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Environmental Science Chapter 5: How Ecosystems Work How Ecosystems Work Big Ideas • Energy is transferred from the sun to producers • Producers then transfer the energy to consumers • Inefficient energy transfer has an effect on community structure Section 1: Energy Flow in Ecosystems GOALS • Describe how energy is transferred from the sun to producers and then to consumers • Describe how consumers depend on producers • Explain how energy transfer in a food web is more complex than energy transfer in a food chain • Explain why an energy pyramid is a representation of trophic levels What makes an ecosystem like this “work?” Life Depends ENERGY, LOTS OF ENERGY…from the Sun • Average Star • 93 million miles away • Nuclear Fusion • No Sun, No Life Life Depends on the Sun ALL organisms need a constant supply of energy or they die Why do plants grow upwards? Life Depends on the Sun Mmmm, solar energy tastes good! • The ultimate source of almost all energy for organisms is the SUN. • What did you eat? (Nuclear Powered?) • Only some deep sea creatures do not get energy from sun What is photosynthesis? CO2 + H2O + Sunlight O2 + C6H12O6 The process of converting carbon dioxide, water and sunlight into oxygen and glucose. (In plants, algae, some bacteria) Occurs in chloroplasts What is chemosynthesis? CO2 + 4H2S + O2 CH20 + 4S + 3H2O The process of converting carbon dioxide, water and chemical energy (hydrogen sulfide) into sugar, sulfur and water. From Producer to Consumer • Producer: an organism that makes it own food • Plants • Autotrophs, selffeeders • Use sunlight • Base of all food chains What role do Autotrophs (Producers) Play? • Gather the energy from the sun and turn it into food via photosynthesis. Lichens are an example. Phytoplankton get no credit From Producer to Consumer • Consumer: gets it energy by eating producers or other consumers • Heterotrophs • Indirectly solar powered What role do Heterotrophs (Consumers) play? Heterotrophs eat other organisms to obtain their energy. Stored energy in food is extracted with or without oxygen. Types of Consumers • Herbivore: eats only producers (vegetarian) • Cows, sheep, deer, grasshopper, mice, rabbits Herbivore Types of Consumers • Carnivore: eats other consumers • Lion, hawks, snakes, alligator, toothed whales Carnivore Types of Consumers • Omnivore: eats both producers and consumers • Bears, pigs, raccoons and most humans Omnivore Types of Consumers • Decomposer: breaks down dead decaying organisms • Critical to ecosystem health • Returns nutrients • Fungus, bacteria Detritivores and decomposers: recycle nutrients within the ecosystem by breaking down nonliving organic matter Decomposer Essential Question: If producers/autotrophs are responsible for supplying the rest of the world’s organisms with sugar molecules (glucose), then how do organisms use the sugar molecules (glucose)? How do Organisms Use Energy Most organisms spend large amounts of time/energy in search of food and a mate. How do organisms get the energy from the food (glucose)? Two ways. Aerobic Respiration – use oxygen to extract energy from glucose Anaerobic Respiration – oxygen is NOT used to extract energy from glucose Cellular Respiration (Aerobic Respiration) allows organisms to use the energy store in glucose. Aerobic Respiration aka “Cellular Respiration” Formula C6H12O6 + O2 CO2 + H2O + ATP Photosynthesis & Cellular Respiration In photosynthetic organisms, the processes of photosynthesis and cellular respiration work together. The products of one can be used for the other. Energy Transfer Each time one organism eats another, energy is transferred Ecosystems are all about energy flowing from one organism to another Energy Transfer • Who are the producers? • Consumers? • Herbivores? • Carnivores? • Omnivores? • Decomposers? • Where does the energy start? How does energy flow through an ecosystem? • A food chain is a series of steps in which organisms transfer energy by eating or being eaten (arrows?) • All food chains have a producer on bottom, which supplies each level above with food • Energy flows in one direction through a Food Chain. • Each step in a food chain is called a trophic level. Energy Transfer • Food Chain: sequence in which energy is transferred from one organism to another • Starts with producers • Energy flows in one direction Food Web A food web shows the various food chains within an ecosystem. Can you describe one food chain within this food web? What is missing from this food web? Energy Flow • Food Web: shows many feeding relationships that are possible in a ecosystem • More complex and realistic Energy Flow • Trophic Level: each step which energy is transferred How is energy monitored in a food chain? Energy Pyramid track available energy in a food chain. Only 10% of the available