The tenacity of the tree

Figure 1: Our subject tree, an English Elm – Ulmus parvifolia – over the roofline in Duke Street, Busselton, WA. The tree’s upper crown is in the process of retrenching resources before leaf fall.

Cassian Humphreys reminds us the mistakes of the past will effect our future, and respects the tenacity of the tree.

No matter where I am in my journey in arboriculture, or rather, my journey as a tree-man being cultured by the lore of the tree, I never cease to be amazed by the tenacity of the tree. How is a stationary organism, subject to resources limited to its environment, possibly able to survive the rigours of the human development site?

I found this recent subject, an English Elm in Busselton, Western Australia. For the sake of honouring individuals, businesses, a local council, and professionalism, I have changed names involving people and location. Yet the brief report I wrote professionally alerting a local council to a major development breach paints a fair picture of humanity and a human development process failing to honour all concerned, least of all the tree.

The report I recount follows a private tree-assessment enquiry, commissioned by a local council, brought about by a homeowner’s request for the tree’s removal. Based on the basic datacollection template I was working with, this article follows the same format as the local council report it is founded on (naturally I have included some personal thoughts and observations in the interests of making for thought-provoking, and hopefully interesting, read).

Figure: 2. The site when development was still in process.

 

Figure 3: Before: July 2017. The deciduous tree minus its foliage is located on the boundary line, sandwiched between the then 47 and 49 Duke Street. This image reveals a gravelled carpark on its north side, with a desertified suburban yard encompassing its root zone. The original blocks of land (45 and 47), with single dwellings prior to the amalgamated 2022 development, are clearly visible.

 

Figure 4: After: December, 2022. The Elm with its 2022 summer coat is visibly wedged between the new unit 7 block and the old fence line. The amalgamated land blocks now make up No: 47 Duke Street.

Observations/background

The tree, located to the rear (north) of the property, is adjacent to a boundary fence line, and currently exhibits excellent health and good crown structure. I acoustically sound tested the tree with a Thor 710 sounding hammer, and excellent wood resonance indicated solid, decay-free timber.

According to the property owner, Mr Bathurst, the tree is heritage-listed (this needs to be confirmed). Based on archival footage, it was stated the tree is as old as 100 years. Being a paddock specimen with a crown height of around eight metres, a crown spread of five metres and a trunk diameter under one metre, it seems unlikely it could be this age. Regardless of any human considered timeline, the multi-layered (super-harmonic) canopy, natural crown subordination, and exceptional vitality of this tree certainly are the hallmarks of a very worthy development-site candidate.

The build was completed in late April 2022, almost exactly one year prior to my recent assessment.

To the rear of the fence line in the neighbouring property is a gravelled dirt road which means the tree now has 100 per cent of its root system under suppression via a heavily compacted soil environment. Considering the root severance it underwent with trenching for stormwater in front of the slab, I think it remarkable the tree is not already showing signs of great stress. It is a testament to the tree’s historical vitality and stored resources that it looks this good, even after 12 months since the build. In fact, I can see no stress response. This may mean the tree is drawing on below-ground resources that are not possible to be observed or validated. However, hard-copy photographs provided by the owner validate the proximity and the nature of damage done to the tree’s root system, with evidence of shattered woody roots piled by the storm-water trench.

Fig: 5. As seen from the front, side and rear of 7/47 Duke Street, the Elm tree has been requested as a removal on behalf of Mr Bathurst. To be able to objectively determine the trees status, in light of the development application further arboricultural investigation (into past reporting) is necessary to validate the trees removal.

In the year since the completion of the build the gutter is now actually touching the trees crown, where, according to the owner, there was an air gap one year prior.

Figure 6: One year after completion of the build.

Wrong from the start

The house slab was installed over the tree’s Tree Protection Zone (TPZ), and the tree’s Structural Root Zone (SRZ) to within 0.5m of the main trunk. This constitutes at least a 40 per cent encroachment on the TPZ.

This is unprecedented in my experience of consulting on trees on development sites, particularly for a heritage-listed tree. A large lower limb was removed prior to the build (approximately 30cm+ in diameter), and this has already started to generate a narrow doughnut of wound wood, supporting the tree’s remarkable vitality and stored energy reserves, and the incremental growth that has led to the tree now touching the gutter. Considering the development impact, I will be surprised if declines in the tree’s crown are not visible by next spring, however, based on the tree’s current vitality, I am open to being proved wrong.

I was advised by Mr Bathurst that he commissioned and received an arboriculturist’s report in May 2022, and was informed by that report and correspondence of failings either at the building’s design phase, or noncompliance on behalf of the builder, and that this allowed for the encroachment of the tree’s TPZ/SRZ.

It has to be asked, based on the Australian Standard for Trees on Development Sites – A/S 4970-2009, was a Project Arborist appointed to manage the tree during the development process? And if so, where are his or her record of events and who signed off on the process? It would also be worth looking at the Development Application (DA) conditions with respect to the tree prior to the build. I know from verbal feedback, as with most DA requirements, it had been assured the tree would be fenced at least to the dripline. The hard copy photographs I glimpsed showed the fence to be behind the stormwater trench.

Fig: 7. The trees trunk and lower crown in proximity to the one year old build.

To be true it must also be questioned whether the build should have occurred. To comply with the needs of the tree and the Australian Standard, Unit 7 should have been left as urban green space in support of the tree.

A problem

The Elm’s heritage status needs to be investigated, as does any arboricultural reporting pre/during/post development phase. Though the tree may not be a liability in the short term – its naturally subordinated multi-canopied crown makes it exemplary at dealing with wind load – because of its root severance, quantifying this is now a major problem for the long term.

Note: the soil grade has also been raised. This adds to the damaging impact on the tree’s health and structural capacity in the long term.

Figure 8: The tree as seen from the unit’s living room. Assuming it does survive development, where is the room for the tree’s expansion?

Management recommendations

• Investigation is essential for us to better qualify and quantify the tree’s status, both in terms of short-term health and long-term liability. This will involve the review of past arborist reports – such as the one discussed by Mr Bathhurst – any record of the root excavation, discussion with the builder and possibly the developer, and most importantly, establishing who was the appointed Project Arborist and who signed off on the development;
• Removal: I am loathe to ever condemn a good tree, and based on this tree’s many great attributes I see it as the perfect tree for the urban environment. Such a well subordinated specimen will outlive the average forest tree. Yet because of this build the tree has had its life cut short and the owner has been put in an understandably unreasonable position. At this point I add that Mr Bathhurst told me during the development he was advised several times that the tree would be removed;
• Monetary evaluation: based on my study of the tree, and consideration of the detail received to date, I advise a monetary evaluation be carried out on the tree. This is to be based on the tree’s attributes and worth to the local environment. Considering the gathering human initiatives in the face of climate change, I believe it essential people either take responsibility for their actions or be held to account. It is clear to me a key stakeholder was knowingly in breach with regard to the wilful destruction of a good tree with a good future.

In closing, arboriculture as it moves into the conservation initiative most certainly has come of age. Yet even with arboriculture being at its most potent with regard to tree retention, risk management and health care, until consulting arboriculturists are taken seriously by the allied stakeholders, until arboriculture is ranked at the same level of priority in the planning process, I am afraid we are peeing into the wind.

Thank goodness for the tenacity of the tree.

Read more from Cassian at arborage.com.au.

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