Unit 4 Lesson 14: Extreme Disturbances in Ecosystems Flashcards
While extreme disturbances are not as common as small or moderate ones, they do happen. What is the big differnece that set exterme disturbances from small or moderate ones
The big differences are that their impact on the local ecosystem is much larger and that these impacts last over longer periods of time.
Extreme disturbance events might include physical events—
i.e., hurricanes, tornadoes, volcanic eruptions, earthquakes, forest fires, glacial movement or retreat
human-influenced events—
severe pollution, unintended consequences of damming or changing the flow of rivers, over-harvesting of forests or other ecosystems
biological events—
locust swarms or introduction of invasive insects into areas where they have no predators.
In recent years, global climate has warmed enough that many glaciers are melting. As they recede, they are leaving behind large barren areas. What impact does this have in the long run? What is primary succesion
In order for life to reclaim the area revealed by a retreating glacier, the cycle has to begin at ground level. This colonization of newly-exposed rock is known as primary succession.
What are lichens and how do they work
Lichen is actually two organisms living together in a mutually beneficial relationship. The two organisms are a fungus and an algae. The fungus secretes acids and other chemicals that break down the rocks. The algae photosynthesize and provide energy for the fungus-algae partnership.
In order for life to reclaim the area revealed by a retreating glacier, the cycle has to begin at ground level. This colonization of newly-exposed rock is known as primary succession. . The rocky barren ground is a perfect habitat for lichens.
Bits of lichens float in on air currents and attach themselves to the rocks. Over time, the lichen break down the rocks, and when the lichen die, their bodies get incorporated into the sand, gradually forming nutrient-rich soil as they decompose. This creates the basis for a new ecosystem.
When the area that once was a galcier finally forms soil organims move in. What are pioneer species
Once soil has been established, other organisms gradually move in. The first on the scene are called pioneer species. These usually include grasses and other tiny plants.
Describe how a glocier became a communit
They grow, develop, reproduce, and then form an even stronger basis for larger bushes to move in. These plants grow for some time, setting the stage for larger trees. Once larger trees are established, the ecosystem becomes a stable community.
Once the volcano has stopped erupting, there is nothing left to the ecosystem. There is no habitat left in which organisms can live. It is essentially dead. Is this true forever
However, like after the glacial retreat, the new rock laid down by the volcano can serve as a basis for the formation of new soil. The same order of succession occurs, over time, to turn the lifeless volcanic field into a thriving ecosystem.
Impacts of volcanoes and glaicers melting
These two extreme disturbances to ecosystems can result in the widespread destruction of habitat. Given enough time, however, new ecosystems can form. These may be similar to the ones that were originally there, or they could be completely different.
When is a disturbance exterme
In other types of disturbances the devastation from the initial event may not be as total. But when their impact on the local ecosystem is severe enough to kill much or all of the local community, these events are still considered extreme. But here the recovery takes the form of secondary succession. The process gets a jump start from the existence of a soil base, but, for example, forest recovery from a fire is still a long process that many take several decades.
What are the two forms of succession involved in creation or restoration of a community after an extreme disturbance? How are they different?
Primary and secondary succession. Primary succession begins at the stage of newly exposed or newly formed rock and includes colonization by primary species. Secondary succession occurs after a major upheaval to an ecosystem and involves gradual progressive change or restoration.
What is the relationship between climate change and extreme disturbances in ecosystems?
The main impact of climate change is increased temperatures. These temperatures are causing glaciers to melt at a faster rate than usual. This results in the formation of new rocky terrain, devoid of life. Additionally, climate change is causing more frequent and more powerful storms, which are causing destruction to ecosystems.
Why are lichen essential to the formation of a new ecosystem after an extreme disturbance?
Lichen break down rocks into smaller particles and when the lichen die, they add nutrients to the new soil.
What happens in the order of succession after the grasses move into a new ecosystem?
Grasses are replaced by short shrubs and other low plants. Smaller trees move in next, until finally, large, tall trees start to grow, forming the climax community.
Why is a retreating glacier considered an extreme ecosystem disturbance?
An extreme ecosystem disturbance completely destroys the existing ecosystem, leaving nothing left in its path. When glaciers retreat, they expose new areas of land that are devoid of all life. Nothing has lived in the area because it was covered with ice for thousands of years.
What would be an example of an extreme disturbance that could affect the ocean ecosystem?
A massive oil spill would be an extreme ocean disturbance.
Oil spills are probably the most significant human activity that can cause an extreme disturbance in the ocean ecosystem. How would an event like this affect phytoplankton in the ocean?
Since phytoplankton is the basis for all ocean food chains, an oil spill could be devastating to the survival of all ocean organisms. If an oil spill were to impact the phytoplankton, then the primary consumers would have nothing to eat. This would then reduce the population size of secondary consumers and so on up the food chain. Ultimately, the entire ecosystem might collapse because of the lack of resources caused by the spill.
