Farm Ecosystems. 8th grade N/A

Transcription

1 SCIENCE LESSON (5-8) Farm Ecosystems OBJECTIVES SWBAT define the term ecosystem SWBAT identify the traits of a healthy ecosystem SWBAT describe why a farm is an ecosystems, and the smaller ecosystems within the farm SWBAT explain how they depend on healthy ecosystems for their health NATIONAL SCIENCE EDUCATION STANDARDS CONTENT STANDARD C: As a result of activities in grades 5-8, all students should develop understanding of: Structure and function in living systems Reproduction and heredity Regulation and behavior Populations and ecosystems Diversity and adaptations of organisms ALABAMA COURSE OF STUDY STANDARDS 5th Grade Describe the relationship of populations within a habitat to various communities and ecosystems Describing the relationship between food chains and food webs Describing symbiotic relationships (9) 6th Grade N/A 7th grade Describe biotic and abiotic factors in the environment Examples: biotic: plants, animals; abiotic: climate, weather, soil Arranging the sequence of energy flow in an ecosystem through food webs, food chains and energy pyramids. (7) 8th grade N/A KEY TERMS Ecosystem Biotic Abiotic Interdependence Symbiotic MATERIALS Soil sample Niches/Farm Ecosystems Map RapiSoil testing kits Ball of yarn

2 WELCOME Good morning, welcome to Jones Valley Teaching Farm. I d like to welcome you to our farm, and to start the day by asking this question: Who has been to a farm before? How is this farm similar or different to the farm you have been to before? Elicit responses: Lead students to answer that this farm is urban, most are rural. This farm is an urban farm, located in a city rather than in a rural area. What is one thing that is similar about this farm to the farms you ve been on? Elicit responses. We have plants! And fruits, and veggies! And today we re going to learn all about how the living things on this farm interact with and support each other, forming an ecosystem. INTRODUCTION TO NEW MATERIAL Today we re talking about the farm as an ecosystem, and the ecosystems within the farm. What s an ecosystem? An ecosystem is made of living/nonliving things that work together with each other, exchange energy and depend on one another for survival. Often, ecosystems have a great deal of biodiversity: this means there are many different things (diversity) that are alive (bio). So, for example, the whole farm is an ecosystem; but how? How is it working together in ways that we can t see? Let s investigate! Ask students to name what is on the farm things they see, or things that exist on other farms. Draw (even abstractly) what they state: and ask each student to tell you how their named plant/animal depends on other things on the farm. Thus, you re basically drawing/creating the ecosystem with them, and they re essentially explaining the ecosystem in action to you. But, there are other, smaller ecosystems existing in the larger one: for example, the beehives, the soil, the compost can all be considered ecosystems that exist within the larger ecosystem of the farm.

3 Examples: The farm as a whole The farm is considered an ecosystem because there are plants, animals, soils, pollinators, etc. that are working off each other/supporting each other and ultimately, helping each other survive. Based on the picture we just drew, can you explain to me what that means? Soil/Soil Food Web There are many living and non-living things within the soil. This makes the soil the healthy organism it is. It s not just dirt! These organisms include: Bacteria Fungi Worms Plants Other small animals Compost These organisms provide for each other, creating a soil food web/ecosystem beneath your very feet! The organisms in compost worms, microorganisms, etc. all have a role to play in breaking down compost to it s nutrient rich final form, called humus. Resource: Now that we know what an ecosystem is, what does it mean for our farm ecosystem to be healthy? We do want our ecosystem to be healthy! It means we have: Healthy, fertile soil Diverse plant and animal species A chemical free, organic environment Given that, do you think that Jones Valley has a healthy ecosystem? One of the ways we can check is by doing soil tests to make sure our soil is healthy and strong. Test soil according to instructions found on RapiSoil Packaging insert.

4 Plant Nutrient Facts: Nitrogen It is responsible for plants being green, and for leaf growth Not enough nitrogen causes leaves to be yellow in color Too much nitrogen causes leaves to grow too rapidly, and delays the growth of flowers Phosphorus Phosphorus is essential for seed development: it helps increase the number of seeds a plant produces, helps fruit develop, and helps the plant build resistance to disease. A phosphorus deficiency means the plant does not grow as well as it could, and may make the seed useless (sterile.) Potash Potash helps make the plant strong. It encourages carbohydrate and protein formation within the plant. It helps the plant grow with a strong stem, and helps protect the plant from cold, and helps develop a strong root system. Plants that do not grow in soil with enough potash have frail, dried leaves. ph: Plants need to grow in soil that has the proper ph. Different plants need different levels of ph. In this context, ph is defined by how much acidity or alkalinity is in the soil. What do our results from the soil testing tell us about our soil and it s health, and thus the health of the ecosystem? On organic farms, the ecosystem is considered balanced because we are using natural resources to control pests and weeds, etc., rather than chemicals. We do this by using biological pest control, natural fertilizers, and natural methods of weed control (among other things) This helps keep the farm, and our ecosystems, in balance. How do you depend on ecosystems? Do ecosystems have anything to do with you, your school, or your community? Yes! Healthy ecosystems help keep you strong and healthy! What would happen if, for example, Jones Valley wasn t a healthy ecosystem and we couldn t grow our fruits and vegetables? Would they be available at the farmer s market for you to pur chase? What if the ecosystem wasn t strong at the dairy farm, where your milk is produced for your ce real? Tell me: how else do you depend on ecosystems? What do you think?

