lecture #2 ecological succession unit 7: ecology
Post on 20-Jan-2016
239 Views
Preview:
TRANSCRIPT
Lecture #2 Lecture #2 Ecological SuccessionEcological Succession
Unit 7: Ecology
Ecological succession- the regular progression of species replacement over time in a new or disturbed community.
1) Biomass increases over time.
2) An increase in the number & proportion of longer-lived species.
3) Increased species diversity. Succession on Mt. St. Helens
Succession shows some general trends that include:
There are two types of terrestrial succession
1)Primary Succession 2)Secondary Succession
This colonization of new sites by communities of organisms takes
place on bare rock
Primary succession: The establishment and development of an ecosystem in an area that was previously uninhabited
Primary succession: The establishment and development of an ecosystem in an area that was previously uninhabited
New bare rock comes from 2 sources
1. A volcanic lava flow cools and forms rock
– This is how the Galapagos islands and the Hawaiian islands formed!
New bare rock comes from 2 sources
2. Glaciers retreat and expose rock
How does the process begin?
Pioneer organisms- the first organisms
to colonize a new site – Ex: lichens are the first to colonize lava
rocks
These guys are TOUGH! They thrive where no other species can.
What do they do and what happens next ?
– As lichens add organic matter and form soil, mosses and other plants can colonize and grow.
– As organic matter continues to accumulate, other species move in and change the environment further. First fast growing plants, then slower growing plants.
– Over time, more and more species can find suitable niches and survive.
Primary succession-
Is there an ‘end’ to succession?
Climax Community - a stable, mature
community that undergoes little or nosuccession.
** This is not necessarily a ‘permanent’ community however. What would cause it to change?
Answer: A changing environment!
Secondary succession-
Definition: Sequence of community changes that takes place when a community is disrupted by natural disaster or human actions
• This type of succession occurs in areas where there HAD been previous growth. Because of this, the process is much faster than primary succession.
What can cause secondary succession to
occur? 1) Forest fire
• The regrowth that happens after a fire levels a portion of a forest.
What can cause secondary succession to
occur? 2. Abandoned Agricultural Field
• Native plant life from the areas surrounding the agricultural field reinvade the area.
Secondary succession-
Case Case Study- Study-
YellowstonYellowstone National e National
ParkPark1988 – Park mapshowing areas
(1.6 million acres)
burned by theseries of fires.
Yellowstone National ParkYellowstone National Park1988 fires – The immediate aftermath.
Photo: National Parks Service
Yellowstone Yellowstone National National
ParkPark• One year after the
fires• Note the
appearance of fireweed
Photo: National Parks Service
Yellowstone National Yellowstone National ParkPark
• Ten years after the fires (1998)
Photo: National Parks Service
Yellowstone National Yellowstone National ParkPark
• Twenty years after the fires (2008)
Is the Yellowstone Case study an example
of primary or secondary succession?
Case Study - ChernobylCase Study - Chernobyl
• In April, 1986, a nuclear power plant in the former USSR experienced a core meltdown and a catastrophic release of radioactivity into the environment.
ChernobylChernobyl
• Surrounding towns and villages had to be immediately, permanently abandoned.
Chernobyl – Twenty Years Chernobyl – Twenty Years LaterLater
Chernobyl – Twenty Years Chernobyl – Twenty Years LaterLater
Pripyat town square.
Chernobyl – Twenty Years Chernobyl – Twenty Years LaterLater
Chernobyl – Twenty Years Chernobyl – Twenty Years LaterLater
A local highway.
Is the Chernobyl Case Study an example of Primary or Secondary Succession?
Take 2 minutes to describe what succession is,and to identify the similarities and
differences that exist between primary andsecondary succession.
top related