Jarrah Forest is an interim Australian bioregion located in Western Australia. This bioregion has been split into two subregions for ease of management and research; Northern Jarrah Forest (JAF01) and Southern Jarrah Forest (JAF02).
Location and description
The bioregion stands on the 300 metres (980 ft) high Yilgarn block inland plateau and includes wooded valleys such as those of Western Australia's Murray River and the Helena River near the city of Perth as they descend from the Darling Scarp that overlooks the west coast. On the west coast further south the jarrah forest region also covers the Leeuwin-Naturaliste Ridge. At the southern end of the plateau stands the Whicher Range and the lower Blackwood Plateau inland from there. The eastern interior of the region includes the peaks of the Stirling Range, now preserved within Stirling Range National Park. The name refers to the region's dominant ecosystem: Jarrah forest; that is, a tall open forest in which the dominant overstory tree is the jarrah (Eucalyptus marginata). Soils in the jarrah forest are fertile, but often salt laden. The area has a warm Mediterranean climate, with more annual rainfall (1,300 millimetres (51 in)) on the scarp than inland or to the north-east (700 millimetres (28 in)).
As well as jarrah (Eucalyptus marginata), the original flora of the forest includes other eucalypt trees particularly marri (Corymbia calophylla), while the wetter valleys sometimes contain Bullich (Eucalyptus megacarpa) and Blackbutt (Eucalyptus patens). Marri is a prevalent canopy species; the jarrah forest is commonly called jarrah-marri forest. Heath is a common understorey of the jarrah forest in the north and east.
On the eastern (inland) side, the jarrah forest grades into wandoo woodland, dominated by the canopy species wandoo (Eucalyptus wandoo), and, on breakaways, powderbark (also known as powderbark wandoo) (Eucalyptus accedens). Other eucalypts in these eastern areas include York Gum (Eucalyptus loxophleba). The upland areas are particularly rich in plant life, while the drier inland plateau is less so.
The Southern Jarrah Forest subregion contains extensive areas of wetland vegetation in the south–east, dominated by paperbarks such as Swamp Paperbark (Melaleuca rhaphiophylla), and Swamp Yate (Eucalyptus occidentalis).
Wildlife of the area includes a number of endangered marsupials such as the Numbat (Myrmecobius fasciatus), Western Quoll (Dasyurus geoffroii), Woylie (Bettongia penicillata), Tammar Wallaby (Macropus eugenii), Western Ringtail Possum (Pseudocheirus occidentalis), Western Bearded Dragon (Pogona minor minor), Southern Brown Bandicoot (Isoodon obesulus), and Red-tailed Phascogale (Phascogale calura). Another local species is the salamanderfish which burrows into damp sand in riverbeds during the dry season. Birds include the nectar eating Western Spinebill and reptiles include a large number of endemic frogs such as the Small Western Froglet (Crinia subinsignifera) and the Western Marsh Frog (Heleioporus barycragus). The jarrah forest provides food and shelter for the endangered Carnaby's Black Cockatoo (Calyptorhynchus latirostris) and Baudin's Black Cockatoo (Calyptorhynchus baudinii).
Threats and preservation
Most of the native vegetation has been cleared for wheat farming or for timber, especially on the inland plateau with consequent destruction of wildlife which is further threatened by: the replacement of original vegetation with grasses and other introduced weeds; introduced animals including grazing species and also predators such as foxes; further loss of natural vegetation as it suffers from Phytophthora dieback; exploitation of water sources for agriculture. There are many small areas of parkland while larger protected areas include the Dryandra Woodland, Lane-Poole Reserve, and the Perup Forest Ecology Center.
- Environment Australia. Revision of the Interim Biogeographic Regionalisation for Australia (IBRA) and Development of Version 5.1 - Summary Report. Department of the Environment and Water Resources, Australian Government. Retrieved 2007-01-31.
- IBRA Version 6.1 data
- Williams, Kim; Mitchell, Dave (September 2001). "Jarrah Forest 1 (JF1 – Northern Jarrah Forest subregion)". A Biodiversity Audit of Western Australia’s 53 Biogeographical Subregions in 2002. The Department of Conservation and Land Management. Retrieved 8 May 2012.
- "Biodiversity and Vegetation - Jarrah Forest". Australian Natural Resources Atlas - Natural Resource Topics. Australian Government. 15 Jun 2009. Retrieved 8 May 2012.
- Hearn, Roger; Williams, Kim; Comer, Sarah; Brett Beecham (January 2002). "Jarrah Forest 2 (JF2 – Southern Jarrah Forest subregion)". A Biodiversity Audit of Western Australia’s 53 Biogeographical Subregions in 2002. The Department of Conservation and Land Management. Retrieved 8 May 2012.
- Dell, B., J.J. Havel, and N. Malajczuk (editors) (1989) The Jarrah forest : a complex mediterranean ecosystem Dordrecht ; Boston : Kluwer Academic Publishers, ISBN 90-6193-658-6
- Thackway, R and I D Cresswell (1995) An interim biogeographic regionalisation for Australia : a framework for setting priorities in the National Reserves System Cooperative Program Version 4.0 Canberra : Australian Nature Conservation Agency, Reserve Systems Unit, 1995. ISBN 0-642-21371-2