1. 3.1 Communities

2. Communities Remember: a communities are interacting populations of different species

3. Communities Why do certain populations live in certain communities? Polar bears only live in cold Catfish can live in warmer water than trout Abiotic and biotic conditions make life suitable for some organisms, not others

4. Communities Limiting factors affect an organisms ability to survive For example, food, temperature, predators

5. Communities Range of tolerance is the ability of an organism to withstand changes in the environment Organisms thrive under optimum conditions and don’t do as well when conditions change

6. Succession in Communities Over time change can happen, one community is replaced by another If a lawn is not cut, the grass gets taller and it becomes a meadow. Later shrubs and trees begin to grow into a forest

7. Succession in Communities Succession is orderly, natural changes and species replacements Succession occurs in stages, each stage creates conditions suitable for the next

8. Succession in Communities Primary succession is the colonization of new sites that don’t even have soil Lava flows, avalanches The first species to grow there are called pioneer species. When they die, decomposition forms soil lichen

9. Succession in Communities Primary Succession

10. Succession in Communities As conditions become suitable, new organisms move in Climax community is a stable, mature community

11. Succession in Communities Secondary succession is the sequence of community changes after disturbance by natural disaster or human action Soil already there, just needs rebuilding

12. Succession in Communities Secondary succession