47 – Ecosystems



46 EcosystemsChapter Outline 46.1 too much of a good thing46.2 The Nature of EcosystemsOverview of the ParticipantsTrophic Structure of Ecosystems46.3 The Nature of Food WebsHow Many Transfers?46.4 Energy Flow Primary ProductionEcological PyramidsEcological Efficiency46.5 Biogeochemical Cycles46.6 The Water CycleHow and Where Water MovesLimited Fresh Water46.7 the Carbon CycleTerrestrial Carbon Cycle Marine Carbon Cycle Carbon in Fossil Fuels 46.8 Greenhouse Gases and Climate ChangeThe Greenhouse Effect Changing Carbon Dioxide Concentrations Changing Climate 46.9 Nitrogen CycleReactions That Drive the CycleHuman Effects on the CycleNitrous OxideNitrates46.10 The Phosphorus Cycletoo much of a good thing (REVISITED)summaryself-quizdata analysis activitiescritical thinking Learning Objectives46.1 Illustrate eutrophication using an example.46.2 Examine the trophic structure of ecosystems.46.3 Describe the different trophic levels with examples for each level.46.4 Determine how energy flows from primary producers to other trophic levels.46.5 Illustrate the biogeochemical cycle using a diagram.46.6 Illustrate the water cycle using a diagram.46.7 Demonstrate the carbon cycle using a diagram.46.8 Discuss how a change in carbon dioxide concentration changes the climate.46.9 Examine the nitrogen cycle on land using a diagram.46.10 Outline the role of human activities in the disruption of the nitrogen cycle.46.11 Examine the significance of the phosphorus cycle in the ecosystem.Key Termsammonificationaquiferatmospheric cyclebiogeochemical cyclebiomass pyramidcarbon cycleconsumersdecomposersdenitrificationdetrital food webdetritivoresecosystemenergy pyramideutrophication food chainfood webglobal climate changegrazing food webgreenhouse gasgroundwaternitrificationnitrogen cyclenitrogen fixationphosphorus cycleprimary producersprimary productionrunoff sedimentary cyclesoil water trophic levelswater cyclewatershedLecture Outline46.1 Too Much of a Good ThingA. Phosphorus is a substance that is necessary for life.1. Plants obtain phosphorus from the soil and animals get their supply from consuming plants or other animals.2. If the soil is depleted of phosphorus, fertilizers may be added to supplement the soil.B. When fertilizers enter the runoff, it can cause problems in water supplies.1. In the water of lakes and rivers, eutrophication may occur. a. Algae blooms cause the water to become polluted and make it inhabitable for many other organisms.C. Now scientists are aware of the problems man has created by disrupting the nitrogen cycle. 46.2 The Nature of EcosystemsA. Overview of the Participants1. An ecosystem is the sum of the organisms residing there and the environment. a. A primary producer is the plant that serves as an autotroph by harnessing the sun’s energy. b. A consumer is the animal or heterotroph that derives energy from consuming the plant or other animals. c. A detritivore is an animal that consumes debris and small bits of organic matter. d. A decomposer eats wastes and remains of plants and animals. e. Minerals increase and decrease in natural cycles. B. Trophic Structure of Ecosystems1. The organisms of an ecosystem develop trophic levels or feeding relationships. a. A food chain represents the passage of energy from one trophic level to the next. b. Plants are the primary producers, and they represent the first trophic level. c. The second trophic level is represented by primary consumers, animals that eat plants. d. Secondary producers (third trophic level) consume animals at the second trophic level. e. Finally, the fourth trophic level (third-level consumers) consume animals from the third trophic level. 46.3 The Nature of Food WebsA. A food web is a complex interaction among many species of the ecosystem.1. In a grazing food chain, the energy goes from producers to consumers.2. In a detrital food chain, the energy goes from producers to detritivores and decomposers.B. How Many Transfers?1. An alteration in one species of a food web may affect many different organisms. a. Scientists have discovered how complicated food webs are, “Everything is linked to everything else.” 46.4Energy FlowA. Primary Production1. Primary production is the rate at which plants harness the sun’s energy.2. This depends on the availability of water and nutrients.3. Primary production is higher on land than in water.B. Ecological Pyramids1. A biomass pyramid is used as a tool to represent the dry weight of the organisms at each trophic level. a. The plants or producers make up the base of the pyramid. b. Consumers make up the upper portion of the pyramid, with the largest carnivores at the very top.2. An energy pyramid helps show how energy is lost when transferred to each trophic level.C. Ecological Efficiency1. Only about 5–30 percent of the energy in the tissues of an organism ends up in the tissues of the next trophic level. a. Energy is lost because some is lost as heat, and many parts of an animal cannot be digested. 2. The energy transfer in watery ecosystems is usually more efficient than those on land. 46.5 Biogeochemical CyclesA. In biogeochemical cycles, nutrients move through environmental stores and living organisms.1. The elements enter the living portion of the cycle by becoming incorporated into plants.2. Examples of biogeochemical cycles are the water, carbon, nitrogen, and phosphorus cycles. 