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Suburban expansion on Perth’s fringe pushes into the SouthWest Ecoregion. Richard Weller/Donna Broun, Author provided

Squandering riches: can Perth realise the value of its biodiversity?

Perth is not known as a model for suburbia and its suburban condition is similar to that of developed cities the world over. However, it does stand out in one respect: it sits in an exceptionally biodiverse natural setting. A strong, informed vision for this setting’s relationship with the city could help Perth become an exemplar for similarly positioned metropolises everywhere.

The greater Perth region has been designated the Southwest Australia Ecoregion (SWAE). This is one of only 35 “biodiversity hotspots” in the world.

Reconciling future growth with biodiversity is a key issue for urban design and planning this century. Indeed, if current trends continue, global urban land cover will increase by 1.2 million square kilometres (equivalent to half the area of Western Australia) by 2030. Much of this will happen in biodiversity hotspots.

This is important because it is estimated we will lose nearly half of all terrestrial species if we fail to protect the hotspots. We will also lose the ecosystem services upon which human populations ultimately depend.

If we fail to protect the world’s 35 biodiversity hotspots we risk losing nearly half of all terrestrial species. Conservation International, Author provided

“Ecosystem services” may sound like abstract jargon, but it’s actually a term used to describe the services nature provides – such as clean air, water and food, and heatwave and flood mitigation. Without these, human life would be extremely unpleasant, if not unviable.

Perth has a reputedly strong planning system and is comparatively wealthy. If it can’t control its city form to protect biodiversity – compact cities generally being recognised as the best model for protecting land for conservation – then city administrators elsewhere, particularly in the developing world, are likely to struggle.

Misreading the land

The current treatment of the Australian environment has its roots in the European annexation of Australia, which has been characterised by catastrophic misreadings of the land. Governor James Stirling, who was singularly responsible for the European annexation of Perth, was the kind of man who saw what he wanted to see rather than what was there. In The Origins of Australia’s Capital Cities, Geoffrey Bolton writes:

…arriving at the end of … an uncommonly cool, moist summer, [Stirling was] misled by the tallness of the northern jarrah forest and the quality of the alluvial soils close to the river into believing that the coastal plain would offer fertile farming and grazing. It was, Stirling wrote, equal to the plains of Lombardy; and he persuaded himself that the cool easterly land breeze of these early autumn nights must originate from a range of snowy mountains.

Vegetation of Southwest Australia Ecoregion near current-day Perth at the time of European settlement. Based on statewide mapping by John Beard between 1964 and 1981. DPAW
Remnant vegetation of SWAE near Perth in 2015. DPAW/WALGA, courtesy of AUDRC, Author provided

The results of such misinterpretations of the land were generally less poetic. Stirling sited the settlement of Perth on a narrow, constrained strip of land between swamps to the north and marshy river edges to the south. These low-lying areas fuelled plagues of mosquitos and, once polluted, deadly typhoid outbreaks.

In time, due to a lingering discomfort with Perth’s “unsanitary” wetlands, more than 200,000 hectares – an area equivalent to 500 Kings Parks – were drained on the Swan Coastal Plain. These biologically productive areas directly or indirectly support most of the coastal plain’s wildlife, so the effects on biodiversity have been catastrophic.

Furthermore, a perception of the Banksia woodland and coastal heath on Perth’s fringes as unattractive and useless has seen much of it cleared for the expansion of the city. Between 2001 and 2009, suburban growth consumed an annual average of 851ha of highly biodiverse land on the urban fringe.

The lesson from this experience is that any future growth in a biodiversity hotspot, or indeed elsewhere, has to be founded on the understanding that we cannot continue to bend nature to our will. We must learn how to work with it.

Within this humbling process, we need to recognise that working with the land is not an entirely pure or noble act; rather, it is imperative for humanity’s survival. As species and ecosystems become threatened and vanish, so too do the ecosystem services that support human wellbeing.

Perth’s Green Growth Plan

The release of the state government’s long-anticipated Perth and Peel Green Growth Plan for 3.5 million may herald a shift in the relationship between the city and the biodiversity hotspot. The plan encapsulates two broad goals:

  • to protect fringe bushland, rivers, wetlands and wildlife in an impressive 170,000 hectares of new and expanded reserves on Perth’s fringe

  • to cut red tape by securing upfront Commonwealth environmental approvals for outer suburban development.

Proposed new and existing reserves – light and dark green respectively – on Perth’s fringe (indicative only). DOP, courtesy of AUDRDC, Author provided

While ostensibly positive achievements, a question remains as to the implications of clearing a further 9,700ha* (3% of the Swan Coastal Plain in the Perth and Peel region) of remnant bushland which is not protected by the conservation reserves.

At the same time as the Green Growth Plan’s reserves to the north of the city create a largely legible and connected edge to the city, in the south the reserves are isolated and disconnected due to the extent of historic clearing. This potentially stymies the public’s ability to conceptualise the city’s edge, which leads them to care about it (like London’s greenbelt, for instance).

Finally, a question remains about how a plan that places restrictions on outer suburban development will accommodate the powerful local land development industry over time. This is a concern given the frequent “urban break-outs” – where urban development occurs outside nominated growth areas – between 1970 and 2005.

In 2003, the ABC asked revered Western Australian landscape architect Marion Blackwell, “Are we at home now in the land we live in?” She replied, “No, we’re not. We don’t know enough about it, and not enough people know anything about it.”

We still have work to do on our engagement with biodiversity in Western Australia, and Perth specifically, before we can become a model for future cities.

*This article was corrected on October 26 2016. The original article wrongly cited 45,000ha of remnant bushland, and has been corrected to 9,700ha. Secondly, the characterisation of the Green Growth Plan in the following paragraph has been clarified.

The Conversation is co-publishing articles with Future West (Australian Urbanism), produced by the University of Western Australia’s Faculty of Architecture, Landscape and Visual Arts. These articles look towards the future of urbanism, taking Perth and Western Australia as its reference point. You can read other articles here.

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