1. Ecology Project Alex Shaw

2. Ecosystem Engineers  Cause physical changes to their environment for own needs  By behavior, or large collective biomass  Beaver  Facilitators; have positive impact due to their effects  Juncus gerardi (Black rush)

3. Bottom-up Top-down  3 possible relationships between plants and herbivores  V  H: V  H: V  H, as an indication of increase of biomass  V  H indicates an increase in vegetation results in an increase in herbivores  V  H indicates an increase in herbivores will decrease plant life  V  H indicates that both trophic levels are sensitive to change

4. Bottom-up Top-down Cont.  V  H is considered a bottom-up model. Nutrient availability controls plants, controlling herbivores, controlling predators; N  V  H  P  Change of the bottom level affects the top level of predators. The removal of upper level predators would not affect lower tropisms.  V  H; Top-down involves predation that controls organization, limiting herbivores, plants, and then nutrients. This is symbolized N  V  H  P

5. Disturbance  Ecosystems were thought to be stagnant and equilibrated  Disturbances are the main flaw  Intermediate disturbance hypothesis suggests that small disturbances can foster greater species diversity  High reduces through stress on populations; low allows dominant species to overcome

6. Human Disturbance  Humans have the greatest impact on ecosystems throughout the world  The severity of human disturbances results in the lowering of diversity

7. Ecological Succession  Ecological succession is the replacement of species with newer ones over time  Primary succession begins in a barren area  Secondary succession involves a disturbance leaving the soil intact  Depending on the early species that inhabit an area, a different type of community will emerge  New species turn into different ones as the environment is changed by their presence.