46.6 The Water CycleA. How and Where Water Moves1. The water cycle begins when water evaporates from bodies of water and transpiration occurs in plants.2. Next, water condenses in clouds and rains down.3. Water collects in watersheds, aquifers, and groundwater. a. Most individuals get water supply from groundwater. b. Groundwater can be easily polluted and difficult to correct.B. Limited Fresh WaterGroundwater is the major water supply for about half of the U.S.Salt water is replacing many coastal aquifers.Other areas, especially in the southwest, have depleted groundwater. A future water supply may be the ocean through utilization of a desalinization process to remove the salts. 46.7 Carbon CycleA. Terrestrial Carbon Cycle1. Soil, consisting of humus and soil organisms, contains much more carbon than the atmosphere.In tropical areas more carbon is in living plants, whereas in the temperate zone the majority of the carbon is in the soil.2. Tilling the soil increases the amount of carbon in the atmosphere.B. Marine Carbon Cycle1. Most of the carbon is in seawater. a. The carbon in the ocean is formed from the shells of small organisms. b. The crust lifts up and becomes part of the land mass.Eventually erosion breaks down the rocks and the carbon travels back to the sea.C. Carbon in Fossil Fuels1. Fossil fuels are formed from decayed plants and plankton.2. Man adversely affects the carbon cycle by releasing more carbon into the air, contributing to global warming. 46.8 Greenhouse Gases and Climate ChangeA. The Greenhouse Effect1. The sun’s heat is absorbed by the Earth’s surface.2. Some of the heat is reflected back into the atmosphere, but atmospheric gases send some heat back to Earth.The greenhouse effect is a natural, necessary phenomenon to maintain reasonable temperatures on Earth.B. Changing Carbon Dioxide Concentrations1. When scientists began to measure carbon dioxide levels in 1959, they saw annual fluctuations. a. The carbon dioxide levels drop in the summer when plants use it for active photosynthesis. b. The carbon dioxide levels rise in the winter when there is less photosynthesis occurring.2. Overall, the carbon dioxide levels in the atmosphere are rising. a. Scientists were able to check carbon dioxide levels in the past by drilling deep into glaciers or by examining fossil foraminiferan shells. b. The carbon dioxide level in the atmosphere is the highest it has been in 15 million years.C. Changing Climate1. Currently a global climate change is occurring, which can be defined as a long-term change in the Earth’s climate. a. Global warming is causing a warmer ocean temperature, which results in melting glaciers and more severe storms.2. Scientists in 2007 determined that the rise in temperature was due to human activities. b. Efforts are underway to reduce the use of fossil fuels as energy sources.46.9 Nitrogen CycleA. Nitrogen exists in the atmosphere as N2, which is not in a usable form for plants.1. Some natural processes such as lightening and volcanoes can convert the nitrogen to a usable form.2. The bacteria rhizobium that exists in nodules on legumes also converts the nitrogen to a usable form. 3. Plants obtain ammonium from the soil, which is later broken down by fungi and bacteria in a process called ammonification.4. Nitrification is the process that converts ammonium to nitrates. a. First, ammonia is converted to nitrite by bacteria and archaea. b. Then other types of bacteria change nitrites into nitrates. c. Nitrates and ammonium are used by producers.5. Denitrification is the process in which bacteria convert nitrate to nitrogen gas in the atmosphere.B. Human Effects on the Cycle1. Nitrous Oxide—A Double Threata. From testing the nitrous oxide level in ice core, scientists have seen the level rise from 270 ppb to 325 ppb.b. Increases in nitrous oxide are due to commercial fertilizers, livestock production, and the burning of fossil fuels.2. Increased amounts of nitrous oxide in the atmosphere can lead to global warming and depletion of the ozone layer.C. Nitrate Pollution1. Nitrates are common contaminants in the water supply.a. They may result from fertilizer use or septic tank malfunctions.2. Nitrates have been known to increase the risk of thyroid cancer, respiratory infections, diabetes, and other cancers.3. The EPA has said that drinking water should contain no more than 10ppm of nitrate.a. Usually private wells go untested. 46.10 The Phosphorus CycleA. Phosphorus cycles between the land and the ocean. 