Community Ecology

Community Ecology Overview

  • Definition of Community Ecology: Ecological study focused on a community.

    • Community: All organisms occupying the same geographic area, capable of interaction.

    • Research Example: Investigating consumer-prey interactions between salmon and other species, and their population dynamics.

Case Studies

Lyme Disease Case Study

  • Lyme Disease: Infectious disease caused by the bacterium Borrelia, transmitted by ticks.

    • Current Trends: Rising numbers of infected humans; understanding ecological interactions is key to comprehension of disease spread.

Forest Ecology and Ticks

  • Influencing Factors: Interactions between habitat and various taxa can affect Lyme disease infection rates.

    • Forest Patch Size: Larger patches may support more ticks.

    • Implication: Forest fragmentation can heighten the risk of Lyme disease.

Community Structure Metrics

  • Components of Community Structure:

    1. Species Composition: The species present in the community.

    2. Species Richness: The number of different species per habitat area, indicating species diversity.

    3. Population Density: The number of individuals of a species within a given area, showcasing abundance.

  • Importance of Diversity: Communities with higher species diversity exhibit greater resiliency to environmental changes.

Factors Influencing Species Richness

  1. Regional Species Pool: Higher species richness in tropical wet forests compared to arctic tundra due to the species availability related to latitude.

  2. Dispersal & Immigration: Species richness increases when similar ecosystems are nearby, facilitating new population introductions.

  3. Abiotic Factors:

    • Nonliving resources positively influence species richness.

    • Severe disturbances can reduce richness.

  4. Biotic Factors (Species Interactions):

    • Commensalism: One species benefits while the other is unaffected.

    • Mutualism: Both species benefit from the interaction.

    • Competition: Both species are negatively affected by shared resource use.

    • Consumption: One species benefits by consuming another, often leading to a decrease in prey populations.

Ecological Succession Stages

  • Overview of Stages:

    1. Pioneer Stage:

      • Dominated by non-woody plants (r-selected strategies).

      • Initial species richness is low, but increases due to low competition and improved soil quality.

    2. Intermediate Stage:

      • Dominated by shrubs and small trees.

      • Species richness is high and continues to grow, driven by ecological interactions.

    3. Climax Stage:

      • Dominated by tall trees.

      • Species richness is high but stabilizes or begins to decline due to intense competition for resources.

Applications of Community Ecology

  • Human Disease Prevention: Understanding ecology aids in managing diseases like Lyme disease.

  • Species Identification: Recognizing essential species to maintain diversity and ecosystem services.

  • Sustainable Resource Use: Ensuring resource usage that does not compromise species diversity or community resiliency.