1. Ecological Niche – Role a species plays in a biological community – Total set of environmental factors that determines a species’ distribution. – Generalists - Broad niche – Specialists - Narrow niche When generalists and specialists collide, generalists usually win.

2. No two species will occupy the same niche and compete for exactly the same resources for an extended period of time. (G.F. Gause) One will either migrate, become extinct, or partition the resource and utilize a sub-set of the same resource. Given resource can only be partitioned a finite number of times.

3. Gause’s Study These two species have the same niche. In competition, one will win out (exclude) the other.

4. Resource Partitioning Placing another closely related species in with the previous “winner” gives a different result – both species persist. Why? Each species occupies a different part of the environment (i.e. they have different niches) – there’s been a partitioning of resources.

5. Competition

6. Resource Partitioning

7. How is Energy Moved and Utilized in Ecosystems? Trophic levels are the “steps” in a food chain moving from producers to different levels of consumers. The efficiency of energy transfer between different levels puts a limit on the number of trophic levels.

8. A Food Web Describes the Way Energy is Transferred Within an Ecosystem

9. Celebrating Rot and Decay - Detritivores Energy isn’t transferred only upwards between trophic levels. Detritovores use the energy available in dead organisms and allow recycling of essential nutrients in ecosystems.

10. Only a Fraction of the Energy Present in Organisms of One Trophic Level Is Captured by Organisms of the the Next This limits the number of trophic levels.

11. Ecological succession is the set of changes in community composition that occur over time in a new or disturbed community. Succession at Mt. St. Helens. Ecological Succession Succession after the Yellowstone fires.

12. Terrestrial Primary Succession

13. Primary Succession Primary succession involves the changes from pioneer species which colonise an environment through the seral stages to the climax community. Changes in abiotic factors lead to more favourable conditions and increasing species diversity

14. Primary Succession Begins in a place without any soil Sides of volcanoes Landslides Flooding Starts with the arrival of living things such as lichens that do not need soil to survive Called PIONEER SPECIES

15. http://botit.botany.wisc.edu http://www.saguaro-juniper.com/

16. Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil Primary Succession

17. http://www.life.uiuc.edu

18. Simple plants like mosses and ferns can grow in the new soil http://uisstc.georgetown.e du http://www.uncw.edu Primary Succession

19. The simple plants die, adding more organic material The soil layer thickens, and grasses, wildflowers, and other plants begin to take over http://www.cwrl.utexas.edu Primary Succession

20. These plants die, and they add more nutrients to the soil Shrubs and tress can survive now http://www.rowan.edu Primary Succession

21. Insects, small birds, and mammals have begun to move in What was once bare rock now supports a variety of life http://p2-raw.greenpeace.org Primary Succession

22. Primary Succession at Glacier Bay, Alaska A Lithosere

23. A Hydrosere

24. Other types of sere Xerosere – Succession in a region with lmted water availability e.g. deserts Psammosere - Succession that began with exposed sand e.g. sand dunes, beach Halosere – Succession which began in a saltwater environment e.g. a saltmarsh

25. Secondary Succession Begins in a place that already has soil and was once the home of living organisms Occurs faster and has different pioneer species than primary succession Example: After forest fires, human activity

26. http://www.scienceclarified.com/images/uesc_10_img0552.jpg

27. http://www.ccs.k12.in.us/chsteachers/BYost/Biology%20Notes/secondarysuccession.jpg

28. http://www.ux1.eiu.edu

29. Climax Community A stable group of plants and animals that is the end result of the succession process The climax community produced is controlled by the climate. eg water present all year – generally woodland distinct wet and dry seasons – grassland wet and acidic – blanket bog Does not always mean big trees – Grasses in prairies – Cacti in deserts – Reeds and grasses in saltmarshes

30. Influencing Factors Various factors will influence the rate and direction of change. These include: Edaphic conditions (type of soil) Climatic conditions Biotic factors (including anthropogenic)

31. Speed of Succession Changes are slower if the abiotic conditions are less suitable for life – too hot/cold, too dry or if the availability of plant nutrients is a limiting factor. Changes are usually slower during the early stages of succession. Secondary succession is usually a faster process than primary succession, in the same environment

32. General Trends in Succession Biomass increase over time. An increase in the number and proportion of longer-lived species. Increased species diversity over time. Succession on Mt. St.Helens – another site of intense study.

33. When human activity interferes What happens when human activities interfere with the natural process of succession? The succession process is altered, this is called DEFLECTED SUCCESSION Types of activity that can interrupt succession include: deforestation; ploughing; grazing; water drainage; weeding/coppicing; introducing new species.

34. Plagioclimax community Plagioclimaxes are what is produced at the end of a deflected succession. Most habitats in the UK are plagioclimaxes produced by grazing, burning, mowing or cutting. Examples include grassland and heathlands which are used of agriculture Coppiced woodlands