energy is passed from one trophic level to the next. Energy Pyramid 1 unit of energy 10 units of energy 100 units of energy 1,000 units of energy 10,000 units of energy Energy Pyramid Energy Flow • At each trophic level about 90% of energy is lost • Cellular respiration • Lost to heat body and carry out living Energy Flow • Why are there fewer organisms at the top? (Why fewer bears than the fruit they feed on) • Why aren’t there more than 4-5 trophic levels in a energy pyramid? How energy Loss Affects an Ecosystem • So much energy is lost there are fewer organisms at higher trophic levels • Loss of energy from level to level limits the number of trophic levels in an ecosystem • Not enough energy to support higher levels What does this diagram show? Biological Magnification Certain toxic substances, such as mercury or pesticides, can’t be easily broken down (will stay in your system) This results in biological magnification, when each trophic level consumes and stores higher concentrations of the substance Biological Accumulation Occurs when there is an increase of a pollutant from the environment to the organisms in a food chain Niche (“nitch”) A species role in its ecosystem Ex - Spiders eat many smaller insects, bees help to pollinate flowers. No two species occupy the same exact niche in their environment How do biotic factors interact? 1. Competition – organisms fight for places to live, food to eat and organisms to mate with. 2. Predation – things are eating or being eaten. 3. Symbiosis – two species living closely together Types of Symbiosis: Mutualism – both species benefit. (flowers & bees) Commensalism – one member benefits the other is unaffected. (barnacles & whales) Parasitism – one member benefits and the other may be harmed. (Tapeworm) Ecology Review Video Section 1 Review • Energy is transferred from the sun to producers through the process of photosynthesis • Consumers use the glucose made by producers for energy • Food webs show more complex & realistic feeding relationships in a ecosystem • Energy pyramids track available energy in a food chain. Only 10% of the available energy is passed from one trophic level to the next. Section 2 – The Cycling of Matter GOALS • Describe the short-term and long-term processes of the carbon cycle • List the stages of the nitrogen cycle • Outline the phosphorus cycle • Describe the hydrologic cycle • List the steps in the rock cycle • Identify one way that humans have affected each cycle BIOGEOCHEMICAL CYCLES consumers animals eaten Matter within ecosystems is recycled. die die producers decomposers green algae bacteria and fungi water and salts soil minerals and humus decay All Cycles Are Related SO2, NO2 CO2 H2O Respiration Decompositio n Transpiratio n Fossil Fuel Combustio n N2 H2O Carbon, Nitrogen, Sulfur, Phosphorusin Plants and Organisms Urea Nitrogen Fixing Bacteria Nitrates, Sulfates, Phosphates Phosphate Runoff Nitrite, Dead Organic Mattrer & Decomposers Phytoplankton Zooplankto n Nutrient Recycling Ocean Sediment s BIOGEOCHEMICAL CYCLES • Water, carbon, oxygen, nitrogen, phosphorus & other elements cycle from the abiotic (“geo” nonliving environment) to biotic (“bio” living organisms) & then back to the environment. biotic abiotic BIOGEOCHEMICAL CYCLES • Water, carbon, oxygen, nitrogen & other elements move through a regularly repeated sequence of events. • Define a cycle. A cycle is a repeated sequence of events. H2 O C N O BIOGEOCHEMICAL CYCLES • Most element cycles have an atmospheric “bank” where the element is found in large amounts. atmosphere “bank” BIOGEOCHEMICAL CYCLES • Elements move from the “bank” into organisms. atmosphere “bank” BIOGEOCHEMICAL CYCLES • Organisms release elements in daily activities or after death. • Give an example of an activity that releases elements. atmosphere “bank” RIP BIOGEOCHEMICAL CYCLES • Decomposers (or combustion or erosion) break down organic matter. • What is a result of their actions? atmosphere “bank” RIP BIOGEOCHEMICAL CYCLES • Four examples of cycles: – – – – Hydrologic (Water) Carbon (carbon-oxygen) Nitrogen Phosphorus H2 O C N P Link COMBUSTION – human and natural sources CARBON CYCLE • Why is the Carbon Cycle often called the Carbon-Oxygen Cycle? CO2 respiration photosynthesis O2 CARBON CYCLE • Like other element cycles, the carbon cycle links nonliving & living parts of the environment. biotic abiotic CARBON CYCLE • The exchange of gases during photosynthesis and respiration is a major example of the living-nonliving cycle of carbon-oxygen. CO2 respiration photosynthesis O2 CARBON CYCLE • How does carbon enter the living part of the cycle? CO2 CO2 CO2 CO2 CO2CO2 CO2 CO2 Using the process of PHOTOSYNTHESIS, plants use CO2 to make food CO2 + H2O ----> C6H12O6 + O2 CARBON CYCLE • Carbon is returned to the atmosphere environment by: – – – – cellular respiration