2. Disturbances are Common in Communities

3. Negative-Natural disasters can lead to injuries and many worse things. such as loss of property, land and lives. Positive-They could bring people together as they work to help each other recover How disturbances can have positive and negative effects

4. Primary Succession occurs when a major, massive disturbance such as a glacial retreat, volcanic eruptions, etc. destroys all the plants in an area, allowing other species to colonize The initial colonists on a terribly disturbed site vary depending on the nature of it: smooth, bare rocks will attract lichens, gravel will attract perennial herbs, and sand will be covered by grasses. These plants increase the amount of nitrogen in the soil, attracting legumes and other nitrogen fixers, which further develop the nitrogen pools

5. Secondary Succession Occurs when a disturbance (fire, windstorms, etc.) occurs but does not wipe out all the plants in an area Leaves behind a seed-bank or a number of vegetative areas. Short lived, fast growing plants take over first, followed by herbaceous perennials, short-lived trees, and finally slow- growing, long-lived trees.

6. Comparison between both Primary succession occurs following an opening of a pristine habitat, for example, a lava flow, an area left from retreated glacier, or abandoned strip mine. In contrast, secondary succession is a response to a disturbance, for example, forest fire, tsunami, flood, or an abandoned field. Secondary Primary

7. How do human activities affect species diversity? Over-exploitation pollution and habitat conversion are the main threats to species diversity. They cause a gradual loss of species on local, regional and global levels. Additionally, the introduction of species into new ecosystems destroys natural balance.

8. Articles http://www.katrina.noaa.gov/ http://news.bbc.co.uk/2/hi/8455629.stm