1. Disturbances

2. Disturbances • an event that causes damages to an ecosystem; can involve the elimination of of organisms and modify the availability of resources

3. Variation in Type, Frequency, and Severity of Disturbances Not All Disturbances are equal; depends on • Type: ex. snow storms, sand storms, hurricanes, volcanic eruptions • Frequency: yearly, occasionally, frequently • Severity: lots of damage, very little damage

4. Natural Disturbances • Not caused by humans but cause damage to ecosystems • Ex. Storms, volcanic eruptions, forest fires, droughts, floods • Storms over oceans affect surface and bottom when water mixes

5. Human Disturbances • Damages caused to ecosystems by humans • Logging, offshore oil • Oil spills in oceans affect plants, birds, animals

6. Ecological Succession • Series of changes that operate in an ecosystem after a disturbance until the ecosystem reaches an equilibrium state • Ex. Trees cut down causes birds to leave (no place to nest), mice come to feed, predators of mice enter to eat mice • Each change brings about another one

7. Bird Expert Worries about drop in numbers • Based on your knowledge of ecology and the Earth explain what will happen as the ecosystem reaches equilibrium (beginning, middle, end)