2.5 Zonation, Succession & Change in Ecosystems (DP IB Environmental Systems & Societies (ESS): SL): Flashcards
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Define zonation.
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Define zonation.
Zonation is the gradual change in the composition of species and communities across a landscape, based on an environmental gradient.
Name three environmental factors that can create a gradient responsible for zonation.
Environmental gradients responsible for zonation can be based on factors such as elevation, tidal level and moisture.
In a rocky intertidal zone, which organisms typically dominate the driest, highest spray zone?
Lichen and other hardy plants typically dominate the driest, highest spray zone of a rocky intertidal zone.
True or False?
Sea stars, anemones and sea urchins are typically found in the highest, driest zone of a rocky shore.
False.
Sea stars, anemones and sea urchins are typically found in the low tide zone, where water is constantly present.
Which organisms are typically found in the high tide zone of a rocky intertidal shore, and what allows them to survive there?
Organisms such as barnacles and mussels are typically found in the high tide zone because they can attach to rocks and withstand waves.
Define a transect.
A transect is a line used to measure biotic and abiotic factors along an environmental gradient, in order to determine the variables affecting the distribution of a species.
Define a kite diagram.
A kite diagram is a graph that visually represents both the distribution and abundance of species along a transect.
In a kite diagram, the width of the 'kite' around the central line represents the of a species.
In a kite diagram, the width of the 'kite' around the central line represents the abundance of a species.
In a kite diagram, what does a species' position along the central horizontal line represent?
A species' position along the central horizontal line represents its distribution along the transect.
True or False?
A kite diagram can only show the distribution of species, not changes in abiotic factors along a transect.
False.
Additional sections can be added to a kite diagram to show changes in abiotic factors, such as elevation or soil pH.
Define primary succession.
Primary succession is the colonisation of newly formed or newly exposed land, with no species present, by an increasing number of species over time.
Define secondary succession.
Secondary succession is a similar process to primary succession, but occurs on bare soil where a community already existed, such as an abandoned agricultural field.
Give two examples of newly formed land where primary succession can occur.
Primary succession can occur on newly cooled volcanic rock and bare rock or moraines left by a retreating glacier.
Why is marram grass well-suited to being a pioneer species on coastal sand dunes?
Marram grass has deep roots to access water and can tolerate the salty conditions caused by sea spray.
Define a pioneer species.
A pioneer species, often moss or lichen, is the first species to colonise newly exposed land during succession.
How does the death and decomposition of pioneer species help later stages of succession?
As pioneer species die and decompose, the dead organic matter forms humus, creating a basic soil that later species can grow in.
Define a seral community (sere).
A seral community, or sere, is a temporary and intermediate stage in the ecological succession of an ecosystem.
How does one seral community typically get replaced by the next during succession?
Each seral community changes the environmental conditions, allowing the next community to replace it, often through competition.
Define a climax community.
A climax community is the final, stable community formed at the end of succession, containing all the species that have colonised the land.
True or False?
Energy flow through an ecosystem is typically high during the earliest stages of succession.
False.
Energy flow is typically low during the earliest stages of succession, since there are only a few species present.
What happens to gross and net productivity as an ecosystem becomes more complex during succession?
Gross and net productivity increase as an ecosystem becomes more complex during succession.
Species diversity increases as succession progresses because a more complex ecosystem provides more available .
Species diversity increases as succession progresses because a more complex ecosystem provides more available niches.
True or False?
Nutrient cycling is dominated by abiotic processes and remains simple throughout succession, even in a climax community.
False.
Nutrient cycling is simple in the early stages of succession but becomes more complex as more species with unique nutrient requirements establish.
Define resilience of an ecosystem.
Resilience is the ability of an ecosystem to recover after a disturbance.
What does high resilience mean for how quickly an ecosystem recovers from a disturbance?
High resilience means an ecosystem quickly returns to its original state after a disturbance.
Define species redundancy.
Species redundancy is when multiple species perform similar ecological roles, so if one is lost, others can fill its role.
How does genetic variation within a species contribute to ecosystem resilience?
Genetic variation within a species can help it adapt to changing conditions, contributing to greater ecosystem resilience.
True or False?
Greater diversity within an ecosystem is generally associated with lower resilience.
False.
Greater diversity is generally associated with greater resilience.
Name four human activities that can divert the progression of ecological succession.
Human activities such as burning, agriculture, grazing pressure and resource use (e.g. deforestation) can divert the progression of succession.
If a human disturbance is mild and the ecosystem is highly resilient, it may be able to and return to its original state.
If a human disturbance is mild and the ecosystem is highly resilient, it may be able to recover and return to its original state.
What happens to an ecosystem if a human disturbance is severe and the ecosystem has low resilience?
If a disturbance is severe and the ecosystem is less resilient, the ecosystem will be permanently changed, leading to a new stable state.
Give two impacts of deforestation and agriculture on a tropical rainforest ecosystem.
Deforestation and agriculture in tropical rainforests can cause biodiversity loss and disrupt nutrient cycling.
True or False?
Mining has no significant effect on water quality in nearby ecosystems.
False.
Chemicals used in mining can pollute water sources, negatively impacting aquatic life.
What can deforestation transform a tropical rainforest into, as an alternative stable state?
Deforestation can transform a tropical rainforest into a savanna or grassland.
True or False?
An alternative stable state formed after rainforest deforestation, such as a savanna, is typically more resilient than the original rainforest.
False.
An alternative stable state, such as a savanna formed after deforestation, typically has lower resilience than the original rainforest.
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