Succession-
a series of changes in a community in which new populations of organisms gradually replace existing ones
Succession VocabularyPioneer species—first species to appear in primary succession. Usually lichens and mosses.Climax community—the final stage in a succession. The plants tend to be larger and the community has the most biodiversity. It is a stable, mature community that undergoes little or no successionBiodiversity – different kinds (varieties) of life forms found in an area. High biodiversity means there is a large number of different species found in one area.
Primary successionOccurs where the surface is rock only. No soil present!
1. Pioneer organisms are the first species present. Pioneer species tend to be mosses and lichens who release
weak acids that begin breaking the rock into smaller pieces.
2. Simple plants such as grasses then appear. Roots are shallow and continue breaking the rock into even smaller pieces.
3. Insects and birds begin to appear. As plants and animals die, their bodies mix with crumbling rocks to eventually form soil.
Primary Succession continued…
4. Gradual appearance of more complicated and larger plants and animals as the habitat changes.
5. Ends with a “climax community” – ecosystem stays constant, provided there are no changes in abiotic influences. Biodiversity is at its highest.
Secondary succession-
sequence of community changes that takes place when a community is disrupted by natural disaster or human actions – takes place on existing soil
Secondary succession1. Begins in an area where soil is already present. Much faster than primary succession (making soil is a
VERY slow process!)2. First species in an area tend to be grasses + weeds.3. Next community may include taller grasses + golden
rod4. Then small trees (cherries, dogwood, sumac) begin
to appear.5. Final step is a mature climax forest (oak, beech-
maple, hickory)
Stages of Pond Succession
Stage 1: Plankton growth is rich enough to support animals that entered when the pond was connected to the lake. Fish make nests on the sandy bottom. Mussels crawl over the bottom.Stage 2: Cattails, bulrushes, and water lilies grow in the pond. These plants have their roots in the bottom of the pond, but they can reach above the surface of the water. This pond is an ideal habitat for the animals that must climb to the surface for oxygen. Aquatic insect larvae are abundant. They serve as food for larger insects, which in turn are food for crayfish, frogs, salamanders, and turtles.
Pond Succession continued…Stage 3: Decayed bodies of plants and animals form a layer of humus over the bottom of the pond. Chara, a branching green algae, covers the humus. Fish that build nests on the bare bottom have been replaced by those that lay their eggs on the Chara.Stage 4: The pond is so filled with vegetation that there are no longer any large areas of open water. Instead, the pond is filled with grasses. The water dries up during the summer months.
Primary vs. SecondaryNo soil
Pioneer species
Weathering of rock & decomposition of pioneer plants and insects build soil base.
End = climax community where biodiversity is at its greatest
Soil already exists
Seeds have suitable soil conditions from the beginning.
Occurs much faster
End = climax community where biodiversity is at its greatest
May occur on dry land or with ponds