Ecosystems at risk: vulnerability and resilience Flashcards
What are the factors affecting vulnerability and resilience? and the importance of dynamic equilibrium
Biodiversity
Extent
Linkages
Location
Malleability
Amplitude
Elasticity
ecosystem must function in this state of interconnections between biosphere, lithosphere, hydrosphere and atmosphere. If one sphere changes, all change as well –> if beyond limits= vulnerability
What is biodiversity? and 2 eg:
genetic, species, ecosystem diversity within a system
Genetic: variety in plants, animals and micro-organisms
Species: no. of species within each trophic level, more species –> more pathways of ecological processes, more resilient
Ecosystem: diversity within ecosystems, habitat difference, biotic community, ecological processes
Wetlands: flora –> not diverse, very specialised (saltmarsh, mangrove). Fauna –> lots of diversity, detritivores, bird species BOTH R/V
Reef: flora –> immense diversity, fauna –> lots RESILIENT
What is extent? and 2 eg:
size of ecosystem in question, larger in extent –> more resilient
wetlands: small extent, 58 ha VULNERABLE
reef: large, 348 000km2 RESILIENT
What is linkages? and 2 eg:
interdependence of species to survive: higher level of this, better chance to absorb change
wetlands: no specific, but heavily dependant on mangrove BOTH (more resilient)
reef: lots of variety, RESILIENT (both: Zoo X –> v)
What is location? and 2 eg:
depending on where the ecosystem is located, esp. if in extreme environments affects degree specialisation of species –> more vulnerable to change
wetlands: located in estuary, surrounded by urban development and no room to expand VULNERABLE
reef: proximity to coast, urban growth/mining and affected by El Nino bleaching events, cyclones VULNERABLE
What is maleability? and 2 eg:
difference between final recovery level and pre-stress –> bigger difference, less resilient
wetlands: worst polluted areas in city BOTH (resilient from human intervention, yet vulnerable from past land use)
reef: complicated by many threats, from multiple sources and climate change. never fully return to pre-stress VULNERABLE
What is amplitude? and 2 eg:
threshold beyond which ecosystem can no longer return to original state
wetlands: given proper management since 1988 but still BOTH (resilient from human intervention, yet vulnerable from past land use)
reef: reached limit with mass bleaching events, only getting worse with climate change /multiple threats VULNERABLE
What is elasticity? and 2 eg:
rate of recovery following stress event
wetlands: no benchmark and still suffering from past land use, limited knowledge on overall impacts –> ongoing scientific research BOTH (resilient from human intervention, yet vulnerable from past land use)
reef: low rate, slow to recover 12-15 years VULNERABLE
Natural stress impacts on 2 eg: (and rate of change)
wetlands:
salinity –> catastrophic, although adapted with less frequent precipitation/more intense rainfall can alter salinity completely –> mangroves need hypersaline conditions
tide –> gradual, adaptations to cope with ebb and flow of water, rising sea levels
reef:
cyclones –> catastrophic, major source of damage creating huge waves destroying coral reef, alter salinity levels (bring large freshwater amounts)
Crown of Thorns –> gradual, boom or bust organism (either small no. or large), with increased nutrients from runoff, eat coral polyps, inefficient predators/human killing, slow (giant triton snail eats one a week)
Human induced stress impacts on 2 eg: (and rate of change)
wetlands:
negative:
past land use –> gradual, industry chemical use (DDTs, oils) created by-product dioxins –> runoff affect bioaccumulation
straightening Powells creek –> catastrophic, heats up and loses oxygen, also stop deposition of nutrients/silt to mangroves (fast water velocity)
positive:
exclusion –> gradual, restrict public access of certain areas, allow to naturally regenerate
education –> gradual, through school excursions, signs change public perception –> know how important wetlands are
reef:
negative:
climate change –> catastrophic, many impacts, on organisms, rainfall, sea temperature, acidification
overfishing –> unsustainable practice, deplete resources, threatened by illegal fishers (foreign trawlers, recreational etc.)
positive:
Zoning plan –> special zones for human activity, protect for future generations (intergenerational), but also present to use too (intragenerational)
exclusion of certain islands –> vital for animal species (bird rookeries, turtle laying) and stop public access to minimise disruption and monitered
