The Drip Zone Effect

The microscopic harbingers of Canada’s forgotten inland rainforest. Words :: Andrew Findlay.

Botanist Trevor Goward has spent his career looking at tiny things: lichen. But sometimes bigger picture perspectives reveal things that would otherwise go unnoticed. 

“One of my few talents is being able to see patterns where other people don’t,” Goward explains one day over the phone from his home in the Clearwater Valley of British Columbia.

Years ago, he stumbled across a species of lichen growing where it had no business being: on the branches of a western hemlock that is normally too acidic to support such a lichen. It piqued his scientific curiosity about the inner workings of the inland rainforest, a name Goward coined in the 1980s to draw conservation attention to the unique rainforests of BC’s interior. These forests once covered more than 160,000 square kilometres and stretched 500 kilometres from just south of Revelstoke north to Prince George. More than a quarter of this ecosystem has been clearcut logged and less than ten per cent has been protected. Some people refer to this area as Canada’s “forgotten rainforest.” 

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The inland rainforest is one of the world’s most unique forest ecosystems. In the Incomappleux Valley, south of Revelstoke, thousand-year-old cedars soar among hemlocks above a forest floor carpeted with thick moss. Though it’s in the Columbia Mountains, it could just as easily be the Walbran Valley 650 kilometres away on the west side of Vancouver Island. Such damp, coastal conditions so deep in the interior are made possible by a fascinating interplay of topography and climate. Rainfall in places like Incomappleux fall below the threshold of annual precipitation that defines a rainforest, roughly 1,400 millimetres. However, winter is the difference maker. Weather systems, laden with Pacific moisture, collide with the interior mountain ranges to deliver a deep snowpack that compensates for the moisture deficit, creating localized conditions that mimic the coast.

They are also a frontier for scientific discovery. University of Alberta biologist Toby Spribille has been studying lichens in the upper Incomappleux River valley and has catalogued more than 280 species, nine of them new to science. A survey of mushrooms in the Incomappleux identified 50 species, half of which are normally found only in coastal forests. 

Darwyn Coxson, a University of Northern BC lichenologist, studies the rainforests of the upper Fraser Valley, near the northern extremis of BC’s interior rainforests. He says similar temperate rainforests are found this far inland in only in two other places on the planet: southern Siberia and Russia’s far east.

Coxson, Goward and other scientists have so far identified more than 2,400 moss, lichen and plants species, including many new to science, in an area that includes both Chun T’oh Whudujut (Ancient Forest) Provincial Park and the 50,000-hectare Sugarbowl-Grizzly Den Provincial Park. However, the fate of the inland rainforest mirrors the decline of the critically endangered mountain caribou, which depend on lichens that grow in abundance in ancient forests like these.

The lichen growing on western hemlock branches that caught Goward’s attention that memorable day is one he had previously discovered on Vancouver Island and named Sphaerophorus venerabilis, also called oldgrowth coral. But why was it thriving on this normally inhospitable tree? 

It took the ability to step out of the microscopic world of lichens and into the bigger realm of ecosystem dynamics to solve this puzzle. 

“The gestation of new scientific concepts isn’t linear but more like the flow of a braided stream, its current amplified over time by a continuous rain of observations and insights,” Goward says, reflecting on this scientific mystery.

A hypothesis emerged and it went like this: western red cedar absorbs nutrients from the soil, which then leach out from the upper tree and rain down upon the branches of any trees below, including hemlocks. This repeated pulse of nutrients has the effect of raising the pH and lowering the acidity of the hemlock tree, therefore allowing this lichen to thrive. Research proved the hypothesis. Goward and his collaborators called it “the drip zone effect,” one of nature’s exquisite processes that happens beyond the scope of easy observation.

Over decades of botanizing, during which time he has published more than 100 scientific papers and formally described dozens of new lichens, Goward says he has witnessed the death by a thousand cuts to an ecosystem he loves.

Old growth forest has been a hot-button issue in BC for decades. Successive reports and government-appointed panels have red flagged the need to protect what remains of BC’s ancient forests. As far back as 1992, Mike Harcourt’s then-NDP government published the Old Growth Strategy. It was supposed to chart a new course for sustainable forest management and biodiversity protection. Instead, the report sat on the shelf and more or less gathered dust. 

So last fall when BC Premier John Horgan announced logging deferrals on 26,000 square kilometres of coastal and inland old growth, including 400 square kilometres in the Incomappleux Valley, Goward said it felt like “too little, and too late.”  

A postage stamp of inland rainforest near the north end of Duncan Lake in the West Kootenays is exactly what Goward is referring to. One hot summer day, I visited this remote forest with Craig Pettitt, a founding director of the Valhalla Wilderness Society. It was a long and dusty drive along the Duncan River, past its namesake lake, before we parked where the forest service road crosses the Duncan River and does a 180-degree swing southward.

“This is part of our Selkirk Mountain Caribou Park proposal,” Pettitt told me, gesturing at a wall of what looked like nondescript coniferous green lining the logging road. 

For the past decade, the New Denver-based conservation group has been championing the concept of a 2,500-square-kilometre protected area linking Goat Range Provincial Park and Glacier National Park that would capture remnants of old growth inland rainforest and critical mountain caribou habitat.

Pettitt and I pushed through the undergrowth. It was slow going. Though this 70-hectare patch of forest is designated mule deer winter ungulate range, Pettitt says it’s far from sacrosanct. The designation could easily be scratched with a change of government. Either way, it is a mere relic of what would have at one time covered this entire valley. 

It was cool and shady despite the mid-summer heat. We waded through devil’s club twice my height. Pettitt had a goal in mind: to show me one of the inland rainforest’s secrets. After a half hour of balancing across nurse logs crowded with hemlock seedlings, clambering over fallen branches and around cedar trees with trunks as wide as a car, we arrived at a massive fallen tree and root mass torn from the ground and tilted on its axis. Pettitt knelt down, flicked on a flashlight, and pointed the beam into the dark cavern of earth beneath the stump. 

Tiny fluorescent green-gold filaments glowed in the soil, like ornamental LED lights.

“Look, goblin’s gold,” Pettitt said.

This moss, known also by its scientific name Schistostega pennata, has evolved to occupy a light-starved ecological niche. Special cells act as lenses that are able to collect the faintest of light. Chloroplasts absorb the useful wavelengths and reflect back the residual light, creating a surreal glow. These inland rainforests are indeed a world of natural wonder—small and large.

For Goward, they represent a continuity made possible by moist conditions that have spared them from massive fire events, fostering a rich biodiversity centuries or even millennia in the making.

“Old forests have gone on, and on, and on. Their processes are very long-lived,” he says.

But these days, walking among these inland rainforest giants feels ominously like walking through a museum.

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