In The World's Tallest Forest Canopy

by

Mark Bailey

The roar in the air was a physical sensation. It sounded like the pounding surf a few miles to the west. Or maybe a heavy downpour of rain. Yet the sky was clear. There was no rain falling and the surf was far too distant to be heard. The source of the sound was the wind in the trees. Not just any trees, either but The Tall Trees: the redwoods. The molecules of air were banging against the ancient giants causing their mighty branches high up in the canopy to heave to and fro as these very branches had done for over a thousand years.

Here the tallest forest canopy in the world stands. This is Humboldt Redwoods State Park but the name is ephemeral. It has no bearing on the forest. Most of these trees were standing before the language you are reading was even being spoken. Many will likely be standing when this language is no more.

We stand in awe as most do when they come to this dramatic and precious place along the banks of Bull Creek, an Eel River tributary. But we are here at the base of this tree, nicknamed Paradox, for another purpose today. We are a pack of forest canopy researchers on a mission. Our purpose is to study the structure of the redwood canopy and learn of its relationship to the surrounding forest stand. We have been mapping the crown structure of this one tree in a first of its kind investigation of a standing Sequoia sempervirens. Ultimately, my intent is the study of relationships between the complex branch and trunk structures and the types and abundance of organisms living within the canopy of these forest giants. Our hope is that by studying and quantifying the attributes of this highest of forest canopies that we can spread the word about the redwood forest: it's not just a bunch of big, beautiful trees. It is an exquisitely orchestrated and dynamic ecosystem not just at the ground but hundreds of feet up too.

Way up there, where few have dared to go, another world exists. It almost seems isolated from the rest of the forest in its beauty and ecology but of course this is only an illusion. It is intimately connected with the whole. Our research has found terrestrial communities of plants and animals in the crowns of these giant trees. Often unappreciated by the resource extraction folks is the significance of the size of these trees. It's on the broad branch tops of their massive tree-sized limbs that some of the most interesting processes in the canopy take place. These branch tops intercept large quantities of falling debris from the canopy above. Branches, leaves, bark, and anything else passing downward through the crown of the tree accumulates on these surfaces often forming "canopy soil" as the debris decays. Earthworms, salamanders, centipedes, millipedes, wasps, flies and mites are all here on branch top gardens. It is here that an often sizable assemblage of shrubbery can form. We have documented numerous terrestrial shrubs thriving high above the ground, rooted in these perched soils. Huckleberry thickets have been observed in many ancient trees-typically flourishing and even cranking out large crops of juicy berries hundreds of feet from the ground. These canopy plants are collectively called epiphytes. Epiphytes are plants that grow on other plants without harming their supporting plant. They use them as a place to sit on. There has been very little published work on redwood forest epiphytes. At this writing, only two papers have been published about this lofty realm in the redwoods. Both of those have only been published within the past year. Now a long list of epiphytes that we have found in our exploration within the redwood canopy is accumulating. Each new discovery is ground breaking for redwood canopy research. It's an awesome feeling making fundamentally new discoveries in the world famous redwood forest.

Ascending these towering stems is no easy task. Using climbing ascenders we "inchworm"our way up the arborist rope. This particular rope was laboriously hauled over the first branch that seemed safe enough to hold the weight of a climber with six hundred feet of rope and gear. The first branch on this tree we have chosen sprouts from the trunk at 200 feet from the ground. Most forests of the world would fit handily well below this first branch. The Amazon rain forest is famous for its size, yet our redwood forest towers over the tallest of the Amazonian giants. Typically the Amazonian rain forest won't exceed 100 feet to the treetops. Here in the redwoods of Bull Creek the canopy doesn't even start until well above this height.

Our hearts are pounding as we reach this first branch-both from the exertion and excitement of the adventure. It has taken fifteen minutes of hard climbing to reach this point. The whole while, we've been staring at the ancient, furrowed bark as we haul our way ever upward. Fire scars mar the red, fibrous bark. Wonderfully adapted, these forest titans readily survive fires that would naturally keep the understory open by regular and beneficial low intensity fires. Evidence of past fires abound. Burnt bark has been recorded at nearly 200 feet up the trunk of a perfectly healthy tree. Of course, the flames probably weren't that high or the entire forest would have been consumed. It is likely that the fire slowly smoldered up the trunk. It's hard to say how old some of these burns are. It is difficult to decipher fire history without using destructive means. Fire scars are readily dateable if you care to cut the tree down to look at the rings. This is where much of our knowledge of redwood fire history comes from. After all, when you've already sawn through the stems of 96% of these giants, you're bound to gain some extensive information about fire history of these stands even if you only occasionally looked closely at the severed trunk. Some researchers have studied fire history in such a manner.

