Transcript human impact - Hicksville Public Schools / Homepage

Aim: How have humans negatively
affected diversity in the
environment?
Do Now: What is meant by carrying
capacity? What is the carrying
capacity of the human population?
Test on Friday - Ecology/Human
Impact
Human Impact
Although not the most numerous
organisms on earth, humans have the
greatest effect on the environment.
How do humans usually impact
the balance in ecosystems?
Why are humans disrupting the
balance in ecosystems?
•The human population shows exponential
growth- it has just reached 7 billion!!!
•This large number of people puts a huge
strain on the environment.
How did this rapid growth
occur?
Increased Food Supply
Improved Health Care
Improved Sanitation
and hygiene
Carrying Capacity- is the
number of individuals the
environment can support.
Limiting Factors- are
factors in the
environment that limit the
size of populations.
What are some of our limiting factors?
Food, Water, Oxygen, Space
Carrying Capacity
Time
Have we reached earth’s
carrying capacity?
No, because we
continuously come
up with new
technologies to
produce more
food
What are some of the detrimental
effects of overpopulation?
Over Consumption
Technology
Waste Disposal
What are some of the detrimental
effects of overpopulation?
Overcrowding
Habitat Destruction
Industrialization
Deforestation
Deforestation
Why?
• Provide land for farming
• provide people places to live
• Provide Resources to use in building or
manufacuring
Effects:
1)Deforestation leads to habitat destruction.
2) Organisms have no place to live.
3)Organisms can become endangered or
extinct.
4) Biodiversity decreases.
Direct Harvesting
• Organisms (plants and animals) are
removed from the environment and NOT
replaced.
• Organisms are usually obtained through
hunting or poaching (illegal hunting).
• Often results in the loss or elimination of a
species & a decrease in biodiversity.
• Examples: Ivory, Exotic Birds
Imported Species
Non-native or Invasive species
(not belonging to)
•animal and vegetation species often become
invasive when introduced into environments
lacking natural predators or other
mechanisms to keep the dominating species
in check.
•These species become pests & disrupt the
• Highly adaptable animal. Not a
picky eater and breeds very fast.
• Destroyed massive amounts of
vegetation & reduced
biodiversity.
• In Australia, it spread like wildfire
because its natural predators
from back home, the weasel and
fox, were not originally present.
• The dingo and Tasmanian wolf,
Australia's native carnivores(and
potential rabbit consumers), were
themselves being kept in check
The European Rabbit
by local sheep and cattle
ranchers.
New York’s Biggest Pest:
Gypsy Moth
The Gypsy Moth originally
evolved in Asia & was
introduced here accidentally
in 1868.
What can happen when non-native species are
added to a new environment?
1)They often have no natural predators.
2)Rapidly overpopulate.
3)They then crowd out, feed on, or otherwise
eliminate native species.
4) Biodiversity decreases.
How do ecologists solve these
pest problems?
• A virus was promptly
released into the wild
in Australia and
effectively spread like
wildfire through
mosquito and rabbit
flea bites, and killed all
but 0.2% of the rabbits.
This small percentage
had built a resistance
to the virus, bred like
rabbits, and passed on
the resistance to the
virus.
Disease
Organism
Specific for the
Pest:
How do ecologists solve these
pest problems?
Use of Pesticides
or Insecticides:
These chemicals/poisons can kill the
pest, but also other organisms native to
the ecosystem.
Biological Control
• The release of natural predators of a pest
species is a safe way to control pest problems
without reducing diversity.
• If a non-native predator is imported to
control the pest, it may choose to feed on
other native organisms reducing biodiversity.
•Ex. The ladybug is released to eat aphids
(bugs that eat crops).
What are the effects of farming?
•
•
•
•
What happened to biodiversity?
What happened to ecosystem stability?
What would happen if an insect came along?
What do farmers use to get rid of insects?