1. Succession and Stability Changes in the Environment

2. IN: 244 million years ago Nevada was part of a vast sea. What are some factors that could have caused a change leading to the current ecosystem?

3. What does it take to keep this lawn looking like this? What will happen to this lawn over time if it is not maintained?

4. What are the first types of plants that will take hold in this yard?

5. I. Ecological Succession The gradual and fairly predictable change in species composition of a community over time.The gradual and fairly predictable change in species composition of a community over time. Some species colonize and their populations increaseSome species colonize and their populations increase Other species populations decline.Other species populations decline. Continues until a stable stage is reached; climax community.Continues until a stable stage is reached; climax community.

6. II. Two major types of succession 1. Primary Succession Occurs where there is no soilOccurs where there is no soil Lifeless area where no community existed beforeLifeless area where no community existed before Examples:Examples: –On land from retreating glaciers –On the surface of new Lava flows –On newly exposed islands

7. Molles: Ecology 2 nd Ed. Primary Succession – Glacier Bay, Alaska Reiners et.al. (1971)

8. Molles: Ecology 2 nd Ed.

10. Glacier Bay Succession Soil Development Bare rock & soil Lichens Mosses Grasses Forbs Shrubs Aspen Black spruce White spruce Increasing Vertical Structure

11. Molles: Ecology 2 nd Ed. Coral Reef Succession On Lava Flows Lava Flow From Land Into Sea

12. Molles: Ecology 2 nd Ed. Coral Reef Succession On Lava Flows Underwater Lava Flow

13. Molles: Ecology 2 nd Ed. Coral Reef Succession On Lava Flows

14. Molles: Ecology 2 nd Ed. Coral Reef Succession On Lava Flows

15. Molles: Ecology 2 nd Ed. Coral Reef Succession On Lava Flows

16. Molles: Ecology 2 nd Ed. Coral Reef Succession On Lava Flows

17. Molles: Ecology 2 nd Ed. Coral Reef Succession On Lava Flows

18. Molles: Ecology 2 nd Ed. Coral Reef Succession On Lava Flows

19. 2. Secondary succession Occurs after the disturbance of an existing communityOccurs after the disturbance of an existing community Re-building on remaining soil.Re-building on remaining soil. Examples:Examples: –Re-growth after NATURAL forest fire. –Natural vegetation re-growth after abandonment of farmland.

20. Molles: Ecology 2 nd Ed. Old Field Succession

21. Molles: Ecology 2 nd Ed. Old Field Succession: 1 Year After Abandonment Grasses and Weeds Dominate

22. Molles: Ecology 2 nd Ed. 5 Years After Abandonment Goldenrod and Other Perennial Weeds Dominate

23. Molles: Ecology 2 nd Ed. Tree saplings and shrubs begin to establish 10 Years After Abandonment

24. Molles: Ecology 2 nd Ed. Trees and shrubs begin to replace herbaceous plant species 20 Years After Abandonment

25. Molles: Ecology 2 nd Ed. Where Did the Grasses and Goldenrod Go ? 20 Years After Abandonment

26. Stop

27. III. Primary vs. Secondary Succession A. Primary succession is slower. Establishment of organisms requires migration into the area.Establishment of organisms requires migration into the area. Soil development limits variety.Soil development limits variety.

28. IV. How succession works A. PIONEER (r-selected) SPECIES First to arriveFirst to arrive Produce large numbers of offspring.Produce large numbers of offspring. Grow fastGrow fast HardyHardy Reach sexual maturity fast.Reach sexual maturity fast. Short life spansShort life spans Poor competitive ability.Poor competitive ability. Ex = Mosses, dune grass, lichens, weeds *teachers-see notes below

29. Lichens role in forming soil  http://www.teachertube.com/video/ecological- succession-182733 http://www.teachertube.com/video/ecological- succession-182733

30. B. Late-Succession (K-selected) Species Produce fewer, larger young.Produce fewer, larger young. arrive later (require soil conditions first).arrive later (require soil conditions first). slower growth rate.slower growth rate. Longer time to sexual maturity.Longer time to sexual maturity. Long-lived (hold onto space / resources)Long-lived (hold onto space / resources) Good competitive ability (displace pioneer species)Good competitive ability (displace pioneer species) Ex = beech trees, Oak, FirEx = beech trees, Oak, Fir

