Chapter 20 Lesson: Impacts on the Land – p724-731 – page 1

Vocabulary

Deforestation (725) – the removal of large areas of forests for human purposes

Desertification (726) – the development of desert like conditions due to human activities and/or

climate change

Urban Sprawl (728) – the development of land for houses and other buildings near a city

Reforestation (730) – planting trees to replace trees that have been cut or burned down

Reclamation (730) – the process of restoring land disturbed by mining

Using Land Resources

Obtaining resources from nature for books, pens, everything requires people to use land for timber

production, agriculture, and mining.

All of these activities impact that environment

Forest Resources

Trees are cut for fuel and to clear land for ______________________, grazing, or building houses or

highways

Sometimes large portions of forests are cleared

Deforestation is the removal of large areas of ______________________ for human purposes.

o Approximately 130,000km2 of tropical rainforests are cut down each year.

o Tropical rain forests are home to an estimated ________% of all the species on Earth.

Deforestation destroys habitats, which can lead to species’ __________________________.

Figure 1. Borneo Deforestation

Deforestation can also affect _________________________ quality.

o Plant roots hold soil in place.

o Without these natural anchors, soil erodes away.

Deforestation can also affect ______________________ quality

o Trees remove carbon dioxide from the air when they undergo ________________________.

o With fewer trees more CO2 remains in the air.

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Agriculture and the Nitrogen Cycle

It takes a lot of food to feed 7 billion people

o To meet the food demands of the world’s population, farmer often add fertilizers that

contain nitrogen to soil to increase crop yield

Living things must use __________________________________ to make proteins

o When living things die and __________________________ they release that nitrogen back

into the soil and the atmosphere

Although nitrogen gas makes up about 79% if Earth’s atmosphere, most living things cannot use the

________________________ form of nitrogen.

o Nitrogen must be converted into a usable form.

o _______________________ that live on the roots of certain plants convert atmospheric N

into a form useful for plants.

Fertilizers used today contain a abundant amount of Nitrogen in its usable form

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Scientists estimate that human activities such as manufacturing and applying fertilizers to crops

have _____________________________ the amount of nitrogen cycling through ecosystems.

o Excess nitrogen can kill plants adapted to low nitrogen levels and affect organisms that

depend on those plants for food.

o Fertilizers can seep into groundwater supplies, ______________________ drinking water

o They can also run off into streams and rivers, affecting aquatic organisms

Other Effects of Agriculture

Soil erosion can occur when land is ______________________________ or overgrazed

High rates of soil erosion can lead to desertification

Desertification is the development of _________________________-like conditions due to human

activities and/or climate change

A region of land that undergoes desertification is no longer useful for ______________ production

Mining

Many useful rocks and mineral are removed from the ground by mining

o For example, copper is removed from the surface by digging a ___________________ mine.

Coal and other in-ground resources also can be removed by digging __________________________

mines

Mines are essential for obtaining much-needed resources.

o However, mines disturb habitats and change the landscape.

o Runoff that contains heavy metals can also pollute water sources if not regulated.

Strip Mining

Underground Mining

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Construction and Development

Land itself is also a very important resource. People use land

for living space.

Urban Sprawl

The development of land for houses and other buildings near

a city is called urban sprawl

o In the 1950s, large tracts of rural land in the US were

developed as suburbs, _________________ areas on

the outside edges of a city.

o When the suburbs became more crowded, people moved farther out into the country.

Urban sprawl impacts the environment by ____________________ destruction and loss of valuable

farmland

As more ground is paved for sidewalks and streets, runoff increases because rainwater cannot drain

into the soil.

Typically runoff from cities and suburbs contain many pollutants,

like sediment and chemicals, which can reduce the water quality

in streams, rivers, and groundwater

Roadways

Only a small percentage of Americans owned cars before the

1940s.

o By 2005, there were ________________ million vehicles

for __________________ million people

In 1960, the U.S. had about 16000km of interstate highways.

In 2012, the interstate highway system includes 47000km of

paved roadways

This, like urban sprawl, also destroys habitats.

Recreation

People also use land for recreation

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Waste Management

Everyday, each person in the U.S. generates about 2.1 kg of trash.

That adds up to 230 million metric tons per year.

Landfills

Facts

o About 31% of trash in the U.S. is recycled and composted.

o About 14% is burned

o About 55% is places in landfills where trash is buried

A landfill is carefully _____________________________________ to meet government regulations.

Trash is covered by soil to keep it from blowing away.

Special _____________________ help prevent pollutants from leaking into soil and groundwater

supplies.

Hazardous Waste

Some trash cannot be placed in landfills because it contains ____________________ substances

that can affect soil, air, and water quality.

This trash is called hazardous waste.

o The substances in hazardous waste can also affect the

health of __________________ and other living things.

Both industries and households produce hazardous waste

o Medical hazardous waste includes used needles and

bandages

o _____________________ hazardous water includes used

motor oil and batteries

The EPA (U.S. Environmental Protection Agency) work with state

and local agencies to help with safe ______________________.

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Positive Actions

Human actions can have negative effects on the environment, but they can have positive impacts as

well

Governments, society, and individuals can work together to reduce the impact of human activities

on land resources.

Protecting the Land

Yellowstone National Park was the ______________ national park in the

world, establish in 1872.

o This set an example to other countries for setting aside land for

preservation

o State and local governments also followed this example in the U.S.

Protected forests and parks are important habitats for wildlife and are

enjoyed by millions of visitors each year

o Mining and logging are _____________________ on some of these

lands

o However, the removal of resources must meet environmental

regulations

Reforestation and Reclamation

A forest is a complex ecosystem,

o With careful planning, it can be managed as a _________________________ resource.

o For example, trees can be ____________________-cut

That means that only some trees in one area are cut down, rather than the entire

forest.

People also can practice reforestation

o Reforestation involves planting trees to ___________________ trees that have been cut or

burned down

o Reforestation can keep a forest healthy or help reestablish a deforested area.

Mined land also can be made environmentally healthy through _____________________________.

o Reclamation is the process of restoring land disturbed by mining.

o This happens by reshaping the area, covering it with soil, and replanting trees and other

vegetation.

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Green Spaces

Many cities use green spaces to create natural environments in urban settings.

Green spaces are areas that are left _________________________________ or lightly developed.

o They include parks within cities and forests around suburbs

o Green spaces provide recreational opportunities for people and shelter for wildlife

o They also reduce _____________________ and improve air quality as plants remove excess

CO2 from the air

How can you help?

Individuals can have a big-impact on land use issues by practicing the 3-Rs.

o _____________________ is using an item for a new purpose

o _______________________ is using fewer resources

Recycling paper reduces deforestation and _________________ use

o Recycling is making new products from a used product

Composting also lessens land impact

o You can compost food scraps into a material that is added to soil to increase its fertility

o Compost is a mixture of decaying organic matter that improves soil quality by adding

nutrients.

o Speeds up the rate of ______________________________________