Successiona series of changes in a community in

Successiona series of changes in a community in which new populations of organisms gradually replace existing ones

Succession Vocabulary Pioneer 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 succession Biodiversity – 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 succession Occurs 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.

Primary succession. New bare rock comes from 2 sources: 1. volcanic lava flow cools and forms rock

Primary succession. New bare rock comes from 2 sources: 2. Glaciers retreat and expose rock

Bare Rock Lichens, Mosses Small Herbs, Shrubs Evergreens, Aspen Climax Community

Primary succession-

Secondary successionsequence of community changes that takes place when a community is disrupted by natural disaster or human actions – takes place on existing soil

Secondary succession 1. 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 rod 4. Then small trees (cherries, dogwood, sumac) begin to appear. 5. Final step is a mature climax forest (oak, beechmaple, hickory)

Secondary succession. Ex: A fire levels portions of a forest

Secondary succession. Ex: A farmer stops plowing his field

Secondary succession-

Secondary succession-

Pond Succession

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.

Pond Succession

Primary vs. Secondary No 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

Table 53. 2 The Pattern of Succession on Moraines in Glacier Bay

Figure 53. 20 Alders and cottonwoods covering the hillsides

Figure 53. 20 Spruce coming into the alder and cottonwood forest

Figure 53. 20 Spruce and hemlock forest