Ecosystems

Georgia Performance Standards S4L1: Students will describe the roles of organisms and the flow of energy within an ecosystem. Identify roles of producers, consumers, and decomposers in a community. Demonstrate the flow of energy through a food web/food chain beginning with sunlight and including producers, consumers, and decomposers. Predict how changes in the environment would affect a community (ecosystem) of organisms. Predict effects on a population if some of the plants or animals in the community are scarce or of there are too many.

Essential Questions What is necessary for life? Are all organisms important? Why is a food web called a food web? Why do organisms become extinct? What are the roles of producers, consumers, and decomposers in the community? How does the flow of energy go through the food chain? Where does the energy come from? How will changes in the environment affect a community of organisms? How does population affect the number of plants and animals in the community?

ECOSYSTEM An ECOSYSTEM is made up of all the living and nonliving things that interact in an area. Nonliving things in a ecosystem can include water, air, soil, and light. Nonliving things help the living things meet their needs.

Using nonliving things to survive. Soil is the loose material that covers much of the Earth’s surface. It is made up of tiny pieces of rock, minerals, and organic matter. Organic matter is the remains of decaying plants and animals. Most plants grow best in this type of soil.

Using nonliving things to survive Sunlight is needed by both plants and animals. Plants need sunlight to make food. Some plants and animals can only survive in warm temperatures. Some plants grow better in the shade. Shade protects living things from direct sunlight and high temperatures.

Using nonliving things to survive Water is a nonliving thing that all plants and animals need in order to survive. A stream provides needed water for some of the animals and plants in the forest. Other plants and animals get their water from the rain.

Using nonliving things to survive Air is a nonliving thing that all plants and animals must have in order to survive in an ecosystem.

Different Ecosystems Each ecosystem has its own amounts of light and water, range of temperatures, and soil types. These conditions helps determine the kinds of living things that are able to survive there. A living thing can only survive in an ecosystem where its needs are met.

Relationships in an ECOSYSTEM Every living thing has a role to play within its ecosystem. Every organism, plant, and animal has a particular job in its environment. Plants play the role of a PRODUCER. A producer is an organism that makes its own food.

The food that plants make is used for energy by the organisms that eat the plants. All organisms need energy.

Remember that plants use energy from the sunlight to make food. The plants use this food to grow and produce offspring (other plants). Some of the food is stored in the leaves, stems, and roots of the plant.

When an animal eats the plant, the energy from the plant is transferred to the animal. All animals are CONSUMERS. A consumer gets energy by eating plants, or by eating other animals that eat plants. Consumers use this energy to live.

ALL consumers in an ecosystem depend on producers for food. Without producers, the other organisms in an ecosystem could not survive.

PHOTOSYNTHESIS Remember that plants make their own food by using energy from sunlight. The process by which plants make their own food is called PHOTOSYNTHESIS. This takes place in the plants leaves.

An animal that hunts other animals for food is called a PREDATOR. A PREY is an animal that is hunted for food by another animal. For example: an owl is one kind of predator that and snake is one kind of prey that they owl hunts for food.

When a frog eats a plant, the frog gets energy from the plant. When the snake eats the frog, the snake gets energy from the frog and a smaller amount of energy from the plant. When the owl eats the snake, it also receives a small amount of energy from the plant and it also receives energy from the snake

FOOD CHAIN A food chain shows the path of food energy in an ecosystem from plants to animals. Food chains are different in different ecosystems.

FOREST FOOD CHAIN The FIRST link in any food chain is always the PRODUCER.

FOREST FOOD CHAIN The SECOND link in a food chain is the VOLE. A vole is an herbivore or animal that eats only plants. The vole get energy from the plant.

FOREST FOOD CHAIN The THIRD AND FOURTH links in a food chain are either carnivores or omnivores. A carnivore eats only other animals and an omnivore eats both plants and animals.

FOOD WEB When TWO OR MORE food chains overlap, they form a FOOD WEB. In a food web, at least one plant or animal from each food chain is part of another food chain.

FOOD WEB

Helpful Organisms in an ecosystem. A helpful organism in an ecosystem is called a DECOMPOSER. A decomposer is a living thing that breaks down the remains of dead organisms. All food chains end with DECOMPOSERS

Decomposers help the environment Decomposers help the environment. They keep it from becoming crowded with the remains of dead plants and animals.

MICROORGANISM A microorganism is a tiny living thing that can only be seen with the aid of a microscope. Bacteria are one type of microorganism. Fungi is another type of microorganism.

Why are decomposers important to an ecosystem? They release nutrients that plants and animals need to survive. The nutrients are released into the soil and water. This helps the plants and animals stay healthy. Decomposers also keep the environment clean and remove dead and decaying plants and animals so other living things can use the space.

COMPOST People can create an ideal environment for decomposers by making a COMPOST. A compost pile or compost bin is a place that is set aside for the decay of materials that were part of once-living things.

What type of things can go in a compost? You can put grass clippings, leaves, kitchen scraps, and many kinds of paper. These materials will be recycled by the fungi and bacteria in the compost. The decayed material can then be mixed with soil that can be used to grow plants for food.

How do organisms change the environment? Whether it is an ant, a plant, an animal, or a human, every living thing causes changes to its environment. Sometimes the change to the environment is harmful to one organism but is helpful to another.

Think about a maple tree growing near a garden Think about a maple tree growing near a garden. As it grows, the tree provides a home to animals such as squirrels, birds, and other animals. Yet, the tree blocks sunlight and over time, only plants that require little light will be able to survive beneath the tree.

How do humans change the environment? Humans change the environment in many ways. People have changed forests into cities, rivers into lakes, and hillsides into rubble. Some of these changes are good and some are bad.

For example, a DAM is used to hold back flood waters For example, a DAM is used to hold back flood waters. It helps control the flow of the water which can improve river travel and it can provide electricity. The DAM can also cause harm because the flood waters used to deposit SILT along the river’s bank. The silt helped enrich the soil. Now farmers must use chemical fertilizers to help their plants grow.

Humans can be the biggest threats to the survival of a species. A SPECIES is a group of living things that produces living things of the same kind.

At one time, passenger pigeons numbered in the millions At one time, passenger pigeons numbered in the millions. Since humans killed so many of this species, it became EXTINCT. EXTINCT means that the species is no longer around.

POPULATION What would happen to an ecosystem if there were not enough plants or animals? We have learned about the food chain. If there were not enough plants and animals in an ecosystem, the animals could not survive and would have to move or MIGRATE to another area in order to meet their needs and be able to survive.

POPULATION What would happen if there were TOO many plants and animals in an ecosystem? All plants need sunlight. The more plants and trees, the less sunlight plants on the forest floor can get. Without this sunlight, the plants will die. If an ecosystem has too many animals and not enough food sources, the animals will have to migrate in order to meet their needs and be able to survive.

Essential Questions What is necessary for life? Are all organisms important? Why is a food web called a food web? Why do organisms become extinct? What are the roles of producers, consumers, and decomposers in the community? How does the flow of energy go through the food chain? Where does the energy come from? How will changes in the environment affect a community of organisms? How does population affect the number of plants and animals in the community?