and Transpiration The hydrologic cycle or water cycle collects, purifies, and distributes the earth’s fixed supply of water – The cycle of natural water quality renewal Incoming solar radiation moves water at the surface into the atmosphere through evaporation – Mainly via transpiration (evaporation from the surface of plants) © 2016 Cengage Learning. All Rights Reserved.  The Water Cycle – Precipitation and Surface Runoff Condensation in the atmosphere and effects of gravity create precipitation which returns water to the earth’s surface – Surface runoff – Aquifers and ground water Only a very small portion of earth’s water is fresh water – The rest is in oceans, stored as ice or is too deep to access © 2016 Cengage Learning. All Rights Reserved.  Natural Capital – The Hydrologic Cycle © 2016 Cengage Learning. All Rights Reserved.  How Do Humans Alter the Water Cycle? By withdrawing fresh water resources faster than natural processes replenish it By replacing forests/vegetation with urban development – reducing transpiration and increasing runoff By draining and filling in wetlands, which disturbs the renewal abilities of the hydrologic cycle © 2016 Cengage Learning. All Rights Reserved.  The Carbon Cycle Atmospheric carbon dioxide, a key component of the carbon cycle, has a significant temperature effect (greenhouse effect) How does carbon cycle through the biosphere? – Photosynthesis by producers – Aerobic respiration by producers, consumers and decomposers © 2016 Cengage Learning. All Rights Reserved.  Natural Capital: The Global Carbon Cycle © 2016 Cengage Learning. All Rights Reserved.  How Do Humans Alter the Carbon Cycle? By extracting and burning fossil fuels at a much higher rate than they are naturally formed – This adds carbon dioxide to the atmosphere By clear cutting forests faster than they re- grow – This destroys carbon-absorbing vegetation © 2016 Cengage Learning. All Rights Reserved.  The Nitrogen Cycle: Bacteria in Action How does nitrogen cycle through the biosphere? – Atmospheric nitrogen cannot be absorbed or used directly by most organisms – Bacteria convert the nitrogen into a usable form so it becomes a useful plant nutrient – Consumers (herbivores) and decomposers convert the nitrogen back into nitrogen gas which is then released into the atmosphere © 2016 Cengage Learning. All Rights Reserved.  Natural Capital: The Nitrogen Cycle © 2016 Cengage Learning. All Rights Reserved.  How Do Humans Alter the Nitrogen Cycle? By burning fossil fuels that adds nitric oxide to the atmosphere – Nitrogen dioxide gas/nitric acid vapor causes acid rain By removing atmospheric nitrogen to make fertilizer – Agricultural runoff from fields into the water supply leads to algal overgrowth that disrupts the oxygen balance in aquatic systems © 2016 Cengage Learning. All Rights Reserved.  The Phosphorus Cycle How does phosphorus cycle through the biosphere? – Cycles through soils, rocks, water and plants, but not through the atmosphere – Can be temporarily removed from natural cycling when washed into oceans and trapped in marine sediments – As with nitrogen, contributes to agricultural runoff © 2016 Cengage Learning. All Rights Reserved.  Natural Capital: The Phosphorus Cycle © 2016 Cengage Learning. All Rights Reserved.  How Do Humans Alter the Phosphorus Cycle? By mining phosphorus deposits to make fertilizer Through clearing of tropical forests, which reduces phosphorus in the topsoil Through agricultural runoff and topsoil erosion, which disturbs biogeochemical cycling © 2016 Cengage Learning. All Rights Reserved.  The Sulfur Cycle How does sulfur cycle through the biosphere? – Via mining of ore deposits/ocean sediments – From active volcanoes – as poisonous hydrogen sulfide and sulfur dioxide gases – Through decomposition of organic matter in wetlands – From sea spray, dust storms, and forest fires – Absorption by plant roots © 2016 Cengage Learning. All Rights Reserved.  Natural Capital: The Sulfur Cycle © 2016 Cengage Learning. All Rights Reserved.  How Do Humans Alter the Sulfur Cycle? By releasing sulfur dioxide into the atmosphere – Burning sulfur containing coal and oil in power plants to generate electricity – Refining sulfur containing oil to make gasoline – Mining and smelting metals from sulfur deposits The key components of acid rain are nitrogen dioxide and sulfuric acid © 2016 Cengage Learning. All Rights Reserved.  3.5 How Do Scientists Study Ecosystems? Scientists learn about ecosystems by: – Using field and laboratory research – Designing controlled experiments – Developing mathematical and statistical models © 2016 Cengage Learning. All Rights Reserved.  Some Scientists Study Nature Directly Make direct observations and take measurements of ecosystems in the field Fly over ecosystems to photograph them Carry out controlled experiments Use radio transmitters and remote sensing to track organisms Run mathematical models for issues that cannot be studied in the lab or field © 2016 Cengage Learning. All Rights Reserved.  Some Ecologists Use Laboratory Experiments or Modeling How do scientists model ecosystems in the lab? – With culture tubes, aquariums, greenhouses, and in indoor/outdoor chambers with controlled variables (light, temperature, etc.) Pros: small, controlled lab experiments save money and are faster to carry out Con: these experiments may not reflect reality well enough © 2016 Cengage Learning. All Rights Reserved.  We Need To Learn More About the Health of the World’s Ecosystems The 2005 ecosystem assessment shows that more baseline ecologic data is needed to: – Evaluate the status of the world’s ecosystems – Develop effective strategies for preventing and slowing ecosystem degradation – Identify planetary boundaries that lead to irreversible changes if passed – and help us to avoid reaching or passing them © 2016 Cengage Learning. All Rights Reserved.  Additional Case Study: Ecosystems – An Overview Ecosystems – watch the video and learn how scientists study ecosystems to understand them and predict how they change over time – Choose an ecosystem from the video and describe its components and structure – How did the scientists study the ecosystem you chose? © 2016 Cengage Learning. All Rights Reserved.  Ecosystems and Three Big Ideas Life is sustained by the flow of energy and nutrients through ecosystems which are continually recycled Ecosystems are characterized by producers, consumers, and decomposers – All aid in the cycling process Human activities impact ecosystem cycling, sometimes negatively, sometimes positively (e.g., Yellowstone) © 2016 Cengage Learning. All Rights Reserved.