Disturbed about Succession. Facilitator: Hilary Swain Laurie Anderson Paul Benzing Suzanne Koptur Linda Nagel

Transcription

1 Disturbed about Succession Facilitator: Hilary Swain Laurie Anderson Paul Benzing Suzanne Koptur Linda Nagel

2 Learning Objectives Students will be able to define and describe the processes of (three) contrasting models of succession Students will work in groups and use their knowledge of plant life history traits and successional theories to predict ecosystem change over time for a given scenario Students will be able to identify successional processes in their local environment

3 Pre/post test questions: beginning and end of course For each of the following statements about ecological succession, indicate true or false. If the answer is false, explain why. Ecological succession is the process of vegetation change on a site over time. The mechanisms that cause the groups of species dominating a site to change over time are the same for all ecological communities. Changes in resource availability are important in ecological succession. Interactions between species are important in ecological succession. Random events can change the course of ecological succession. I have observed examples of succession in the local environment.

4 Class period before: Prior knowledge assessment On a 3x5 card: What is ecological succession? Purpose: identify misconceptions and current understanding of ecological succession

5 Homework assignment Use your ecology text to find the definitions of the following terms: Disturbance Succession Primary succession Secondary succession Sere Pioneer species Climax community Facilitation Competition

6 Day 1

7 Think-pair-share Independent: Think of as many ecological disturbances as you can, across a range of spatial scales from one square meter to an entire landscape Make a list with your neighbor of disturbances at both small and large scales Call on random students to report on their answers

8 Examples of succession

9 Hog Island (S. end) - coastal Virginia LTER site

10 Sleeping Bear Dunes National Lake shore

11 Coastal Dune Succession Sleeping Bear Dunes S. Manitou Island

12 Changing shoreline, shifting dunes, moving lighthouses! Nauset Light Pitcher s thistle

13 Cape Cod National Seashore shifting dunes

14 Pt. Reyes National Seashore

15 Death Valley

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17 Boreal forest fire succession

18 Yellowstone National Park fire 1988

19 Fireweed abundant post-fire

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21 Serotinous cone of lodgepole pine

22 Young lodgepole pines several years post-fire

23 Succession monitored at various locations, experiencing different levels of damage. Two example areas: Studebaker ridge (intense blast), Pine Creek (mild scour) Photos by Dr. Roger del Moral, University of Washington

24 Studebaker Ridge 1984 Primary Succession

25 Pine Creek 1981 Secondary Succession

26 Landslide - Slovenia

27 Example: Old-field Succession Photos of the dioramas are from: Forester, D.R., J.F. O Keefe, and J. Green New England Forests Through Time: Insights from the Harvard Forest Dioramas. Harvard University Press.

28 Pre-settlement forest 1700 A.D.

29 Clearing of a homestead by an early settler 1740 A.D.

30 Farm abandonment 1850 A.D.

31 Old-field white pine on abandoned land 1910 A.D.

32 White pine is succeeded by hardwoods 1915 A.D.

33 An aggrading forest of hardwoods 1930 A.D.

34 The modern forest landscape

35 Early succession: Farm abandonment 1850 A.D.

36 Think-pair-share On a 3x5 card (in groups): Side one: Identify the resource conditions at these three stages of succession Early Mid Late Side two: Identify plant life history strategies that would enable plants to take advantage of the resources available at each stage

37 The Eastern United States vegetation patterns following field abandonment

38 Key points to introducing successional models 1. Successional processes have some degree of repeatability in different environments. 2. This repeatability leads us to wonder if there is some set of common mechanisms underlying these processes. 3. As yet, there is no agreement on what those mechanisms are. Several models describing succession have been proposed. 4. A model is a simplified approximation of a process provides a starting point for studying complex natural processes.

39 Succession Model 1: Relay Floristics (Facilitation) Relay floristics is where one species or group of species invading a given area are replaced by successive species or groups. By modifying the environment, one group of plants favors or facilitates the establishment of the next group in the sequence.

40 Succession Model 2: Initial Floristics Initial floristics is where all species invade at approximately the same time after a disturbance but assert dominance at different times. This implies that succession is a function of individual species life history traits rather than facilitation by earlier arriving species. Note: this model shows all species present at the start, with no additional species invasions.

