The Warren region is defined as the coastal sandplain between Cape Naturaliste and Albany. Extending from the ocean to the edge of the Yilgarn cratonplateau, for most of its extent it may be adequately approximated as the land within ten kilometres (6mi) of the coast. North of Point D'Entrecasteaux, however, it extends inland almost as far as Nannup and Manjimup. It has an area of about 8,300 square kilometres (3200mi²), making it about 2.7% of the South West Province, 0.3% of the state, and 0.1% of Australia. It is bounded to the north and east by the Jarrah Forest region.[5] Much of the region is unpopulated, but there are a number of towns with substantial populations, most notably Margaret River, Augusta, Pemberton, Walpole, Denmark and Albany.
The Warren region, with agricultural areas in yellow, and native vegetation in green
Warren has a moderate Mediterranean climate. It has the highest rainfall in the state, with annual falls of from 650 to 1500 millimetres (25.6–59.1in), and a short dry season of only three to four months.[8]
Climatic Table for Pemberton, a town in the Warren region
The karri forest occurs in deep loam, and covers nearly half of the region. Although very moist in winter, it is not considered to be a rainforest because the dry season precludes the establishment of a characteristic rainforest understory of epiphytes, liverworts, ferns and mosses. Some rainforest relict species do occur, however, such as Anthocercis sylvicola, Albany pitcher plant (Cephalotus follicularis) and wild plum (Podocarpus drouynianus).[6]
The poorer, lateritic soils, about a quarter of the region, are vegetated by medium forest of jarrah (Eucalyptus marginata), which can grow up to 40m tall, and marri (Corymbia calophylla) (up to 60m). Other significant vegetation forms include low woodland of E.marginata and Banksia species (8%); Agonis flexuosa woodlands or scrub on Holocene marine dunes (5%); and swamps supporting sedges (5%) or low woodlands of Melaleuca (4%).[5]
The region is considered one of the most important centres of plant endemism in the South West. As well as the three tingle trees other species endemic to the region include Corymbia ficifolia (red flowering gum). The area around Albany is especially rich in endemics such as Cephalotus follicularis.[6]
The Warren ecoregion, with main native remnant vegetation from Forest Ecosystem's Parks & Wildlife corporate data.
Fauna
The Warren region supports a rich diversity of fauna, much of which is apparently Gondwanan in origin. Mammal species include the western ringtail possum (Pseudocheirus occidentalis), chuditch (Dasyurus geoffroii) (particularly found in Jarrah forest), the squirrel-like brush-tailed phascogale (Phascogale tapoatafa), quokka (Setonix brachyurus), yellow-footed antechinus (Antechinus flavipes leucogaster), southern brown bandicoot (Isoodon obesulus), and woylie (Bettongia penicillata ogilbyi). The first four of these are endangered species and numbers of many of the indigenous marsupials have declined as their habitats are removed and altered.[6]
As with the rest of southwest Australia, in contrast to comparable forest of the south east, there is a low diversity of bird species. Endemism is similarly low, as most South West bird species are habitat generalists with wide distributions. Exceptions include the red-eared firetail (Stagonopleura oculata) and the white-breasted robin (Eopsaltria georgiana), both of which occur only in the karri forest; the western bristlebird (Dasyornis longirostris), western whipbird (Psophodes nigrogularis nigrogularis) and western ground parrot (Pezoporus wallicus flaviventris), all of which inhabit the region's heath vegetation; and the noisy scrub-bird (Atrichornis clamosus), which inhabits densely vegetated gullies.[6] Other forest birds include the purple-crowned lorikeet.[citation needed]
The freshwater streams of the Warren region support only a low diversity of fauna, but much of it is highly endemic. A number of frog species are endemic or nearly so, including the orange-bellied frog (Geocrinia vitellina), the white-bellied frog (Geocrinia alba), and the sunset frog (Spicospina flammocaerulea). Endemic freshwater invertebrates include worms of the family Phreodrilidea, and crayfish of the genera Cherax and Engaewa.[6]
Land use
Karri forest near Pemberton. This forest is recovering from extensive logging, and most trees pictured are quite young.
