BIOREGIONAL SPOTLIGHT #1: KWONGAN


BIOREGION /ˈbīōˌrējən/ – noun

A region defined by characteristics of the natural environment rather than by man-made divisions.

For most of human history, borders and boundaries were determined by natural phenomena; a mountain range, a desert, a major river, ect. When first seeking to identify a Bioregion, one must start the big two: water and earth. Without water, there is no life, and the earth dictates where the water gathers and how it travels.

One of the best unions of hydrology and geology are drainage basins, also known as  “catchments” or, “watersheds” which detail which lakes, rivers, and oceans water drains into. Of course, there are also closed systems, known as endorheic basins, in which water is retained either permanently or seasonally.

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In the case of Australia, the majority of its water flows into the Indian Ocean, with the rest either being locked within endorheic basins or flowing out to the Pacific Ocean. The exact divisions of these drainage basins can be seen in detailed maps of continental watersheds.

Australia's 13 drainage divisions.

Australia’s 13 drainage divisions.

Australia's topographical drainage divisions adapted from the BOM's hydrological geospatial fabric (Geofabric) map.(ABC Weather: Kate Doyle)

Australia’s topographical drainage divisions adapted from the BOM’s hydrological geospatial fabric (Geofabric) map.(ABC Weather: Kate Doyle)

Occasionally there can be variation in maps or classifications, as seen in the Australian government’s “topographical drainage divisions” or listing of “Freshwater ecoregions in Australia”

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Freshwater ecoregions in Australia. Ecoregions are represented by different shading. Source: Freshwater Ecosystems of the World (http:// www.feow.org./) and Abell et al. (2008).

Freshwater ecoregions in Australia. Ecoregions are represented by different shading. Source: Freshwater Ecosystems of the World (http:// www.feow.org./) and Abell et al. (2008).

Climate maps are another important layer, as they also help inform the landscape, and give one an idea of what the local flora pattern might be like.

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Some countries or government agencies, for their own reasons, have extremely useful data regarding bioregions, ecoregions, and other landforms, and Australia is no exception; the Interim Biogeographic Regionalisation for Australia (IBRA) was developed in 1993-94 and is endorsed by all levels of government as a key planning tool for identifying land for conservation under Australia’s Strategy for the National Reserve System 2009-2030. The current version, IBRA7, was developed in 2012, and divides the Australian continent into 89 ‘bioregions’ and 419 ‘subregions’. 

[Note that the Australian government apparently uses the term ‘bioregion’ to mean ecoregion’]

[Note that the Australian government apparently uses the term ‘bioregion’ to mean ecoregion’]

One can also overlay maps detailing biomes (large, naturally occurring communities of flora and fauna occupying a major habitat, e.g. forest or tundra):

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In this map, terrestrial biomes are represented by different shading overlaying the Interim Biogeographic Regionalization for Australia (IBRA) regions, represented by lines. 

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This map of Australia shows IBRA bioregions that represent plant diversity and vegetation structure at a coarse scale, with colors used to amalgamate these into phytogeographic regions based on plant species turnover. An astute reader may have already noticed some patterns emerging just by examining the past few maps. To explore the final layers of determining a Bioregion, we will shift focus on southwestern Australia in an area referred to by the Australian government as the South-West Floristic Region (SWAFR), home to one of the continent’s best wildflower displays, featuring an enormous variety of color, shapes, and sizes.

Ecoregions of Southwest Australia, as defined by the WWF.  1. Jarrah-Karri forest and shrublands; 2. Southwest Australia woodlands; 3. Southwest Australia savanna; 4. Coolgardie woodlands; 5. Esperance mallee.

Ecoregions of Southwest Australia, as defined by the WWF. 1. Jarrah-Karri forest and shrublands; 2. Southwest Australia woodlands; 3. Southwest Australia savanna; 4. Coolgardie woodlands; 5. Esperance mallee.

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Covering 356,717 km2, consisting of a broad coastal plain 20-120 kilometers wide, transitioning to gently undulating uplands made up of weathered granite, gneiss, and laterite. Desert and xeric shrublands lie to the north and east across the center of Australia, separating Southwest Australia from the other Mediterranean and humid-climate regions of the continent.

Due to its ancient geology, the soils in this region are almost all poor in nutrients, but this is likely the secret to the southwest’s astonishing diversity, which has been determined by environmental filtering from the regional flora, driven by soil acidification during long-term pedogenesis, and reflects processes shaping species pools over evolutionary time scales.

Southwest Australia is a major center of biodiversity, with over 90% of all Banksia species occurring only there, from Exmouth in the north, south, and east to beyond Esperance on the south coast. These Australian wildflowers and popular garden plants,  easily recognized by their characteristic flower spikes and fruiting “cones” and heads. 

Finding the habitat range of regionally specific animals can also help identify the boundaries of a Bioregion. 

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For example, the Noolbenger, or Honey Possum (Tarsipes Rostratus), is a tiny species of marsupial that feeds on the nectar and pollen of a diverse range of flowering plants, and is also an important pollinator for such plants as Banksia Attenuata, Banksia Coccinea, and Adenanthos Cuneatus.

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The termite-eating Numbat (Myrmecobius fasciatus), the only truly diurnal marsupial with sentinel behavior similar to that of the African meerkat, also occupies the region.

