1. What is an Ecosystem SECTION 16.1

2. Interactions of Organisms and their environment Populations don’t live by themselves – they are in an area with other populations Community – all the populations in a certain location Ecosystem – the community along with the physical parts of the environment ◦Biotic factors – the living organisms in an ecosystem (the community) ◦Abiotic factors – the nonliving parts in an ecosystem (sunlight, soil, weather…) ◦Within this is the organism’s habitat – the actual location where it would be found (the soil for an earthworm, a tree for a bird…)

3. Biodiversity All the different organisms within an ecosystem Includes the plants, animals, fungi, bacteria We also think about the genetic diversity Ecosystem boundaries – there is rarely a sharp line between one type of ecosystem and another

4. Changes in ecosystems - Succession Primary succession – occurs in areas where no life has existed before ◦Example: a new volcanic island ◦First thing that happens is soil formation ◦Then small, fast growing plants – the pioneer species ◦As the soil gets deeper, these plants are replaced by larger species

5. Changes in ecosystems – Succession… Secondary succession – in areas where life has existed but it has been disrupted – by farming, a forest fire, or some other major disturbance ◦The soil is already in place ◦This happens faster than primary succession