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Grey on Green: The Quiet Decline of One Tree in Alaska’s Temperate Rainforest

Culturally vital, ecologically unique, and economically valuable, the yellow cedar’s fate is closely tied to snow

I am in the middle of the most pristine forest in North America; in all likelihood no one has stood where I stand for hundreds of years. And I am surrounded by dead trees. Huge, monolithic individuals, three feet across and over a hundred feet tall – and the vast majority are dead. From a distance, the hillsides appear carpeted in grey; from within, one is surrounded by the dull silvery spires, some with dry branches, some stark and bare.

dying yellow cedar in Alaskaphoto by Brian BumaThe key change that has been triggering the massive decline of yellow cedars is not the lack of precipitation but what form it is appearing in.

The thick forests of southeast Alaska and coastal BC constitute the largest remaining, intact temperate rainforest in the world, and one of the thickest collections of biomass, of sheer stuff, in the world. It is a maze of fjords, mountain peaks, vertiginous river canyons, and wide glacial valleys. The forests, dense with an underbrush of Devil’s club and false azalea, forbid rapid movement or long views. Moving through them is like swimming on land, it requires all four limbs and full body coordination simply to stay upright. The weather is famously bad; rain over 250 days a year, measured in yards, and if not rain then fog. The drip, drip, drip of the canopy leaking onto the forest floor is constant.

The landscape is so topographically difficult that despite the ample amounts of natural resources, from timber to salmon to bears to gold, there are few people around and fewer roads. The majority of towns and villages have less than 500 people, and only a couple are connected to the outside world via roads. Float planes, boats, and the occasional ferry are the main methods of transport and people stick to the low fringes and fingers of land. Here civilization are the islands, and the wilderness the sea in which they reside. And it’s often forbidding: From my perch, slightly north of a place called Poison Cove (bad shellfish), off of Deadman’s Reach (150 people died there), I can see Peril Strait, so named for the treacherous currents that have kept mariners on edge for thousands of years. And this is the norm, for hundreds and hundreds of miles. 

This place has every right to call itself pristine. Yet here they stand, these dead trees. Silvery grey bark against the grey sky. They are, or were, yellow-cedar, a beautiful tree revered for thousands of years by Native peoples like the Tlingit and Haida, more recently by western loggers and Japanese markets. The Natives put the tree to a variety of uses, weaving baskets from the bark and building beautiful bentwood boxes from the wood — thin planks would be carefully steamed and bent 90 degrees, multiple times, to make a complete box from a straight grained piece of wood. It carves extraordinarily well, like butter under the right hands. It is also highly resistant to rot. And ecologically, it plays a unique role in the forest’s nutrient, cycling as a calcium hoarder and supplier, altering the acidity of the soil, and making nutrients available for itself and nearby flora. 

Yet these cedars that I am standing amid are, generally speaking, dead. The snags will stand for 80 years before falling, and some are indeed that old — so the mortality started early in the nineteenth century and is continuing. The occasional bright orange individual is one that must have succumbed within the last year. There are a few of those, too.

***

I flew into Poison Cove on a chartered floatplane, the pilot weaving though clouds and peaks on the bumpy trip out. The weather, generally fickle, has nearly trapped me here before. There’s not a soul for miles, save one or two fishing boats grumbling down Peril Straight, several miles offshore. The main companions are large brown bears, famous for their general grumpiness and apparent cross-breeding with polar bears, which likely did not improve their disposition. There’s not a lot of sign of humans; no settlements have ever been here, and humanity’s imprint is limited to prehistoric, seasonal salmon harvesting, if anything. 

The grey swath covering the landscape looks like a bathtub ring from the muskeg where I’m sitting, about 600 feet above the waterline. It covers the hillsides to about that level; lower-lying islands are almost completely encased. Above that, green — so much green, in an infinite variety of hues – healthy cedars, hemlocks, and spruces.

