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.

Warm- Up Answers (cont’d) #1. A young longleaf pine is low to the ground, so it can survive fire that sweeps through the canopy. Deciduous trees may burn because they are not as low to the ground.

Warm-up Answers (cont’d) #2. The tallgrass prairie, have evolved in an environment of frequent fires. In these communities, controlled fires can kill any competitors that try to move in to the ecosystem. Disadvantages to using fire: Risk to human property Chance that competitive species may not be destroyed.

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

Primary Succession Sides of volcanoes Landslides Flooding 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, lichens that do not need soil to survive grow on rocks Next, mosses grow to hold newly made soil

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

Lichens Lichens are algae and fungus growing together in a mutualistic relationship. Algae make the food Fungus anchor and capture water.

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

Primary Succession with lichens and mosses.

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

Primary Succession 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 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.

Warm-up: Primary succession Explain some of the adaptations of plants, especially in California’s Chapparal Biome.

Ceanothus americanus (pictured below) has leaves covered with flammable resins that help fuel a fire. This adaptation benefits the species because ceanothus seeds require intense heat for germination. “Fire-resistant” roots also enable the plant to resprout quickly in recently burned areas.

Knobcone pine (pictured below) have seed cones that require the heat of a fire to open. The seeds are protected from fire behind tightly closed resin-coated scales, often so well insulated that even when the outer part of the cone is charred, the seeds inside are protected. High temperatures cause the cone to open, releasing the seeds that fall to the ground into a cool bed of ash and mineral soil.

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

Secondary Succession Newer communities make it harder for the older communities to survive. Example: Younger birch trees will have a harder time competing with taller, older birch trees for sun, but a shade loving tree may replace the smaller birch trees.

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.

Crash Course video, Succession (10:02) http://www. youtube. com/watch Bozeman, Ecological Succession (6:21) http://www.youtube.com/watch?v=V49IovRSJDs Succession Song, Mr. Parr (3:58) http://www.youtube.com/watch?v=rzE6BNNLew0 Animation with bird, Succession (6:22) http://www.youtube.com/watch?v=k03vxRYsJ4Y