1. Phosphates are necessary for major cellular components like nucleic acids, plasma membranes, and ATP. 2. Plants get phosphorus from the water and soil, and animals get it from consuming plants or other animals.a. Phosphorus levels are quite often a limiting factor for plant growth.b. A lack of phosphorus in the soil can be due to the absence of crop rotation.B. An excess of phosphorus can result from water that runs off from fertilized fields.1. Excessive amounts of phosphorus in a watery environment can cause eutrophication.a. An algae bloom occurs that harms other plant and animal species.b. Eutrophication is difficult to reverse.46.12Too Much of a Good Thing (Revisited) Fertilizers are used heavily in agricultural areas to improve crop yields. This causes excess nitrogen and phosphates to enter water supplies through runoff. These increases enter the Mississippi River and ultimately flow into the Gulf of Mexico.These excess nutrients produce a “dead zone” in the Gulf of Mexico.Eutrophication causes low oxygen levels and, therefore, causes the death of many organisms. Suggestions for Presenting the Material ?Approach the study of the various cycles of an ecosystem by first explaining the necessity of that particular component in the environment. Then examine the deleterious effects of too little or too much of that substance.?Begin by showing a simple food chain and an example of a representative animal at each trophic phase. Then stress that life and nature are rarely that basic. Show the students an example of a complex food web and discuss the unlikelihood that an animal would have only one food source. Create a disruption in the food web by imagining the destruction of a population of one species of animal. Let the students see that a seemingly small change in a food web could have a dramatic impact on many other species. Students will become aware of the unity that joins all organisms.?Have the students view the award-winning documentary “An Inconvenient Truth.” This powerful film may help to launch a discussion of the consequences of global warming and the impact that this movie has created worldwide. ?Use as many local examples of ecosystems as possible in discussions, demonstrations, and lab work. While it may seem overly simplistic and sometimes inaccurate to identify and describe the different levels of an ecosystem, students should see that it is useful because it helps us to understand the functioning of an ecosystem as a whole. Such ecosystem descriptions provide a valuable baseline against which we can measure the effects of changes.?Stress the fact that, in various sections of the chapter, the authors show how humans have altered the natural ecosystems and their functioning.?Use overhead transparencies to present the biogeochemical cycles.?Invite a representative of the EPA, the state coastal commission, or another environmental group to address the class.?Have students build their own food web using the online resource: around the room and have the students name examples of producers, consumers, detritivores, and decomposers that would be in the area surrounding your campus.See if your students can devise a food chain (or better yet, a food web) for organisms in your area. This will serve to show them how complicated and intertwined these relationships are.Classroom and Laboratory Enrichment ?Have some of the students choose a cycle discussed in this chapter and make a poster depicting the stages. Each participant should explain his poster to the class and how human intervention may alter the natural cycle.?Set up aquatic ecosystems in the lab and monitor them throughout the semester. Identify the trophic levels of the ecosystem and analyze the cycling of materials and nutrients within it. In what ways are the aquatic ecosystems in the lab similar to, or different from, a real aquatic ecosystem??Discuss the primary productivities of different regions of the United States. How can human intervention change primary productivity??Each student could undertake a study near their home of an environmental issue regarding an upset of one of the natural biogeochemical cycles. Are there any reasonable solutions to this issue? If so, write to your senator or congressman expressing your views.?Test various water supplies for the presence of nitrogen and phosphorus. Are they within the recommended standards? If not, how far do they deviate from a normal level? Use a nursing or anatomy text to determine if an excess of either substance would cause any short-term or long-lasting effects??Determine the pH of water samples from several local bodies of water in your area. How much does the pH vary? If you have suitable equipment at your school, you can use a Global Positioning System to create maps of exactly where you obtained your samples. Since you are somewhat familiar with the area, can you find a reason to explain these differences in pH??Fill an aquarium with water and organisms from a nearby pond or lake. Add amounts of phosphorus and nitrogen to mimic eutrophication. What effects do you see in your artificial ecosystem? ?Analyze local soils to determine the mineral and organic contents.?Divide the class into small groups. Have each section debate the pros and cons of different energy sources. Each group should be prepared to discuss the merits and drawbacks of one of the following energy sources: oil, coal, natural gas, hydropower, solar power, nuclear power, or other alternatives. Can the class come to any consensus about the safest method or combination of methods??Assuming that a flat 10 percent of the energy in one trophic level is conserved to the next, and that the producer represents 100 percent, calculate what percent is received by the marsh hawk in Figure 46.4.?Write down the models of cars driven by some of your classmates. Research