You might turn your attention to the microscopic and ask if some sort of low elevation native species run amok, or worse yet, invasive pathogen, is causing all the death, similar to mountain pine beetles in the Rockies or Sudden Oak Decline in California. But a long series of careful experiments and studies in the 1980s and 1990s by local scientists ruled out pathogens as the primary cause of mortality.

In a practice reminiscent of CSI, except carried out on a 30-ton individual in the middle of nowhere, infections, insects, and lesions were all probed to see if they were the murder weapon, or simply opportunists taking advantage of a fresh kill. Long laboratory work, carried out over many years, led to repeated blanks.

Some wondered if it could be drought, which is causing massive forest mortality among aspen trees in the southwestern US. But a sustained lack of water here is almost laughable, a place where more than five days without steady rain is rare and humidity hovers above 90 percent most days, year round. You might then be tempted to blame it on acid rain, the scourge of many eastern forests, but that’s not it either – the beauty of the place extends to its clear air and waters that support immense runs of Pacific salmon.

After years of work, the culprit was identified in the mid 1990s. The key change that has been triggering this massive decline, is not the lack of water but what form it is appearing in. 

One thing you’ll realize after sitting through a southeast Alaska or coastal BC winter is that it’s not actually that cold here. The warm ocean and consistent westerly winds keep it relatively balmy compared to most peoples’ perception of the Great White North. “Baja Alaska” is an apt nickname. Snow at sea level is common but not consistent, and the white blanket that many take for granted in winter doesn’t last here. It comes and goes by the week, a snowy front followed by gusty rain that melts it away. But in the past decades the region has been seeing more and more rain and less and less snow.

yellow cedar bark strppinglPhoto by Brian Buma.A yellow cedar with stripped bark. Native Americans used the bark for
a number of items, including rope, mats, clothing, and basketry.

In 1794, when George Vancouver sailed through this landscape, he found it choked with ice; Glacier Bay wasn’t a bay, and inlets that now contain whole towns were full of frozen debris.  The Little Ice Age was not global, but it was intense in southeast Alaska. Things have been warming since, observed by the Tlingit and Haida peoples and recorded faithfully in the area by the Russians who first settled around Sitka, then Americans, who bought their claim later. Carbon pollution is accelerating the warming, of course, and the effect is most keenly felt in the winter. In fact, this part of the world is losing freezing days faster than any other. 

As the weather gets warmer, snow is replaced by rain. The annual snowpack becomes sporadic, then nonexistent. But there’s a sweet spot in there, where the winters are still occasionally cold — think cold air outbreaks, Arctic blasts, polar vortex type action — but there’s no snow on the ground. This transitional period, where the air is frequently cold but not consistently so, leads to an interesting paradox — the winter ground gets colder while the air gets warmer. Colder soils in a warmer world, as Peter Groffman of the Cary Institute of Ecosystem Studies and his colleagues put it.

People have noticed that the “bathtub ring” of dead yellow cedar trees along Peril Strait, and the strip of dead elsewhere for 1,000 kilometers, neatly conforms to this snow-rain transition point.  This beautiful tree, culturally vital for thousands of years, ecologically unique, and economically valuable around the Pacific, has its fate closely tied to that of snow.  As the snow goes, so do the cedars.

***

It’s hard to be a tree.  Competition is fiercer than many realize.  When a bear, or a bird, or a person feels like they are losing in the competitive arena — can’t get that fish, that seed, that job – there’s generally an option to leave, to walk away, to move to greener pastures. If there isn’t, folks feel trapped. I like to think that is what a tree feels all the time — stuck where the fates dropped its seed, a tree must do or die in the spot it sprouted. In old, thick forests it gets worse. Light is at a premium. The dark floor of these primeval forests are much too dim for most everything — mosses, scraggly herbs, and the occasional emaciated hemlock seedling gasp for light as they can.  Most species bide their time, waiting for an opening triggered by a windstorm, or a landslide, and then join in the mad rush for space and resources in the blasted land.

