Chapter 20 Lesson 2P724-731

IMPACTS ON THE LAND

Vocabulary

Deforestation – the removal of large areas of forests for human purposes

Desertification – the development of desert like conditions due to human activities and/or climate change

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

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

Reclamation – 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

agriculture, grazing, or building houses or highways

Sometimes large portions of forests are cleared

Deforestation is the removal of large areas of forests for human purposes. Approximately 130,000km2 of tropical

rainforests are cut down each year. Tropical rain forests are home to an estimated

50% of all the species on Earth. Deforestation destroys habitats, which can

lead to species’ extinction.

Borneo Deforestation

Forest Resources

Deforestation can also affect soil quality. Plant roots hold soil in place. Without these natural anchors, soil erodes

away. Deforestation can also affect air quality

Trees remove carbon dioxide from the air when they undergo photosynthesis.

With fewer trees more CO2 remains in the air.

Agriculture and the Nitrogen Cycle It takes a lot of food to feed 7 billion people 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 nitrogen to make proteins

When living things die and decompose they release that nitrogen back into the soil and the atmosphere

Agriculture and the Nitrogen Cycle Although nitrogen gas makes up about 79%

if Earth’s atmosphere, most living things cannot use the gaseous form of nitrogen.

Nitrogen must be converted into a usable form.

Bacteria that live on the roots pf certain plants convert atmospheric N into a form useful for plants.

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

Agriculture and the Nitrogen Cycle Scientists estimate that human activities

such as manufacturing and applying fertilizers to crops have double the amount of nitrogen cycling through ecosystems.

Excess nitrogen can kill plants adapted to low nitrogen levels and affect organisms that depend on those plants for food.

Fertilizers can seep into groundwater supplies, polluting drinking water

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

Other Effects of Agriculture

Soil erosion can occur when land is overfarmed or overgrazed

High rates of soil erosion can lead to desertification

Desertification is the development of desert-like conditions due to human activities and/or climate change

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

Mining

Many useful rocks and mineral are removed from the ground by mining For example, copper is removed from the

surface by digging a strip mine. Coal and other in-ground resources also can be

removed by digging underground mines Mines are essential for obtaining much-

needed resources. However, mines disturb habitats and

change the landscape. Runoff that contains heavy metals can also

pollute water sources if not regulated.

Underground Mining

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

developed as suburbs, residential areas on the outside edges of a city.

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

Urban sprawl impacts the environment by habitat 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. By 2005, there were 240 million vehicles for

295 million people In 1960, the U.S. had about 16000km of

interstate highways. In 2012, the interstate high system

includes 47000km of paved roadways This, like urban sprawl, also destroys

habitats.

Recreation

People also use land for recreation

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

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

About 14% is burned About 55% is places in landfills where trash is

buried

A landfill is carefully designed to meet government regulations. Trash is covered by soil to keep it from blowing

away. Special liners help prevent pollutants from leaking

into soil and groundwater supplies.

Hazardous Waste

Some trash cannot be placed in landfills because it contains harmful substances that can affect soil, air, and water quality.

This trash is called hazardous waste. The substances in hazardous waste can also affect the

health of humans and other living things Both industries and households produce hazardous

waste Medical hazardous waste includes used needles and

bandages Household 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 disposal.

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 first national park in the world, establish in 1872. This set an example to other countries for

setting aside land for preservation 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 Mining and logging are allowed on some of

these lands However, the removal of resources must meet

environmental regulations

Reforestation and Reclamation A forest is a complex ecosystem,

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

For example, trees can be select-cut That means that only some trees in one area are

cut down, rather than the entire forest. People also can practice reforestation

Reforestation involves planting trees to replace trees that have been cut or burned down

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

Reforestation and Reclamation Mined land also can be made

environmentally healthy through reclamation. Reclamation is the process of restoring

land disturbed by mining. This happens by reshaping the area,

covering it with soil, and replanting trees and other vegetation.

Green Spaces

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

Green spaces are areas that are left undeveloped or lightly developed. They include parks within cities and forests

around suburbs Green spaces provide recreational

opportunities for people and shelter for wildlife

They also reduce runoff 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. Reusing is using an item for a new purpose Reducing is using fewer resources Recycling is making new products from a used

product Composting also lessens land impact

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

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