Grade 8 Integrated Science Chapter 20 Lesson 2 on human impact on the land. This lesson is a detailed look into the positive and negative effects of humans to land biomes. This lesson includes topics such as resource management, the nitrogen cycle, deforestation, mining, agriculture, and urban sprawl. Students should consider the many different impacts we have on the environment everyday.

1. Chapter 20 Lesson 2
P724-731
IMPACTS ON THE
LAND

2. 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

3. 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

4. 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.

6. Borneo Deforestation

7. 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.

8. 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

10. 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

12. 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

13. 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

15. 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.

19. Underground Mining

20. Construction and Development
 Land itself is also a very important resource.
People use land for living space.

21. 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

24. 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.

26. Recreation
 People also use land for recreation

27. 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.

28. 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.

29. 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

31. 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.

32. 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

34. 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.

36. 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.

37. 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

39. 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.