online to see if you can determine the emissions from each of these models. When you announce the results to the class, will that influence anyone’s choice for their next vehicle??Visit a sewage treatment plant. Discuss the biological steps involved in the treatment of your local sewage. In what way could sewage treatment be improved??Research the steps that will be undertaken to convert the astronauts’ urine into drinkable water in space.?Collect some soil from what appears to be a detrital food web in a forest or field system. Can you identify any organisms as decomposers and detritivores? Do you imagine that some of the organisms performing these duties may be too small to see??Contact the epidemiologist at your local hospital. Inquire how they handle their dangerous biomedical wastes. In the past it was sufficient for a hospital to simply contract with a company to dispose of hazardous wastes. Now hospitals are required know the pathway of the dangerous trash after it leaves the building. This makes it clear that all parties involved are responsible for proper environmental procedures.?Design a simple survey containing a few concise questions relating to environmental concerns addressed by this chapter. Have each student poll 10 fellow students outside of the classroom. How do your peers feel about environmental issues? Do they consider this an urgent matter to address? And most importantly, would they be willing to put their money where their mouth is? Look online for an example of a biomass pyramid for an ocean ecosystem. How does it differ from those seen in Figure 46.8?Have your students bring in containers from detergents and fertilizers that they use in their own homes. Read the labels to see if there is a significant difference between them. Would your students be willing to switch to a brand that contains less phosphorus, even if it costs more?Classroom Discussion Ideas?Does anyone see the ironic dichotomy that Morgan City in Louisiana celebrates a shrimp and petroleum festival on the same day? The production of oil may be emitting pollutants into the air that are increasing the greenhouse effect. The result of the increasing greenhouse gases, as we know from the text, is contributing to global warming. As global warming intensifies, polar ice caps will melt and, therefore, raise the water level. The lowlands of Louisiana, with some of the lowest levels of coastal area in the United States, may disappear at an alarming rate. If this continues at this current rate, the shrimp festival may have to be moved to a city farther inland, where it will have become the new coastline!?In addition, scientists have discovered that an increase in ocean temperature does not cause more hurricanes, but the ones we do have will worsen in intensity. As we know from Hurricane Katrina, the devastation from a strong hurricane can result in the displacement of millions of people, and many billions of funds are needed to attempt to repair the area.?The Louisiana bayou area may be one of the areas that will show the early effects of global warming. We need to observe the damage that is being done now and address it dramatically before it is too late. The nations of the world must band together to consider global warming as a very serious worldwide problem that must be aggressively attacked with manpower and financial means.One consequence of global warming that may not be immediately evident is the spread of tropical diseases. As the Earth warms, the boundaries of where tropical diseases can exist may expand. Diseases such as malaria and dengue fever may eventually become common in the U.S.Additional Ideas for Classroom Discussion?Discuss the rapid deforestation of the rain forests. How does this impact the biogeochemical cycles that we have addressed??Discuss what would happen to an ecosystem if all of the producers disappeared. What would happen to the ecosystem if all of the consumers, decomposers, or detritivores disappeared? Can you think of examples of ecosystems in which any of these events has occurred? How can an ecosystem recover from such a disturbance??Show examples of various biomass pyramids. Can the students match them with the proper ecosystems? How would a biomass pyramid from the open ocean differ from the one in Figure 46.8??Describe several trophic levels of a typical ecosystem and ask the students to arrange them in the correct order.?How and where do humans fit into a food web??The pesticide DDT is just one example of a substance that undergoes biological magnification as it travels through an ecosystem. Can you think of others? (One possible example is the movement of strontium 90, a byproduct of nuclear testing in the 1950s, through the food web.)