Michael Taylor hardly eats or sleeps. He spends dizzying hours at a time on the computer, behind the steering wheel of his car, or in trackless wilderness in search of the world’s tallest conifers. He is a live wire impassioned by trees and he pours himself into his work as a professional tree hunter.
Taylor’s background as an engineer is one of the secrets to his success, because he has learned to manipulate LiDAR data with the patience and precision of a Zen master.
LiDAR – short for Light Detection and Ranging – employs laser technology to generate 3D maps of the Earth’s surface. As a LiDAR specialist, Taylor uses a bit of computer wizardry to process the LiDAR of forested areas and search for tall trees before ever setting foot on the ground. This approach is highly effective and very accurate if the data are clean. When the LiDAR is bad, it takes a whiz like Taylor to resurrect and make use of the information.
Last August, Taylor came across an obscure LiDAR set for measuring snowpack across the interior of the Olympic Peninsula. The data came with a warning label, “This LiDAR set cannot be processed.” Ever the zealot, this did not deter Taylor. Instead, he grappled with mislabeled axes, poor scan density and improper scaling. He even concocted a new algorithm to make use of the data – for he knew that the highly productive rainforests protected within the boundaries of Olympic National Park are capable of housing arboreal giants and he was determined to find them.
What Taylor found once he re-worked the LiDAR was incredible: multiple hot spots of enormous coastal Douglas-fir (Pseudotsuga menziesii var. menziesii). Thus began a spate of record-breaking Douglas-fir discoveries in 2021.
Taylor invited his old tree hunting partner and friend Dr. Steve Sillett to ground-truth the LiDAR hits in Washington with him.
Sillett is the Kenneth L. Fisher Chair of Redwood Forest Ecology at Humboldt State University. Not just a redwood ecologist, he has conducted extensive studies on the world’s five tallest tree species, including Douglas-fir. In 2018, he published a seminal paper in the scientific journal Forest Ecology and Management entitled “The Development and Dominance of Douglas-fir in North American Rainforests.” As a Douglas-fir expert, it is significant that when Sillett accompanied Taylor to Olympic National Park, he was blown away by the gloriously intact forest and specimens that they found in previously unexplored areas.
By investigating the LiDAR hits, Taylor and Sillett found four of the ten tallest known Douglas-fir in the world. The two tallest trees that they found in Olympic National Park measured 315.3 ft and 313.6 ft and are now respectively ranked #4 and #5. Sillett deemed Taylor’s LiDAR work that led them to these trees “a stroke of genius.”
Because Douglas-fir has long been the most economically important timber species in the Pacific Northwest, the finest specimens were logged off in the late 19th and early 20th centuries. Historically, Douglas-fir often grew 300+ ft tall, and some forests were studded with ~1000-year-old titans perhaps surpassing 400 ft in height. Douglas-fir may well have been the tallest tree species on the planet. To put things in perspective: the tallest reliably measured Douglas-fir was 393 ft tall; the tallest known tree in the world today is a 381 ft coast redwood (Sequoia sempervirens) in California that Taylor co-discovered. As Sillett says of Douglas-fir, “This species was persecuted even worse than the redwoods.”
The problem with losing the tallest, oldest Douglas-fir across their range from British Columbia to central California is that it is a “keystone species” with great influence over countless ecological functions. According to Sillett, the “table scraps” of old-growth Douglas-fir forests that remain provide “unreplicated habitat” for the many plants and animals that live in, on, and around these ancient trees. Tall, old trees also store enormous amounts of carbon and are critical for soil stabilization, regulating temperature and hydrologic functions, and many more ecosystem services.
In his 2018 article, Sillett describes allometric equations – derived from tedious sampling and extensive measurements of 60 representative trees – that can be used to calculate biomass and carbon storage by an individual Douglas-fir.
