Unit 3 science notes

Global extinction

A species goes extinct everywhere.

Local extinction

A species goes extinct only in a specific region.

Functional extinction

A species’ population is so small that it can no longer perform its ecological role.

Background extinction rate

Most extinctions happen naturally and gradually at a rate of 0.1 – 1 species per 10,000 species per 100 years.

Mass extinction

At least 5 mass extinction events have occurred, wiping out 50-95% of species each time.

Sixth mass extinction

Current extinction rate is 100-1000 times higher than the background rate.

Endangered species

Species in danger of extinction throughout all or most of its natural range.

Threatened species

Species likely to become endangered in the near future.

Habitat loss

The single greatest threat to biodiversity.

Habitat fragmentation

When human development divides landscapes into small, disconnected habitat islands.

Aquaculture

The cultivation of aquatic organisms in controlled environments.

Tragedy of the commons

When short-term self-interests of a few lead to tragedy for all.

Invasive species

A non-native species that thrives in a new environment.

Pollution

Air and water pollution degrade habitats and contribute to the disappearance of some species.

Deforestation

Approximately 20,000 square miles of forest lost each year.

Reforestation

The process of planting trees to restore a forest.

Ecological restoration

Assisting the recovery of an ecosystem back to its natural state after degradation.

Proxy records

Preserved physical characteristics of past environments that stand in for direct observation.

Prescribed fire

Intentionally-set, low-intensity fires used in land management.

Tallgrass prairie restoration

Restoring tall-grass prairie ecosystems using bison and fire as key elements.