1. 3.1 Community Ecology

2. ecological succession
Vocabulary List
community
limiting factor
tolerance
ecological succession
primary succession
climax community
secondary succession

3. BIOLOGICAL COMMUNITY is a group of interacting populations that occupy the same area at the same time.
There are many factors restrict the growth of a population in communities

4. Limiting factors What factors limit populations in communities?
Any abiotic factor or biotic factor that restricts the numbers, reproduction, or distribution of organisms
Limiting factors
Factors that limit one species might enable another to thrive.
(Water is a limiting factor and organisms that need less water can survive in a desert community.

5. Organisms have a range of tolerance for each limiting factor that they encounter
For any factor, there is an upper limit and a lower limit that defines the conditions in which an organism can live.
Tolerance is the ability of any organism to survive when exposed to abiotic or biotic factors

6. Organisms have a range of tolerance for each limiting factor that they encounter
Steelhead trout live in cool, clear coastal rivers and streams with the ideal range of water temperature for steelhead trout is between 13˚C and 21˚C

7. Organisms have a range of tolerance for each limiting factor that they encounter
However, steelhead trout can also survive water temperatures lower than 13˚C (9˚C) and more than 21˚C (up to 25˚C)
At these temperatures, steelhead trout experience physiological stress = inability to grow or reproduce, but they still survive

8. Organisms have a range of tolerance for each limiting factor that they encounter
Beyond the upper tolerance limit of 25˚C and the lower tolerance limit of 9˚C, there are no steelhead trout, as they would die living there
Therefore, water temperature is a limiting factor for steelhead when water temperature is outside the range of tolerance

9. Ecological Succession
Ecosystems constantly change (a tree falling, a fire…)
The process of one community replacing another as a result of changing abiotic and biotic factors is called Ecological Succession
Primary
Secondary

10. Primary Succession
Is the establishment of a community in an area of bare rock that does not have topsoil
For example, retreating glacier or volcanic eruptions can alter an ecosystem

11. Primary Succession ONLY ORGANISMS PRESENT: Bacteria Fungal spores or
Pollen grains
FIRST TO GROW (The first organisms to appear = pioneer species):
Lichens begin to grow on the rock first
Mosses
Algae

12. Pioneer Species Help Create Soil
Pioneer species physically and chemically break down rocks.
As pioneer species die, their decaying organic materials mix with small pieces of rock  the first stage of soil development

13. Pioneer Species Help Create Soil
Small weedy plants begin to grow in the soil, and as they die, they add to the soil
Seeds brought by animals, water, and wind begin to grow.

14. Pioneer Species Help Create Soil
Eventually, enough soil forms to support trees and shrubs.

15. Pioneer Species Help Create Soil
It might take hundreds of years for the ecosystem to become balanced and achieve equilibrium (the number of species remain relatively constant)

16. Pioneer Species Help Create Soil
This is a climax community  a stable, mature community in which there is little change in the number of species.

17. Secondary Succession
Disturbances such as fire or flood can disrupt a community

18. Secondary Succession
Is the orderly and predictable change that takes place after a community of organisms has been removed by such disturbances but the soil remains.

19. Secondary Succession
New species of plants and animals might occupy the habitat and also the species belonging to the climax community are likely to return.
Pioneer species begin the process of restoring a habitat after a disruption.

20. Secondary Succession
New species of plants and animals might occupy the habitat and also the species belonging to the climax community are likely to return.
Pioneer species begin the process of restoring a habitat after a disruption.
Leading again to a mature climax community

21. Classwork/Homework
3.1 Reading Notes
3.1 Study Guide
3.1 Quick Check

22. Answer both Questions

23. Graph the following data to determine the range of tolerance for catfish.
The first number in each pair of data is temperature in degrees Celsius, and the second number is the number of catfish found in the stream: (0, 0); (5, 0); (10, 2); (15, 15); (20, 13); (25, 3); (30, 0); (35, 0)

25. describe the stages a population goes through as it increases in size, with reference to terms such as exponential growth, logistic growth, cyclic growth, carrying capacity, steady state
describe density-dependent and density-independent factors that limit and control population growth