EAR - Vulnerability (BELL) and Resilience Flashcards
What is vulnerability
The likelihood of an ecosystem being affected by stress events
What are stress events
Events that cause damage to ecosystems
What is resilience
The ability of an ecosystem to recover from stress events
What are the types of stress events
Stresses can be human (anthropogenic) or natural. They can also be fast-acting (catastrophic) or slow-acting (gradual).
How does biodiversity effect vulnerability
Less biodiversity usually makes ecosystems more vulnerable. Multiple species in a food chain offer more pathways for the cycling of nutrients in the event of a species loss.
Loss of genetic, species and ecosystem biodiversity all makes ecosystems more vulnerable.
How does extent effect vulnerability
The smaller an ecosystem is, the more vulnerable it becomes.
Human activities such as land clearing of road constructions often result in fragmentation.
An ecosystem might extend beyond its own boundaries. For example, a river extends into the entire catchment area. Migratory birds also have extent far beyond a particular ecosystem.
The Sumatran rainforests have a number of species that are small in number, but require large ranges… the clearance of large areas of rainforest makes these species highly vulnerable
How does location affect vulnerability
More extreme ecosystem locations are usually more vulnerable to stress than moderate ones as they require highly specialised organisms
Ecosystems that are closer to human interference are more likely to be vulnerable.
Corals are highly specialised and require water temperatures of 23˚C-29˚C.
How do linkages affect vulnerability
The fewer the linkages within an ecosystem, the more vulnerable it will be (how reliant species are on each other e.g. zooxanthellae)
What key terms can be used to describe the resilience of an ecosystem
Key terms elasticity, malleability, amplitude and resilience phase (refer to glossary)
How do stresses affect ecosystems
Some ecosystems are “stress dependant”. They require a stress event to regenerate. Eucalyptus woodlands are an example of this.
Some ecosystems are adapted to catastrophic stress and have a number of pioneer species.
The effect of a stress is determined by the intensity and duration of the event.
Ecosystems are adapted to the locations they inhabit. Consequently, ecosystems have adaptations to recover from natural stress events. After a catastrophic stress event, forests will pioneer species to begin a succession process to regenerate.
Ecosystems are rarely entirely affected by a single stress. This allows for a resilience phase to take place. Mass coral spawning encourages regeneration from unaffected areas.
Ecosystems are not well adapted to human modifications. Human modifications to ecosystems can also occur on a time scale and area that does not allow for regeneration.
What does resilience look like in coral reefs
e.g. spawning events
Coral begin a recovery phase after bleaching and tropical cyclone stress events. However, this can result in longer term changes.
Changes in coral composition - less branching corals, more brain corals
Mass bleaching events result in more heat resilient corals being present, however, rate of change is critical in this process.
