By Bob Gordon, Managing Director
The world's tallest hardwood tree has been discovered less than five kilometres from Forestry Tasmania's Tahune Airwalk tourism attraction.
It is the only known standing hardwood tree in the world to be over 100 metres tall.
Forestry Tasmania staff found the Eucalyptus regnans using an airborne laser scanner (LiDAR), which had been flown over the area in August. This technology is world leading and FT has been developing it to measure tree volume, develop digital terrain maps and to monitor carbon storage.
The LiDAR imagery appeared to show two very tall trees standing side by side.
Laser signals reflected off the canopy of the higher of the two trees showed it was at least 99 metres above the ground.
The trees were located and inspected from the ground on Monday. The two trees, included what is believed to be the world's tallest hardwood, which stands at 101 metres tall.
Details of the two trees are as follow:
The Centurion - (A Roman officer in charge of 100 soldiers)
Height 100 –101 metres, (measured with a laser using the “sine method”). Because the sight to the very top of the tree was partially obscured by the tree’s healthy crown, it may be taller.
Diameter: 405 cm
Species: E. regnans (Swamp Gum)
Triarius - (Latin for veteran soldier)
Height 86.5 metres, (measured with a laser using the “sine method”). Clear sight to the very top of the tree.
Diameter: 390 cm
Species: E. regnans (Swamp Gum)
For Forestry Tasmania staff, finding the tree was definitely one of those "Wow" moments. Two such moments, in fact.
First, in the office, Resource Officer Mayo Kajitani and Resource Information Manager David Mannes were routinely screening some new LiDAR data for giant trees when they found a large canopy whose maximum height reading was showing 99 metres.
They were amazed, especially knowing that LiDAR tends to underestimate tree heights because of pointy tops, tree lean, and dense undergrowth.
Scarcely containing their excitement, they raced to the Huon to check their giant from the ground.
Using special ground-based laser survey equipment, they got clear sightings to just below the top of the tree, confirming its height at over 100 metres.
"I had been saving the name 'Centurion' for our 100th giant tree", said David. "None of us ever imagined that we would find a 100 metre tree instead!"
"Interestingly, it looks as if the tree was once even higher. It appears to have broken off at the top, then re-sprouted a new healthy crown."
The trees are located in State forest, about 4 km northeast of the Tahune Airwalk, south of Hobart.
They were not previously in a reserve, but were reserved immediately in accordance with Forestry Tasmania’s Giant Tree Policy.
The forest surrounding the two giant trees has had an eventful history. The ridge above and to their west appears to have been in the path of the 1934 wildfires, which left few older trees intact. These areas are now mostly stocked with tall natural fire-regenerated regrowth forests. Thirty years later, the forests immediately to the east of the giant trees were burnt (and regenerated) by the major wildfires of 1966 and 1967. The 1967 fire (the same one that burnt Hobart) devastated much of the Arve Valley and resulted in a large area of fire regenerated forest.
Because of the major fire disturbance in the surrounding forests, none of this area is classified as “oldgrowth” under the Regional Forest Agreement.
The tallest of the two newly-discovered trees becomes the tallest known tree existing in Tasmania or Australia. It is the tallest Eucalyptus tree in the world, the tallest hardwood tree in the world, and the tallest flowering plant in the world.
(Californian Redwood trees are taller, but these are softwood trees, and botanists do not classify them as flowering plants).
The previous tallest known existing hardwood tree was “Icarus Dream”, a Swamp Gum (E. regnans), measured at 97 metres in the Styx Valley (west of New Norfolk) in 2005.
Records from Victoria, mostly from the 19th Century, describe a number of trees that are claimed to have been much taller than 100 metres, but many of these measurements are disputed. None of these giants now exist.
Historic records from Tasmania generally cite lesser heights than those claimed from Victoria. The highest were two Blue Gums (E. globulus), one near Hobart and the other near Geeveston, which were each measured in 1906 at 330 feet high (101 metres). The highest contemporary record is 322 feet (98 metres), a Swamp Gum (E. regnans) in the Styx forest, measured in 1956. These trees have since shrunk in height due to old age.
Forestry Tasmania’s Giant Tree Policy
All giant trees on Tasmania’s State forests are protected and managed in accordance with Forestry Tasmania’s Giant Trees Policy. Giant Trees include all those trees that are at least 85 metres tall or 280 cubic metres in volume. Based on current known examples, trees of this volume are generally at least 5m in diameter at chest height
To achieve this policy our objective is to:
Protect currently known Giant Trees;
Periodically remeasure known Giant Trees;
Undertake surveys to identify any Giant Trees within coupes in the Three Year Plan that have the potential to contain these trees;
Maintain registers of the 10 tallest and 10 largest volume extant trees known on all lands in Tasmania and of the 10 tallest trees ever recorded in Tasmania;
Promote with other forest managers a statewide tourism strategy for Giant Tree appreciation on all tenures and participate in its implementation.
Comprehensive information about the tallest and most massive trees in Tasmania can be found at the following website: www.gianttrees.com.au. The site is managed by the Giant Tree Consultative committee, a body established by Forestry Tasmania to provide independent advice on the protection, management and promotion of Giant Trees.
Will Centurion continue to hold the record?
Who knows? By using leading edge LiDAR technology, it is possible that even taller trees will be discovered in Tasmania. Unlike many other giants, the Centurion appears to be healthy, with a strong crown. Many of the other giants are reaching the end of their lives, and with each passing year are shrinking.