Ecological-Succession

Ecological Succession

Definition

  • Ecological Succession: The gradual and continuous change in species composition and community structure over time in the same area.

    • Environment changes due to climatic variations, physiographic factors, and species activities.

    • Continues until a stable terminal community is reached.

    • According to E.P. Odum (1971), it's an orderly process of community change.

    • Represents ecosystem development in nature.

Importance of Understanding Ecological Succession

  • Understanding succession is vital for:

    • Restoring natural ecosystems and maintaining biodiversity.

    • Identifying and influencing driving factors in ecosystems.

Types of Ecological Succession

  1. Primary Succession:

    • Occurs in bare areas or newly exposed sites not previously occupied by life.

    • First community called pioneering species.

  2. Secondary Succession:

    • Starts at locations with existing substrate and living organisms.

  3. Autogenic Succession:

    • Vegetation causes its replacement through new communities.

  4. Cyclic Succession:

    • Involves repeated occurrences of certain stages.

  5. Allogenic Succession:

    • Replacement caused by external conditions rather than existing vegetation.

  6. Autotrophic Succession:

    • Early dominance of green plants (autotrophs).

  7. Heterotrophic Succession:

    • Early dominance of heterotrophs like bacteria and fungi.

  8. Induced Succession:

    • Caused by human activities such as overgrazing and pollution.

Mechanism of Ecological Succession

Sequential Phases

  1. Nudation:

    • Development of a bare area without life.

    • Causes include soil erosion, landslides, volcanic activity, etc.

      • Topographic Causes: Soil erosion or deposition.

      • Climatic Causes: Events such as fires, storms can destroy communities.

      • Biotic Causes: Human activities affecting natural habitats.

  2. Invasion or Migration:

    • Successful establishment of species in a bare area brought by air, water, or other agents.

  3. Ecesis / Establishment:

    • Successful adjustment to new conditions leading to reproduction in the area.

    • Completion is marked by the plant's ability to reproduce sexually.

  4. Aggregation:

    • Increase in the number of individuals of a species post-establishment.

  5. Competition and Co-action:

    • Competition for space and nutrients among individuals.

    • Co-action influences survival, favoring fit individuals for ecosystem survival.

  6. Reaction:

    • Modification of the environment affects soil, water, temperature, etc.

    • Changes make the current community unsuitable for existing conditions; leads to the sere (sequence of communities).

  7. Stabilization (Climax):

    • Final community stabilizes, maintaining equilibrium with the area's climate.

    • Climax community represents a steady state of species composition and energy flow.