Human Environmental Impact

Humans can have significant effects on the environment around them Humans can have significant effects on the environment around them. These effects can be either positive or negative.

Pollution Some human activities, such as burning fossil fuels to power cars or to create electricity, release pollutants into the air, water, or soil.

Some pollutants released into the air return to Earth as acid rain. Acid rain can damage forests, lakes, and streams. Damage to forests is particularly likely to happen at elevations about 2,000 feet. Tree death, like that shown below, can occur as acid rain damages leaves. This reduces that amount of nutrients the tree can produce to support itself.

Pollution can also cause smog, decrease the water quality of an environment, and kill plant and animal life.

Habitat Destruction Humans impact the environment when they change or destroy habitats. For instance, rainforests are being used for logging, farming, or mining more and more often.

When parts of the forest are destroyed to prepare the land for these uses, plants and animals that lived in that part of the rainforest then no longer have a habitat in which to live.

Humans also destroy environments through the construction of towns and cities. When humans move into an area, the resources of the habitat can no longer be used by the organisms that lived there. These organisms must find a new habitat or they will die.

Agriculture Humans often use large sections of land for farming and raising domesticated animals. This can change the environment in many different ways.

Farming can change the type and quality of the land, depending on the farming method that is used. For example, slash and burn farming is a type of farming that consists of cutting down and burning forests to make enough room to grow crops. This ruins the area for future farming, removes the oxygen-producing trees from the area, and creates harmful gases from the large fires needed to burn the area. Even traditional farming can deprive the soil of nutrients and make it difficult for anything to grow.

Raising domesticated animals, such as cows, can harm the environment if ranchers allow the animals to overgraze. Overgrazing removes too much vegetation from an area, which increases erosion and reduces soil fertility.

Warm-up What does the word “overfishing” mean to you?

Overfishing Objective: Understand how over using a resource can have negative effects on the entire ecosystem

Schedule Warm-up PowerPoint Presentation Over Fishing Videos Tragedy of the Commons Lab Exit Slip and Clean-up

Vocabulary Resource – something is found in nature that is necessary or useful (ex. Water) Ecosystem – a community of living things and the environment they live in

Fishing Humans fish to get food or for recreation. If done responsibly, fishing can cause minimal harm to an environment. Sometimes, though, humans do not fish responsibly and can cause irreparable damage to ecosystems.

For example, drift nets are huge nets that can be several kilometers long and catch many more fish than do smaller, more traditional nets. Widespread use of these nets around the world can greatly reduce fish populations.

Also, many other marine animals, such as dolphins, turtles, seabirds, and whales, are commonly caught and killed by drift nets. To help prevent these scenarios, the United Nations and national governments have enacted resolutions and regulations limiting the size and use of drift nets.

Reflective Question What do you think about the use of drift nets?

Overfishing is another issue that can occur. This happens when humans catch too many of a specific type of fish. This disrupts the balance of the ecosystem and can lead to extinction.

A oceanic ecosystem

http://www.youtube.com/watch?v=WFHpDWyLLyA

Organisms & the Environment Plants and animals can have an impact on their environment. They can change the way their environment looks, the nutrients available in their environment, and the overall function of their environment.

How does he/she change his/her environment?

Animals can impact the environment around them. For example, beavers cut down trees in order to build lodges and dams over water sources, such as streams. The lodges and dams provide shelter for the beavers. These shelters change the beavers' environment by changing the amount of vegetation and the rate of stream flow in the environment.

Termites are another kind of animal that can have major impacts on their environment. Termites build large above-ground mounds out of soil, mud, and wood. These mounds can be several meters high and affect both the way the environment looks and the nutrients available for other animals.

Plants can also cause changes in their environment. For example, plants release oxygen when they make food. This means that as the number of plants in an ecosystem changes, the amount of oxygen available in the ecosystem also changes.

Plants also influence the amount of nutrients available in the soil where they grow. Plants use nutrients during growth. If plants continue to grow in soil that is not receiving new nutrients, the quality of the soil will eventually decrease.

Biodiversity Some ecosystems are more sustainable than others. Sustainable ecosystems are able to maintain their balance because they have a great deal of biodiversity.

The biodiversity of an ecosystem is the variation, or differences, among living organisms within that ecosystem. This includes genetic variation within a species as well as the variety of different species within an ecosystem. The biodiversity of an ecosystem increases with the number of different species of organisms that live in that ecosystem.

Biodiversity is not evenly distributed on Earth Biodiversity is not evenly distributed on Earth. Some ecosystems are more diverse than others. Usually, the more diverse that an ecosystem is, the more sustainable it is. Biodiversity on land is generally highest at the equator and decreases as you move toward the poles.

Disturbances, such as those caused by human activity, can cause ecosystems to become unstable. When an ecosystem is disturbed, individual organisms, as well as entire species, can die out. Ecosystems can better handle disturbances whenever there is a high amount of biodiversity within that ecosystem. The more varied the organisms within an ecosystem, the more likely it is that some of them could use their specialized and unique adaptations to survive major changes or disturbances in the ecosystem.