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United we stand: Urban trees face an existential crisis

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Melbourne developed an Urban Forest Strategy in order to keep its tree population thriving (Screenshot via YouTube)

In our isolation from physical contact, Nature offers solace, but urban trees have to reckon with their own mortality. Locked down in apartments and houses, it's time to reflect on whether they, too, can snap back, writes Dr Peter Fisher.

LAST NOVEMBER, the Mayor of Melbourne’s Manningham City Council spearheaded a campaign to save a 300-year-old red gum from the chop in Bulleen at the hands of a North East Link road. Along with other councils like Frankston and Moonee Valley, Manningham succeeded in having a resolution passed at the Municipal Association of Victoria convention requiring that these botanic senior citizens be granted special significance status.

Large trees can be seen all over cities like Melbourne but, like old houses, they can be there one day and gone the next as our whole environment continues to be transformed into impervious surfaces. There are in consequence real concerns about the loss of aggregate biomass despite things like 31 councils signing up to an Urban Forest initiative.

Plant intelligence: Do trees have a sense of community?

Most of us would be highly sceptical to learn that trees and other plants, for that matter, have a sense of community, not to mention a level of ingenuity we would normally associate with intelligence. Nonetheless, there’s plenty of evidence that trees go to considerable lengths to balance themselves against winds.

And they have also figured out how to maximise their chances of survival given they have no fight or flight option to draw upon, unlike birds and animals. Think about it, if you’re riveted to a single spot and a hostile agent fronts up wanting to devour much of you (or kids wanting to tag you with chemically-laced paint), you can’t run away. Surviving such transgressions means decentralising your neurological elements so life can go on even with a loss here and there, whereas at the end of the day birds and animals can scoot with their brain still intact.

Plane trees in Park Street St Kilda. Do they benefit from each other’s company? (Image supplied)

Add to this the fact that no lesser identity than David Attenborough, accompanying the Queen through her forested garden at Windsor, highlighted the ability of trees to talk to each other and share things. Reaching further up the hierarchy to non-human animals, we’re already witnessing an undercutting of the notion that only language can be the basis of effective communication.

Single purpose agencies: They certainly aren’t listening to the trees

Such revelations add a new dimension to the conservation of trees in our landscapes. There’s scant evidence, though, that authorities including the single purpose variety are cognisant of these subtleties.

VicRoads’s bid to remove 300-year-old river red gums upon the widening of the Western Highway near Beaufort and the trashing of sugar gums at Gandolfo Gardens near Moreland Station by the Level Crossing Removal Authority (LXRA) are cases in point. LXRA ignored community protests as well as its statutory obligation to protect and maintain vegetation, the functioning of ecosystems and biological diversity.

From ecosystem to asphalt system at Moreland station - all in a day's work (Image supplied)

Actions like translocating the Matted Flax-lily in the Mernda rail corridor are poor recompense for the destruction of mature sugar gums at Moreland Station. Moreover, an Anthropocene climate ravaged by intense heat, aridity and destructive winds – the sort of stuff we have just witnessed – could render it impossible to grow replacement trees in the form of saplings to the same stature.

Symbiotic chemistry

For every felled tree, every excised tree limb, there’s often an entity down below ready to devour the pickings — the woodchipper with its nothing wasted product, moisture retention, weed control and landscape appeal. Cleaning up vegetation after extreme weather events and/or liability fears inextricably makes for a reliable supply. 

Alleged risk can be a common thread in opportunistic tree removal (Image supplied)

This, in turn, is lending impetus to the arborist profession — it’s recording strong growth if the plethora of TAFE oriented training courses is any guide. 

Some of the curricula, however, have a very practical albeit engineering bent devoid of nature values. They raise the question as to how a profession which can shape local landscapes and wildlife by its practices/protocols sees itself fitting in with progression towards a biophilic city. Should commercial mulch, for example, be given an accreditation that it was not the result of an action leading to the destruction of habitat or contributing to species loss?

Furthermore, what is or should be its view on the evolution that is taking place under its nose in stark contrast to the Darwinian notion that evolution could never be seen in a single lifetime? City organisms are on their way to becoming entirely novel and very urban species.

Scoring the industry

In this scheme of things, tree loppers occupy a rudimentary end of a spectrum grading through services offering things like tree health management/tree risk review, to a systemic science-based approach to tree preservation/survival, to one integrative of habitat and fauna. 

On the spectrum: Shifting the knob south to meet biophilic objectives (Image supplied)

Boroondara has begun that process by incorporating anthropocentric values into its significant trees register.

Biomass accounting

This leads to the ramifications for urban tree cover (UTC) and, in particular, the biomass balance in cities like Melbourne. Are the losses in the name of development on private land through infill and subdivision and/or safety exceeding new plantings? The evidence is fragmentary as collecting data on trees is very labour-intensive.

Tree surveys in Melbourne’s eastern and northern suburbs suggest that losses due to clearing ahead of construction and actual construction have been offset by new plantings. But this calibration is now three years old and since that point, there’s been a huge swathe of development on private land as the city’s population has leapt beyond five million accompanied by major infrastructure projects involving the likes of LXRA and VicRoads.

Stepping into the breach, it’s now possible to apply AI to satellite data to pinpoint where tree losses/gains are occurring across a city.

Private land clearing ahead of construction may be amounting to an overall loss of UTC (Image supplied)

Reset

The reoccupation of cities by animals and birds as they have emptied of people under lockdown is uncanny and evocative of a post-human world. The upending to our expansive 24/7 presence has given Mother Nature a chance to regroup and for us, a once-in-a-century chance to reflect on reaching an enhanced understanding and respect for other species. That means awarding Attenborough’s advocacy on trees, their sense of community and ability to look out for each other, extra attention. 

These botanical goliaths have been hanging out on this planet for 380 million-odd years. We descended from them onto the Savannah eons ago. Time to return the favour.

Dr Peter Fisher is an Adjunct Professor at the School of Architecture & Built Environment, Deakin University.

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