Human Influences on ecosystems IGCSE Biology

ppt igcse biology

1. HUMAN
INFLUENCES ON
ECOSYSTEMS

2. Human pressures: Food Production
◦Agricultural Machinery
◦Agricultural chemicals: Fertilisers, insecticides,
herbicides.
◦Selective breeding.

3. Human pressures:
Monocultures
◦Monocultures make sowing, tending, harvesting and
selling a crop more efficient for the farmer.
Advantages:
More easy and efficient to cultivate
It can be harvested at once.
Can be treated with the same herbicides or pesticides.
Produce more seeds, fruits or more product.
Disadvantages:
Reduction in biodiversity.
Increase in pests
Reduction in soil fertility

4. Human pressures: Intensive/Extensive
livestock production
◦In the extensive livestock productionthe cattle can feed on grass
in large areas. This type of livestock production do not take too
much from the environment, and do not do much damage to it.
◦In the intensive livestock production large numbers of livestock
are kept in an area that would not normally be able to support
more than a very small number of animals.
◦
Advantages: more food, cheaper food, uses less land.
◦Disadvantages: Welfare issues, Diseases, High amount of waste,
low energy efficient, transport, water.

5. Human pressures: Intensive/Extensive
livestock production

6. Habitat destruction
◦Deforestation
◦Damage of different habitats
◦Polluted environments
◦Removing key species

7. Deforestation
◦The cutting down of large numbers of trees is
called deforestation.
◦This occurs in rainforests. These are places with a
high biodiversity of plants and animals. When an
area of rainforest is cut down, the soil is exposed
to the rain and is washed away (run-off). This is
known as soil erosion.
◦Can causes floodings in different regions.

8. Deforestation
◦The cutting down of large numbers of trees is called
deforestation.
◦This occurs in rainforests. These are places with a
high biodiversity of plants and animals. When an
area of rainforest is cut down, the soil is exposed to
the rain and is washed away (run-off). This is known
as soil erosion.
◦Can causes floodings in different regions.
◦Danger of extinction

9. Greenhouse gases

10. Eutrophication
◦Fertiliserscontains the mineral ions
nitrate and phosphorus which help
producersto grow rapidly. When
fertilisersenter water algae can
grow into a bloom that covers the
surface of the water.

12. Maintaining resources
◦Forest:
◦setting quotasfor logging, which may mean banning logging
entirely in some areas
◦using educationprogrammesto help local people to understand
why the forest is important creating protected areas.
◦Fishing:
◦Education
◦Closedseasons
◦Protectedáreas
◦Quotas
◦Controllednet typesand mesh size
◦Monitoring
Many of the strategies used to maintain and conserve forests
and fish are similar. The strategies are just applied within a
different context.

14. Threats to wildlife
A species may become endangered, and may even become
extinct, by factors including:
•destruction of habitat
•pollution
•climate change
•hunting
•introduced species
•overharvesting.

15. Threats to wildlife
A species may become endangered, and may even become
extinct, by factors including:
•destruction of habitat
•pollution
•climate change
•hunting
•introduced species
•overharvesting.

16. Threats to wildlife
A species may become endangered, and may even become
extinct, by factors including:
•destruction of habitat
•pollution
•climate change
•hunting
•introduced species
•overharvesting.

17. Threats to wildlife
A species may become endangered, and may even become
extinct, by factors including:
•destruction of habitat
•pollution
•climate change
•hunting
•introduced species
•overharvesting.

18. Threats to wildlife
A species may become endangered, and may even become
extinct, by factors including:
•destruction of habitat
•pollution
•climate change
•hunting
•introduced species
•overharvesting.

19. Threats to wildlife
A species may become endangered, and may even become
extinct, by factors including:
•destruction of habitat
•pollution
•climate change
•hunting
•introduced species
•overharvesting.

20. Population size and variation
◦As the size of a
population
decreases, genetic
variation within the
population is also
reduced. This means
that there are fewer
different alleles
expressing different
phenotypes, so the
population is less
able to adapt to
changes in the
environment.

21. Conservation programmes
Monitoring
and
protecting
Education Seed banksCaptive
breeding
programs
Monitor
migration
routes
Raise
awareness
Samples of
seed of many
plant species
Helps to
increase the
number of
individuals
Record
changes to
habitats
Pressure on
governments
Needs to use
Artificial
insemination
or IvFto
maintain
variation.
Note
changing in
behaviour
Pressure on
industries
Conservation is an important activity because it:
•reduces extinction of species
•increases biodiversity
•protects ecosystems
•maintains important ecosystem functions