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Secondary Succession

Secondary Succession. I. Forest & Brush Fires II. Retrogression. I. Succession After Forest & Brush Fires.

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Secondary Succession

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  1. Secondary Succession I. Forest & Brush Fires II. Retrogression

  2. I. Succession After Forest & Brush Fires

  3. A forest fire in southern California in late summer. They are very dangerous because they spread across hillsides in seconds, destroying hundreds of acres of land. They can also change direction very quickly, fueled by dry winds.

  4. A smoke cloud from a forest fire can be seen from miles around. It carries ash and debris from the ecosystem it has burned.

  5. These are charred leaves that showered down on a city in southern California. These were carried by the smoke cloud shown in the previous slide.

  6. This is a rattlesnake moving across the charred soil one day after a fire. Although fires kill most of the organisms in the ecosystem, some are able to survive.

  7. Despite the damaged soil, new sprouts of a chamise shrub are able to grow around the charred branches of a shrub that used to grow there. The flakes are pieces of the boulder that were shed due to the extreme heat of the fire.

  8. Now, leafy branches are resprouting because of the vegetative buds buried deep in the ground. These chamise shrubs have subterranean stumps that allow them to regnerate despite being destroyed above-ground. They are well adapted to surviving fires.

  9. When most trees are charred by fire, they rarely recover. These oak trees, however, can resprout from the trunk and upper branches. This picture shows sprouting 4 months after a fire.

  10. Because the bark of these trees is thick and fire-resistant, it creates a layer of heat insulation to protect the living cells below the bark. The bark is also very smooth, which prevents the fire from moving up the trunk.

  11. After the fires, the rains of winter and spring cause wildflowers to bloom. As one species dies, another species will replace it. Vines of wild flowers grow over and cover the burned shrubs.

  12. The seeds of these wildflowers can remain dormant for up to 40 years, and then germinate after a fire. Their tough seed coats can be broken down by a fire, allowing the seeds to soak up water and germinate. The ashy soil also promotes these flowers’ germination.

  13. These are the pinecones of fire-adapted pine trees. Their woody scales open slowly and release their seeds after the fire has burned through the area. Without fire, the pinecones can remain closed for over 100 years. The cones are attached very tightly to the trunks of trees.

  14. This is a naturally regenerated pine forest, 15 years after a fire. This is a burned pine forest.

  15. II. Retrogression

  16. This is a dense marsh in a canyon.

  17. This is the same canyon after a flood. All of the vegetation and soil have been washed away.

  18. Still Curious? • Check out this website for A LOT more pictures and explanations! • http://waynesword.palomar.edu/lmexe10a.htm#succession

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