Ecosystems: Lesson 4, Activity 1 Environmental Literacy Project Michigan State University Ecosystems: Lesson 4, Activity 1 Farms are Ecosystems, Too

Humans and Ecosystems From previous Lessons, you’ve learned that ecosystems are comprised of different carbon pools (e.g., producers, herbivores, carnivores) and that matter and energy move among these pools through carbon-transforming processes. Are humans part of ecosystems? How? Introduce a farm as an ecosystem. Ask students to share ideas about how people are a part of ecosystems and how people use ecosystems. Point out that humans get all of our food and oxygen from ecosystems. Point out that farms are ecosystems, too, and that these are the focus of the Activity today. Pass out Lesson 4.1 Farm Ecosystems Worksheet to each student. Use Slides 2-5 of Lesson 4.1 Farm Ecosystem Presentation to talk about how farms are ecosystems too, and humans are part of those ecosystems. Image Credit: Hannah Miller, Michigan State University

Humans and Ecosystems Of course humans are part of ecosystems! All of the matter and energy that we need to survive come from ecosystems, as well as the oxygen we breathe. One key type of ecosystem that we greatly depend on are farms. Introduce a farm as an ecosystem. Ask students to share ideas about how people are a part of ecosystems and how people use ecosystems. Point out that humans get all of our food and oxygen from ecosystems. Point out that farms are ecosystems, too, and that these are the focus of the Activity today. Pass out Lesson 4.1 Farm Ecosystems Worksheet to each student. Use Slides 2-5 of Lesson 4.1 Farm Ecosystem Presentation to talk about how farms are ecosystems too, and humans are part of those ecosystems. Image Credit: Hannah Miller, Michigan State University

Farms are Ecosystems? Yes! But they operate a bit differently than natural ecosystems. How are farms and natural ecosystems alike? How are farms and natural ecosystems different? Use Slides 4-5 to collect student ideas about how farm ecosystems are different from natural ecosystems, and to compare the student ideas to some other ideas (in blue). Image Credit: Hannah Miller, Michigan State University

Farms are Ecosystems? Yes! But they operate a bit differently than natural ecosystems. How are farms and natural ecosystems alike? Have similar carbon pools (e.g., producers, herbivores) Experience the same carbon-transforming processes (photosynthesis, cellular respiration) How are farms and natural ecosystems different? Humans help regulate carbon and energy movement through pools (e.g., planting crops, harvesting, animal slaughtering) Use Slides 4-5 to collect student ideas about how farm ecosystems are different from natural ecosystems, and to compare the student ideas to some other ideas (in blue). Image Credit: Hannah Miller, Michigan State University

Farms are Ecosystems? We’ve seen this box and arrow diagram before when talking about carbon pools and movement in ecosystems. Carnivores Atmosphere How do farm organisms fit in the boxes? Where are humans are located? Herbivores Use Slide 6 to point out the different pools of carbon: This ecosystem has carbon pools just like the others we have studied: atmosphere, producers, herbivores, and carnivores, and soil carbon. Ask students to locate humans in the food chain. Use Slides 6-9 to discuss where humans can be placed in the diagram. Ask: Are we herbivores or carnivores? In the ecosystem model in the presentation, humans can be placed either in the herbivore pool (if they eat a plant-based diet) or in the carnivore pool (if they eat a meat-based diet). Tell students that since humans eat both plants and animals, we can choose where we go on the food pyramid. Use Slide 6 to ask students where humans belong in this ecosystem. IN which box do humans belong? Image Credit: Craig Douglas, Michigan State University Soil Carbon Producers

Farms are Ecosystems? In farm ecosystems, humans are the primary carnivores (we eat hamburgers, pork chops, fried chicken). But humans also eat a lot of plant products that are grown on farms (wheat, oats, corn, lettuce, other vegetables). Therefore, humans are both carnivores and herbivores. They don’t fit neatly into just one box, but sometimes it’s simpler to think that way. Herbivores Soil Carbon Atmosphere Carnivores Producers Use Slide 7 to explain that humans do not neatly fit into one box, but that we will place them in one box for the purpose of this Activity. Image Credit: Craig Douglas, Michigan State University

