2.5 - Natural Disturbances to Ecosystems

Natural disturbance

A natural event that disrupts the structure and function of an ecosystem

- can occurs on periodic, episodic, or random time frames

- ex. Tornadoes, floods, forest fires, drought

**NOTE: These can be even greater than human disruptions

Periodic

Occurs with regular frequency

- dry/wet seasons

Episodic

Occasional events with somewhat regular frequency

- hurricanes, droughts, fires

Random

No regular frequency

- tornadoes (massive), asteroid

Natural Climate Change

Earth's climate had varied for millions of years for numerous reasons before out time

- slight change's in Earth's orbit and tilt -> changes in amount and distribution of solar energy

- causes mini ice ages and warmer periods

Natural Climate Change -water level

Sea level has varied over geological time as glacial ice on earth melts and forms

- warmer periods = ice melts and rises

- colder periods = water freezes and lowers

Habitat Destruction

Environmental Change =

- Major environmental disturbances result in widespread habitat changes and/or loss

- ex. Rising sea level -> floods coastal and estuary habitats

Migration

Wildlife may migrate to a new habitat as the result of natural disruptions

- ex. Wildebeests migrate to follow rain patterns of African savanna

- ex. Ocean species moving further north as temperature warms

- ex. Bird migration and breeding shifting earlier as insect hatching shifts earlier with warming climate