Carl Hansen and Jan Corigliano report on a recent mission to catalogue newly discovered forest giants.

This story first appeared in the Mountain Journal print magazine for 2021 (available here).

The tallest and biggest living things in the world are trees. While the biggest and tallest are the well-known Coast Redwoods of California, the towering Mountain Ash (Eucalpytus Regnans) of Victoria and Tasmania have largely escaped the limelight, despite being the tallest trees in the southern hemisphere.

In the Tasmanian Wilderness World Heritage Area, to the west of the Florentine River in the vicinity of McLeod’s Creek, grows a patch of extremely tall forest unmatched in extent and integrity in Australia. Remote, rugged and barely visited by Europeans, it contains 29 LiDAR-identified “‘hits’ over 85 meters tall. In recent years, the advent of LiDAR (a 3D scan of tree heights from a small plane) has uncovered many previously undiscovered giant trees. But what’s shown on LiDAR doesn’t always stack up with what’s on the ground, so ground surveys must be done in order to see how big the trees really are.

In much the same way that climbers search for new routes on far away peaks, Jan and myself have been slipping, sliding and tumbling through dark old-growth forests, on the hunt for Australia’s biggest and tallest trees. We decided to combine our love for big trees and remote places with the challenge of off-track navigation, in a 3 day expedition in search of the unseen giants of McLeod’s Creek.

We weave our way down dirt roads through the regrowth that now dominates the floor of the Florentine Valley, the occasional huge stump giving an indication of the trees that once grew here. Leaving Jan’s car on an overgrown track near our exit point, we rattle my car down progressively deteriorating roads, even squeezing it under a fallen tree to get to where we will commence our walk. Some tension is palpable as we nurse cups of tea over a lunch of baked beans, musing over what we’re getting ourselves into – impenetrable scrub, sinkholes and snakebite are not out of the question. We’ve packed light, taking a sil-nylon tarp for shelter and minimal warm clothes. Food is a mix of home dehydrated dinners and bin-dived cheese. Shouldering homemade backpacks, we set off into the bush.

We nervously begin walking through fairly thick regrowth; although the total distance we need to travel is not great, off-track walking in tall, wet forest can be extremely slow going. Herein lies the unknown of the trip, if we encounter bad walking and horizontal scrub, there is a fair chance our planned route may not be feasible. Luckily the forest quickly opens up into stunning and quite unique tall Sassafras dominated rainforest. Later in the day we unexpectedly encounter burnt forest from the 2019 fires. We begin to wonder if our target trees will have been burnt and fallen before anyone was able to measure and record them.

Although these forests are fire adapted, and dependent; things may not be the same for much longer. With a warming climate and more frequent bushfires, Tasmania is rapidly losing its giant trees. 13 of the 20 biggest trees were lost in the 2019 bushfires alone. Only time will tell what will happen to the globally significant giant trees of Tasmania. We continue walking, measuring some trees along the way, and arrive at the main stand on the afternoon of the second day.

“Eighty eight point one, eighty seven point eight… eighty eight point four!” Jan’s lying on the forest floor, head skyward, peering through a laser rangefinder measuring hit number 12. With no branches for 50 metres and at 88.4 meters tall, ‘King McLeod’ is the tallest tree we find. It is as tall as a 28 story building and although significantly shorter than ‘Centurion’, (the tallest tree in Tasmania and the southern hemisphere at 100 metres), it is still a great find. Luckily, none of the tall trees in this area have succumbed to the fire, which has only trickled through this area.

We end up recording 13 new trees over 80 metres, including 6 in the super-tall height class of over 85 metres. All of them are the fire dependant, but not particularly fire resistant, Eucalyputs regans, or Mountain Ash/Swamp GumHaving only surveyed 14 of the 29 hits, we might just have to come back.