2. EAR vulnerability & resilience Flashcards
What are the influences of vulnerability?
location, extent, biodiversity and linkages/interdependence
How does location make an ecosystem vulnerable? - 3 factors
(1) Ecosystems located in extreme environments are populated by highly specialised organisms (specifically adapted to specific climatic conditions). More specialisation = more vulnerable to change.
(2) Ecosystems near human habitation with its many impacts, e.g. coastal dunes - often cleared for high rise and parking lots and are treated like wastelands or valuable land for further human development
(3) Connectivity - geographical proximity of same ecosystems in order to reseed populations within change, e.g. coral reefs are relatively isolated, and thus coral reefs have difficulty repopulating organisms during a change, as they do not have the capacity to migrate and regenerate
How does extent make an ecosystem vulnerable? Give 2 examples
Size and overlap ecosystems - which may result in boundaries overlapping and forming unique environments
Restricted ecosystems (large species diversity and small space or extensively destroyed) are especially vulnerable e.g tropical rainforests have small populations but large biodiversity in a small localised area, any loss of land can have extreme detrimental impacts (extinction). Conversely, savannahs have big populations, small biodiversity and big land, so losing land may not have quite a significant impact.
Biodiversity - vulnerability
Larger/varied populations recover quicker during change (ability to rely on different organisms in the food web) and exist in a wider range of habitats
THIS INCREASES LIKELIHOOD OF SOME SPECIES SURVIVING
Linkages/interdependence - vulnerability (including explanation & example)
greater the level of interdependence within an ecosystem = greater the ability to absorb change
Loss of a primary consumer is unlikely to have a major impact on secondary consumers if there are a variety of alternative primary consumers.
e.g. In the oceans around Antarctica, there are few linkages through the food chain. Krills are the dominant primary consumers and the main source of energy (food) for some species of whale. No intermediary stages in the food chain. Any reduction in the supply of krill (humans may carry out large-scale commercial harvesting) will directly impact the number of whales the ecosystem can support.
COASTAL DUNES - LOCATION VULNERABILITY
Coastal dunes develop in specific locations with the necessities of prevailing trade winds (40 degrees NE and SE) where dominant angle of incidence impacts direction of coastal dunes
Increases vulnerability due to reduced connectivity
COASTAL DUNES - BIODIVERSITY VULNERABILITY
- Wide range of unique flora/fauna along plant zonation allows for increased stability of dunes
- However lack of species variety in each zonation level increases vulnerability as there are few reliable replacements for loss of a species
COASTAL DUNES EXTENT VULNERABILITY
Despite being located in every continent (except Antarctica), they have a relatively small extent as each individual dune ecosystem is limited to coastal areas and dominant wave directions
The ability to reseed populations from different coastal dune systems is difficult
COASTAL DUNES INTERDEPENDENCE/LINKAGES - VULNERABILITY
Low levels of interdependence with fewer species in each trophic level which increases vulnerability
e.g. Spinifex is hard to be replaced due to its adapted nature of fast growing, strong root systems - if primary species impacted, entire chain of flora and fauna is affected
CORAL REEFS LOCATION - VULNERABILITY
Coral reef species are endemic/highly specialised, requiring specific physical environment, i.e. temperature (20-27 degrees), light intensity (low), turbidity (low), oxygen levels (high), salinity (high), concentrations of nutrients (low), lack of freshwater, sea level depth (2-30m) with low elasticity/recovery rates from alterations in these physical requirements
> places coral reefs at HIGH RISK from natural/human-induced change
CORAL REEFS BIODIVERSITY - VULNERABILITY
While high levels of biodiversity are present in coral reef ecosystems (housing 25% of all marine species) and allows for the resilience of coral reefs (able to absorb the shock of a loss of a species as there are many other species in the same trophic level), the loss of the keystone species coral essentially disintegrates coral reefs as they house all marine flora and fauna in this ecosystem.
Also loss of small part of ecosystem can have significant impacts to species diversity
CORAL REEFS EXTENT - VULNERABILITY
Despite coral reefs being widespread over a large area e.g the GBR covers 348 000km^2, the global trend of spatial separation (of hundreds of kms) between reefs places significant vulnerability to coral reefs (GBR = 2900 individual reefs) with the lack of continuity.
Thus, when natural stress events occur there is an increasing difficulty for populations of coral reefs to reseed and repopulate from surrounding reefs due to the vast distance and the specialisation of coral reef flora and fauna (which often cannot pass through other marine ecosystems due to physical requirements).
