SC912L174 Describe changes in ecosystems resulting from seasonal variations climate change and succession By Dr Suris Soto What Is Disturbance A disturbance Is an event that changes a community ID: 574643
Download Presentation The PPT/PDF document "Ecological Disturbances and Succession" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Ecological Disturbances and Succession
SC.912.L.17.4
Describe changes in ecosystems resulting from seasonal variations, climate change and succession.
By Dr. Suris SotoSlide2
What Is Disturbance?
A disturbance
Is an event that changes a community
Removes organisms from a communityAlters resource availabilitySlide3
Disturbances
Natural
Human-Caused
They are common in
ecosystems
Fire
Hurricanes
Floods
Volcanic Eruptions
Are the most widespread agents of disturbance
Usually reduces species diversity
Humans also prevent some naturally occurring
disturbances
Deforestation and land cleared
Farming
Urbanization (Developments)Slide4
Ecological Succession
Ecological succession
Is the
gradual sequence of community and ecosystem changes after a disturbance
One community of organisms replaces anotherSlide5
Types of Ecological Succession:
Primary succession
Occurs where
no soil, (barren terrain)
exists
when succession
begins
No pre-existing plant or animal life Examples: After volcanic eruption, retreating glacier (natural), abandon parking lot (human-caused)Secondary successionBegins in an area where
soil remains
after a
disturbance
Some organisms may still be there
Examples: After a flood, hurricane, tornado (natural) or after
land cleared for farming, deforestation (human-caused)Slide6
Primary Succession ----
No Soil, barren rock
Glacier Retreating
Volcanic Eruption
Abandon parking lotSlide7
Secondary Succession after a fire
A Fire
Is
a significant disturbance in most terrestrial ecosystemsIs often a necessity in some communities
(a)
Before a controlled burn.
A prairie that has not burned for
several years has a high propor-
tion of detritus (dead grass).
(b)
During the burn.
The detritus
serves as fuel for fires.
(c)
After the burn.
Approximately one month after the controlled burn, virtually all of the biomass in this prairie is living.
Figure
a–cSlide8
The large-scale fire in Yellowstone National Park in 1988Demonstrated that communities can often respond very rapidly to a massive disturbance
Figure 53.22a, b
(a) Soon after fire.
As this photo taken soon after the fire shows, the burn left a patchy landscape. Note the unburned trees in the distance.
(b) One year after fire.
This photo of the same general area taken the following year indicates how rapidly the community began to recover. A variety of herbaceous plants, different from those in the former forest, cover the ground.Slide9
Secondary Succession Slide10
Pioneer species
Always the first species to move into a devastated area
Must be able to live on limited resources
Must be able to live in barren rockThey include
Bacteria
Lichens
Lichens are a symbiosis (close relationship) of a fungus and a green algae
Each organisms depends on each other for survival (mutualism)
Fungus anchors lichen to a surface, absorbs water and nutrients, and protects the algae from direct sunlight.
The algae performs photosynthesis to make its own food and also feed the fungus
As lichens grow, they make break down rock , help form soil. When it dies it decomposes enriching the soil. Slide11
Pioneer species
Lichens
Mosses
Bacteria Slide12
Primary Succession Slide13
Climax community
Fairly stable community
Marks the end of succession in an area
Organisms present depend on the climate and physical features of the areaEx. In areas with little rain the climax is a grasslandNothing lasts forever: A new disturbance can happen at any time
Disturbances in climax communities can lead to secondary succession or primary in the event of volcanic eruption covering the soil with lava, hardened to rock Slide14
Draw it yourself:Slide15
Which of the following is not a possible cause of secondary succession?
Fire
Flood
Earthquake
Change of seasonsSlide16
Which of the following is an example of primary succession?
Lichens growing on rocks after a volcanic eruption
Grasses growing after a forest fire
Oak trees replacing pine trees in a forest
Nonnative species introduced into a climax communitySlide17
Which term refers to final forest’s development?
Pioneer forest
Secondary forest
Climax forest
Conifer forest