Does it matter if humans are primarily carnivores or herbivores? There are 7 billion people on the earth. It takes A LOT of food to feed that many people, and food production takes a lot of resources. Does it matter if humans are in the carnivore or the herbivore box when it comes to feeding all those people? Let’s find out… Use Slide 8 to set up the question for this activity: which diet produces the greatest amount of food for people, a plant-based diet or a meat-based diet? Image Credit: Hannah Miller, Michigan State University

Let’s compare: Which ecosystem below produces the most food for people? Meat-based diet (humans are carnivores) Plant-based diet (humans are herbivores) Herbivores Soil Carbon Atmosphere Carnivores Producers Herbivores Soil Carbon Atmosphere Producers Use Slide 9 to introduce the two model ecosystems for this Activity: in the ecosystem on the left, humans are herbivores (plant-based diet), and on the ecosystems on the right, humans are carnivores (meat-based diet). Image Credit: Craig Douglas, Michigan State University

In this ecosystem, humans are the herbivores. Round 1: Plant-based diet PREDICTION Corn plant photosynthesis occurs, so let’s start with 500 carbon atom units in the producer pool. Herbivores Soil Carbon Atmosphere Producers Make a prediction: if we start with 500 atoms in the producer pool, how many atoms are available for human growth? Hint: use what you know about the organic matter pyramid to make your prediction. Have students make a prediction about the plant-based ecosystem. Tell students that in round 1, we will look at how carbon moves from pool to pool in an ecosystem where humans are herbivores. When we say “plant-based diet,” we mean a diet in which a person eats meat about 1-2 times a week. Display Slide 10 of the presentation. 500 atom units will begin in the producer pool as a result of plant photosynthesis. Have students make a prediction: if 500 atoms begin in the producer pool, how many carbon atoms will make it to the herbivore pool (thereby feeding the person)? Encourage students to use what they know about the organic matter pyramid from previous Lessons to make their prediction. What causes atoms to move from the producer to the herbivore pool? Image Credit: Craig Douglas, Michigan State University

Corn plant cellular respiration occurs. In this ecosystem, humans are the herbivores. Round 1: Plant-based diet Corn does photosynthesis, so let’s start with 500 carbon atom units in the producer pool. Corn plant cellular respiration occurs. 200 carbon atom units move from the producers to the atmosphere. Corn ears are harvested while the rest of the corn plant dies. 100 carbon atom units move from the producers to the soil. Corn ears are harvested. 100 carbon atom units move from the producers to the herbivore pool. 200 carbon atoms go back to the atmosphere when plants use the sugar for cellular respiration. 160 170 180 200 100 110 190 120 130 140 150 320 360 370 380 350 340 300 310 290 250 150 160 170 140 130 100 110 120 180 190 390 260 270 240 230 200 210 220 280 330 460 470 490 400 500 480 410 420 430 440 450 90 10 80 50 10 40 60 70 20 60 50 70 80 30 90 40 30 20 Atmosphere 100 90 10 20 80 40 60 30 50 70 500 carbon atoms become part of sugar molecules through photosynthesis. Herbivores 100 carbon atoms go to herbivores when they eat plants. 300 carbon atoms become part of the plant through biosynthesis. Have students record their prediction on their worksheet and continue with Slides 11-13 to complete round 1. 100 carbon atoms go to the soil when plants or leaves die. 100 carbon atoms stay in the living plants. 100 70 90 60 80 40 10 50 20 30 480 430 460 410 150 260 280 290 130 140 160 240 200 190 210 220 170 320 330 440 110 100 470 490 400 390 350 120 360 370 380 180 230 420 450 500 310 340 250 270 300 30 20 10 40 80 90 50 70 60 Soil Carbon Producers