erosion combustion decomposition CARBON CYCLE • Use the next diagram to help you define the relationship of the following terms to the carbon cycle. – respiration – photosynthesis – decomposition – combustion – erosion CARBON CYCLE CO2 in Atmosphere combustion decomposition assimilation by plants “BANKS” – CO2 in photosynthesis plant respiration by algae atmosphere and soil erosion trapped respiration by algae RESPIRATION underground inPHOTOSYNTHES and aquatic animals IS Plants use CO2 is released fossil fuels litter dioxide to into the EROSIONback - CO2 is carbon make food atmosphere when released back into the COMBUSTION - CO2 is fossil fuels is food (glucose) oceans, limestone decomposition released atmosphere when back into the coal, gas, petroleum lakes broken down during DECOMPOSITION - COdown 2 is released erosion breaks atmosphere when animal respiration • Write a descriptive summary of the events shown. RED DOTS WHITE BLUE GREEN DOTS DOTS DOTS - -carbon -water, represents carbon note dioxide how trapped respiration theyin or released collide glucose combustion with from from combustion the photosynthesi note white the red dots (forest to s flash - represent note offire, green how burning photosynthesi green dots into dots fossil fuels) dots s move white through or at respiration organisms soil (soil and then respiration flashplant red & animal to and represent animal & carbon cycle animated Link Bacteria in soil and water add Nitrogen back into the atmosphere NITROGEN CYCLE • 79% of the atmosphere is nitrogen gas but it is in a form most living things cannot use. N2 free nitrogen NITROGEN CYCLE • If we can’t take in free nitrogen, how do we acquire it so we can use it in our bodies? • Why do we need nitrogen in our bodies? NITROGEN CYCLE • How do we acquire usable nitrogen? • Nitrogen-fixing bacteria convert nitrogen into nitrates. • Plants absorb nitrates. • Animals eat plants. N2 in air NITRATES nitrogen-fixing bacteria NITROGEN CYCLE • How does the nitrogen return to the atmosphere? • Denitrifying bacteria convert the nitrates back into nitrogen. denitrifying bacteria N2 in air NITRATES nitrogen-fixing bacteria NITROGEN CYCLE • Why do we need nitrogen? protein ? Nitrogen NITROGEN CYCLE • Can plants & animals use free nitrogen? N2 free nitrogen • In what form must N2 be to be used by plants? nitrates • What organisms can fix the N2 into a usable form? nitrogen-fixing bacteria NITROGEN CYCLE Simplified • Use the next diagram to help you define the relationship of the following terms to the nitrogen cycle. – free N2 bank – nitrogen fixation – nitrates – organisms – organic material – denitrification NITROGEN CYCLE Simplified organisms Free N2 in DENITRIFICATION Atmosphe Denitrifying bacteria re N2 “BANK” ORGANIC MATERIAL - FREEfrom convert nitrates Pure nitrogen Deaddenitrifying organisms, decomposition backnitrogen-fixing “banked”bacteria in the bacteria animal waste and into free nitrogen. atmosphere which organic litter are NITROGEN FIXING ORGANISMS is made up of 79% decomposed by BACTERIA - nitrogenPlants take in RIP nitrogen. NITRATES bacteria and other fixing bacteria convert nitrates and use Organic NITRATES - the decomposers material free nitrogen into them in their form of nitrate compounds tissues; animals nitrogen that NITROGEN CYCLE gaseous losses (N2, NOx) denitrifying bacteria lightning fixes N2 into nitrates nitrates nitrogen-fixing bacteria organic matter NITROGEN CYCLE • Nitrogen Cycle Animation • http://www.bbc.co.uk/schools/gcseb itesize/biology/ecology/nitrogencycl erev1.shtml (scroll down to view) • http://www.bbc.co.uk/schools/gcseb itesize/flash/bi01013.swf (same graphic but alone on a page) Nitrogen Cycle • Find the brown dots entering plants and animals. • In what form is the nitrogen? • What main organisms “fix” the N for use? (N-fixing bacteria) Link Phosphorus (P) Cycle • No phosphorus in atmosphere • Rocks PP – Phosphorus released by weathering of rocks Phosphorus (P) Cycle • Plants – Absorb P into their roots P Phosphorus (P) Cycle • Animals P – Ingest P when plants eaten – P continues to move up food chain Phosphorus (P) Cycle • Decomposers – Breakdown dead matter and release P into soil P P Phosphorus (P) Cycle P P P P P P • Human Contribution – Adding excess P from fertilizers – P washes into lakes, etc… – Excess P causes extreme algae Link WATER CYCLE • Use the next diagram to help you define the following: – evaporation – condensation – precipitation – transpiration – runoff – accumulation water cycle diagram Condensation Precipitation PRECIPITATION - water vapor (gas) changing into a liquid or solid such as rain, hail, sleet or snow Condendation (clouds form) Transpiration CONDENSATION - water vapor Run-off (gas) changing to a tiny drops Evaporation of water (liquid) form across RUN-OFF - waterthat moving clouds or rain the Earth’s