?Look into articles about the effects of biological magnification in Lake Erie? Which animals are affected? What steps have been undertaken to remedy some of the environmental issues there??What do you think were the first producers to evolve on Earth? Do we know what they might have looked like?It is expected that sea level rise will be the most immediate and serious consequence of climate change. What are the two primary drivers of seal level rise. Are there communities already being impacted? What are the long-term social consequences if sea levels continue to rise and meet future projections??Examine the composition of several plant and garden fertilizers. What are the major ingredients? What components provide the “miraculous” growth rates??Why is the term food chain rarely used when describing actual ecosystems??Why are humans at the top of nearly every food web of which they are a part? Are they ever at any other level? How has man’s role in food webs evolved through the centuries??What would the personal and ecological advantages be to humans if they were to eat “lower down” on the energy pyramid??Why does a pyramid of energy usually narrow as it goes up??Research some alternative fuel sources for automobiles. Why do you feel these are not readily available??Is it environmentally wise to rely on large quantities of nitrogen-rich fertilizers for crop production? What are some alternatives? Discuss the pros and cons of commercial fertilizers.?Try to locate examples of energy pyramids from various locations. It may be impressive for students to see the loss of energy at each phase. Contrast the amount of energy lost by endotherms and ectotherms, and explain why this difference occurs.?Why is a pyramid of biomass a more accurate representation of an ecosystem than is a pyramid of numbers??Investigate the source of your home water supply. If applicable, see if you can find the name of the aquifer that supplies the water.?Why does normal rain water have a pH of around 5.6? (Note: A pH of 7 is neutral.)?How have coal-burning power plants changed in the past 20 years??Perform some research on the ozone layer above the Earth. Where did they first discover a hole in the ozone layer? Can anything be done to repair the damage that has occurred??Tropical forests are highly productive ecosystems, incorporating extremely large amounts of carbon and other nutrients into plant material. Yet, when cleared of vegetation, such areas make poor farmlands. Why??About 500,000 trees are needed for Sunday newspapers for Americans. Is this necessary? When will we no longer be able to afford such extravagance? How would the environmental and economical impact change if you received your paper online??In each of the biogeochemical cycles indicate the route each component takes in recycling. What invisible component is not recyclable??Make a list of renewable and non-renewable energy sources. Which method or combination of methods would you recommend??Draw a timeline indicating the dates of the different legislative actions relating to car emission standards.?Ask students to make a list of ways in which they could modify their own lifestyles and behaviors to reduce environmental pollution.Make sure your students understand what happens to the energy that is lost at each trophic level. Who loses more energy, ectotherms or endotherms?There are lots of terms in this chapter that must be defined. Make sure your students know these before they attempt to learn the overall concepts.Contact the local weather service to determine which tests are performed on collected rainwater.How Would You Vote? Classroom Discussion Ideas?The major source of nutrient pollution is the result of agriculture and sewage systems. However, one easy solution is to eliminate phosphate-rich detergents and home fertilizers that contain excessive amounts of phosphates. This would not be an extra expense for the consumer, but it would result in detergent and fertilizers that, perhaps, would not be as powerful as those on which the consumer has grown dependent.The question boils down to whether the public would accept products that are somewhat inferior for the sake of the environment.Probably the first step in the process would be to educate the public on the consequences to the environment of excess nutrients. An educated consumer would be much more apt to realize the ultimate damage caused by the current products. This would require a massive media campaign to enlighten the public. Ask the students to design a pamphlet or commercial that would effectively explain the issue to the average consumer. Do your students feel the public would comply if they really understood the process of eutrophication? Poll the class on this issue.Term Paper Topics, Library Activities, and Special Projects?Read “Silent Spring” by Rachel Carson and report a summary to the class. What specific species exhibited symptoms related to DDT exposure? Considering that it was written in 1962, do you find the material to be controversial? Do you feel the author made a significant impact toward the restriction of DDT? ?Write a report detailing the events at Three Mile Island in 1979. Were there any effects on the local ecosystems? How does the accident at Three Mile Island differ from that at Chernobyl??Write a report on ecosystems deep on the ocean floor at depths impenetrable by light. What kinds of organisms make up the first trophic level in such ecosystems? How are these organisms obtaining energy? Are these organisms well-studied by scientists??What happens to an ecosystem if any one of its levels is removed? Find descriptions of ecosystems in which this has happened and describe the results.?Describe the chemical changes that occur during nitrogen