3) People digest & biosynthesize 2) People digest food & respire. In this ecosystem, humans are the herbivores. In this ecosystem, humans are the herbivores. One of three things can happen to food (corn) in a person’s stomach: 3) People digest & biosynthesize Large molecules in corn are broken down into small molecules. Small molecules are made into a person’s organic matter. 2) People digest food & respire. 50 carbon atom units move from the herbivores to the atmosphere. 1) People defecate indigestible food. 25 carbon atom units move from the herbivores to soil. 25 carbon atoms stay in the living people. 240 250 200 230 210 220 Atmosphere 50 carbon atoms go back to the atmosphere when people use the food for cellular respiration. 100 35 55 45 65 75 80 25 85 90 95 Herbivores 25 carbon atoms go to the soil when people defecate. Have students record their prediction on their worksheet and continue with Slides 11-13 to complete round 1. 125 105 120 110 115 100 100 Soil Carbon Producers

In this ecosystem, humans are the herbivores. Add it up! How much carbon is available to humans when they are herbivores? 250 Atmosphere 25 Out of 500 carbon atoms that originally went through photosynthesis, 25 carbon atoms are used for human growth. Herbivores On Slide 13, have students compare their predictions with the results. 125 100 Soil Carbon Producers

If people eat a plant-based diet, where are they in the organic matter pyramid? Plant-based diet (humans are herbivores) Organic Matter Pyramid Herbivores Soil Carbon Atmosphere Producers ? Use Slide 14 to have students compare the farm ecosystem they just observed and the organic matter pyramid. Where are humans located in the organic matter pyramid when humans are herbivores? Image Credit: Craig Douglas, Michigan State University  

Think Pair Share Question 1: Answer the carbon pools question. How are carbon pools changing size? Question 2: Answer the carbon fluxes question. How are carbon atoms moving among pools? Question 3: Answer the energy question. How is energy moving through this farm ecosystem? Use Slide 15 to have students practices answering the Three Questions about the farm ecosystem they just observed.

Let’s compare: In round 2, we will look at an ecosystem in which people are the carnivores. Round 1: Plant-based diet (people are herbivores) Round 2: Meat-based diet (people are carnivores) Herbivores Soil Carbon Atmosphere Carnivores Producers Herbivores Soil Carbon Atmosphere Producers Have students make a prediction about the meat-based diet ecosystem. Tell students that in round 2, we will look at how carbon moves from pool to pool in an ecosystem where cows are herbivores and humans are carnivores. In this scenario, the cows eat the corn and the humans eat the cows. When we say “meat-based diet,” we mean a diet in which a person eats meat 5 or more times a week. Use Slides 17-21 to walk students through Round 2. Have students predict: if 500 atoms begin in the producer pool, how many carbon atoms will make it to the carnivore pool (to feed the people)? Encourage students to use what they know about the food pyramid from previous Lessons to make their prediction. Have students record their prediction on their worksheet and continue with Slides 16-20 to complete Round 2.

Round 2: Meat-based diet predictions Corn plant photosynthesis occurs, so let’s start with 500 carbon atom units in the producer pool. Carnivores Carnivores Atmosphere Make a prediction: if we start with 500 atoms in the producer pool, how many atoms are available for human growth? Hint: use what you know about the organic matter pyramid to make your prediction. Herbivores Have students make a prediction about the meat-based diet ecosystem. Tell students that in round 2, we will look at how carbon moves from pool to pool in an ecosystem where cows are herbivores and humans are carnivores. In this scenario, the cows eat the corn and the humans eat the cows. When we say “meat-based diet,” we mean a diet in which a person eats meat 5 or more times a week. Use Slides 17-21 to walk students through Round 2. Have students predict: if 500 atoms begin in the producer pool, how many carbon atoms will make it to the carnivore pool (to feed the people)? Encourage students to use what they know about the food pyramid from previous Lessons to make their prediction. Have students record their prediction on their worksheet and continue with Slides 16-20 to complete Round 2. Soil Carbon Producers

