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Ecological Succession
Primary vs. Secondary Succession
Ecological Succession• Ecological succession is a series of predictable
changes that occur in a community over long periods of time.
Primary Succession• Primary succession occurs in an area where
there was no prior life.
Cooled Lava
Flows
Rock Exposed
from Glacial Melt
Rocky Cliffs
Pioneer Species• The first species to inhabit bare rocky surfaces
and begin primary succession are called “Pioneer Species”.
Lichen (like-in) are a common example of a pioneer species. Lichen is a symbiotic organism composed of a type of fungus and a type of algae. The fungus secretes acid that slowly dissolves the rock to release nutrients. The algae is a producer that can carry out photosynthesis to create sugar. Both organisms help each other to survive . What kind of symbiotic relationship is this?
Primary Succession Continues• As layers of pioneer species such as lichen die a
thin layer of soil forms which is enough for moss to grow.
• Succession continues as shrubs then fast growing trees like pines begin to grow followed by slow growing hardwoods like oak, hickory and maple
• As moss grows and dies the amount of soil and nutrients increases allowing grass and small plants to grow.
Climax Community• Succession continues until a mature, stable
community is established. This is called a “climax community”.
The climax community
in the northeast is a hardwood deciduous
forest
Secondary Succession• Secondary succession occurs in an area when
a disturbance destroys the plant life but the soil remains so growth can occur faster.
Forest FireClear
Cutting a Forest for Lumber
Land Cleared
for Farming