Warm-up: Succession

• Read the Case Study, “Communities Maintained by Fire” on pages 130 – 131.

• Write two things you have learned and • answer questions #1 & 2.

Warm-up Answers

• • • 1. New things you have learned… The purple plant Fireweed covers the burned forest areas of the Rocky Mountains. Ecological Communities (Biomes) that are maintained by fire are: Chaparral of California, Temperate Grasslands of the Midwest, many Southern and Western Coniferous forests.

• Seeds of some species will not germinate until exposed to temperatures of several hundred degrees.

Changes in Ecosystems:

Ecological Succession

What is Ecological Succession?

• Natural, gradual changes in the

types of species that live in an area

• Can be

primary or secondary

• The gradual

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

Primary Succession

• Primary succession occurs where there

was no previous community , such as on bare rock or sand .

• Begins in a place

without any soil:

»Sides of volcanoes »Landslides »Flooding »Glacial retreat

• Primary succession begins with

PIONEER SPECIES.

Pioneer organisms can tolerate extreme conditions : hot and cold; dry and wet.

Moss, dune grass, and lichens are pioneer organisms.

• First, • Next,

lichens survive grow on rocks mosses that do not need soil to grow to hold newly made soil

Pioneer Species

Lichens break down rock to form soil.

Low, growing moss plants trap moisture and prevent soil erosion

Lichens

Lichens are algae and fungus together in a mutualistic growing relationship.

• Algae

make the food

• Fungus

anchor and capture water.

Primary Succession

• Soil

help starts to form as break down rocks lichens and the forces of weather and erosion into smaller pieces

• When lichens die

, they decompose , adding small amounts of organic matter to the rock to make soil

Primary Succession with lichens and mosses.

Primary Succession

• Simple plants like

mosses can grow in the new soil and ferns

Primary Succession

• The • The

over simple plants die , adding more organic material (nutrients to the soil) soil layer thickens , and grasses, wildflowers, and other plants begin to take

Primary Succession

• 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.

Secondary Succession

• Begins in a place that

already has soil and was once the home of living organisms

• Occurs faster and has

different pioneer specie s than primary succession

Secondary Succession

• Newer communities make it

harder for the older communities to survive.

– Example: Younger birch trees will

have a harder time competing the smaller birch trees.

with taller, older birch trees for sun, but a shade loving tree may replace

When does secondary succession occur?

• After forest fires • After cultivated land is abandoned • Temporary flooding from storms, etc.

Climax Community

• A relatively stable group of plants

and animals that is the end result of the succession process

– However,

stability never happens for long in ecology! The only constant is CHANGE !

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

• The following slide is an example of the Secondary Succession of a deep freshwater pond.

https://www.youtube.com/watch?v=k03vxRYsJ4Y