Corn plant cellular respiration occurs. Round 2: meat-based diet In this ecosystem, humans are the carnivores. Corn plant cellular respiration occurs. 200 carbon atom units move from the producers to the atmosphere. Corn ears are harvested while the rest of the corn plant dies. 100 carbon atom units move from the producers to the soil. Corn does photosynthesis, so let’s start with 500 carbon atom units in the producer pool. Corn ears are harvested. 100 carbon atom units move from the producers to the herbivore pool. Carnivores 200 carbon atoms go back to the atmosphere when plants use the sugar for cellular respiration. 170 180 200 110 130 120 100 190 140 150 160 230 280 290 300 260 250 220 240 430 200 130 140 150 160 120 110 360 370 100 380 170 410 310 420 190 180 350 390 400 210 270 470 490 500 320 460 480 450 330 340 440 40 20 30 10 80 70 10 90 50 20 80 90 60 60 70 30 40 50 Atmosphere 100 10 40 30 20 60 90 50 80 70 500 carbon atoms become part of sugar molecules through photosynthesis. Herbivores 100 carbon atoms go to herbivores when they eat plants. 300 carbon atoms become part of the plant through biosynthesis. Have students make a prediction about the meat-based diet ecosystem. Tell students that in round 2, we will look at how carbon moves from pool to pool in an ecosystem where cows are herbivores and humans are carnivores. In this scenario, the cows eat the corn and the humans eat the cows. When we say “meat-based diet,” we mean a diet in which a person eats meat 5 or more times a week. Use Slides 17-21 to walk students through Round 2. Have students predict: if 500 atoms begin in the producer pool, how many carbon atoms will make it to the carnivore pool (to feed the people)? Encourage students to use what they know about the food pyramid from previous Lessons to make their prediction. Have students record their prediction on their worksheet and continue with Slides 16-20 to complete Round 2. 100 carbon atoms go to the soil when plants or leaves die. 100 carbon atoms stay in the living plants. 100 60 90 80 70 40 10 50 20 30 480 460 430 320 180 170 190 200 220 210 160 150 110 100 120 130 140 240 260 400 390 410 440 470 380 370 290 280 330 350 360 490 420 250 230 500 300 270 450 340 310 30 20 10 40 80 90 50 70 60 Soil Carbon Producers

1) Cows defecate indigestible food. (ew!) One of three things can happen to food (corn) in a cow’s stomach: In this ecosystem, humans are the carnivores. 13 14 12 10 11 15 7 5 2 1 3 4 8 6 9 1) Cows defecate indigestible food. (ew!) 25 carbon atom units move from the herbivores to soil. Cows got eaten by people! (Burgers anyone?) 15 carbon atom units move from the herbivores to carnivores. 2) Cows digest food & respire. 50 carbon atom units move from the herbivores to the atmosphere. 3) Cows digest & biosynthesize Large molecules in corn are broken down into small molecules. Small molecules are made into a cow’s organic matter. Carnivores 15 carbon atoms go to carnivores when they eat herbivores. 200 230 240 210 220 250 Atmosphere 50 carbon atoms go back to the atmosphere when herbivores use the food for cellular respiration. 10 carbon atoms stay in the living herbivores. 100 45 55 35 65 18 17 19 20 22 21 16 15 11 10 12 13 14 23 24 90 85 80 75 25 95 Herbivores 25 carbon atoms go to the soil when herbivores defecate. Have students make a prediction about the meat-based diet ecosystem. Tell students that in round 2, we will look at how carbon moves from pool to pool in an ecosystem where cows are herbivores and humans are carnivores. In this scenario, the cows eat the corn and the humans eat the cows. When we say “meat-based diet,” we mean a diet in which a person eats meat 5 or more times a week. Use Slides 17-21 to walk students through Round 2. Have students predict: if 500 atoms begin in the producer pool, how many carbon atoms will make it to the carnivore pool (to feed the people)? Encourage students to use what they know about the food pyramid from previous Lessons to make their prediction. Have students record their prediction on their worksheet and continue with Slides 16-20 to complete Round 2. 100 105 110 125 115 120 100 Soil Carbon Producers