fixation. Can you envision a way that this could be done in the laboratory??Name some other materials that could potentially be biomagnified as they move through the food chain. Are there any current regulations to prevent this from happening??Discuss farming techniques designed to minimize nitrogen loss in the soil.?What are the biological effects of acid rain on fish populations??Obtain records of the yearly average temperatures and rainfall amounts from your local weather bureau. How far back do these records go? Graph the data. Are there any trends??How do you think greenhouse gases affect the respiratory system? Are there any statistics to back this up??Discuss the primary productivities of various regions around the world. Which areas have the highest and lowest primary productivities? Why??Read “Earth in the Balance: Ecology and the Human Spirit” by Al Gore. Summarize the book to the class and state the three facts that surprised you most from the book.?Describe the history of the use and subsequent banning of DDT in the United States. Draw a timeline that shows the significant events in its usage.?Write a letter to your congressman asking for more information about how one of the environmental issues in this chapter is being addressed.?What were the commercial uses for chlorofluorocarbons? Why were they banned? What substances have served as safer alternative??Contact your local weather department to find out, on the average, how many days per year are rated as having an unsafe quality of air? What does this mean for humans and other animals??Discuss the environmental effects of strip-mining on biogeographical cycles.?Read several articles on crop rotation. How does this help the farming industry? Name a series of crops that should be rotated through one field so that valuable nutrient levels are maintained.?List and describe some of the primary producers in an open ocean ecosystem off of the United States coastline.?Describe the biochemical steps used by chemosynthetic autotrophs to produce energy.Review Figure 46.14 and explain the causes of the different carbon levels, both in plants and in soil, to the class.In this chapter, nutrient levels are measured by sampling ice cores and sedimentary rock. Can you research where and how these measurements were obtained?Possible Responses to Critical Thinking Questions1.The vegetable gardens in Maine and Florida would differ greatly based on climate (e.g., rainfall, temperature, latitude, length of growing season, soil content, and perhaps proximity to the ocean), depending on their exact locations. All of these factors would greatly influence what types of crops would be best suited to each region. Florida would have a longer growing season, so I would expect the garden in that area to have a higher annual productivity.2.The website listed takes you to a site that is sponsored by the United States Geological Survey Department. At this website you can click on a map to increasingly zoom down to about the county level. It will then give you information about your particular watershed, such as water quality, location of groundwater inventory sites, etc. In addition, it offers detailed definitions of all technical terms for the layperson’s interpretation.3.One would not be able to test the air in bubbles in frozen ice for phosphorus, because phosphorus does not occur naturally in that form. The best way to check phosphorus levels from the past would be to test the levels in sedimentary rock, since this is the major reservoir for phosphorus.4.If you increased the number of nitrogen-fixing bacteria in an aquatic ecosystem, it could result in an algae bloom and eutrophication. The additional nitrogen would encourage an overgrowth of algae, which may cause a hypoxic atmosphere for the animals that reside there. This eutrophication would lead to an increase in carbon production and an increase in carbon accumulation.5.If the mycorrhizal fungi were used to provide plants with phosphorus and nitrogen, the risk of eutrophication would decrease dramatically. The runoff from the fields would not contain the excessive amounts of nutrients that would be seen in an area exposed to large amounts of fertilizers. Some research should be performed before such a widespread plan is initiated to ensure that the fungi in large amounts would not cause any significant disruption in the overall balance of nature.Possible Responses to Data Analysis Activities QuestionsScientists are attempting to show that human activities have impacted the amount of carbon dioxide in the atmosphere. In Antarctica, there is thick ice that can be used to measure the carbon dioxide level over time. The highest carbon dioxide level between 400,000 and 0 A.D. was 300 ppm.During this same time period, the carbon dioxide level never reached the level attained in 1980.The trend in the carbon dioxide level for the 800 years prior to the advent of the industrial revolution was fairly constant, with some slight variations. After 1800, the carbon dioxide level began to rise dramatically.The rise in the carbon dioxide level between 1980 and 2013 was much higher than the rise between 1800 and 1975. ................
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