New thinking and new trees
Steve Forbes, Director, Botanic Gardens of Adelaide

Tim Flannery’s lack of enthusiasm for Plane Trees or Elms as new plantings on North Terrace is shared.  Issues such as biodiversity loss, salinity, water (quality and quantity) and land degradation argue strongly that, for any future, the twenty first century has to be about reconciliation with the Australian environment, and that this reconciliation will be achieved through plant-based solutions. 

While North Terrace seems removed from these issues, progress towards environmental reconciliation is being governed from the city.  The challenge of linking Australians to their environment is at the soul of reconciliation with the Australian environment.  A ‘not in my backyard’ approach to the landscape associated with our cultural and scientific institutions will send a clear message to South Australians and our visitors.

In the nineteenth century South Australians pioneered the exploration of Adelaide’s designed landscape – none of the exotic flora had ever been grown in Adelaide before.  It was all a great experiment!  While the nineteenth century was about the transplantation and adaptation of European agricultural and horticultural systems, the twenty-first century is about conserving an environment that allows these systems to continue, and about conserving Australia’s incredible biodiversity.  A new challenge, and one the city is currently inclined to leave to the country.

We still seem reluctant to explore the potential of Australian plants with anything like the enthusiasm the nineteenth century applied to exotics.  The issue is a serious one.  Tim Flannery reflects on our reluctance to embrace Australia as Australians.  The issue is less about rejecting exotic floras (- which certainly have their place), and much more about reconciliation with our own flora and our own land.

The suggestion that Victorian architecture was expected to have a curtilage of European trees is unconvincing!  Victorian architecture stretched well beyond the range of European floras, and in Adelaide, the potential of European trees was only being explored as public buildings were being constructed.

Ignorance of Australia’s flora beyond a few cultivated species is profound and cannot be overstated.  For example, the single most significant factor for the germination of Australia’s 12,000 temperate species (other than water) was only discovered in the past decade!  The discovery of a water soluble germination factor in smoke has proved a quantum leap in understanding ecosystem function.  However, the fact that it has taken over 200 years to establish this simple ecological truth underscores our ignorance.

There is another debate around the landscape potential of indigenous trees.  However, in a highly modified and highly trafficked environment the net might be spread more widely.  Some native shade trees that might be explored for North Terrace as alternatives to Eucalyptus maculata (Spotted gum) include Eucalyptus scoparia (Wallangara white gum), a beautiful white barked tree with graceful weeping branches, Eucalyptus populnea (Poplar box), a grey barked tree with round, blue leaves and Eucalyptus grandis (Rose gum), a stately tree with beautiful pink bark.  Others might include densely crowned trees such as Argyrodendron actinophyllum (Tulip oak) and Flindersia australis (Crows ash) or Flindersia maculosa (Leopardwood).  While some of these trees might not satisfy an expectation for an instant landscape, trees, like people, take time to grow and mature. 

Our future on the planet will be dependent on our ability to utilise living plant materials to manage the environment as effectively as we utilise construction materials in the built environment.  North Terrace may be a good place to start, and certainly in line with the poetic mission I like most for the world’s botanic gardens in the twenty-first century – ‘To promote ecological imagination’.