The World's Tallest Tree: a Christmas saga from the karri country

Boranup karri forest, oil painting by Rick Sneeuwjagt

Once upon a time, back in the day when people sent and received Christmas Cards, there was a Christmas season when the first card I received that year was especially noteworthy. It had a lovely photograph of karri (Eucalyptus diversicolor) forest on the front.

“Boranup State Forest, by the look of it” I thought.

Boranup is a forest I have known very well for over fifty years and I was confident I recognised it. Turning over to the back of the card to see if the spot was identified, all it said was “Karri Forest, Western Australia, The World’s Tallest Tree.”

This Christmas Card had been sent to me by a respected scientist from a reputable and federally-funded organisation in Canberra, so I had to accept its authenticity. But I wondered what some of my forester friends in Tasmania, California or Oregon would think if a card containing this provocative message lobbed up on their desks. In fact, karri is only the second tallest tree in Australia and is well down on the league table of Tall Trees of The World.

All of this reminded me of an afternoon spent measuring the height of a tall tree in the karri forest on another Christmas, many years before. It was Christmas Eve, December 24^th, 1969. I was the DFO at Pemberton at the time and my mate Jack Bradshaw was running the Department’s Forest Inventory Branch just up the road at Manjimup. Jack had ordered from Sweden and had that very day taken delivery of a new and beautiful hypsometer, a surveyor’s instrument for measuring tree heights. This new instrument was of the latest design and was guaranteed to provide extremely accurate measurements. Back in those days foresters measured the heights of trees for all sorts of purposes, often for important technical and forest management reasons, and accuracy was essential … especially to Jack who was a perfectionist in such matters.

I was tolerant of Jack’s little fastidities. He and I had long been friends, were passionate about the same sorts of things and worked well together. Thus it came as no surprise when he asked me to help him give his new hypsometer its first test run.

Jack told me he needed something that was very tall, and whose height was already precisely known, against which we could validate the new instrument. I had an inspiration.  Just down Burma Road from the Pemberton forestry office stood the famous Gloucester Tree fire lookout, one of the five fire lookout trees of the karri country that were in use every summer in those days. These fire lookout trees, it will be remembered, had been constructed in the 1940s and early 1950s by intrepid foresters who had pegged a spiral ladder up the trunk of the tree, lopped off the branches and constructed a little cabin in the uppermost forks. The cabin was connected by telephone to the other lookouts and to the district office. In the treetops a lookout man (or woman) spent the summer months, watching over the forest and reporting the first signs of smoke that might portend a dangerous bushfire.

The precise height of Gloucester Tree was known. The sign at the bottom of the tree, the pamphlet put out by the Tourist Bureau and the information brochure issued to visitors by the Forests Department, and indeed the incontestable and incontrovertible truth of the matter, was that Gloucester Tree fire lookout was “212 feet tall, measured to the floor of the cabin”. It was a figure I had confidently quoted on numerous occasions, not the least to Lord Casey himself, the Governor-General of Australia who had inspected the tree (from the ground) under my guidance earlier that year. I give the measurements in feet here, of course, as all this occurred before Australia went metric. Anyway, 212 feet always sounds much taller than 65 metres.

Gloucester Tree Fire Lookout, not long after construction in 1948, the towerman’s living quarters at its foot.

Furthermore, because there was a slight clearing around the hut at the foot of the tree, and Burma Road in those days went right past, there was unusual (for the karri forest) room and visibility to make sightings and measure horizontal distances. It was the ideal situation to validate Jack’s hypsometer. It was also handy that Gloucester Tree was straight and vertical and on level ground – getting an accurate height of a leaning tree, or of trees on hillsides, can be tricky, usually requiring the averaging of several measurements from different directions, but with Gloucester Tree we didn’t have to worry about that.

Full of Christmas joie de vivre, good humour and confident of a short and successful trip to the field, possibly followed by a Christmas noggin after work, Jack and I drove out to Gloucester Tree and set about measuring its height “from the floor of the cabin to the floor of the forest”.  The new hypsometer was a compact little instrument, and it gleamed in the sunshine as Jack took it from its special box. He had also brought a surveyor’s chain, an essential component of the exercise. The hypsometer basically measured angles, so that to get a height you had to obtain the angle from your observation point to the top of the tree, then measure the horizontal distance to the foot of the tree and then do a bit of simple trigonometry. Child’s play for someone with Jack’s technical expertise.

A reminder for those whose trigonometry has become rusty over the years:

If the angle (a) from the observer’s eye to the top of the tree is 45 degrees, the height of the tree is the horizontal distance from the feet of the observer to the foot of the tree (AD), plus the height of the observer (AE).

Jack and I measured the height of Gloucester Tree that afternoon from the west, the south, the east, the north and for all I remember from slightly south-southeast of south. No matter how we did it we could not make the tree to be 212 feet from the floor of the forest to the floor of the cabin. In fact, we could not make it taller than 185 feet. Jack minutely checked his instrument and re-read the instructions in all five languages at least five times. His face began to darken ominously.

In desperation I went back to HQ and picked up a stick of timber crayon, a 66-foot cloth tape and a brass plumbob from the forestry store. Jack and I then climbed the tree and with the plumbob attached to the end of the tape so we could lower it straight down from each twist of the spiral ladderway to the one below, we meticulously measured vertically down along the tree trunk from the floor of the cabin to the floor of the forest.

It was 185 feet.

