Transcript Ecological Succession

Ecological Succession
http://static.howstuffworks.com/gif/wildfire-deer.jpg
How do ecosystems respond
following a disturbance?
Vocabulary
Climax Forest
Lichen
Pioneer Species
Primary Succession
Secondary Succession
ecological succession: series of
changes that occur over time in an
ecosystem
1.primary succession: succession that
occurs on surfaces where no soil
exists
2.secondary succession: succession
that occurs following a disturbance
that changes an existing community
without removing the soil
Primary Succession
• Occurs when bare rock is exposed by a
retreating glacier or created by cooled
lava. – The soil is gone!
• pioneer species: first species to populate a
previously uninhabited area (mosses,
lichens)
Mosses and
Lichens:
Fungus/algae
that can grow on
bare rock
Succession progresses from pioneer species
to more complex ecosystems and longer-lived
trees, ultimately resulting in a Climax
Community
This process may take hundreds of years from
the first plants until a climax forest is reached.
Craters of the
Moon National
Monument
Idaho, US
Craters of the
Moon National
Monument
Idaho, US
Secondary Succession
• Occurs following natural or human-caused
disturbances: wildfires, clearing of land for
agriculture or development, wind storms,
lakes that dry up, etc.
• The soil is still in place
Secondary succession is quicker than primary
because the soil is in place.
It may start with grasses as pioneer species.
South side of Mount St. Helens and Shoestring Glacier prior to the 1980 eruption.
(USGS, D. Miller)
http://www.fs.fed.us/gpnf/mshnvm/research/faq.html#forests
Muddy River lahar deposit following the Mount St. Helens eruption.
(USDA Forest Service,
F. Valenzuela, 1981)
http://www.fs.fed.us/gpnf/mshnvm/research/faq.html#forests
Fresh pyroclastic flow deposits directly north of the crater at Mount St. Helens.
(USGS, 1980)
http://www.fs.fed.us/gpnf/mshnvm/research/faq.html#forests
Twenty-five years later the Pumice Plain north of the crater is covered in wildflowers.
(USDA Forest Service,
P. Frenzen, 2004)
http://www.fs.fed.us/gpnf/mshnvm/research/faq.html#forests
Mount St. Helens
Washington, US
Eruption May 1980
Photos taken August 2005