BIO1042 Lecture 14: BIO1042 Lecture 14 Origins and evolution of the Australian flora 2
7 Sep 2018
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BIO1042 Lecture 14 –Life and Diversity
Origins and evolution of the Australian flora 2
Climate exerts a major control over plant distribution
• Climate linked with many other factors: drought, and fire frequency and intensity –and thus
the distribution of animals
o Example: river red gum (Eucalyptus camaldulensis)
▪ seed germinates after flooding
▪ floods determine geographic range => important for fauna.
▪ Flooding important regeneration requirement for many plant species lack of
flooding = serious implications for many species
Australian climates and the impact on major vegetation types
• Large climatic variations
• Much of Australia arid or semi-arid
• Geology: Continent, , lack of orogeny (mountains)
• Meteorology: wind and ocean currents
• Greenhouse modelling -prognosis for Oz not good -drier, more frequent droughts, greater
climatic amplitudes
Climate: ocean circulation
• Thermohaline circulation
• Normal pattern of air circulation across the Pacific Ocean
• Regional Currents
o The East Australia current moves warm water from the tropical coral sea down the east
coast of Australia
• El Nino Southern Oscillation (ENSO)
• Disruption of Walker circulation
o Warming of eastern Pacific Ocean
o Formation of high pressure systems in Asia and northern Australia
o Resulting in drought in eastern Australia
Soils, climate and vegetation
• Vegetation composition and structure operates at many geospatial scales:
• micro(local)
o affected by local aspects (water table effects, soil nutrients, patch size(s), etc.
• Regional
o broadly shaped by upstream / catchment dynamics, effects of fire, flooding, etc.
• Continental
o tectonics, wind & water currents, etc. e.g. Southern Oscillation Index / El Nino
Soils: Why are Australian soils considered “poor”?
• Australia’s land surface very old geologically, with some variation.
• Some of the oldest rocks and land surfaces on Earth -e.g. Pilbara region of WA
• Current status a result of weathering processes on stable, dry landscape for much of the past
400 Ma
Soils, climate, vegetation and isolation
• Paradoxically, nutrient-poor soils often support very high species diversity.
Document Summary
Origins and evolution of the australian flora 2. Flooding important regeneration requirement for many plant species lack of flooding = serious implications for many species. Australian climates and the impact on major vegetation types. Large climatic variations: much of australia arid or semi-arid, geology: continent, , lack of orogeny (mountains, meteorology: wind and ocean currents, greenhouse modelling -prognosis for oz not good -drier, more frequent droughts, greater climatic amplitudes. Oils: why are australian soils considered (cid:862)poor(cid:863): australia(cid:859)s land surface (cid:448)ery old geologically, with some variation, current status a result of weathering processes on stable, dry landscape for much of the past. Some of the oldest rocks and land surfaces on earth -e. g. pilbara region of wa. Soils, climate, vegetation and isolation: paradoxically, nutrient-poor soils often support very high species diversity, e. g. calcareous sands north of perth (cid:858)k(cid:449)ongan(cid:859) (cid:448)egn-supports diversity of species in.
