Chapter 13 Succession pages 323343

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Chapter 13 Succession (pages 323-343)
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Chapter outline

• I. Introduction
• II. Patterns of Successional Change
• III. Mechanisms of Successional Change

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I. Introduction

• A. Definitions
• B. Disturbance

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A. Definitions

• Succession sequential change in relative
  abundances of dominant species in a community
  following a disturbance
• Seen as 1 community replacing another
• Both plants and animals change
• Climax community final community, relatively
  self-maintaining until disturbance
• Fig. 13.1, 13.2

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B. Disturbance

• Small creates gaps
• May see nearby suppressed individuals released
• May see similar species colonize
• What creates a gap depends on community
• Badger, groundhog digging in field
• Tree fall in forest

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B. Disturbance

• Large creates secondary succession
• Includes volcanoes, fires, hurricanes, ice storms
  
• Sets back to earlier stage of succession by
  killing current species
• Impact depends upon several factors (Fig. 13.3,
  13.4)
• Severity how intense?
• Frequency how often?
• Spatial extent how large an area affected?

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B. Disturbance

• Type of habitat also important
• Hurricane Andrew (1993)
• Little impact on sawgrass community of Everglades
• Hurricane Hugo (1989) (Fig. 13.3)
• Severe impact on pine forests of SC
• Little impact on tropical forests of Puerto Rico

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II. Patterns of Successional Change

• A. Primary Succession
• B. Secondary Succession
• C. Variation in the Patterns

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A. Primary Succession

• Establish community on sterile sites, abiotic
  situation
• Without soil or plants
• Places like sand dunes, lava flow, receding
  glaciers, receding waters of pond
• Typically, as plants become established, they
  improve the environment
• Add soil nitrogen, organic matter, and shade
• Lessen stress for later species

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A. Primary Succession

• Dune succession (Fig. 13.6)
• (Indiana Dunes _at_ Lake Michigan, studied by HC
  Cowles, 1901)
• Was larger Lake Chicago (10,000 yrs ago), periods
  of draining/ decreasing, then stability, then
  draining
• Dunes represent transect through time
  recognized that all these habitats had passed
  through similar earlier stages

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A. Primary Succession

• Foredune
• Frequent disturbances from waves, storms, wind
• High light, little to no soil or water (fast
  draining)
• First stabilized dune
• Marram grass (Ammophila) adds organic matter
• Little bluestem (Andropogon) present
• Shrubs
• Dune willow, sand cherry, grape
• Requires well-stabilized dunes more soil
• Adds more nutrients to soil, shades (lower
  temperature)

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A. Primary Succession

• Pines
• White pine, jack pine, junipers
• Still xeric
• Requires more nutrients than shrubs, but not lots
• Deciduous trees
• Black oak, northern red oak, hickory, witch hazel
• Takes approx. 12,000 yrs to look like surrounding
  climax forest

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A. Primary Succession

• Glaciation succession (Fig. 13.8, 13.9)
• (Glacier Bay in Alaska, studied by Cooper, 1939)
• Lots of increases and decreases, both major and
  minor
• Glacier Bay has had a quick retreat in last 200
  yrs (over 80 miles)
• Get details from book!

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B. Secondary Succession

• Succession on sites where disturbance hasnt
  removed soil or all life, biotic situation
• Places like abandoned fields, waste places
  (ruderal sites), roadsides, after forest fires or
  blow downs.
• Much more frequent than primary, and much more
  rapid
• Resembles later stages of primary succession

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B. Secondary Succession

• Old field succession of Carolinas
• (Oosting 1942)
• Annuals (1-2 yrs)
• Crabgrass, horseweed, ragweed
• Perennials (2-20 yrs)
• Goldenrod, aster, broomsedge (grass)
• Shrubs softwoods (20-100 yrs)
• Pine and cedar trees
• Hardwoods (100 yrs)
• Oak, hickory, maples (dogwoods, redbuds)

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B. Secondary Succession

• Old field succession of Midwest (Table 13.2)
• Annuals (1-15 yrs)
• Foxtail, ragweed, Queen Annes lace
• Perennials (16-25 yrs)
• Goldenrod, aster, broomsedge (grass)
• Shrubs (26-50 yrs)
• Sumac, multiflora rose, blackberry
• Softwoods (51-100 yrs)
• Tulip poplar, cottonwood, red maple, cedar
• Hardwoods (100 yrs)
• Sugar maple, American beech, Red oak

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B. Secondary Succession

• Lodgepole pine succession in Yellowstone (Fig.
  13.12)
• For fire to be important, need
• Accumulated organic matter to burn (not
  decomposition)
• Dry weather conditions (wet/ dry cycles)
• Landscape favorable to fire spread
• Source of fire (lightening, humans)

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B. Secondary Succession

• Lodgepole pine succession in Yellowstone
• Stage I (0-50 yr)
• Young pines that germinated from serotinous cones
• Resistant to fire with little fuel
• Stage II (50-150 yr)
• Maturation, dense closed canopy
• Few lower branches, tree farm
• Little fuel, no way for fire to get to canopy

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B. Secondary Succession

• Stage III (150-250 yr)
• Trees begin to die ? gaps
• Seedlings of lodgepole, Douglas fir, subalpine
  fir
• Fire more likely with fuel and path for fire to
  canopy
• Stage IV (250 yr)
• Lots of dead lodgepole (and firs)
• Regeneration of fir and spruce
• Very vulnerable to fire

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B. Secondary Succession

• Yellowstone fires of 1988 (Fig. 13.13, 13.14)
• Finger pointing and suggestion that fire
  suppression led to large areas burned
• Historical fire record suggests a natural cycle
  of large burns, with unusually dry weather
  conditions as a contributing factor

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C. Variation in the Patterns

• Succession isnt always a completely linear
  progression.
• Depends on both abiotic and biotic factors.
• Examples
• Lake Michigan sand dunes (Fig. 13.15)
• Alaska taiga (Fig. 13.16)

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III. Mechanisms of Successional Change

• A. Connell-Slatyer Model
• B. Interactions among the succession models

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A. Connell-Slatyer Model

• Three possible mechanisms (Fig. 13.17)
• 1. Facilitation model
• Pioneer species modify/ improve physical
  environment (add nitrogen, organic matter, etc)
• Important for primary succession
• 2. Tolerance model (Fig. 13.20, 13.22)
• Early species modify physical environment
• Later species are those that can tolerate
  conditions (ex shade created by early shrub or
  tree species)

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A. Connell-Slatyer Model

• 3. Inhibition model
• Individuals hold space against competitors
• Succession occurs only with death or replacement
  of established organisms
• Succession moves toward long-lived individuals

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B. Interactions among the succession models

• Old field example from Carolinas (Keever, 1950)
• Annuals arrive quickly (in seed bank)
• Annuals are self-allelopathic (tolerance) and
  outlasted by perennials (inhibition)
• Within perennials, broomsedge outsurvives/
  outcompetes aster for water NOT shade!
  (tolerance)
• Broomsedge shaded by pines (tolerance)
• Oaks hickorys are shade tolerant, longer-lived
  than pines (tolerance, inhibition)

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Conclusions/ summary

• Communities are dynamic after a disturbance,
  succession occurs, with different communities
  replacing each other over time.
• A variety of mechanisms may act at the different
  stages of succession to create or allow these
  changes.