HUMAN ACTIVITIES AND

THE LOSS OF DIVERSITY

1. Direct Harvesting• It is the process of collecting or removing animals and plants from their habitats

Cause:•Overhunting & overfishing •Clearing of forests for agriculture

Effects:• It leads to the extinction or endangered of a species• Loss of biodiversity• Disruption of food chains

Examples: •passenger pigeons (extinction); •lion, blue whale, tiger, panda…(endangered species)

Positive actions: •Laws & legislation to protect endangered species

Passenger pigeon

3 billions to 5 billions is the estimated population when Europeans arrived America

Overhunting, and the clearing of forest for agriculture.

Because passenger pigeon was a colonial and gregarious bird and needed large number of breeding conditions

September 1st, 1914

It disrupted food chains in which passenger pigeons were important part of.Predators of passenger pigeons decreased in population size, and producer populations increased.

Endangered Species

Mountain lions and big horn sheep are part of the natural food web in the Sierra Nevada mountains. The Fish and Wildlife Service recently declared these sheep an endangered species. This action could lead to the shooting of mountain lions.

1) State one reason placing these sheep on an endangered species list could lead to the shooting of mountain lions where the sheep live.

To increase the sheep population, the population of its predator, the mountain lion, would need to be reduced.

OR In order to protect the endangered sheep, any mountain lion found to be attacking sheep may be shot.

2) State two reasons some people would oppose the shooting of the mountain lions.

Mountain lions may become extinct.

OR There would be an increase in competition between sheep and other herbivores.

OR Ethics because it's not right to kill one animal to benefit another.

OR It may disrupt the food chain.

3. How might the lack of genetic diversity found in populations of endangered species hinder their recovery?

If all of the individuals in the small endangered species population are genetically very similar none may have the particular combination of traits needed to survive if the environment changes, leading to the loss of the entire species.

2. Habitat destruction and deforestation

• It occurs when people take over land and forest for their own use, and species have nowhere to live.

• Cause:• Human population growth• Natural resources, land, space and needs increase

• Effects:•Extinction or endangered of a species• Loss of biodiversity

•Example: pandas & tigers.

Logging

wildfire

draining a marsh

clearing woodland to grow crops

Grazelivestock

strip mining

Human Activities that Destroy habitats

Deforestation

How the rainforest is destroyed?

•Timber logging•Plants being burned to clear the land.

How does rainforest deforestation affect organisms?

•Loss of biodiversity

•Disrupting food chains

•Killing predators, leading to increases in some animals' populations.

Deforestation of the Rainforest

How this destruction can be limited?

•Using better farming methods on land that is already cleared •Reforestation•Laws & legislation to set up protected areas

This destruction can be limited by a) using better farming methods on land that is already cleared b) Establishing laws and legislation to protect the rain forestc) Reforestation

a) Two human activities that contribute to the destruction of this habitat

b) Three ways the destruction of this habitat has affected plants, humans, and other animals

c) Two ways to limit further destruction of this habitat

The rainforest is being destroyed by a) timber logging or deforestation d) strip miningb) plants being burned to clear the land e) graze livestock

These activities affect organisms by:a) Loss of biodiversity b) Extinction or endangered of speciesc) killing predators, leading to increases in some animals' populations.d) disrupting food chains and destroying their food supply

•Clearing the land for the mall would cause a decrease in the amount of plant life or biodiversity.

•Destroying the plants would reduce the habitat available for some animals.

•The mall will attract more automobile traffic to the area, increasing the amount of air pollution

The Pine Barrens is a government-protected environment located on the eastern end of Long Island. A proposal has been made to allow a shopping mall to be built in the middle of the Pine Barrens. Although the developer has promised jobs for people in the surrounding communities, some community members oppose the building of the mall due to the negative effects it would have on this fragile ecosystem.

Identify two negative effects this mall would most likely have on the Pine Barrens.

Amphibians have long been considered an indicator of the health of life on Earth. Scientists are concerned because amphibian populations have been declining worldwide since the 1980's. In fact, in the past decade, twenty species of amphibians have become extinct and many others are endangered.

Scientists have linked this decline in amphibians to global climatic changes. Warmer weather during the last three decades has resulted in the destruction of many of the eggs produced by the Western toad. Warmer weather has also led to a decrease in rain and snow in the Cascade Mountain Range in Oregon, reducing the water level in lakes and ponds that serve as the reproductive sites for the Western toad. As a result, the eggs are exposed to more ultraviolet light. This makes the eggs more susceptible to water mold that kills the embryos by the hundreds of thousands.

3) The term used to identify the worldwide climatic changes referred to in the passage isA) global warming B) industrialization C) deforestation D) mineral depletion

4) State two ways the decline in amphibian populations could disrupt the stability of the ecosystems they inhabit.

•Prey populations increase. •Predator populations decrease•It reduces the biodiversity in these areas. •Food chains are disrupted.

3. Imported speciesBiodiversity is often reduced when people import an release a species from one environment into another.

• Cause: They often have no natural enemies in their new environment and rapidly overpopulate the area

• Effect: Many species become pests•Loss of biodiversity, endangered species, and extinction

• Examples: rabbits in Australia, Japanese beetles, gypsy moths

How to fight a pest?• Spraying chemical pesticides• Introducing a predator species of the pest species• Finding a disease organism that only affects the imported species• Setting traps that use chemical scents to attract insects

In July 1997, about 25,000 Galerucella pusilla beetles were released at Montezuma Wildlife Refuge in western New York State. These beetles eat purple loosestrife, a beautiful but rapidly spreading weed that chokes wetlands. Purple loosestrife is native to Europe, but here it crowds out native wetland plants, such as cattails, and does not support wildlife the way the native plants do. Purple loosestrife grows too thick to allow birds to nest. Most native insects do not eat it, leaving little for insect-eating birds to eat. Bernd Blossey, a professor at Cornell University, spent 6 years in Europe trying to find out what limited the loosestrife population there.

1) Explain why the introduction of the Galerucella pusilla beetle is an advantage over the use of herbicides to control the purple loosestrife population.

2) Describe one possible environmental problem that may result from the introduction of the Galerucella pusilla beetle.

It will cause water and land pollutionThe herbicides might kill other plants besides purple loosestrife

The beetle might overpopulate the area and become a pestThe beetle might eat a lot of the other plants instead, and the native species would not have enough food.

3. How can the introduction of a foreign species lead to the extinction of species that are native to an area?

•Foreign species may be better adapted. • Increase of competition•No natural predators of the foreign species •Foreign species may carry disease or parasites.