1. Fire and Secondary Succession
Natural fires caused by lightning are a necessary part of secondary succession in some communities.
Minor forest fires remove accumulations of brush and deadwood that would otherwise contribute to major fires that burn out of control.
Some animal species also depend on occasional fires because they feed on the vegetation that sprouts after a fire has cleared the land.

2. Heat causes the pine cone to open and release seeds.
Lodgepole Pine Cone
Heat causes the pine cone to open and release seeds.

3. One year after the fire in Yellowstone Park
Lodgepole Seedlings
One year after the fire in Yellowstone Park

4. Four years after the fire in Yellowstone Park
Lodgepole Pines
Four years after the fire in Yellowstone Park

5. Ten years after the fire in Yellowstone Park
Lodgepone Pines
Ten years after the fire in Yellowstone Park

6. Ten years after the fire in Yellowstone Park
Lodgepole Pines
Ten years after the fire in Yellowstone Park

7. Old-field Succession
Old-field succession is a type of secondary succession that occurs when farmland is abandoned.
When a farmer stops cultivating a field, grasses and weeds quickly grow and cover the abandoned land.
Over time, taller plants, such as perennial grasses, shrubs, and trees take over the area.

10. 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