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Ecological Succession-a series of changes that occur in a community over time • Primary succession- changes that occur in an area where no ecosystem previously existed. Example: a new island forms and the rock then lichens and mosses begin growing on the new land. • Secondary Succession- changes following a disaster occurs in a place where an ecosystem was already established. Occurs more rapidly than primary succession. Primary Succession :Case study in Acadia National Park in Maine lichens and algae Secrete acids which begin to extract nutrients from the rock and which form tiny cracks which are widened by freezing and thawing. As the cracks widen they trap enough organic material and moisture for mosses to take hold. http://www.marietta.edu/~biol/biomes/succession.htm Larger cracks have enough soil to support grasses and small shrubs. The largest cracks come together to form small basins where trees can take root, although the tree in the photo below didn't make it too long; perhaps a drought exhausted the water in the small basin. However, in the background the climax coniferous forest is visible where enough soil has accumulated to support the trees Primary Succession Case Study: Mt.Rainier (volcano) in Washington The lichens are the first to appear (although they are hard to spot here). More obvious are the mosses, grasses and small plants like flowers Each stage accumulates soil and organic material that facilitates the growth of the next stage Primary Succession-Dune Succession: Indiana Dunes of Lake Michigan Here, sand washed up onto the beach is piled by the wind into tall dunes which slowly moves away from the lake (above). If plants can get root, they slow the wind, encourage it to drop its sand, and stabilize the dune, stopping its motion Secondary Succession: Lake Succession A former bog in Maine has almost completely filled. A former lake, formed originally when a large piece of ice broke off a retreating glacier, is now well along the transition to dry land. These kettlehole lakes often support an extensive mat of floating vegetation. Fire and Secondary Succession at Yellowstone National Park 11 years after the fire Fire plays a complex role in succession. Usually, a fire stops the progression of succession and sets the stage for new, secondary succession as plants take root and grow in the soil enriched by the mineral ashes of their predecessors. Reflection: Write your response on your own sheet of paper. • 1. How is the primary succession seen in the Indiana Dunes of Lake Michigan alike and different from the primary succession in Acadia National Park in Maine? • 2. How is the succession of the forest fire in Yellowstone National Park different from the succession on Mt.Ranier in Washington? Explain your answer with details.