Ecological Succession Objectives: Explain and describe how succession happens. Describe primary succession. Describe secondary succession.

Important Vocabulary Ecological Succession Primary Succession Secondary Succession Old-field Succession Pioneer Species Climax Community

Ecological Succession Ecosystems change over time A shallow lake gradually fills in over time and becomes a meadow.

A forest burns and becomes a field.

A beaver dams a stream and creates a pond.

These changes occur in a regular pattern and are called ecological succession.

Succession is the change in an ecosystem from simple to more complex over time. Remember a complex ecosystem is one that has great biodiversity.

REMEMBER THIS!!! Succession is a process where the ever-changing environment favors one species over another. Certain species will replace another species because they are more suited to the new environment. (ex. shade vs. full sun)

Two Types of Succession 1. Primary succession 2. Secondary succession

Primary Succession 1. Primary succession is when plants grow where they have never grown before, such as on a new volcanic island.

A good definition of primary succession is when life begins to grow in an area that previously did not support life. It is also defined as the type of succession that occurs where no ecosystem existed before.

Primary succession can occur on rocks, sand dunes, after volcanic eruption, or glacial retreat. Usually the first species to begin primary succession is some type of algae, lichen (likens), or moss. All of these species are very hardy and simple plants. You normally see them as a green film growing on the shady sides of trees and sometimes houses. Once these pioneers get established, they can change the area so that more complex organisms can live there.

Secondary Succession 2. Is when plants grow in an area that had plants growing before, such as a field or forest that was cleared or burned.

Secondary succession is more common than primary succession Secondary succession is more common than primary succession. Secondary succession occurs in ecosystems that have been disturbed or disrupted.

After a forest fire, forest clearing, or a field is abandoned, new sun-loving plants, such as grasses, are often the first to begin secondary succession. As they grow they create shade. Shade-loving plants, such as mountain laurel, grow and create even more shade. The increased shade creates a lack of sunlight for the sun-loving plants. Because of the shade, the sun-loving plants fail to reproduce and eventually die. The sun-loving plants are replaced in the ecosystem by the shade-loving plants that reproduce successfully in the shade. As plant species change, so do the animal species that occupy the area.

A good example of secondary succession is when a fire destroys an area and the plants and animals begin to reestablish themselves in the area that was burned.

Old-field Succession occurs when farmland is abandoned Old-field Succession occurs when farmland is abandoned. When the field is no longer cultivated, grasses and weeds grow rapidly and produce many seeds to cover larger areas.

REMEMBER THIS!!! Primary succession occurs where there has not been a previous ecosystem. Secondary succession occurs after a disturbance in an existing ecosystem. Secondary succession is usually much faster than primary succession.

Whether it’s the lichen, moss, or algae invading rock during primary succession, or grasses invading an area after a disturbance during secondary succession; the first organisms to colonize the area are known as Pioneer Species.

REMEMBER THIS!!! Pioneer species are the first organisms to invade an area during ecological succession.

Climax Community Ecological succession will occur until a climax community is reached. A climax community is when the vegetation has reached a stable state; equilibrium. The climax community will continue to exist until there is a disturbance. 1. Natural disasters 2. Human disturbance

Climax communities typically contain hardwood trees such as oaks, hickory, maples, and beech trees. Climax Community