Succession

1
Succession

• Mt. St. Helens, Washington
• 1980

2
Before the Big Eruption

• Snow covered
• Mt. St. Helens on April 10, 1980
• View of Johnston Ridge on
• May 17, 1980

3
Boreal Forest Biome
4
Mt. St. Helens Erupted on May 18, 1980

• First day of the eruption.
• Car buried in ash and debris on May 31, 1980.

5
After the Eruption

• Helicopter hovering above ash on August 22, 1980
• Blast area at
• Spirit Lake with
• Mt. Rainier in background,
• October 4, 1980

6
What Happened Here?Spirit Lake from 1980 - 1984

• Spirit Lake, May 1980
• Blast Area, Oct. 1980
• Fireweed Growing,
• Sept. 1984

7
Smith Creek from 1980 - 1986

• Blowdown of trees,
• Sept. 1980
• Blast area, Sept. 1980
• New Growth, June 1986

8
Make a list of all the differences you notice
between the scenes.

• 1980 soil is bare, scorched, and covered with
  ash trees are fallen and damaged water is
  polluted and clouded
• 1982, 1984, 1986 grasses and weeds are
  beginning to grow water appears clear
• ash or lava is still visible in both

9
What happens to populations when conditions in an
environment change permanently?

• affects both animal and plant species and
  populations
• gradual change if due to changing environmental
  conditions
• sudden change, such as when floods, fires,
  volcanic eruptions, or other natural disasters
  occur
• populations will rebuild over time

10
Regrowth of North Fork Toutle River
October 5, 1980 May 15,
1989 Succession
11
SuccessionHow does succession happen?

• The island begins from bare sand, with NO plants
  or animals
• Seeds from plants on neighboring islands can be
  carried to the island by wind, water, or animals
• Some may sprout and begin to grow

12
Does succession happen only on newly formed
islands?

• No, succession can happen in any environment
  where change occurs.
• Plowed farm field
• Burned forest
• Grassland that gradually receives less rainfall
• After a hurricane, volcano, flooding
• Abandoned mine
• Removal of a building

13
Define primary succession

• series of changes that occur in an area where no
  ecosystem previously existed
• no soil is present
• pioneer species such as lichens and mosses are
  often the first species
• volcanic eruption, melting glacier

14
Define secondary succession

• occurs where an ecosystem has previously existed
• soil is present
• fires, hurricanes, tornadoes, farming, logging,
  mining
• occurs more rapidly