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?

HW: h/o human impact regents questions

Quarterly Oct. 29-30

Human ImpactAlthough 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 SupplyImproved 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?

Technology

Waste Disposal

Over Consumption

What are some of the detrimental effects of overpopulation?

Overcrowding

Industrialization

Habitat Destruction

Deforestation

Deforestation

Effects:1)Deforestation leads to habitat destruction.

2) Organisms have no place to live.3)Organisms can become endangered or

extinct.4) Biodiversity decreases.

Why?

• Provide land for farming

• provide people places to live

• Provide Resources to use in building or manufacuring

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 (not belonging to)

•animal and vegetation species often becomeinvasive when introduced into environments lacking natural predators or other mechanisms to keep the dominating species in check.

•These species become pests & disrupt the current ecosystem by reducing biodiversity.

• 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 by local sheep and cattle ranchers.

The European Rabbit

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.

• 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.

Biological Control

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?