There’s another strategy though. There’s so much water that bogs form wherever the ground even thinks about flattening out, known locally as muskegs (from the Cree word for low-lying marsh). The oversaturation of the soil leads to sphagnum moss taking over, leaving a soggy sponge of a space that only hosts the occasional scrubby pine. There’s lots of light, but the very high water table makes life difficult. Roots need air, they respire just like you and me, and are just as susceptible to drowning. Yellow cedar is particularly good at seizing this opportunity, living on the edges of muskegs, keeping its roots barely above the water while harvesting all the light it can in the cloudy coastal summer. 

Yellow cedar has another trick too. Like all trees that experience cold winters, it “cold hardens,” meaning it adjusts its chemical balance to go to sleep each winter, increasing its cold tolerance dramatically to survive potentially harsh conditions. These are the same adaptations that allow some species to survive -60 degree Celsius conditions in Siberia. But that frost armor is not conducive to growth, at some point the trees must shed their biochemical cold tolerance and “de-cold harden” in the spring, essentially to wake up.  And just as the early bird gets the worm, the early tree “awakening tree” gains the most nutrients — nitrogen released by bacteria that died over the winter, the first flush of decomposition in the spring releasing potassium, the first runoff bringing phosphorus. 

The yellow cedar is the first among trees in this region to wake up.  It’s a precocious species and for a long time its precociousness help it survive tough conditions, but now it’s leading to its downfall. 

Living on the edges of muskegs means light, but results in the need for very shallow roots due to the waterlogged depths below. Early season wakefulness means nutrients, but also exposure to the occasionally wild weather that the north brings. Now the snow comes back into the picture – with a thick winter blanket, roots, even shallow ones, are insulated from that rocking cold that can pour over the mountains and into the coast, putting a film of ice even on the ocean tides.  Without it, and the soil, always wet due to the consistent precipitation, freezes as hard as any pond, and the roots with it.  While a cold hardened tree can tolerate quite a bit, active root tissue can only take conditions down to about -5 C (23 F), and even then for only a short period of time.  When all your roots are in that shallow basket, you become extremely vulnerable to low snow + cold snap conditions, exactly those conditions that have been on the rise with the warming climate. 

Once a tree’s fine roots die, it can’t get enough water to its photosynthesizing leaves, no matter how wet the landscape.  The death of the little roots at the base cause lesions near the base, turn its foliage orange, then brown, then to the leafless grey dead spires now spanning the landscape, tracing the snow line throughout the wilderness. As the world’s snowy winters transition to rainy drizzle, that mortality is likely to spread, whether anybody is out there to record it or not.

The warmth, the rain, the lack of snow – they all power this wave of mortality, 70-95% dead in a few short pulses, washing through the remote region, a wave serious enough to prompt an ongoing endangered species listing petition. The wave is pushing north with climate change, and uphill, leaving an impoverished forest in its wake.  What comes next is unclear. 

There’s a bit of light though. Usually a few individual trees survive, even in the worst affected areas. It is unclear why – good genes or a choice rooting spot are potential explanations. Yellow cedar, like all species, will send its roots down deep given a chance. It’s also tough species, sometimes 95 percent of the tree will die due to root freeze, but a thin strip of live tissue running up the side of the tree to a skinny branch with green leaves betrays the fact that it’s not completely dead, that some deep roots were not touched by the frost. 

In the warmest parts of southeast Alaska and coastal BC, there are some signs that the rate of mortality is abating, even as the death rate ramps up further north and higher.  This aligns with the hopeful observations from further south, on the shores of Vancouver Island is Nootka sound, where the species received its scientific name, nootkatensis. It is warm here, 100 latitude south of Peril Strait. The winters never get consistent snow. But they also never get cold, either.  And yellow cedar is, if not dominating, at least still a presence. Other species like red cedear compete for space, but for now, the yellow cedar appears to be holding onto its own, though diminished, role in the warmer world of the south.