Two hundred feet up and the stem is still six feet across! Below here is where the "gravity" of our situation is most apparent. Man, it's a long way down! The rope is looking pretty thin as we ponder it's importance to our future happiness-or unhappiness as the case may be. But from here up, we enter the magical realm of the redwood forest canopy and everything changes. Passing a few more thousand year old branches, we find ourselves absorbed by the surrounding canopy. The ground is far below but mostly hidden by the luxuriant foliage. Suddenly the height factor seems less mortifying.

The ground vanishes as we ascend even higher. The wind in the needles begins to sound like a welcoming song. The tree dances around us as its wind-blown crown sways like a long pendulum, carrying us this way and that. As we approach the 300 foot mark, gaps in the foliage allow a look out into the surrounding forest. From within this glorious tall canopy, everything looks as though modern civilization doesn't exist. The world is again as it was once before: unspoiled, untrodden, respected…Each of the other trees is moving in its own magnificent gyrations. A swirling mass of vegetation in motion. Is that a twinge of sea sickness? Who said plants are stationary beings? This one is hurling back and forth ten or fifteen feet every couple of seconds. It's the same ballet they have all been dancing together since the beginning of the forest primeval.

Occasionally, the branches or even the trunks from adjacent trees knock against each other. This often causes breakage of limbs or even trunks and can contribute to an astonishing array of wounds and responses to these injuries. Often, breakage within the crowns of trees will allow the passage of more light into the foliage. Greater structural complexity results as new sprouts emerge from the trunk in response to new resources available. In one particular case we've observed, rubbing of a branch against a trunk wounded the trunk enough to expose the cambium below the bark. Astonishingly, the branch then fused to this trunk. As continued movement occurred, the branch actually broke off from its base but remained fully alive. The fusion with the trunk seems to have included fusion of the vascular tissue as well and now the severed branch is kept fully alive with luxuriant foliage by side tracking water from its new trunk. The branch's original, broken and jagged base hangs out in open space.

Upward we climb. The branches are covered by an epiphytic load of lichens and mosses. Names are bandied about. Lobaria, Cladonia, Usnea, Hypogymnia. These are not unusual species. Here, in this lofty realm, they thrive. Most redwoods in our region have a thick covering of lichens on branches and trunks near their tops where conditions are more hostile to other more sensitive epiphytes. Occasionally encountered are epiphytic trees. So far, the most astounding is a 40 foot tall epiphytic western hemlock tree rooted in the crotch of a resprouted trunk 180 feet up on a redwood. Epiphytic Sitka spruce are not uncommon in the groves further north. Other species of epiphytic trees in redwoods no doubt await discovery.

Geotropic branches drape downward for fifty or sixty feet from their bases in the furrowed trunk. One such branch has foliage that extends nearly the entire way around this behemoth of a tree. It fans out to more than thirty feet from the stem--skirt-like all the way around the tree. What praise for branches! Do branches make a tree? These have made a spectacle to behold! We record the diameter, inclination, extension (how far out it reaches), and azimuth of each branch with a diameter greater than five centimeters. There are 167 of them in this tree and many others that are smaller and thus unmapped. Eventually a diagram of the tree will be generated from the data. It's a wonder that there are still undiscovered marvels going unnoticed right in our own back yard! This tree, Paradox, has a rather straight-forward structure to its crown. It consists of a single trunk with regularly spaced branches to near the top. Many redwoods that have been mapped since the time of this climb exhibit far more bizarre crown complexity. One such tree in Redwood National Park has 148 trunks. These trunks may resprout from the main trunk following damage to the tree, usually from wind breakage. Or these resprouts may simply be responding to increased light levels on the trunk. This can happen when a branch is thrown from the tree during wind storms, allowing more sunlight deeper into the crown.