31. C. C limax Community Late successional community r reached equilibrium Slight changes in species over time normal (elm to maple) Relative types of organisms stable (broadleaf trees) Remains stable until disturbed

32. Stop

33. Species Richness During Primary Succession at Glacier Bay Study Plots Fig 20.2

34. Change of Plant Growth Forms During Succession Fig 20.3

35. Molles: Ecology 2 nd Ed. Woody Plant Species Richness During Secondary Forest Succession (Eastern USA) Piedmont Plateau

36. Woody Plant Species Richness During Secondary Forest Succession (Eastern USA) Fig 20.4

37. Breeding Bird Species Richness During Secondary Forest Succession (Eastern USA) Fig 20.5

38. Species Richness of Macroinvertebrate and Macroalgae Species During Secondary Succession on Intertidal Boulders Fig 20.7

39. Algal species Diversity During Secondary Succession in Sycamore Creek After Flooding Fig 20.8

40. Molles: Ecology 2 nd Ed. Fig 20.9 Fig 20.8

41. V. How Does Disturbance Influence Succession? A. Moderate disturbances 1. Frequency allows recovery. 2. Some k-selected species remain 3. Soil left in tact 4. Periodic forest fires from lightning Jack pine cones only open to seed when under extreme heatJack pine cones only open to seed when under extreme heat Allows elimination of dead woodAllows elimination of dead wood Replenishes nutrients to soilReplenishes nutrients to soil Sprout vegetation feeds certain animalsSprout vegetation feeds certain animals

42. 5. Sustainable logging and farming Limit the amount of trees/land cleared.Limit the amount of trees/land cleared. Limit the frequency of logging/farming in an area.Limit the frequency of logging/farming in an area.

43. B. High intensity/magnitude disturbances 1. Too frequent and drastic to allow recovery 2. Reduce soil nutrients 3. Eliminate k-selected species 4. Climate change Effects the whole planetEffects the whole planet Habitat destructionHabitat destruction Conditions cannot be reversedConditions cannot be reversed Possible extinction of many speciesPossible extinction of many species

44. VI. Ecosystem Stability A. Factors that effect stability 1. Fragility - How easily is the system disturbed 2. Resilience - How quickly can it recover 3. How many biotic and abiotic factors are effected 4. Community structure – keystone species.

45. Keystone species: A species that has a large effect on its environment relative to its abundance.speciesenvironment

46. Exert strong control not by numerical might but ecological role; niche.Exert strong control not by numerical might but ecological role; niche. The loss of a keystone species would drastically alter the community or possibly destroy it.The loss of a keystone species would drastically alter the community or possibly destroy it.

47. B. Equilibrium 1. Ecosystem will always work towards equilibrium of energy flow and nutrient recycling 2. Destruction of an ecosystem leads to succession 3. Evolution and adaptation allow for a new ecosystem to flourish

48. VII. Implications for Human Activities A. Human populations typically increase the frequency, magnitude, and intensity of disturbance. Entire landscapes dominated by r- selected species b/c succession never finishes before next disturbance.Entire landscapes dominated by r- selected species b/c succession never finishes before next disturbance. Depletion of biomass, soil organic matter, and nutrient pools.Depletion of biomass, soil organic matter, and nutrient pools.

49. B. Humans sometimes suppress disturbances (e.g. fire), increasing return time, but often with increase in magnitude and intensity. Entire landscapes become dominated by K-selected species, and accumulate biomass.Entire landscapes become dominated by K-selected species, and accumulate biomass. Communities may become more susceptible to catastrophic disturbance (e.g., recent fires in western U.S.)Communities may become more susceptible to catastrophic disturbance (e.g., recent fires in western U.S.)

50. Effects of Fire Suppression Eastern Hardwood Forest Fire Suppression Begins ▲ Logging Number of trees

51. Effects of Fire Suppression Western Conifer Forests Frequent Low- Intensity Fires ▼▼▼▼▼▼▼▼ Fire Suppression Begins Fuel build-up leads to catastrophic crown fire Number of trees

52. VII. Implications for Human Activities A. Humans depend on rapid growing, r- selected species for agriculture and forestry. Humans use disturbance to prevent succession and maintain open environments required by these pioneer species.Humans use disturbance to prevent succession and maintain open environments required by these pioneer species. Frequent human disturbance to maintain crop species can deplete soil organic matter and nutrient pools.Frequent human disturbance to maintain crop species can deplete soil organic matter and nutrient pools.