Ecological Succession Ecology Succession after the Yellowstone fires. 11/14/2018 Ecological Succession Ecological succession is the set of changes in community composition that occur over time in a new or disturbed community. Succession at Mt. St. Helens. G. Podgorski, Biol. 1010

Terrestrial Primary Succession

Primary Succession Primary succession involves the changes from pioneer species which colonize an environment through the seral stages to the climax community. Changes in abiotic factors lead to more favourable conditions and increasing species diversity

Primary Succession Begins in a place without any soil Sides of volcanoes Creation of new land Starts with the arrival of living things such as lichens that do not need soil to survive Called PIONEER SPECIES

http://botit.botany.wisc.edu http://www.saguaro-juniper.com/

Primary Succession Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil

http://www.life.uiuc.edu

Primary Succession Simple plants like mosses and ferns can grow in the new soil http://www.uncw.edu http://uisstc.georgetown.edu

Primary Succession The simple plants die, adding more organic material The soil layer thickens, and grasses, wildflowers, and other plants begin to take over http://www.cwrl.utexas.edu

Primary Succession These plants die, and they add more nutrients to the soil Shrubs and tress can survive now http://www.rowan.edu

Primary Succession Insects, small birds, and mammals have begun to move in What was once bare rock now supports a variety of life http://p2-raw.greenpeace.org

A Lithosere Primary Succession at Glacier Bay, Alaska Ecology 11/14/2018 Primary Succession at Glacier Bay, Alaska A Lithosere G. Podgorski, Biol. 1010

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 fires, human activity

http://www.scienceclarified.com/images/uesc_10_img0552.jpg

http://www.ccs.k12.in.us/chsteachers/BYost/Biology%20Notes/secondarysuccession.jpg

http://www.ux1.eiu.edu

Climax Community A stable group of plants and animals that is the end result of the succession process The climax community produced is controlled by the climate. eg water present all year – generally woodland distinct wet and dry seasons – grassland wet and acidic – blanket bog Does not always mean big trees Grasses in prairies Cacti in deserts Reeds and grasses in saltmarshes

Speed of Succession Changes are slower if the abiotic conditions are less suitable for life – too hot/cold, too dry or if the availability of plant nutrients is a limiting factor. Changes are usually slower during the early stages of succession. Secondary succession is usually a faster process than primary succession, in the same environment

General Trends in Succession Biomass increase over time. An increase in the number and proportion of longer-lived species. Increased species diversity over time. Succession on Mt. St.Helens – another site of intense study.