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13 Cards in this Set
- Front
- Back
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Australian Flowering Plants |
> 21,000 species > 90% of Australian species are endemic |
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Examples of southern hemisphere distributions
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Bony-tongue freshwater fishes Ratites (flightless birds) Nothofagus - flowering plant (southern beech trees) |
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Glossopteris
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Permian age (286-248 mya) •Dominant trees •Grew in swamps that formed coal deposits •Fossils also in India, South America, South Africa & Australia (many species)
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Moving Continents |
•Earth has experienced a number of tectonic cycles of continents coming together and moving apart •Last major cycle started c. 320 mya, by c. 230 mya continents were coalesced into supercontinent Pangea •Within Pangea, northern land masses joined to form Laurasia; southern lands formed Gondwana •Pangea began to break up in mid Jurassic |
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Australia during the Tertiary (Paleogene & Neogene): Consequences of drifting northwards |
Contraction of rain forest •Evolution and expansion of more arid-adapted plants, e.g. sclerophylls and animals adapted to them |
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Consequences of drifting northwards |
Fire Evidence from charcoal and pollen fossil record ! Infrequent but present in wetter periods ! Caused by lightning, volcanoes ! Increased frequency with aridity ! Rain forest contracted further, sclerophylls fire-adapted |
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Importance of Australian Rain forests |
•Surviving remnants of Gondwanan flora & fauna •Provide a glimpse back in time to vegetation of Gondwana •High conservation value, NE Queensland Wet Tropics World heritage area |
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Types of Rain forests |
Tropical Rain forests
• Lowland - most species rich • 100-200 tree species per hectare • 1000 beetle species per tree • Many ferns and palms • Trees with large leaves - mesophylls (>12.5 cm) e.g. Daintree, NE Qld TYPES OF RAINFORESTS ! |
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Types of Rain forests |
Temperature Rainforests Fewer species, South, few vines •Fewer layers, simpler structure •Microphyll leaves (2.5-7.5 cm) |
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Types of Rain forests |
Lowland tropical rain forests
Climate uniformly warm wet • Rainfall >1800 mm, alt.<1000 m • Rapid nutrient cycling • Regional differences in composition Evergreen woody plants • No single species dominant >10-15% • Dense overhead canopy cover (90%), low light, high humidity |
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Leaf adaptations - guttation |
Pores on leaf edge drip water - root pressure forces water (& mineral nutrients) up plant When humidity high, little evaporation & transpiration stream |
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Great diversity of types of rainforest plants |
Epiphytes - a plant growing on another Great diversity of types of rainforest plants!Dendrobium • Advantages: get water and dissolved nutrients as run-off; reach the light (not parasites)
• orchids, ferns,lichens; often xerophytic, mycorrhiza |
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Mymecotrophic plants - ant feeding plants
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Plant base bulbous, hollow chambers that house ants
Debris & excretia provide plant with nutrients |