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The Short-Tailed Scrub Wallaby, also known as the Quokka (Setonix brachyurus), are small, mainly nocturnal marsupials about the size of a domestic cat that in recent years have earned a reputation on the internet as “the world’s happiest animals” and as symbols of positivity due to their beaming smiles. Quokkas are found on some smaller islands off the coast of Western Australia, particularly Rottnest Island, just off Perth, and also Bald Island near Albany, and in isolated, scattered populations in forest and coastal heath between Perth and Albany. A small colony exists at the eastern limit of their range in a protected area of Two Peoples Bay Nature Reserve, where they co-exist with the critically endangered Gilbert’s potoroo. In the mid-2010s, quokkas earned a reputation on the internet as “the world’s happiest animals” and symbols of positivity due to their beaming smiles.

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The Brush-Tailed Bettong, or Woylie (Bettongia penicillata) was until recently very abundant in the south west but, starting in 2006, it has suffered a dramatic decline and is now listed as Critically Endangered. While the direct causes are unknown, it does highlight the critical need for protection of these unique species and their habitat in a biodiversity hotspot under increasing pressure from urbanisation. This leads into one of the final overlays to identify a modern bioregion: human habitation.

The prolific effects of Humans on global systems cannot be overlooked. Nor should they be, since historically the patterns of human habitation and material culture were directly affected by the other aspects of a bioregion.

Even today, the Australian continent as a whole is relatively sparsely populated, as best illustrated by nighttime maps showing major population centers.

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Furthermore, examining growing populations centers and developing megaregions can help identify environmental systems and topography, as well as regional economic and infrastructural linkages.

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Both the spareness of the human population, combined with the vast scale of the Australian continent, can also be put into context when one looks at the proximity of current human settlements to the largest population centers on the continent. This can give insight into regional associations, both positive and negative, and serve as a framework for seeing how people identify with each other.

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Even humorous and less than flattering regional stereotypes can provide insight into emerging cultural distinctions and regional character.

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Of course, the best datapoint to examine regarding human habitation is that of the material culture and range of indigenous peoples. Humans have inhabited the continent of Australia for at least 65,000 years (though recent archeological evidence and new findings estimate that it could have been as long as 120,000 years) and people have been living in southwestern Australia for well over 40,000 years. Naturally, these indigenous peoples lived with very different boundaries than today, centered on intimate cultural relationships with the land and sea.

The AIATSIS map of Indigenous Australia is an attempt to represent all the language, tribal, or nation groups of Indigenous Australia. Aboriginal and Torres Strait Islander groups were included on the map based on the published resources available between 1988 and 1994 which determine the cultural, language, and trade boundaries and relationships between groups.

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It shows only the general locations of larger groupings of people which may include clans, dialects, or individual languages in a group. And while not exact, and not considered legally suitable for native title or other land claims, it does provide another data point, creating another level of comparison.

Again focusing on the south-west corner of Western Australia, we find that the region has historically been inhabited by the Noongar people (also spelled Noongah, Nyungar, Nyoongar, Nyoongah, Nyungah, Nyugah, and Yunga). The members of the collective Noongar cultural block descend from peoples who spoke several languages and dialects that were often mutually intelligible, and were part of the larger Pama-Nyungan language family.

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The area called Nyungar Boodjar (litteraly, ‘People’s Country’) is made up of 14 related groups who occupy a roughly triangular range from north of Jurien Bay and Geraldton on the west coast, inland to the north of Moora and down to the southern coast between Bremer Bay and east of Esperance.

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This cultural region is spread over three different geological systems: the coastal plains, the plateau, and the plateau margins; all areas are characterized by relatively infertile soil. The north is characterized by casuarina, acacia, and melaleuca thickets, the south by mulga scrubland but it also supported dense forest stands. However, one of the major unifying features of the region is the kwongan heathland.

Banksia cuneata is a rare and threatened kwongan species. It occurs in only 13 small populations over a range of 110 km in a highly-fragmented landscape. Photo: Jean Hort.

Banksia cuneata is a rare and threatened kwongan species. It occurs in only 13 small populations over a range of 110 km in a highly-fragmented landscape. Photo: Jean Hort.

The word “Kwongan”, or “kwongkan”, comes from the Bibbelmun (Noongar) term of wide geographical use, describing open, sandy countryside without timber-sized trees but with scrubby vegetation, and is roughly analogous to South Africa’s fynbos, California’s chaparral, France’s maquis, and Chile’s matorral as seen in these other regions of the world experiencing a Mediterranean climate.

There are two principal plant formations in the kwongan, scrub heath and broombush thicket, both of which are sclerophyll shrublands and possess a certain unity when contrasted with woodland and forest or steppe and succulent steppe communities. Prior to clearing, approximately 30% of southwest Australia was covered by healthy and colorful swathes of Kwongan. Now, however, most of the original Wheatbelt Kwongan has disappeared due to land clearing, with the only significant remnants remaining in coastal and near-coastal areas.

After examining several layers of data, when taken together, it is clear that the southwest of the Australian continent is a distinct bioregion.

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With its wet-winter, dry-summer Mediterranean-climate (one of five such regions in the world) and home to diverse and distinctive flora and fauna, the bioregion is recognized in scholarly works, though it is addressed clinically as the South-West Floristic Region, or sometimes as the Southwest Australia Global Diversity Hotspot. However, thanks to one of the major unifying floral features and the indigenous people of the region, we have a name for our newly identified bioregion: Kwongan.

Kwongan Heath, dominated by orange Eremaea brevifolia, Lambswool bush (Lachnostachys eriobotrya) and other Spring flowers in Alexander Morrison National Park, western Australia.

Kwongan Heath, dominated by orange Eremaea brevifolia, Lambswool bush (Lachnostachys eriobotrya) and other Spring flowers in Alexander Morrison National Park, western Australia.

Kwongan, Western Australia, Wheatbelt, Dryandra forest, September 2018

Kwongan, Western Australia, Wheatbelt, Dryandra forest, September 2018


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