The Warren region falls entirely within what the Department of Agriculture and Food calls the "Intensive Land-use Zone" (ILZ), the area of Western Australia that has been largely cleared and developed for intensive agriculture such as cropping and livestock production. Despite this, only a small amount of the region's natural vegetation has been cleared and given over to agriculture. The proportion of cleared land was calculated as 13.2% in 2002,[11] although Beard gave a much larger figure of 31% in 1984.[5] The remaining land is considered to be native vegetation, but this need not be pristine; a substantial proportion of the remaining native vegetation has been degraded by selective logging and other human activities.[citation needed]
Historically, logging was the primary land use in the region, and this remains a significant industry. There has been substantial selective logging in the region, and some clearfelling. There has also previously been some bauxite mining in the area, but this has now ceased, and the mining areas are at least partially reforested. Dams have also been constructed in high-rainfall forest areas.[citation needed]
Because so much of the Warren region is already protected, it has low priority under Australia's National Reserve System.[12]
Protected areas
45.47% of the ecoregion is classified as a terrestrial protected area.[13] Terrestrial connectivity is rated at 42.5%.[13] Protected areas include:[13]
The Warren region first appeared in Ludwig Diels' 1906 biogeographical regionalisation of Western Australia. Diels' concept of Warren region was effectively all the land south of a line from Albany to Busselton; thus it included a substantial area east of Margaret River that is now part of the Jarrah Forest region. The region was not recognised as one of Edward de Courcy Clarke's "natural regions" in 1926, but was resurrected in Charles Gardner's regionalisations of the 1940s and 1950s.
In 1980, John Stanley Beard published a phytogeographical regionalisation of the state based on data from the Vegetation Survey of Western Australia. This new regionalisation included a "Warren Botanical District" that is essentially identical with the present-day Warren. By 1984, Beard's phytogeographic regions were being presented more generally as "natural regions", and as such were given more widely recognisable names. Thus the "Warren Botanical District" became the "Karri Forest Region".
When the IBRA was published in the 1990s, Beard's regionalisation was used as the baseline for Western Australia. The Warren region was accepted as defined by Beard, but reverted to the name "Warren". It has since survived a number of revisions. When the IBRA subregions were introduced in IBRA Version 6.1, the whole of Warren was defined as a single subregion.
Leeuwin-Naturaliste National Park is a national park in the South West region of Western Australia, 267 km (166 mi) south of Perth. It is named after the two locations at either end of the park which have lighthouses, Cape Leeuwin and Cape Naturaliste. It is located in the Augusta-Margaret River and Busselton council areas, and is claimed to have the highest visiting numbers of any national park in Western Australia. The park received 2.33 million visitors through 2008–2009.
Eucalyptus diversicolor, commonly known as karri, is a species of flowering plant in the family Myrtaceae and is endemic to the south-west of Western Australia. It is a tall tree with smooth light grey to cream-coloured, often mottled bark, lance-shaped adult leaves and barrel-shaped fruit. Found in higher rainfall areas, karri is commercially important for its timber.
The Carnarvon xeric shrublands is a deserts and xeric shrublands ecoregion of Western Australia. The ecoregion is coterminous with the Carnarvon Interim Biogeographic Regionalisation for Australia (IBRA) bioregion.
Southwest Australia is a biogeographic region in Western Australia. It includes the Mediterranean-climate area of southwestern Australia, which is home to a diverse and distinctive flora and fauna.
Esperance Plains, also known as Eyre Botanical District, is a biogeographic region in southern Western Australia on the south coast between the Avon Wheatbelt and Hampton bioregions, and bordered to the north by the Mallee region. It is a plain punctuated by granite and quartz outcrops and ranges, with a semi-arid Mediterranean climate and vegetation consisting mostly of mallee-heath and proteaceous scrub. About half of the region has been cleared for intensive agriculture. Recognised as a bioregion under the Interim Biogeographic Regionalisation for Australia (IBRA), it was first defined by John Stanley Beard in 1980.
Mallee, also known as Roe Botanical District, is a biogeographic region in southern Western Australia. Located between the Esperance Plains, Avon Wheatbelt and Coolgardie bioregions, it has a low, gently undulating topography, a semi-arid mediterranean climate, and extensive Eucalyptus mallee vegetation. It has an area of 73,975.59 square kilometres (28,562.13 sq mi). About half of the region has been cleared for intensive agriculture. Recognised as a region under the Interim Biogeographic Regionalisation for Australia (IBRA), it was first defined by John Stanley Beard in 1980.
