Lecture 2- Evolution of Australian Biomes Flashcards
How does the Great Dividing Range affect the climate?
-much wetter on the east of it and drier in the west, more inland
What are the areas of plant species richness?
-the tropics, Nth Queensland
What are the areas of high plant species endemism?
- tropics
- southwestern Australia is a hotspot
What are some examples of different habitat types across Australia?
- Rainforest
- Woodland
- Hammock grassland
- Tall shrubland
- Open Heath
- Tall open forest
What are the two parameters in how we classify plants?
- Height
2. Extent of canopy closure
What is the plant classification? (detail) up to a meter high
Tussocky or tufted grasses and graminoids
a) closure 70% is closed tussock grassland or closed sedgeland
b) closure 30-70% tussock grassland or sedgeland
c) closure 10-30% open tussock grassland
What is the plant classification? (detail) above 2 m, below 10m
Tall shrubs
a) 70% closure= closed shrub
b) 30-70% closure= open shrub
c) 10-30% closure= tall shrubland
What is the plant classification? (detail) 10-30m
Medium trees
a) 70% closure= closed forest
b) 30-70% closure= open forest
c) 10-30% closure= woodland
What is a closed forest also called?
Rainforest
What were the consequences of Australia drifting northwards during the Tertiary (Paleogene and Neogene)? (climate) (5)
Climate changed
- Warm, humid, rainforests initially widespread
- Circum-polar current: cooling of Antarctica
- Reduced wind-bearing rains over Australia and increased aridity from Oligocene (30my ago)
- Contraction of rainforest
- Evolution and expansion of more arid-adapted plants e.g. sclerophylls and animals adapted to them
What were the consequences of Australia drifting northwards during the Tertiary (Paleogene and Neogene)? (landforms changed) (5)
- Old land surface, little mountain building or volcanic activity
- Weathering during warm-wet periods leached nutrients from soils
- Soils became low in nutrients e.g. phosphorus
- Drier cooler periods increased wind erosion. Mobile dunes and inland lakes dried up and became salt plains
- Evolution further favoured arid-adapted flora and fauna
What were the consequences of Australia drifting northwards during the Tertiary (Paleogene and Neogene)? (fire) (5)
- Evidence from charcoal and pollen fossil record
- Infrequent but present in wetter periods
- Caused by lightning, volcanoes
- Increased frequency with aridity
- Rainforest contracted further sclerophylls fire-adapted
What were the Pleistocene ice ages and their effect on Australia?
- World-wide fluctuating interglacial (warm) and glacial (cold) periods 2.5my to present
1. Australia warm wet/cool dry periods, virtually no glaciation
2. Mobilisation of sands and expansion of desert regions
3. Changes in sea level= impact on dispersal
What is the history of human arrival to Australia?
- number of immigrant groups (from Indonesia, China)
- direct evidence: bones (Mungo man), tools, middens and paintings 40-50 000yr
- indirect evidence: charcoal deposits 100 000yr?, due to fire stick farming (fire= charcoal left behind)
What happened in Australia during the last glacial period?
- drier rainforest was replaced by fire tolerant vegetation (increased charcoal)
- megafaunal extinctions (most between 35-15K years ago) due climate change? hunting? human use of fire?