3) People digest & biosynthesize 2) People digest food & respire. One of three things can happen to food (cows) in a person’s stomach: In this ecosystem, humans are the carnivores. 6 carbon atoms go back to the atmosphere when carnivores use the food for cellular respiration. 11 12 10 13 14 15 3 5 7 9 8 6 4 3 carbon atoms stay in the living carnivores. 3) People digest & biosynthesize Large molecules in cows are broken down into small molecules. Small molecules are made into a person’s organic matter. 2) People digest food & respire. 6 carbon atom units move from the carnivores to the atmosphere. 1) People defecate indigestible food. (ew!) 6 carbon atom units move from the carnivores to soil. Carnivores 253 252 251 254 250 255 256 6 carbon atoms go to the soil when carnivores defecate or die. Atmosphere 10 Herbivores Have students make a prediction about the meat-based diet ecosystem. Tell students that in round 2, we will look at how carbon moves from pool to pool in an ecosystem where cows are herbivores and humans are carnivores. In this scenario, the cows eat the corn and the humans eat the cows. When we say “meat-based diet,” we mean a diet in which a person eats meat 5 or more times a week. Use Slides 17-21 to walk students through Round 2. Have students predict: if 500 atoms begin in the producer pool, how many carbon atoms will make it to the carnivore pool (to feed the people)? Encourage students to use what they know about the food pyramid from previous Lessons to make their prediction. Have students record their prediction on their worksheet and continue with Slides 16-20 to complete Round 2. 131 125 130 127 129 126 128 100 Soil Carbon Producers

In this ecosystem, humans are the carnivores. Add it up! In this ecosystem, humans are the carnivores. 3 How much carbon is available to humans when they are carnivores? Carnivores Carnivores 256 Atmosphere 10 When we started with 500 atoms, 3 atoms were left for human growth with a meat-based diet. Herbivores On Slide 21, have students compare their predictions with the results. 131 100 Soil Carbon Producers

If people eat a meat-based diet, where are they in the organic matter pyramid? Meat-based diet (humans are carnivores) Herbivores Soil Carbon Atmosphere Carnivores Producers Organic Matter Pyramid ? Image Credit: Craig Douglas, Michigan State University  Use Slide 22 to help students make connections to the farm ecosystem they just observed and the organic matter pyramid. Have students complete the other questions for Round 2 on their worksheet. Have them share their answers about what is happening to carbon atoms and energy in this ecosystem with the class.

Compare the difference between ecosystems where humans eat a plant-based diet (left) and humans eat a meat-based diet (right). Round 1: Plant-based diet Round 2: Meat- based diet Herbivores Soil Carbon Atmosphere Carnivores Producers Herbivores Soil Carbon Atmosphere Producers 3 10 100 131 256 250 25 Image Credit: Craig Douglas, Michigan State University 125 100

Let’s think about the farm ecosystem in two new ways. Help students think about carbon and energy in the farm ecosystem using a new tool. Display Slide 24 of the presentation. Tell students they will use these posters (they discussed these briefly in Lesson 3) to discuss how matter and energy move through pools in farm ecosystems.

Matter and energy are being transformed differently in the two farm ecosystems. Using this graph, describe how matter cycles and energy flows through a farm ecosystems where humans are herbivores. Using this graph, describe how matter cycles and energy flows through a farm ecosystems where humans are carnivores. What are the major differences? Use the questions and graphic on Slide 25 to hear students’ ideas about how matter cycles and energy flows in the two different farm ecosystems.

Carbon pools and fluxes are different in the two farm ecosystems. Using this graph as a tool, describe how carbon moves from the top grey box (CO2) to the bottom grey box (CO2) in farm ecosystems where humans are herbivores. Using this graph as a tool, describe how carbon moves from the top grey box (CO2) to the bottom grey box (CO2) in farm ecosystems where humans are carnivores. What are the major differences? Use the questions and graphic on Slide 26 to hear students’ ideas about carbon pools and fluxes in the two different farm ecosystems.

Think Pair Share Question 1: How many atoms are available for humans if humans eat a plant-based diet? Question 2: How many atoms are available for humans if humans eat a meat-based diet? Use the questions on Slides 27-28 to hear students’ ideas about how their food choices impact carbon cycling and energy flow. After they answer the questions, have students complete the final question on their worksheet.

How might these graphs affect our decisions about what food to eat? Use the questions on Slides 27-28 to hear students’ ideas about how their food choices impact carbon cycling and energy flow. After they answer the questions, have students complete the final question on their worksheet. Image Credit: Craig Douglas, Michigan State University