This was serious. Not only was the sign at the tree and in the tourist brochure incorrect, but also Gloucester Tree (billed in the literature of international tourism as “the world’s tallest fire lookout tree”) was actually significantly shorter than Gardner Tree (on which Jack and I had both worked in our student days) and only on a par with the Beard, Boorara and Diamond Tree Lookouts … all regarded as much inferior to the famous Gloucester Tree.

Jack and I packed up our gear and adjourned back to my office, where we conferred over tea and biscuits. We decided to let the sleeping dog lie, and to tell no-one. If challenged our agreed position was that we had always thought the figure of 212 feet had been obtained by measuring around the spirals, so that it represented the distance climbed, not the tree height. And in any case, we now knew that the new hypsometer was indeed a beauty, having giving us a perfect meaurement. That, after all, had been the main aim of the exercise.

I popped out to Gloucester Tree the next morning, which was Christmas Day, to make sure the tourists were enjoying themselves and to have a chat with the lookoutman and wish him a Merry Christmas. I averted my eyes from the sign at the foot of the tree and avoided discussion on the subject. From the visitors milling around the tree, photographing it (and the sign) or climbing proudly to the top of “the world’s tallest fire lookout tree” I kept my guilty secret to myself.

A handsome couple, posing at the foot of Gloucester Tree

Two or three years later a new cabin was built, replacing the old one in the same place, and the top of Gloucester Tree was strengthened, with steel plates and stays attached. The contractor who undertook the work was a steeplejack down from the city, and when he had finished, he made a new measurement, using a tape along the tree trunk as Jack and I had done. This disclosed that the lookout appeared to have been reduced from its advertised height of 212 feet by 28 feet during the cabin refurbishment process, which was impossible. The contractor mentioned it to me, and I mentioned it to Ralph Kelly, Pemberton’s Tourism Supremo of the time, who tirelessly promoted the legend that Gloucester was the World’s Tallest Lookout Tree. But Ralph seemed not to hear me, or if he heard me, he clearly thought that I was talking the sort of nonsense that could be safely ignored.

I realised that it was the old story — in tourism, as in forestry, it’s the perception that counts, not the reality. Gloucester Tree was not just a fire lookout. It had become Pemberton’s Great Tourism Icon, a myth in its own time, and no foreigner from Manjimup with his Swedish height-gauge was going to change that, no matter how accurate his measurements.

In the end, we came clean, but we did it rather cunningly, even if I say so myself. Firstly, we thought it best to wait for Ralph Kelly to die — had we not done so, the shock of finding that his beloved Gloucester Tree was no longer the pinnacle of its kind would surely have hastened his end. Secondly, I published the real height of the tree in 1974 at the time of the change-over from imperial to metric measure, correctly assuming that few people would be able or willing to convert 212 feet into metres in order to double-check the new sign. This was before the days of the pocket calculator, and you had to do your field arithmetic in your head, or by longhand on the back of an envelope. We got away with it (I think).

Anyway, Gloucester Tree is still understood far and wide to be the world’s tallest lookout tree. Whether or not this is the truth, is beyond the point. As has been so well pointed out by the Sicilian playwright Pirandello, the opposite of a truth is not a lie, but another person’s truth.

Moreover, Gardner Tree, which was in fact the tallest of the lookout trees, was seriously foreshortened when the top snapped off during Cyclone Alby. To further protect the myth, tourists are no longer allowed to climb Gloucester Tree, the department having decided that it was too risky, and the forest around the tree has regrown to the extent that height measurement (using a hypsometer) would be difficult, making any challenge unlikely.

The world’s tallest tree – the last word

For the last word on karri being the world’s tallest tree, we need to return to the Boranup Forest, the subject of that Christmas card that started this story.

Boranup Karri forest growing on limestone 'karst' soils with many deep underground caverns, into which the karri tree roots penetrate (photo by Louise Burch).

It turns out that the karri trees at Boranup are indeed the World’s Tallest Trees. I quote from an impeccable supporting reference. In a deeply authoritative history of the karri forest (of which I was joint-author) published many years ago, the words on the back of that provocative Christmas Card were confidently affirmed.  The Boranup karri is indeed the world’s tallest tree — “but only if the depth of the roots is counted”.

Afterword

Setting aside that whimsy about its roots, Karri is not, of course, the world’s tallest tree. That title (at least for the above ground section) is held by the coastal redwoods (Sequioa sempervirens) growing in northern California and southern Oregon, while the tallest tree in Australia is the mountain ash (Eucalyptus regnans) of Tasmania.

However, to my surprise I recently discovered that the tallest tree in Europe (where karri does not naturally occur) is indeed a karri tree. This is “Karri Knight” grown from a seed imported from Western Australia and planted in 1890 in the Valle de Canas in the Coimbre municipality of Portugal. No detail is available, but I presume the seed would have come from the Boranup Forest, where there was a town and a large sawmill operating in the 1890s, or from the nearby settlement at Augusta.

The Karri Knight in Portugal, the tallest tree in Europe 

Karri Knight is 72 metres in height, substantially taller than the Gloucester Tree (58m) but inferior to WA’s tallest, the Don Stewart Tree (85m), also a karri. All of these are well and truly overshadowed by Hyperion Tree in northern California which is 115m tall.

The height of Karri Knight incidentally, was determined by Dr. Dean Nicolle, an Australian authority on, and perhaps our finest photographer of eucalypt trees. The photo gallery on his website (https://www.dn.com.au/dean-nicolle.html) contains some of the most beautiful photographs of Australian trees I have ever seen.

Finally, my best wishes for Christmas 2025 and beyond to all forestleaves readers, and thanks again for reading and (I hope) enjoying the stories.