Ecological Succession: (Important info in blue) Communities in Transition Ecological Succession: (Important info in blue)

Ecological Succession Ecological Succession – The replacement of one community by another until a climax community is reached May take hundreds or thousands of years Each new community makes it harder for the old communities to survive.

Ecological Succession New environmental conditions allow one group of species in a community to replace other groups. All communities change their structure and composition in response to changing environmental conditions. During succession: Pioneer species arrive first.

Ecological Succession (Examples only – Write what will help you) A forest hundreds of years old may have been a shallow lake thousands of years ago. A dead tree falls and allow sunlight to reach the forest floor. Sunlight allows seeds to germinate. Wildflowers and shrubs grow. Moss, shrubs, and small trees cover the concrete of an old city building.

Ecological Succession Pioneer Species – The first organisms to colonize any newly available area and begin the process of ecological succession. The pioneer organism will alter the environment so that a bigger and better organism can move in. Climax Community – A final and stable community.

Climax Communities A climax community can only be disrupted by a catastrophe. After the catastrophe it will then rebuild itself back up again.

Types of Succession Primary Succession – Succession that occurs on a surface where an ecosystem did not previously exist Secondary Succession – Succession that occurs on a surface where an ecosystem had previously existed.

Primary Succession: Starting from Scratch

Lichens and mosses Exposed rocks Balsam fir, paper birch, and white spruce forest community Figure 7.11 Natural capital: primary ecological succession over several hundred years of plant communities on bare rock exposed by a retreating glacier on Isle Royale, Michigan (USA) in northern Lake Superior. The details vary from one site to another. Jack pine, black spruce, and aspen Heath mat Small herbs and shrubs Time Fig. 7-11, p. 156

Primary Succession DEFINITION: Succession that occurs on a surface where an ecosystem did not previously exist Examples: Bare rock, newly cooled lava, abandoned highway or parking lot Takes a long time because there is no fertile soil to provide the nutrients needed to establish a plant community. Begins when pioneer species arrive and attach themselves to bare rock. Examples of pioneer species: Lichens and mosses

Lichens and mosses Exposed rocks Balsam fir, paper birch, and white spruce forest community Figure 7.11 Natural capital: primary ecological succession over several hundred years of plant communities on bare rock exposed by a retreating glacier on Isle Royale, Michigan (USA) in northern Lake Superior. The details vary from one site to another. Jack pine, black spruce, and aspen Heath mat Small herbs and shrubs Time Fig. 7-11, p. 156

Primary Succession

Primary Succession

Primary Succession: Lichens

Primary Succession: Lichens

Primary Succession: Lichens

Primary Succession: Lichens

Primary Succession: Lichens

Primary Succession

Primary Succession

Secondary Succession Starting Over With Some Help

Secondary Succession Succession that occurs on a surface where an ecosystem had previously existed. Examples: Abandoned farmland, burned/cut forests, heavily polluted streams, and land that has been flooded New vegetation can usually germinate within a few weeks from seeds in the soil and those brought in from nearby plants by wind or by birds and other animals.

Secondary Succession Secondary succession occurs in ecosystems that have been disturbed or disrupted by humans, animals, or natural processes.

Time Mature oak-hickory forest Young pine forest with developing Figure 7.12 Natural capital: natural ecological restoration of disturbed land. Secondary ecological succession of plant communities on an abandoned farm field in North Carolina (USA). It took 150–200 years after the farmland was abandoned for the area to become covered with a mature oak and hickory forest. A new disturbance such as deforestation or fire would create conditions favoring pioneer species such as annual weeds. In the absence of new disturbances, secondary succession would recur over time, but not necessarily in the same sequence shown here. Young pine forest with developing understory of oak and hickory trees Shrubs and pine seedlings Perennial weeds and grasses Annual weeds Time Fig. 7-12, p. 157

Old-field Succession

Secondary Succession: Post-fire

Secondary Succession: Old Field

Secondary Succession: Post-Volcano