Jarrah Forest is an Interim Biogeographic Regionalisation for Australia (IBRA) region in Western Australia.[1][2]
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The ecoregion stands on the 300m 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 rainfall (1300mm per year) on the coast than inland (600mm) where there is usually an annual summer drought.[3]
As well as jarrah the original flora of the forest includes other eucalyptus trees such as marri (Eucalyptus calophylla), Eucalyptus wandoo, York Gum, and tuart mixed with acacias, and cypress pines with an undergrowth of she-oaks and sandalwood and parasites such as the Christmas tree mistletoe. The upland areas are particularly rich in plant life while the drier inland plateau is less so. Trees of this inland wheatbelt include marri and powderbark (Eucalyptus accedens).
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), Dragon (Dragon), 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).
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 vegeatation 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.