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Study Guide
Succession and Catastrophic Events Test
Test is May 6, 2011
Succession: A gradual process of predictable changes, that occurs in a community
over time. (takes many years) . This change helps an ecosystem achieve balance
(stability)
Pioneer species: the first species to populate a new area
Climax Community: A stable (balanced) end stage of succession where plants and
animals use resources efficiently and balance is maintained. This is what completes
succession
“Nothing succeeds like succession”
Primary Succession
o Occurs in an area where no previous
ecosystem existed.
o Begins with bare rock, not soil
o Pioneer species are Mosses and Lichens that
grow in little to no soil
o After soil is formed, grasses, then shrubs
and then trees take over the landscape
o Takes longer than secondary succession
Example:
Starts with a volcanic eruption where lava
cools into igneous rock. Wind and water bring
in moss or lichens and they grow on the rock
surface. Wind and water also break down the
rock, overtime forming soil
Secondary Succession
 Occurs after a disturbance like a wildfire
or hurricane
 After an ecosystem has been developed
 Pioneer species are flowers, grasses and
weeds
Example:
A tornado uproots trees and shrubs and
destroys grass root systems. The tornado drops
debris allover the land. A few months after the
tornado, residents notice green grass starting to
grow back. Two years later hikers enjoy
identifying the small shrubs that have moved in
and 10 years later the area is covered with
beautiful oak trees
Primary Succession
(It starts with exposed rock)
Increase in time
Balanced now
Secondary Succession
(It starts with a disturbance and soil)
In the picture above notice that:
1. After the fire is put out, secondary succession starts
2. The first plants to move in after the fire are small grasses and shrubs
3. As you go through secondary succession you get more types of plant species in your community
which increases biodiversity
4. More biodiversity equals more stability. (biodiversity: many different types of plants and animals
in a specific area)
Catastrophic Events:
Flood
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Rise in water level due to a lot of rain
Occurs in low lying areas
Can cause animals to move or drown
Causes water pollution due to debris and mixing with sewage
Tornados
o
o
o
o
o
Mainly found in central US (grasslands) but can be found all over the world,
Occurs without much notice
Does not last very long but can destroy entire towns
Violent whirling winds
Can causes secondary succession
Hurricanes
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Starts as a tropical storm over warm ocean waters
Can be a few miles wide
Last for several days
Occurs along coastal areas
Strong winds can cause big waves
Causes massive erosion and deposition at beaches
Can causes secondary succession
The center is calm and known as the “eye”
Earthquakes
o
o
o
o
Rocks shift at a plate boundary and faults releasing tension
Knocks down buildings
If it happens on the ocean floor it can cause a tsunami
Can cause secondary succession
Volcanoes
 Can cause primary succession to start if eruption included lava
 Lava burns plants and animals in it’s path
 Ash can suffocate animals and block out the sun for several days
Wildfires
o Puts nutrients back into the soil
o Destroys populations of plants and animals that can not move out of the way
o Causes secondary succession
Droughts
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Little to no precipitation in a given area over a long period of time
Ponds, lakes and aquifers lose water
Animals and plants (crops) die
Can cause wildfires with heat of sun
Can cause secondary succession