Threats to Biodiversity: -Keystone Species -Invasive Species -Fragmentation

Keystone Species A species on which in an ecosystem largely depend upon, such that if it were removed, the ecosystem would change drastically. Ex) Beavers- Construct dams out of trees. The dam changes the free flowing stream habitats into ponds, wetlands, and meadows. This modification leads to a cascade of changes within their ecosystem.

Habitat Fragmentation Occurs when a barrier forms that prevents an organism from accessing its entire home range. Building roads or logging of forests Removal of large portions of the forest small patches or fragments of the original habitat remaining. Wetlands around ponds, lakes, and rivers are drained in order to increase the amount of land suitable for human purposes.

Invasive Species Any organism brought into an ecosystem as the result of human actions. Not native to the area: Few natural predators Tend push out native species. Out-compete native species Reduces the amount of resources (food, water, sunlight) available for the native species. Include plants and animals Examples: Kudzu vine European Starlings Cane toads.

Other Human Impacts

Pollution Any undesirable factor that is added to the air, water, or soil which makes an environment harmful to organisms that live there. Smog is a type of air pollution caused by the interaction of sunlight with pollutants produced by fossil fuel emissions. Some particulates may stay in the atmosphere for weeks before they settle to the ground. Fine particulates can be inhaled and cause many types of health problems. Acid Rain is a type of precipitant produced when pollutants in the water cycle cause rain pH to drop below normal levels. Threatens water supplies and species habitat.

Bio-Magnification A pollutant moves up the food chain as predators eat prey, accumulating in higher concentrations in the bodies of predators. High death rates in young organisms due to high toxic compounds found in the organism’s parents. Persistent organic pollutants are biomagnified and stay in the environment for long periods of time and over long distances.

Overharvesting Taking more from the land (or sea) than it can replace. extreme farming, grazing, fishing, and using fresh water.  harmful in the long run. Forests or wetlands are hard to replace. Damage to nature hurts animals and humans.

Climate Change/ Greenhouse Effect Greenhouse effect occurs when carbon dioxide, water, and methane molecules absorb energy radiated by Earth’s surface and slow the release of this energy from Earth’s atmosphere. automobile use and industry growth Global Warming is the trend of increasing global temperatures. Over the past 100 years, the average global temperature has risen 0.74ºC, with the most occurring within the past few years.

Urbanization Forms when industrial and urban areas produce and retain heat. reduces soil moisture and a reduction in reabsorption of carbon dioxide emissions

Eutrophication Eutrophication is when a body of water becomes overly enriched with minerals and nutrients that induce excessive growth of plants and algae. may result in oxygen depletion of the water body.