Continuing our quest for the top, excitement mounts as our goal is glimpsed through the branches. The swaying top is still way up there! But now, the foliage is becoming more compact. We emerge above the surrounding trees. This tree stands alone now, an emergent in a forest of awesome giants. Many of the neighbors are themselves spectacularly tall, yet we look out over their tops below us. We gaze out at the largest intact stand of redwood forest on earth--the Rockerfeller Forest--named after the famous industrialist who somehow saw the value of something beyond cash and donated enough seed money to insure the protection of this exalted forest. How many other such groves fell to the saw before outsiders knew of them? A sobering thought. The glorious South Fork of the Eel River meanders it's turquoise waters amongst the old ones in the distance. Even now, the steelhead are muscling their way upstream. Grasshopper Peak looms above to the south.

Now the differences in foliage become striking. Nearer the ground, the "typical" redwood leaves, or needles, are nice and flat. All the better to collect light in the low light surroundings of the lower canopy. But as one nears the top of the crown, the foliage changes. The leaves become more pin-like and more densely packed on the twig. This is probably a water saving mechanism. Larger leaves allow more water loss through transpiration. Smaller leaves reduce water loss from their tiny stomata or leaf openings. Smaller leaves, fewer stomata, less exposure to the dessicating intensity of the sun overhead.

The smell within the canopy is like no other. The sweetness of the foliage melds with the dusty bark and scent of lichens and mosses--but without the decaying vegetation smell so often associated with the forest understory. We pause to smell the rope that holds us safely in the tree crown. It has the same smell only magnified many times by repeated suspensions through many trees.

As we near the top, we pass an abandoned raven's nest. Nice neighborhood. Why hasn't it been used recently? It has fallen into disrepair and will soon be reabsorbed into the forest floor. But the ravens are still near. They call back and forth to each other as they pass overhead. Are they croaking at us? Mocking our clumsiness, perhaps? Or are they just jubilant in their freedom to soar? A small mixed flock of chestnut-backed chickadees, ruby-crowned kinglets, and brown creepers pass by amongst the thick branches. A pileated woodpecker zooms past below us calling out in it's distinctive yack, yack, yacking voice.

And now we are there. We have reached the top. Forty five minutes have passed since we left the shady forest floor. It's sunny and warm up here. It's dark and cool at the base of this same tree right now. Paradox indeed.

The tiny vascular tubing, or xylem is the aqueduct of the tree facilitating passage of groundwater all the way to the highest branch tip. It can sometimes be a very delicate balance between loss at the top and supply from below. Studies are currently underway to investigate the movement of water through these giants. If too much water is transpired from leaves, vascular tissue may collapse and block further flow of water. The top may die back. If insufficient water is drawn up to the top for other reasons, such as drought, the top may die back. Look at old redwoods. Many display dead tops. The top of Paradox is no exception. The last six feet of the main trunk is dead wood. It's no wonder. That's over 366 feet that the tree has to get water up through. This in itself is a miracle of biology. Miracles not withstanding, this tree has, in typical redwood fashion, resprouted several new trunks from just below the dead top and has a series of new leaders heading for the sky. Paradox is getting taller even as we watch.

We stretch our heavy duty, extra long measuring tape to the tip top (We've been dragging it up from where we attached the end at the ground). Hmmm. A hefty 366.1 feet. The world's tallest tree--for the moment. Pretty cool. Suddenly the Paradox is glowing with a new light. In fact, the world has just changed even though it doesn't look any different. We pause for a snack and some water, drinking in the view and the vibe as well. It's a mighty good one.

Now we go. Switching from ascenders to repelling device, we zip on down the stem. Branches zoom past. We recognize bark fissures, branch whorls, lichen patches, and "soil" accumulations on branch tops that we sweat our way past on the way up. Effortlessly we descend. The canopy once again engulfs us. The neighboring giants crowd in around us as we near the lowest branch.

Flying past this bottom branch we are again reminded of the precariousness of the adventure, as we look down on the fern-shrouded forest floor once again far below us. We can now smell hot rope as it whips through the narrow, life preserving confines of the repelling device. (when climbing in the rain, it will actually sizzle from drops hitting it). You don't want to stop now. The hot metal might melt and damage the rope if allowed to stay in contact with one place on the line. The forest floor looms larger and larger as we rapidly drop. Easing up on our descent rate we nimbly touch ground with a flourish. The long rope stretches and we bound back up off our feet ever so gently, only to settle back onto the rich and fragrant duff of the resplendent forest floor. Our journey into the tallest tree in the Eel River watershed has ended. What scientists have to do to get their data is often overwhelming!

Since this climb, one other tree has been measured that is just slightly taller. The grand master, in Mendocino county, is 15 inches taller. But at the time of this ascent, we have swung from the tallest known organism. What a day!

Autumn 1997