Changes in Ecosystems:Ecological Succession

Definition:

• Natural, gradual changes in the types of species that live in an area; can be primary or secondary

• The gradual replacement of one plant community by another through natural processes over time

Ecological Succession

• There are two main types of succession, primary and secondary.

Primary succession is the series of changes that take place when there is no soil present. For example, after a volcano or destroyed coral reef.

Secondary succession is the series of changes that take place when there is soil present. For example, after a fire, hurricane, flood, destruction by man, or tornado.

 

Which one do you think takes longer?Answer

Primary Succession

Why?

The rocks need to break down to make the soil before new species will grow

Primary Succession

• Begins in a place without any soil – Sides of volcanoes– Landslides– Flooding

• 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://uisstc.georgetown.edu

http://www.uncw.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

• http://teachertube.com/viewVideo.php?video_id=182733

Pond Succession- Primary or secondary?

• Put the pictures in order

B, C, A, then D.

Secondary Succession

• More common

• Occurs on a surface where an ecosystem has previously existed.

• Occurs on ecosystems that have been disturbed or disrupted by humans, animals, or by natural processes such as storms, floods, earthquakes, and volcanoes.

Secondary Succession: Mt. St. Helens

• Erupted in 1980.• 44,460 acres were

burned and flattened.• After the eruption,

plants began to colonize the volcanic debris.

• Pioneer species: the first organism to colonize any newly available area and begin the process of ecological succession.

• Over time, the pioneer species makes the area habitable by other species.

• Today, Mt. St. Helens in the process of secondary succession.

• Plants, flowers, new trees and shrubs have started to grow.

• If this continues, over time they will form a climax community.

http://www.geo.arizona.edu

http://www.ux1.eiu.edu

Climax Community

• A stable group of plants and animals that is the end result of the succession process

• Does not always mean big trees– Grasses in prairies– Cacti in deserts

Whale Fall Community

• A whale fall is a whale carcass that has fallen to the ocean floor. Whale falls were first observed in the 1980s, with the advent of deep-sea robotic exploration. When a whale dies in shallow water, its carcass is typically devoured by scavengers over a short period of time

Whale Fall• However, in very deep water, fewer

scavenger species exist. The dead carcass of the whale can provide sustenance for the complex localized ecosystem over a period of decades

• This ecosystem does not need plants or light because they can live off off dead whales for long period of time

• There are also many chemosynthetic organisms at those deep depths

Hox gene

• Hox genes are a group of regulatory genes that control the timing and route of development.

• If a Hox gene is turned off for a fruit fly, this fly might not have wings when it is an adult

Hox Gene

• If a giraffe needs to reach higher up on a tree to get its food to survive, will evolution occur?

• It may indeed, the Hox gene may cause a mutation that makes the neck become bigger at birth

• Hox genes may cause great changes in the early development stages