community ecology n.
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Community Ecology - PowerPoint PPT Presentation


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Community Ecology. Community Characteristics. Interactions among species Species diversity Trophic structure. Species Diversity . Species richness The total number of different species Species abundance The proportion each species represents of the total individuals in the community.

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Presentation Transcript
community characteristics
Community Characteristics
  • Interactions among species
  • Species diversity
  • Trophic structure
species diversity
Species Diversity
  • Species richness
    • The total number of different species
  • Species abundance
    • The proportion each species represents of the total individuals in the community
species richness
Species Richness
  • Heterogeneous vs homogeneous distribution
trophic structure
Trophic Structure
  • Feeding relationships between organisms
  • Transfer of food energy through food web
    • Influences community dynamics
    • Producers vs Consumers
  • Primary energy source is sunlight
    • Conversion of this energy source through trophic structure
    • Energy conversion is inefficient
      • Energy enters system as sunlight “lost” as heat
    • Food chain vs food web
      • Illustrates trophic interactions
trophic structure1
Trophic Structure
  • Producer
    • autotrophic
    • Converts sunlight energy into chemical energy
    • Sun to sugars
  • Consumer
    • Primary consumer
      • Trophic level that feeds on producers
      • herbivores
    • Secondary consumer
      • Trophic level that feeds primarily on primary consumers
      • Typically smaller carnivores
    • Tertiary consumer
      • Trophic level that feeds primarily on secondary consumers
    • Quaternary Consumer
      • Trophic level that feeds primarily on teriary consumers
trophic structure2
Trophic Structure
  • Detritivores
    • In soil
    • Feed on detritus (dead material)
    • Soil scavengers
    • Earthworms, soil nematodes
  • Decomposers
    • Recycle nutrients
    • Fungus, bacteria
food chain
Food chain
  • Detritivore
  • Decomposers
  • Omnivores?
food web1
Food Web
  • Linkage based on trophic levels
  • Species can occupy more than 1 trophic level
  • Diagram complex relationships
limitations of food chain
Limitations of food chain
  • 4-5 levels (9)
  • Energetic Hypothesis
    • Inefficiency of E transfer
    • 10 % rule
  • Dynamic stability hypothesis
    • Long chains lack stability
    • Magnification of fluctuations in variable environments
dominant species
Dominant species
  • Species found in highest abundance or biomass in a community
  • Biomass
    • The sum weight of all individuals in a population
  • Important in interspecific interactions
  • Influence abiotic factors
  • Exploit competitive advantage or predator avoidance
    • Ex Invasive species
  • Absence impacts environment
    • Ex chestnut blight (40% of canopy cover)
      • Impacted insect diversity (7 extinct out of 56)
    • Redundancy model of community structure
      • Other tree spp (resources) remained
    • Focus on biotic impact
keystone species
Keystone Species
  • Not necessarily dominant species in a community
  • Occupy a critical niche occupation that controls the community structure
  • Pisaster vs Mytilus (keystone vs dominant)
    • Offset competitive advantage
    • 15-20 ---5
  • Sea Otter
    • Dynamic stability hypothesis??
foundation species
Foundation Species
  • ecosystem engineers
  • Influence environment by causing physical changes to the structure of the community
  • Use behavior or biomass
community stability
Community Stability
  • Ability to resist disturbance
  • Natural disturbances
    • Storm
    • Fire
    • Flood
    • Results in patterns of ecological succession
  • Unnatural
    • Human induced disturbance
disturbance
Disturbance
  • Any event that that changes a community, removes organisms, alters resources
  • Stability
    • Ability of a community to recover from sisturbance
  • Natural disturbance
  • Unnatural disturbance
succession
Succession
  • Ecological Succession
    • Progression of change in plant community in recovery progress
  • Primary Succession
    • Ecological succession in communities where extreme disturbance has occurred
    • Soil not intact after disturbance
  • Secondary Succession
    • Ecological succession in communities where less extreme disturbance has occurred
    • Soil intact after disturbance