4-2.6 Explain how organisms cause changes in their environment.
Living Things Change Their Environment
Essential Question: How do organisms cause change within their environments?
All living things change the places where they live. The changes can be helpful or harmful. They can also help some organisms and harm others. In this lesson, you will learn about some ways in which humans, other animals, and plants change their environment.
Essential Question: How do organisms cause change within their environments?
All living things change the places where they live. The changes can be helpful or harmful. They can also help some organisms and harm others. In this lesson, you will learn about some ways in which humans, other animals, and plants change their environment.
Changes Caused by Humans
Humans depend on their environments. People need and get food, water, and many other materials from nature. People also cause big changes in their environments. People burn fuels such as coal and gasoline to get energy. Burning these fuels puts harmful materials into the air. Farmers use chemicals that run off into streams. People throw away trash that ends up buried in the ground. Factories dump dirty water into rivers. All the things described above are forms of pollution. Pollution is the release of harmful substance, or pollutant, into the environment. Pollutants affect all living things. But people are taking steps to keep air and water cleaner. They are working to build cars and factories that cause less air pollution. People are cleaning the water used at factories before putting it back into rivers. People are creating protected river areas called “greenways.” Humans also change environments by cutting down trees. People use wood from trees to build homes and to make paper and other products. If all the trees in a forest are cut down, animals lose their homes. Bu cutting only some of the trees, people can protect animals that live in the forest. And planting new trees helps replace those that are cut. |
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Changes Cause by Animals and Plants
Animals change their environments in many ways. One way is by building homes. Beavers are a good example. They use their teeth to cut down trees and shrubs near a stream or river. The beavers use the wood and branches, along with mug, to build a dam across the stream. The dam makes the water flood to form a pond. Then the beavers build a home called a lodge in the pond. A beaver dam changes the flow of a river or stream. Plants that depended on the stream for water may die out. Animals that drank from the stream have to follow its new flow. But the dam creates a pond environment for other plants and animals. Animals also change environments by using resources. Animals such as deer live in groups called herds. They can eat so many plants in a field that the soil is left bare. The water or wind may carry the soil away. But while they are feeding, the animals leave wastes. Their wastes add materials to the soil that plants need. These materials help new plants grow. Plants, too, change their environments. Trees and other large plants shade smaller plants nearby. With less sunlight, those smaller plants may die. New plants that need less light may take their place. You may have seen a vine called kudzu. People brought kudzu to the United States from Japan in the 1800s. Today, kudzu covers large areas in South Carolina and other states. Kudzu grows so fast that it can quickly cover trees and other plants. The trees and other plants die because they cannot get sunlight. But kudzu is also helpful. It holds soil in place and provides food for cows, goats, and other animals. |