Succession Slides 2012
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Succession Slides 2012



Slide deck from APES class on 11/13/12.

Slide deck from APES class on 11/13/12.



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  • Fig 10.8 Graphs showing changes in biomass and diversity with succession.
  • Fig 10.9 (a) Hypothesized changes in soil nitrogen during the course of soil development. (b) Change in total soil phosphorus over time with soil development. (Source : P. M. Vitousek and P. S. White, 1981, “Process Studies in Forest Succession,” in D. C. West, H. H. Shugart, and D. B. Botkin, eds. Forest Succession: Concepts and Applications [New York: Springer-Verlag, 1981], Figure 17.1, p. 269.)
  • Fig 10.7 Diagram of bog succession. Open water (a) is transformed through formation of a floating mat of sedge and deposition of sediments (b) into wetland forest (c).

Succession Slides 2012 Succession Slides 2012 Presentation Transcript

  • Population Changes in Context - in Communities!
  • Succession Defined:• The gradual, sequential change in the relative abundances of the dominant species in a biological community following a disturbance…• Primary succession: beginning from an abiotic environment following a cataclysmic disturbance• Secondary succession: beginning from a major disturbance, but all forms of life are not destroyed
  • Primary or Secondary? Volcanic Island
  • Primary or Secondary? 1988 Fires in Yellowstone NP
  • Primary or Secondary? Old Parking Lot
  • Primary or Secondary? Glacial Retreat
  • Primary or Secondary? Old Farm
  • Primary Succession (forest)• Colonization: of bare rock, tiny seedless plants like mosses, and lichens, “pioneer species”• Early: plants typically small with short lifecycles (annuals), rapid seed dispersal, “environmental stabilizers”• Middle: plants typically longer lived, slower seed dispersal (herbs, shurbs, perennials)• Late: plant species are those associated with older, more mature ecosystem-largest vegetation (trees)• “Climax Community” mature forest in this case (but varies by biome) *Note: Consumers and decomposer populations will also vary as producer populations change…as well as nutrient cycling…
  • Research on Primary Succession
  • Research on Secondary Succession
  • Hutcheson Memorial Forest Center (NJ) Old Field Secondary Succession1962-1995
  • Hutcheson Memorial Forest Center (NJ) Old Field Secondary Succession1962-1995
  • Hutcheson Memorial Forest Center (NJ) First Year
  • Hutcheson Memorial Forest Center (NJ) Fifth Year
  • Hutcheson Memorial Forest Center (NJ) Tenth Year
  • Hutcheson Memorial Forest Center (NJ) Twentieth Year
  • Hutcheson Memorial Forest Center (NJ) Twenty-Eighth Year
  • Changes in Biodiversity
  • © 2003 John Wiley and Sons Publishers
  • © 2003 John Wiley and Sons Publishers
  • Succession in Aquatic Ecosystems © 2003 John Wiley and Sons Publishers
  • Succession in a Pond 1960s to 1990s
  • Is a Climax Community Always Inevitable?• New research suggests that we cannot always project the course of a given succession or view it as preordained• Communities are always subject to disturbances and we cannot always know the outcome• Disturbances can be beneficial for communities…
  • The Intermediate Disturbance Hypothesis• Hypothesis: Communities that experience fairly frequent but moderate disturbances have the greatest species diversity• Reasoning: Moderate disturbances are large enough to create openings for colonizing species in disturbed areas, but mild and infrequent enough to allow the survival of some mature species in undisturbed areas
  • ‘General Ecology’, D.T. Krohne
  • Ecotones• Disturbances often create ecotones, but they also exist as natural transitions between biomes or ecosystems• An ecotone is a transition area between two adjacent ecological communities – a sharp boundary or a gradual blending effect – particularly significant for mobile animals, as they can exploit more than one set of habitats within a short distance – this can produce an edge effect along the boundary line, with the area possibly displaying a greater than usual diversity of species
  • Edge Effects• Disturbances can fragment ecosystems and create edge effects• An edge effect describes the differing abiotic and biotic conditions that exist at a border between contrasting environments in an ecosystem – the increased light, greater wind and temperature extremes and lower humidity at the boundaries of fragments favor some plant species over others (native colonizing species or invasive species) – this can make the combination of species present near the boundary different from that inside the fragment (more diverse or less depending on the factors)
  • Remember This Edge Effect? Kudzu at DCEP
  • The Island Theory of Biogeography• Small islands have fewer habitat types and greater risk of extinction-smaller islands have less genetic diversity too• The more distant the island, the less chance of reaching it• Over time, an island tends to maintain a constant number of species, because the rate at which species are added is about the same as the rate at which other species become extinct
  • The Island Theory of Biogeography• Species often evolve to a smaller size on islands because islands often have a limited supply of food, fewer predators, and fewer species competing for the same resources• Examples include island foxes, pygmy mammoths, and a dwarf human species Homo floresiensis
  • The Island Theory of Biogeography• Island concepts can also be applied to “ecological islands”• Ecological islands are comparatively small habitats separated from a major habitat of the same kind – A small stand of trees within a prairie is a forest island
  • Habitat Fragmentation (and ecological islands)
  • Solution: Wildlife Corridors
  • Bibliography•• 20Intro.htm•