The High Rainfall Zone is one of three biogeographic zones into which south west Western Australia is divided, the others being the Transitional Rainfall Zone and the Low Rainfall Zone.
Western Mallee is an Interim Biogeographic Regionalisation for Australia (IBRA) subregion in southern Western Australia. It is a sparsely populated subregion with an area of about 47,000 square kilometres, roughly centred on the town of Newdegate. Largely cleared for intensive agriculture, it still retains patches of native vegetation, but these are under environmental stress from threats such as rising salinity, and are poorly managed.
Eastern Mallee is an Interim Biogeographic Regionalisation for Australia (IBRA) subregion in southern Western Australia.
Coolgardie is an Australian bioregion consisting of an area of low hills and plains of infertile sandy soil in Western Australia. It has an area of 129,122.09 square kilometres (49,854.32 sq mi). It includes much of the Great Western Woodlands.
Gascoyne is an interim Australian bioregion located in Western Australia. It has an area of 180,752.57 square kilometres (69,788.96 sq mi). Together with Murchison bioregion to the south, it constitutes the Western Australian Mulga shrublands ecoregion, as assessed by the World Wildlife Fund.
Hampton is an interim Australian bioregion located in southeastern coastal Western Australia, with a small portion (4%) extending into adjacent South Australia. It has an area of 1,088,198 hectares. The Hampton bioregion is part of the Coolgardie woodlands ecoregion.
Jarrah Forest, also known as the Southwest Australia woodlands, is an interim Australian bioregion and ecoregion located in the south west of Western Australia. The name of the bioregion refers to the region's dominant plant community, jarrah forest – a tall, open forest in which the dominant overstory tree is jarrah.
Yalgoo is an interim Australian bioregion located in Western Australia. It has an area of 5,087,577 hectares. The bioregion, together with the Avon Wheatbelt and Geraldton Sandplains bioregions, is part of the larger Southwest Australia savanna ecoregion as classified by the World Wildlife Fund.
The Walpole Wilderness Area is a group of conservation reserves on the south coast of Western Australia. The area includes vast tracts of jarrah, red tingle and karri forests surrounding granite peaks, rivers, heathlands, and wetlands. Coastal features include inlets and sandy beaches, sheer cliffs and the Southern Ocean.
The Western Australian Mulga shrublands is a deserts and xeric shrublands ecoregion of inland Western Australia. It is one of Australia's two mulga ecoregions, characterized by dry woodlands of mulga trees interspersed with areas of grassland and scrub.
The Cape York Peninsula tropical savanna is a tropical grasslands, savannas, and shrublands ecoregion in northern Australia. It occupies the Cape York Peninsula in Queensland, mainland Australia's northernmost point. It is coterminous with the Cape York Peninsula, an interim Australian bioregion.
Mount Roe National Park is a national park in the Great Southern Region of Western Australia. It was designated in 2004, and covers an area of 1278 km2.
Mount Frankland South National Park is a national park in Western Australia. It lies mostly in the South West region, with the eastern portion in Great Southern Region. It was designated in 2004, and covers an area of 422.99 km2. It is part of the larger Walpole Wilderness Area that was established in the same year.
1 2 3 Beard, J. S.; Sprenger, B. S. (1984). "Geographical Data from the Vegetation Survey of Western Australia". Occasional Paper No. 2.{{cite journal}}: Cite journal requires |journal= (help)
1 2 3 "Jarrah-Karri forest and shrublands". Digital Observatory for Protected Areas (DOPA) Explorer. European Commission. January 2021. Archived from the original on 6 September 2021. Retrieved 29 April 2022.
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. ISBN0-642-21371-2
Wardell-Johnson, G. & P. Horwitz (1996). "Conserving biodiversity and the recognition of heterogeneity in ancient landscapes: a case study from south-western Australia". Forest Ecology and Management. 85 (1–3): 219–238. doi:10.1016/S0378-1127(96)03760-7.
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