European Arrival in Australia Flashcards
What are the six major forces driving the 6th mass extinction?
Habitat destruction Invasive species Pollution Human population Overexploitation Climate change
What is the biggest threat to endangered species?
Habitat loss and fragmentation
What are the causes of habitat loss in the wet tropics and northern Australia?
Initial land-use: Exploitative use (gold, timber, mining, fishing, pearling)
Subsequent land-use:
Intensive cultivation - sugarcane, bananas, mangoes, avocadoes, aquaculture, farming (milk)
Extensive land-use - Cattle grazing
Characteristics of species that are more likely to go extinct in fragmented rainforest habitats
Large animals that tend to have to track food resources up and down mountainsides.
Animals that are rare or have very low survivorship (few individuals - higher extinction risk)
In the wet tropics: we lose the predators (quolls), we lose rainforest specialists (lemur ringtail, terrestrial birds)
Characteristics of animals that remain stable in fragmented rainforest
Frogs, butterflies, small mammals.
Quite high fecundity.
Species with small habitat requirements that tolerate edge and matrix habitats are less vulnerable.
Isolation effects
Species composition differs increasingly from the continuous rainforest composition, the more isolated a fragment is.
The species that are most likely to decline have limited mobility (low dispersal)
Matrix effects
The matrix is the vegetation that surrounds the fragment.
The type of matrix strongly affects the isolation of the fragment.
Matrix regrowth can support resident populations of some forest species.
Invasive species
Second most important factor in the biodiversity decline of Australia.
Major pests: pig, cane toad, dog and cat
Sleepers: future major pest species, some exotic fishes and the European fox.
Diseases
Myrtle rust (fungus that causes disease in Myrtaceae plant spp.) Arrived in 2010.
Myrtaceae is a very important family in rainforests in Australia, very high proportion of the rainforest trees are Myrtaceae.
1659 spp in Australia, so far 350 found susceptible
What is special about the wet tropics of Australia?
Biodiversity hotspot, one of earth’s most irreplaceable sites.
0.26 % land area holds 45 % of Australia’s vertebrate diversity.
669 species in total, 90 species are regional endemics.
Many of the endemic species are restricted to high elevation forest, believed to be result of rainforest contraction to fire-protected refugia during the Pleistocene drying events (ice ages)
Climate change, extreme weather events and wet tropics biodiversity
How does climate change threaten biodiversity?
Climate change threatens biodiversity by increasing the global temperature and rising the cloud base. This means that the wet tropics endemic species living on mountain tops will suffer, as the cool, moist and stable environment they are used to will change.
In 2016 there was unexpected loss of mangroves along 1000 km of coast due to drought and high temperatures.
November 20th 2018, temperatures were 4 degrees higher than normal, mass die-off of spectacled flying foxes. 23.000 individuals in a single day. Mainly females and juveniles are susceptible to heat stress.
Fire in rainforests (crown fire)
Climate change, extreme weather events and wet tropics biodiversity
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