A report tabled at Council today has outlined the actions and processes undertaken by Council since 2005 to monitor and mitigate risks associated with a large Melaleuca tree, which was recently removed at Palm Cove.
The 26-metre high tree on the corner of French Street and Williams Esplanade was removed two weeks ago following 15 years of monitoring, 18 reports from qualified external and Council arborists, and numerous scans that the showed an acceleration of fungal infestation and decay.
Information garnered through scans and arborists’ reports, which highlighted the deterioration of sound wood and the progression of fungal infection and decay, was validated upon the tree’s the tree was removed.
It was noted that as they were removed, some of the upper branches were significantly decayed with limited sound wood.
Sound wood was found at the top of the trunk of the tree, which was consistent with the sonic tomographic scans.
However, towards the base of the tree the very large cavity on the northern side of the tree under the large main leaders was exposed, which was also consistent with the scans.
The report also noted that care needed to be taken when walking on the remaining stump as there was significant decay of the roots.
“It was a beautiful tree – we love these trees and we know how important they are to the Palm Cove community – the last thing we wanted to do is chop it down, but we simply did not have a choice,” Division 9 Councillor Brett Olds said.
“When you looked at the tree, there were quite obvious bulges, cavities, decay, disease and wounds from past limb failures. The tree had issues for years.
“The tree was condemned several times since 2007, but on each of those occasions Council went above and beyond, and at significant expense.
“But, unfortunately, nothing more could be done and it needed to be removed in the interest of public safety.”
Data from sonic tomograph tests in 2010, 2014, 2017, 2019 and early 2020 had showed a significant deterioration of the sound wood at the base of the trunk and at a height of about one-metre.
There was an indication of an improvement of sound wood and a decrease of active fungus in 2014, but by May 2017, further testing revealed the tree had again deteriorated.
Arborist reports in late 2019 identified that the spread of decay and fungus had accelerated rapidly at the base of the tree and a risk assessment identified that there was a high risk of failure.
“To put this into perspective, this tree was about 26 metres high or equivalent to a nine-storey building, and the foundations were rotten or non-existent,” the report stated.
“The foundation of the tree was significantly compromised and a tree, like a building, cannot stand up without a solid foundation.”
It was also noted that the fall zone of the tree extended over Williams Esplanade and French Street, a busy area of Palm Cove that usually carries approximately 2,500 vehicles a day and thousands of people during staged events.
The tree was scheduled for removal in February 2020, but following a request from two community groups, Council engaged the services of an external arborist to undertake another independent assessment.
Council also undertook additional sonic tomographic scans in May 2020.
Those scans indicated that the amount of decay and fungal rot at the base of the tree had advanced further with only 13 per cent sound wood and 80 per cent active fungus and decayed wood.
Based on those results, along with the tree’s long history of decay, it was deemed the tree was at significant risk of failure.
Once the bulk of the tree was removed, the remaining stump was ground to about 300mm below the ground surface.
The site will be left for approximately six months, then three new Melaleuca trees planted in the vicinity.
Fungal samples were taken to the James Cook University Herbarium for analysis and identification to help with future treatment choices for the site to ensure successful re-planting.