1 / 22

Australian savannas

Australian savannas. Aroon Edgar, James Cook University, Townsville, Australia Michelle Waycott, James Cook University, Townsville, Australia Tony Grice, CSIRO Sustainable Ecosystems, Townsville, Australia. Australian savanna systems.

megan
Télécharger la présentation

Australian savannas

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Australian savannas Aroon Edgar, James Cook University, Townsville, Australia Michelle Waycott, James Cook University, Townsville, Australia Tony Grice, CSIRO Sustainable Ecosystems, Townsville, Australia

  2. Australian savanna systems • Savannas in an Australian context are referred to as ‘woodlands’ or ‘shrublands’ • Variations in rainfall and soil determine structure and composition of savanna vegetation Broad Australian Vegetation Types Australian savannas

  3. Australian tropical savannas • Tropical savannas display a number of landforms: • • flat to hilly savanna woodlands • • sandstone country • • black soil plains • Australian savannas tend to be <500 m above sea-level, with local relief generally <100 m. • Australian sites are located along the eastern coast – Townsville and Charters Towers Extent of savannas throughout Northern Australia Australian savannas

  4. Climate of Australian savannas • Australian savannas lie within a tropical climatic zone • Distinctive wet/dry seasons • Variability in climate due to latitude, topography and distance from the coastline Australian savannas

  5. Rainfall and Australian savannas • Rainfall is a major savanna determinant • Savannas may be either: • Wet >900mm/year • Semi-arid 300-900mm/year Australian savannas

  6. Soils and Australian savannas • The exact distribution of soil types in savannas is complicated • Range of soil types found in savannas: • Lithosols • Lateritic soils • Cracking clays • Red/yellow earths • Deep sands • Alluvial soils • Most notable feature of the soils that savanna vegetation grows upon is its low fertility Silver-leaved ironbark open-woodland on shallow soils that have low water-holding capacity and low fertility. Australian savannas

  7. Vegetation Communities in Australian savannas • Savanna communities range from: • Open forests (coastal regions) • Woodlands (semi-arid regions) • Open woodlands (arid regions) • Majority of savanna ecosystems in northern Australia are grassy landscapes. • Classified in relation to the structure and composition of the vegetation Australian savannas

  8. Vegetation structure in Australian savannas • Savanna structure includes: • a grassy component, and • a woody plant component • Tree height can range from 2-20 meters • Canopy cover may vary between <1% and 60-70% • Tree density can range up to 100/hectare Narrow-leaved ironbark and bloodwood woodland Australian savannas

  9. Vegetation dominants in Australian savannas • Australian savanna vegetation dominated by sclerophyllous taxa within: • Eucalypts • Acacia • Other genera found within savannas: • Eurphorbiaceae (Petalostigma) • Combretaceae (Terminalia) • Proteaceae (Grevillea) • Bombacaceae (Adansonia) • Casuarinaceae (Casuarina) Eucalypts dominate the savanna landscape Australian savannas

  10. Understorey in Australian savannas • Savanna understorey dominated by grass species • Sorghum (coastal) • Heteropogon (semi-arid) • Themeda (semi-arid) • Chryspogon (arid) • Aristida (arid) • Type of grassy understorey also varies with rainfall and soil texture Grass species used in Australian experiment Heteropogon contortus Australian savannas

  11. Ecological distinctives of Australian savannas • Australian Savannas have a number of ecological distinctives: • Few large hard hoofed herbivores, soft footed macropods • Large numbers of termites, and the • Influence of fires Australian savannas

  12. Influence of Fire on Australian savannas • Fire has influenced the nature of Australian savannas over the course of their evolution • It has shaped much of the vegetation and ecology of savannas and is an integral part of their management • Aborigines have used fire since their arrival in Australia for a variety of reasons – communication, ‘cleaning’ the country and to maintain food sources • Changes to traditional fire regimes has affected all aspects of the ecology of savannas – plants, animals, nutrients and water Australian savannas

  13. Influence of Fire on Australian savannas Fire frequencies in northern Australia 1997-2005 as detected by NOAA satellites (Landgate) Australian savannas

  14. Biodiversity in Australian savannas • Australian savannas are a refuge for biodiversity of world significance • Savannas are home to a range of species of native plants, mammals, birds, reptiles and amphibians, and a great number of invertebrate species • Many of the plants and animals found in Australian savannas are endemic Australian savannas

  15. Biodiversity Issues in Australian savannas • Extinction rates in Granivorous birds • Savanna grasses are an important food source for a variety of Australian birds • Small mammal decline • Savannas act as a refuge for many of Australia’s smaller mammal species. • Issues stemming from invasive grasses • Invasive grasses have the potential to displace native vegetation, as well as increasing the fire fuel load Australian savannas

  16. Land-use in Australian savannas • Major land uses of Australian savannas include: • Pastoralism • Aboriginal Lands • Conservation Reserves • Military Australian savannas

  17. Land-use in Australian savannas Land use in northern Australia Australian savannas

  18. Australian Savanna Experiment • Sites will be located at: • Oak Valley (Site 1: ) • 25km south of Townsville • Average annual rainfall of 1120mm • Grassland bordered by riparian area • Fletcherview (Site 2: ) • 100km southwest of Townsville • Average annual rainfall of 600 mm • Open savanna woodland combined with patches of dry rainforest or ‘vine thicket’. Australian savannas

  19. Site Locations Site 1 Site 2 Australian savannas

  20. Australian Species • Tree Species: • Wet • Eucalyptus tessellaris • Eucalyptus playtphylla • Casuarina littoralis • Melaleuca viridiflora • Dry • Eucalyptus erythropholia • Eucalyptus creba • Acacia shirleyi • Petalostigma pubescens • Grevillea pteridifolia • Erythrina vespertillio Site 1: Humid Site Australian savannas

  21. Contact Us Phone: 1300 363 400 or +61 3 9545 2176 Email: enquiries@csiro.au Web: www.csiro.au CSIRO Sustainable Ecosystems Aroon Edgar

  22. References • Australian Government, Department of Environment, Water, Heritage and the Arts: http://www.environment.gov.au/ • Australian Natural Resources Atlas: http://www.anra.gov.au • Dyer, R., Jacklyn, P., Partridge, I., Russell-Smith, J. and Williams, D. 2001. Tropical Savanna CRC: Savanna Burning: Understanding and using fire in northern Australia. Darwin • EPA website: • www.epa.qld.gov.au/ • www.epa.wa.gov.au/ • Google Maps: http://maps.google.com.au/ • Groves, R.H. 1981. Australian Vegetation. Cambridge University, Cambridge • Rangelands: http://www.rangelands-australia.com.au/ • Tropical Savanna CRC: http://savanna.ntu.edu.au/ Australian savannas

More Related