Tree height and “diameter at breast height” (DBH) – two of the most fundamental measurements in forestry – are utilized in the formulas. Taylor and Sillett use a tripod-mounted infrared laser and prism to measure height. A pre-calibrated “diameter tape” carefully wrapped around the tree at 4.5 ft (“breast height”) from ground level yields DBH. A LiDAR-equipped iPhone is used to create a 3D model of the lower trunk of the tree and helps calculate “functional DBH” (fDBH) by accounting for irregularities in the lower tree trunk’s shape and “diameter at the top of buttress” (DTB) where the trunk becomes mostly round. A few more laser measurements are taken to calculate the volume of each tree’s crown. Plugging the values for f-DBH, DTB and crown volume into Sillett’s equations generates reasonably accurate estimates of aboveground quantities of wood, bark and leaves, which together comprise a tree’s aboveground biomass, about half of which is carbon.
Finding tall trees and measuring their size and other attributes is an essential part of understanding how intact forest ecosystems function. When combined with repeated measurements of tree size to quantify biomass production and rates of carbon sequestration, such work can critically inform forest management and conservation.
As a result of this year’s discoveries on the Olympic Peninsula – which also included Douglas-fir that now rank as the #8 and #9 tallest of the species – Sillett and colleagues are establishing research plots to quantify biomass and productivity of these superlative forests as a reference for future generations.
Luckily, accessing and studying the newly discovered trees in Washington is relatively easy. The same cannot be said of the two monsters that Taylor and Sillett tracked down in Oregon later this summer. Reaching the #1 and #2 tallest Douglas-firs in the world was an epic adventure.
As usual, Taylor unearthed pockets of unbelievably tall trees in drainages that never could have been logged using his LiDAR skills – but that’s where technological assistance ended. Locating the tallest Douglas-firs on Earth involved risking life and limb on “one of the steepest and most horrendous hikes” of their many exploits together, according to Sillett.
On top of being dangerous, the terrain was riddled with Devil’s club – a nasty large-leaved plant covered in exceedingly sharp spines. As Taylor and Sillett bushwhacked through eye-level Devil’s club, the plant’s spines would break off and embed themselves in their clothing and flesh. Devil’s club spines commonly cause infections. The men were miserable as they slashed through the evil plants – and for weeks afterwards as their wounds festered.
To make matters even worse, once they crossed a steep chasm into a bog full of Devil’s club, they started finding mountain beaver (Aplodontia rufa) tunnels and then mountain lion (Felis concolor) scat and sign everywhere. The cats appeared to be preying upon the mountain beavers in their swampy burrows. While the scene was ecologically fascinating, the smell of cat piss was overwhelming. Sillett recounted, “We were walking through there just gagging on the stench! It was heinous in there, no wonder nobody goes there.”
Nobody except the world’s two most dedicated tall tree hunters, who came away victorious with two new record Douglas-firs measuring 324.1 ft and 326.4 ft tall. The former champ – the famous Brummitt Fir in Coos County, Oregon – is the only Douglas-fir measured over 100 m (328 ft) in modern times, but the top of this magnificent tree has been steadily dying back for decades. Taylor and Sillett’s hard-won finds both feature live tops – and while the #1 tree is undisputedly the tallest known Douglas-fir on Earth, the #2 tree is far more massive. See the table below for stats. Awestruck by the humongous trees that they found deep in the heavily-logged Oregon woods, Sillett said, “It’s just astonishing that they exist.”
Because trees are dynamic organisms that are changing all the time, keeping track of the tallest trees of any given species is a never-ending process that keeps tree hunters like Taylor and Sillett pretty busy – and that’s just fine by them! These men are driven by pure passion and constantly spurred on by their own mind-bending discoveries.
This year, they outdid and even surprised themselves by managing to identify the top ten tallest Douglas-fir lurking in spectacular forests in Oregon, Washington and California. It’s ecologically important successes like this that keep them psyched. As Taylor enthuses in a quiet voice that thrums with energy, “There’s lots more trees to find!” To be sure, thanks to his tenacity and conviction, the list of astounding champion trees is steadily growing. Stay tuned next month for more news of Taylor and Sillett’s major breakthroughs in 2021.