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Ecological Succession

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Presentation on theme: "Ecological Succession"— Presentation transcript:

1 Ecological Succession

2 Ecological Succession
Process by which communities in a particular area change over time Early communities modify the environment causing change to occur This affects biological community as well How?

3 Each successive (new) community is more favorable for new species
Changes in stages until a climax community is established

4 Composition of the community changes with time
Past Community Future Community Present Community Some species in the past community were out-competed, and/or did not tolerate altered abiotic conditions Modifies such abiotic factors as: Light intensity Wind speed Air Temperature Soil composition Light quality Wind direction Soil water Humidity Changes allow new species to become established.

5 Primary Succession Regions with no existing community Bare rock
Receded glaciers Volcanic regions Krakatoa, Glacier Bay Climax Community Lichens, bryophytes And annual herbs Slower growing broadleaf species Grasses and Small shrubs Fast growing trees Bare Rock years

6 Pioneer Species First organisms to live in a new community. Usually brought in by wind or animals

7 Secondary Succession Takes place after a land clearance
Fire, landslide, forest clearing Soil is already there More rapid than primary Climax Community Open pioneer community (annual grasses) Mature woodland mainly oak Primary bare earth Grasses and low growing perennials Scrub: shrubs and small trees Young broad- leaved woodland 150+ 1-2 years 3-5 years 16-30 years 31-150

8 Gap Succession In a forested area with a thick canopy
Reduced light on soil When a tree falls sunlight fills forest floor New communities are formed

9 Wetland Ecological Succession
In open body of water, aquatic plants are introduced Increase in aquatic plants causes sedimentation Swamps may occur and in warmer months may dry off May lead to EUTROPHICATION More production (photosynthesis) Lead to reduced oxygen and fish kills Natural and anthropogenic Type of pollution

10 Aerial view of Lake 227 in Note the bright green colour caused by algae stimulated by the experimental addition of phosphorus for the 26th consecutive year. Lake 305 in the background is unfertilized.


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