Community ecology
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Community Ecology PowerPoint PPT Presentation

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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Community Ecology

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Community ecology

Community Ecology


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 diversity1

Species Diversity


Species diversity2

Species Diversity


Species richness

Species Richness

  • Heterogeneous vs homogeneous distribution


Figure 48 3

Figure 48.3


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 web

Food Web


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


Figure 48 4

Figure 48.4


Pyramid of net production

Pyramid of Net Production


Energetic hypothesis

Energetic Hypothesis


All species are not created equally

All species are not created equally….


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


Competitive advantage

Competitive Advantage


Invasive species

Invasive Species


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??


Dominant species1

Dominant Species


Keystone species1

Keystone Species


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


Natural disturbance

Natural disturbance


Natural fire

Natural Fire


Crown fire

Crown Fire


Ponderosa pine forest recovery

Ponderosa Pine Forest Recovery


Natural disturbance1

Natural 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


Climate evolutionary history

Climate & Evolutionary History


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