surface (stream, TRANSPIRATION ACCUMULATION - water - water loss fromgathering plants when into water an area vapor (pond, goeslake, out stream throughorstomates ocean) (little openings) in leaves river, gully) Accumulation EVAPORATION - water changing from a liquid into a gas (water vapor) WATER CYCLE • Label your diagram of the water cycle. biotic abiotic • Nonliving portions of the water cycle include condensation, evaporation & precipitation. WATER CYCLE WATER CYCLE • Living portions of the water cycle include plants performing transpiration and water intake by all organisms. biotic abiotic WATER CYCLE • Water vapor exits plant leaves during transpiration through tiny openings called stomata. WATER CYCLE • Water loss from plant leaves during transpiration is caused in part by the sun’s heat energy in a process similar to the way we lose water when we perspire. WATER CYCLE • Why are water cycles said to be driven by the sun? HEAT Heat energy from the sun causes water to evaporate returning water vapor to the atmosphere and transpiration to occur from plants. WATER CYCLE • Why are water cycles said to be driven by the sun? WATER CYCLE • If water cycles are driven by the sun’s heat energy, what effect would global warming have on the cycle? Global warming occurs when more of the sun’s heat energy is trapped in the atmosphere causing it to be warmer. When the atmosphere is warmer, it evaporates more water and can hold more water vapor. When large water sources are present, this could result in more clouds and more precipitation. In some areas, especially where water sources are less available, the increased evaporation/transpiration could dry out soil and vegetation resulting in loss of plants and more arid conditions. (We will revisit this in Human Impact.) Link Section 2 – Review • Short-term processes of the carbon cycle occurs when producers convert CO2 to carbohydrates • Long-term processes of the carbon cycle occurs when CO2 is stored in rocks and fossil fuels • In the nitrogen cycle atmospheric nitrogen is converted by organisms into a form organisms can use Section 2 – Review • The phosphorus cycle is the cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment • The hydrologic cycle traces the path of water through the atmosphere, biosphere & geosphere • In the rock cycle rocks are continually formed into new rocks by the process of lithification, melting, and recrystallizing Section 2 – Review • Humans burn fossil fuels affecting the carbon cycle, they add nitrogen & phosphorus to soils, they contaminate our water, and they remove materials from Earth Section 3 – How Ecosystems Change GOALS • Give examples of ecological succession • Explain how pioneer species contribute to ecological succession • Explain old-field succession • Describe the role of lichens in primary succession How do ecosystems change? Natural Changes: Hurricanes, Tornadoes, Earthquakes, Forest Fires, Wind & Water Erosion, Decay, Tsunamis, Flooding. Unnatural Changes: Pollution, Global Warming, Ozone Depletion, Littering, Oil Spills, etc. Succession Ecological Succession: Gradual process of change and replacement of types of species in a community Primary Succession: When succession occurs where no life was present Secondary Succession: Occurs on an area where life had previously existed, can be where humans have disturbed, fires, floods, storms, earthquakes, and volcanoes.. After a Forest Fire Fire and secondary succession link Climax Community: •Final and stable community of large, mature trees •May take hundreds of years to form •Signs of climax community show mature oak, maple, and hickory forests Old-field Succession: Example of secondary succession, which occurs when farmland is abandoned. Begins with weeds and grasses and may end up in a climax community. Poster Project: Primary and Secondary Succession Using the large sheet of paper provided: 1. Divide the poster into 8 sections like shown below. 2. On the top row, draw and color the process of primary succession, label your poster with the following terms: Primary succession, Pioneer Species, Lichens, Mosses, Shrubs, Trees, Climax Community 3. On the Bottom Row, draw and color the process of secondary succession, label your poster with the following terms: Secondary succession, Pioneer Species, grasses, flowers, trees, Climax Community 4. Complete the chart that compares the two processes, on the sheet provided. 5. Staple it to your poster, and hand it in. Section 3 – Review • Organisms in an environment sometimes follow a pattern of change over time known as ecological succession • Primary succession occurs where no ecosystem existed before • Secondary succession occurs where an ecosystem has previously existed • Climax communities are made up of organisms that take over an ecosystem and remain until the ecosystem is disturbed again