C-Notes: Ecological Succession Stnd: 6b C-Notes: Ecological Succession 4/23/2014 Objective: SWBAT identify the process of change in the species that make up a community.

ECOLOGICAL SUCCESSION The gradual replacement of one community by another. Ecological succession eventually leads to the formation of a stable community. Each community slowly changes the environment. The changed environment often is more suitable for new types of organisms and less suitable for the existing organisms. Ecological succession occurs in step stages. A stable community is called a CLIMAX COMMUNITY.

SUCCESSION Primary Succession Occurs in an area that has no existing life. Must begin with the formation of soil. Example: a bare rock, rocky cliffs, sand dunes, newly formed volcanic island, newly exposed land areas. Secondary Succession Begins in a place that already has soil and was once the home of living organisms Occurs faster and has different pioneer species than primary succession Example: After Forest Fire, Tornado, Hurricane

PRIMARY SUCCESSION First Stage Can begin with bare rock. Lichens are usually one of the first organisms to appear because they can live on bare rock. The first organisms are called PIONEER SPECIES Pioneer organisms are able to survive in harsh conditions with few nutrients.

Pioneer Species Low, growing moss plants trap moisture and prevent soil erosion Lichens break down rock to form soil.

Primary SUCCESSION Second Stage Third Stage Fifth Stage Fourth Stage Grasses Third Stage Shrubs and Small Trees Fifth Stage Shade Trees Fourth Stage Sun Trees

Primary Succession Simple plants like mosses and ferns can grow in the new soil

Primary Succession (2nd Stage) The simple plants die, adding more organic material (nutrients to the soil) The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

Primary Succession (3rd Stage) These plants die, and they add more nutrients to the soil Shrubs and trees can survive now

Primary Succession Insects, small birds, and mammals have begun to move into the area What was once bare rock, now supports a variety of life

ECOLOGICAL SUCCESSION

CLIMAX COMMUNITIES If environmental conditions in an ecosystem remain stable over long periods of time, the same species of plants and animals that make up that ecosystem continue to live and interact together. These permanent plant and animal species make up a stable or climax community. This is the END RESULT of the succession process DOES NOT always mean big trees Grasses in prairies Cacti in deserts There is a balance within the population and the environment. A Climax Community remains until a drastic environmental change occurs. Storm, Forest Fire, Flood, Volcanic Eruption The type of climax community is determined by the abiotic factors of the area.

ECOSYSTEM STABILITY Under stable environmental conditions, the number of organisms in naturally occurring populations remains constant (the same), with only small periodic changes. A stable ecosystem will be able to resist invasion by potential competitors. A stable ecosystem will be able to resist change in the face of disturbance. A more diverse ecosystem will be more stable.