u5 l2 human impact on land

Unit 5 Lesson 2 Human Impact on Land

Copyright © Houghton Mifflin Harcourt Publishing Company


Indiana Standard


• 8.2.6 Identify, explain, and discuss some effects human activities have on the biosphere, such as air, soil, light, noise and water pollution.

• 8.2.8 Explain that human activities, beginning with the earliest herding and agricultural activities, have drastically changed the environment and have affected the capacity of the environment to support native species. Explain current efforts to reduce and eliminate these impacts and encourage sustainability.

Land of Plenty


Why is land important?

• It is hard to imagine human life without land.

• Land and its resources affect every aspect of human life.


What are the different types of land use?• Humans use land in many ways, including

recreation, transportation, agriculture, residence, commerce, and industry.

• Natural areas are places that humans have left alone or restored to a natural state.

• Natural areas include forests, grasslands, and desert areas.



What are the different types of land use?• Roads and train tracks connect areas across the

country.

• Roads in the U.S. highway system cover 4 million miles of land.

• Much of the open land in rural areas is used for agriculture. Agricultural land is used to raise and feed cattle and other livestock.



What are the different types of land use?• Residential areas can be rural or urban.

• Rural areas have a lot of open land and low densities of people.

• Urban areas have dense populations.



What are the different types of land use?• Urbanization is the growth of urban areas caused

by people moving into the cities.

• As cities and towns expand, commercial businesses are built, too, replacing rural or natural areas.

• Industrial businesses also use land resources.



Why is soil important?

• Soil is a mixture of mineral fragments, organic material, water, and air.

• Soil provides habitats for organisms such as plants, fungi, and bacteria.

• Plants get much of the water and nutrients they need from soil.




• Soil is a habitat for organisms.

• Many burrowing animals live in soil and find food underground.

• Decomposers, which are organisms that break down dead animal and plant material, live in soil.

• Soil holds plant roots in place.




• Soil stores water and nutrients.

• Different types of soil can store different amounts of water.




• Soils are also part of the nutrient cycle.

• Plants take up nutrients and water from the soil, then are broken down by decomposers.

• The decomposers release the nutrients back into the soil, and the cycle starts again.




Dust Bowl


• In the 1930s, much of the Great Plains of the United States were wiped out by huge dust storms.

• Farmers in the area had overplowed and overgrazed the land. A severe drought dried out the topsoil, and winds carried away the soil in huge black clouds.

• A similar dust bowl is forming now in China because of similar farming practices and drought conditions.

Footprints


How can human activities affect land and soil?• Human activities have positive and negative

effects on land and soil.

• Some activities can degrade land.

• Land degradation is the process by which human activity and natural processes damage land to the point that it can no longer support the local ecosystem.


How can human activities affect land and soil?• Urban sprawl occurs when houses, roads, schools,

and shopping areas replace forests, fields, and grasslands.

• Urban sprawl decreases the amount of farmland available for growing crops.

• It also decreases the amount of natural areas that surround cities.



How can human activities affect land and soil?

• Erosion is the process by which wind, water, or gravity transports soil and sediment from one place to another.

• Erosion can speed up when land is degraded because degradation exposes soil to blowing wind and running water.



How can human activities affect land and soil?• Soil nutrients can get used up if the same crops

are planted year after year.

• Farmers can plant a different crop each year to reduce nutrient loss.

• Pollution from industrial activities can damage land.

• Mining wastes, oil and petroleum spills, and chemical wastes can kill organisms in the soil.



How can human activities affect land and soil?• Desertification is the process by which land

becomes more desertlike and unable to support life.

• Keeping too many livestock in one area can lead to desertification.



How can human activities affect land and soil?• The removal of trees and other vegetation from an

area is called deforestation.

• Logging for wood, surface mining, and urbanization can cause deforestation.

• Deforestation leads to increased soil erosion.



u5 l2 human impact on land

Science

human impact

landand soil

gravitytransports soil

different typesof soil

land resources

land degradation

soil storeswater andnutrients

millionmiles of land