5 How do we manage ecosystems on farms? The beauty of an ecosystem is that it, to a certain extent, manages itself. However, sometimes things become out of balance, and there are ways to correct the system. For example, if there are too many aphids (small green bugs that love to eat plants) we can introduce more ladybugs, which love to eat aphids. Or, sometimes nutrients may become depleted in the soil, and we can plant different plants in that space next season, ones that give nutrients back to the soil or need different nutrients than the previous crop. Finally, what is an ecological niche? Everyone say NICHE on three. Students say the word, then elicit responses. An ecological niche is an animal or plant s job in nature. Every living thing has a special job or role that it plays within its environment that makes it special or different from every other organism. Producers: Plants are producers because they produce their own food from sunlight. The plant s niche in an ecosystem is as a producer because they produce their own food. Producers are first and most important level of the ecosystem because they provide they bring new energy into an environment, are basis of the food web, and create habitat for other organisms--without producers, no other organism would be able to survive! Examples on the farm include everything that s growing. In addition to producers, we also have consumers. Consumers are things that cannot make their own food, and have to eat other things to survive. There are primary, secondary and tertiary consumers. Primary consumers are organisms that eat primary producers. What kinds of organisms can you think of that eat primary producers (i.e. plants)? Elicit responses. Does anyone notice a pattern? Elicit responses. Right--they all eat plants! What do we call animals who eat plants? That s right--herbivores. So primary consumers are often herbivores! Primary consumers/herbivores are important because they provide a food source for other animals. Examples on the farm of primary consumers include aphids, caterpillars, harlequin beetles, squash bugs, mice, etc. Secondary consumers are those that eat primary consumers. Elicit responses. What do we call animals who eat only eat other animals, or, in other words, only eat meat? Elicit responses. RIGHT! Carnivores. What s an animal who called who hunts other animals? (predator). So secondary consumers are predators, and sometimes carnivores, eating only meat. These animals are important because they keep the population of primary consumers in check. (If the group is from a rural area, you can ask if their families hunt deer. They will probably tell you all about how humans have to keep deer populations in check. You can add that this is the case because we ve run out all of the major predators of deer. But it s true, without hunting our deer populations could do some heavy damage to the forest ecosystem.)

6 Examples on the farm include ladybugs, praying mantises, assassin bugs, chickens and other birds (also eat plants, so kind of switch-hitters), frogs, cats, dragonflies et Tertiary consumers are those that eat secondary (and sometimes primary) consumers. If they are hunting/eating other animals, what do we call them? Elicit responses. RIGHT: Predators/carnivores. Animals in this category are top predators in their ecosystem, meaning they have no other natural predators who hunt them, and many of them are keystone species, meaning that they affect many other organisms within the ecological community. (there are keystone species in other levels also) Examples on the farm include red tailed hawks, stray dogs What about animals that eat only dead and decaying things? Get examples: you might have to get them to dig around under leaves and in the compost. These are decomposers, and they are SUPER important because they take all the dead stuff and turn it back into dirt, which is food for plants who then bring that energy back to animals and around it goes again! IF we didnt have decomposers, all the dead things and poop and gross stuff that gets created everyday would have nowhere to go--in just one month without decomposers, the whole earth would be covered in a pile 20 feet deep of just dead flies. And that s just flies! Examples on the farm include soil fungi (white filaments in compost), worms, roly polys, vultures (scavengers), soil bacteria, termites, ants, etc There s one more special niche on the farm that s really important to us because it s how flowers are able to produce fruit and seeds. These animals usually have wings that help them go from flower to flower looking for nectar. What do you think this is? Pollinators! Elicit responses. RIGHT: bees and butterflies. So the niche of these type of animals is that of pollinator, or something that pollinates plants and allows them to reproduce. 80% of the world s crops depend on honeybees so we, as consumers of that food, do as well! Examples on the farm include butterflies, honeybees, some types of flies. ASK: Where do humans fit in? Elicit responses, and encourage conversation about how we might fit in to several categories. SCIENCE ACTIVITY: ECOSYSTEM ILLUSTRATION Hold up a ball of yarn, and explain that this yarn will represent an ecosystem in action. Ask for one student to start with the yarn, and to gently throw or pass it to someone near them (but not next to them).

7 Ask for one student to start with the yarn, and to gently throw or pass it to someone near them (but not next to them). Allow students to continue passing until every student is holding the yarn. ASK students to explain how they are all connected. Cut the string, piece by piece, until students are no longer connected to each other. ASK them how this helps to represent the ways in which an ecosystem can be disrupted, as their interconnectedness has been disrupted. How might this disruption take place in an ecosystem, or what is this cutting a metaphor for? CHECK FOR UNDERSTANDING: What is an ecosystem? What makes a farm ecosystem healthy? How do organic farmers help manage the ecosystem? Name one ecosystem within the larger ecosystem of the farm. What is interdependence or a symbiotic relationship?