Ecological Succession occurs when a series of communities replace one another due to large scale destruction either natural or man-made. This process continues until a stable & mature community develops.
Pioneer Species: 1st species to invade the bare land, thus they are colonisers.
- Include bacteria, fungi, mosses, lichens.
- They show a high rate of growth but short life span.
Successional or seres Species.
- The diff communities or stage (mosses, herbs, shrubs trees) replace one another during succession & are referred to as seral stages or seral communities — These species are slow-growing and long-lived.
- A sequence of communities succeeding each other during the course of succession represents the sere.
- Climax Community/Species Terminal (final) stage of succession forms community which is called a climax community.
- They’re stable, mature, more complex & long-lasting.
STAGES of Ecological Succession
- Takes place on bare areas like newly formed deltas, emerging volcano island.
- Area 1st weathered by physical forces so that soil formation is initiated, then inhabited/ colonised by pioneer species like algae, mosses, lichens which further soil-forming process & prov organic matter to the soil once die [Bacteria & Fungi decompose dead pioneer species).
- Community develop → inc competition & develop a new niche.
- Invasion of new specie and replace pioneer species.
Intermediate Succession — Seral community
- Pioneer community after some time gets replaced by another community with different species combination.
- This transitional community is called stage in succession or seral community or sere.
- Takes place in the area that was prev occupied by living communities but community wiped out after destructive event like a fire.
- The area is re-colonised.
- Bare farmland 1st invaded by hardy species of grass & eventually develop into forest community.
- Unlike the primary, SS starts on a well-developed soil, hence relatively faster.
Therefore, the following sequence can be observed in succession
- Nudation: Bare area without life.
- Invasion: Pioneer species in the bare area.
- Competition & Co-action: Sere stage.
- Stabilisation (climax).
TYPES OF Ecological Succession
Autogenic & Allogenic.
- Autogenic = Succession by living inhabitants.
- Allogenic = Succession bought by outside forces.
Autotrophic & Heterotrophic.
- Autotrophic = green plants are greater in quantity.
- Heterotrophic = heterotroph is greater in quantity.
Hydrarch & Xerarch succession.
- Hydrarch succession takes place in wetter areas and the successional series progress from hydric to the mesic condition [moist – neither too dry nor too wet].
- Xerarch succession takes place in dry areas & series progress from xeric to mesic conditions.
- Retrogressive Succession = Forest → Shrubs → Grass by biotic influence (CC effect).
- Serule = ES for micro-org like fungi, bacteria.