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.

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.

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.

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.

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.

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.

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.

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

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