***

Snow loss is perhaps the most visible of climate changes inevitable effects, the transition from white landscapes to grey and brown puddles a jarring reminder that yes, the world is warming.  This loss is having a variety of secondary effects as well, including low stream flows and longer fire seasons in the southwest. But for primary, direct signs of how life depends on snow, the yellow cedar is a potent symbol — a species that lives for over a thousand years, growing in the most vulnerable habitats and experiencing dramatic, foundational change in its environment, and dying as a result. 

Conservation, human intervention, is important of course, but the first principles of this problem make conversations about it difficult, like talking about saving sea ice for polar bears.  The roots of the issue — a warmer atmosphere — are so far beyond local that effective action is difficult to envision. 

Protecting yellow cedars from harvest could be useful, especially in areas that are, so far, seemingly resistant to freezing. Yet careful silviculture can also maintain the species in deep soil areas where it might survive, even thrive. Silvicultural operations along the coast report few problems in growing the species beyond the deer which snack on them like candy. It seems likely that human intervention, by eliminating the competitors, can nurse this tree along in these areas. It’s a pragmatic flip side to traditional conservation, artificially husbanding a species via logging against the inevitable tide of killing temperatures until that threshold is crossed.

But will it work? There are worrying signs on the horizon. The Forest Service has begun to find dying trees in those secondary stands as well. Also, current science has painfully few records of success of that harvest-oriented conservation in areas where the climate is a negative. 

If you travel to the little Alaskan town of Kake, on Kuprenoff Island (by slow boat or small plane, no roads there either), and then bump along a twisting, pot-holed and lake-size-puddle-filled logging road through clear-cut after clear-cut for about an hour, you’ll eventually come across a little spur road, gravelly, with short alders poking up the center line. It’s a big drop on the right side into a field of younger trees, sprouted after a logging operation in the 1980’s. A little further into a snaggy, boggy landscape is an interesting little piece of land which may help planners in the quest to save the species. Yellow plastic stakes and pink flagging, plus little silver tree tags, flash through the shrubs. These mark out the beginnings of a long-term experiment in change.

The dead yellow-cedar are gone, taken in spirit by climate then in body by humans, for use in specialty wood products — the lifeblood of many in the region. The younger individuals are carefully monitored — tracked, mapped, measured, and prodded with all the intensity of a pre-post-mortem.  They may survive, and if they do, they’ll be the remnant from which the species will survive. But they have company. A second species, western red cedar, is being planted around them. 

When yellow-cedar dies, redcedar grows. When your principle competitor can’t handle the heat, it’s good for you. Quick growth and gradual migration of redcedar seems to follow in the wake of the rapid decline of yellow — a swap of culturally and ecologically significant species.  Will the yellow cedar adapt be fast enough to keep pace with climate change? Not likely. But it  does show some natural adaptation, however sluggish, a sign of the stubborn will of the woods to maintain trees on a landscape. Perhaps that’s the way forward – one form of adaptation in the wild, another in the domesticated clearcuts of silviculture land. 

Preservation of the living stands and the living range of the species is clearly vital. The fate of the yellow cedar affects many, including old loggers in Kake trying to maintain a way of life, indigenous culture bearers trying to maintain traditional practices, conservation groups trying to save the finest old-growth in the world, and the slow ebb and flow of individual species over millennia. Charting a way out of these woods may require more than one route — preservation, conservation, and domestication all at the same time.  

 

Brian Buma
Brian Buma is an assistant professor in the Integrative Biology program at the University of Colorado in Denver, Colorado, and an affiliate professor at the University of Alaska in Juneau and Fairbanks. He has spent many years in the Alaskan woods, and continues to research the changing environment in the wilds of the world in Alaska, the Rocky Mountains, and Patagonia, among other areas.

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