41 Successional Model 3: Tilman s Resource Ratio Hypothesis

42 Successional Model 3: Tilman s Resource Ratio Hypothesis Group work: On transparencies, draw trajectories for light and soil resource change over time in the old-field successional example used in the 3x5 cards Light or Soil resources Based on Tilman 1985 Time

43 Successional Model 3: Tilman s Resource Ratio Hypothesis Report out/discussion: Randomly select graphs from three groups to show to the class. Briefly discuss and correct any misconceptions. Light or Soil resources Based on Tilman 1985 Time

44 Lecture: How does this connect with the kinds of plants that occur at different successional stages?

45 Successional Model 3: Tilman s Resource Ratio Hypothesis Group work: Given the life history traits from your 3x5 cards, and the resource availability curves below, plot population dynamics for species A and B below. Light or Soil resources Species A: lightdemanding Species B: nutrient demanding Based on Tilman 1985 Time

46 Resource ratio hypothesis of succession The relative supply rates of limiting resources determine which species is dominant at a particular successional stage. Based on Tilman 1985

47 Group assignment: Jigsaw Addresses Learning Objective 2 Four students will work together as a group Pictures will be posted on the course website (or could be handed out in class) Assignment is due next class period Each group will turn in a written report (graded); one group of each scenario will present in class (randomly chosen by instructor, not graded)

48 Succession Jigsaw Describe and diagram the probable pathway of succession. One member of your group will describe early succession, one mid-succession, and one late succession The other member will pull it together in an overall diagram. Everyone will prepare their part, then come together in class (or require them to meet outside of class) and spend time putting it all together into one coherent explanation.

49 Jigsaw, continued Include the timeline and the changes that you would expect, the changes in plant life form (herb, shrub, tree, vine, liana) and life-history strategy (pioneer vs. long-lived, high reproductive output vs. low), species composition, and diversity. It is not important to use precise plant names, but general types. As you evaluate this system, reflect on the different models of succession. [See rubrics for evaluation]

50 Jigsaw rubric (Group-level) (2 pts max each item) Logical sequence of events Life-history attributes included Plant life forms addressed Species diversity predicted throughout Time line realistic (days, months, years, etc.) Different stages of development identified Various succession models considered Diagram clear and well-labeled Homework done and brought to class Final product coherent and clear

51 Teamwork rubric Each person will evaluate all other team members using a scale from 1-5 pts (min/max, questions 1-4) and % estimate (25% equal share, question 5) 1) On time for class activity 2) Came well prepared 3) Able to explain their part clearly to others 4) Willing to work with partners cooperatively 5) Percentage contribution to group product Each student receives a score (20 pts max) + %

52 Succession on volcanic lava

53 Succession after fire in the pine savanna

54 Succession on coastal dunes

55 Succession on alpine meadow landslide

56 Succession on an abandoned parking lot (asphalt)

57 Day 2

58 Presentations of succession jigsaw Show photos from website/document projector Students will describe processes verbally Show diagrams if necessary for explanation

59 Florida Scrub as a Model Ecosystem with a focus on fire ecology

60 Fire as a prevalent process continent-wide Fire is key process in most areas of pressing environmental concern. Humans have significantly altered fire processes. Fire processes amenable to observation & multi- scale experimental manipulation; SE has 95% of acreage prescribe burned in US. Broad impacts for public policy and economics.

61 IF/ NF/ /NF FF

62 The Fire Game Learning objective: understand the role of probability in disturbance ecology and the effect on vegetation change over time

63 In-class Assessment: Defining Features Matrix Addresses Learning Objectives 1 & 2

64 In-class Assessment: Defining Features Matrix Addresses Learning Objectives 1 & 2

65 Final Assessment Use the Defining Features Matrix as an exam question Companion question: Given this photo, describe the processes at work in this ecosystem that would support each successional model compared in the matrix. Which model best fits this ecosystem? Why?

66 Optional Exercise Addresses Learning Objective 3 Homework assignment or minute paper: Describe to your friend directions to your favorite restaurant/bar using only stages of ecological succession. Provide a diagram and flow of directions as if generated by Mapquest.

67 Pre/post test questions: beginning and end of course For each of the following statements about ecological succession, indicate true or false. If the answer is false, explain why. Ecological succession is the process of vegetation change on a site over time. The mechanisms that cause the groups of species dominating a site to change over time are the same for all ecological communities. Changes in resource availability are important in ecological succession. Interactions between species are important in ecological succession. Random events can change the course of ecological succession. I have observed examples of succession in the local environment.

68 Photo credits Title slide: EarlyMay2002%20005.jpg fl jpg oldgrowth/image004.jpg Sanderson%20Pictures/... Succession pictures: National Park Service - Sleeping Bear Dunes National Lakeshore Cape Cod National Seashore University of Washington digital image collection