Swaths of pine beetle-infested forest in Manning Park.
Rising global temperatures are wreaking havoc on our forests, a situation thrown into stark relief by the recent mountain pine beetle epidemic. Now a group of B.C. scientists think they have found a way to anticipate—and adapt to—climate change
It used to be that climate change was a nagging but distant concern for British Columbians, spurred by pictures of stranded polar bears and the sinking islands of Tuvalu. Then came the images that brought the devastation home: vast swaths of our iconic B.C. forests laid to waste by the mountain pine beetle.
With the infestation mostly behind us now, Lower Mainland residents might be forgiven for dismissing it as just another blip in the news cycle. Mother Nature has proven resilient; those shocking swaths of red soon faded to black, and the tracts of forest are already filling in as new seedlings take root.
But it wasn’t just a few isolated strands of a minor tree species that were hit by the beetle. Eighteen-million hectares, one-third of the province’s 55-million hectares of forest, were affected. What’s more, experts believe the infestation—which peaked in 2007 and has now for the most part subsided—was not just a one-time aberration but a taste of the future devastation that global warming has in store for the forests of B.C.
“Nature is full of surprises, and climate change is leading to more of those surprises,” says John Innes, dean of the UBC faculty of forestry and leader of the sustainable forest management laboratory, which, among other things, studies the impact of climate change on forest ecosystems. We aren’t likely to see another pine beetle infestation, Innes says, but that’s hardly reason for complacency. It was a series of unusually warm winters that enabled that infestation, and there’s no knowing what the next climate anomaly will be and what havoc it will wreak on our forests.
“There is a likelihood of increased mortality of trees associated with climate change, and we’re looking into that as much as we can,” Innes notes, “but how do you forecast extreme events in the far future? And it tends to be these extreme events that cause the problems: a storm, a hurricane, a particularly severe winter.” Whatever that next weather anomaly is, it could trigger a new pest infestation, the introduction of a new disease or a catastrophic wildfire. Or it could be something we can’t possibly anticipate.
The experts entrusted with overseeing B.C.’s forests are not sitting by idly waiting to see what catastrophe strikes next. In a bold move aimed at helping our forests adapt to the climates of tomorrow, the Ministry of Forests, Lands and Natural Resource Operations—responsible for overseeing the 95 per cent of B.C. that is Crown land—has launched an experimental program that is unprecedented in forest management.
As climates have changed over the millennia, tree populations have always responded by shifting their habitats slightly from one generation to the next. Now, however, climates are changing faster than trees can adapt, and in the early 2000s the ministry began experimenting with what it calls “assisted migration”: a program aimed at speeding up the natural process of adaptation. Every year the province oversees the replanting of about 200,000 hectares of forest lost to logging or natural disaster. This program called for expanding the prescribed planting area of each tree species—typically by a kilometre or two to the north—in anticipation of where the climate of today is expected to be found tomorrow. The idea is that trees better adapted to the climate in which they grow will be healthier and better able to withstand fire, disease or infestation.
It soon became evident, though, that climate change is outpacing this gradual approach, and in 2012 the ministry launched another program, dubbed “climate-based seed transfer,” which involves a total overhaul of the province’s approach to reforestation. Rather than determine where a seedling can be planted according to lines of latitude and longitude on a map, decisions will be made according to anticipated climates of the future. The climate-based approach to reforestation will be implemented starting in 2017.
As B.C. moves into uncharted territory in forest management, the whole province can be seen as a giant petri dish, with the provincial government directing the experiment. And we’ve only got one chance to get it right. Unlike a high-school genetics experiment, where students might observe successive generations of flowering plants over the course of a year, trees take anywhere from 50 to 100 years to reach maturity. If the trees we plant today prove unsuited to the climate of tomorrow, there’s no do-over.
B.C.'s biogeoclimatic zones are expected to change dramatically in the decades to to come impacting which types of trees grow where.
Aitken, 53, moves a little gingerly as she leads the way down the hall to the Wall Institute’s kitchen, explaining along the way that she was “doored” by a motorist as she cycled to work yesterday. She dismisses the incident with a wave of the hand, clearly more interested in talking about trees than the unpredictability of Vancouver drivers. With her afternoon espresso in hand, she retraces her steps back to her office, which is decorated with photos of camping expeditions in the forests of B.C. Ushering me to the visitor’s chair, she proceeds to describe how she and her team have spent the past four years seeking to uncover the genetic secrets of two tree species: interior spruce and lodgepole pine.
With University of Alberta professor Andreas Hamann, Aitken is overseeing a $4.7-million, four-year project funded primarily by Genome Canada. The goal of the project, dubbed AdapTree, is to identify genes responsible for specific climate-related characteristics in the two species.
Aitken’s team analyzed samples taken from 600 trees, hoping to find genetic markers for traits related to adaptation to climate: resistance to drought, for example, or hardy growth in extreme cold. From millions of genetic sequences, the team identified 50,000 genetic markers related specifically to adaptation to climate. The final stage of data-gathering, underway now, involves analyzing samples from another 6,000 trees in the wild to further refine and validate the results. The data will be complete this summer and will be forwarded to the province.
As Aitken explains, the goal is not to use these markers to identify trees that have adapted to warm climates and transport them from one location to another. Rather, the idea is to see if genes suited to warmer climates of the future might already be present at low frequency in a given tree population—and then to propagate those trees in that location.
By 2080, B.C.'s annual mean temperature is expected to rise approximately five degrees Celsius across the province
All the valuable information now resides on her computer, Aitken says, and she swivels the monitor to show me some highlights. The most striking images are a series of maps compiled by her colleague in the faculty of forestry, Tongli Wang. The first pair of maps compares today’s temperatures to those expected in the 2080s. While today’s map depicts much of B.C. in cool blues, by the 2080s there’s no blue in sight; the province is almost entirely orange and red, representing a rise in annual mean temperature of approximately five degrees Celsius across the province.
A second pair of maps illustrates how the rise in temperature is expected to affect the distribution of tree species. In the first of these maps, depicting tree populations today, about a quarter of the province—a vast swath of the Interior with Prince George at its centre—is slate blue, indicating a zone characterized by a preponderance of spruce, pine and fir. Fast-forward to the 2080s, and this slate-blue sub-boreal spruce zone has nearly disappeared: it is now relegated to a couple of small patches in the far north. The area surrounding Prince George is now olive green, depicting a zone that is more typically home to subspecies of cedar and hemlock.
Changes throughout the rest of the province are equally striking: a patch of light green in the north is replaced by purple, representing a shift from a mostly barren alpine zone to one hospitable to forests of spruce and subalpine fir. A light blue patch representing lodgepole pine forest in the Southern Interior gives way to a climatic zone more suited to Douglas fir.
The expected shifting of the province’s climate zones doesn’t mean that all the spruce, pine and fir now growing near Prince George, for example, will be dead by 2080; it means that because those trees won’t be growing in conditions ideally suited to their species, they’ll be susceptible to threats such as drought, disease and insects. The aim of current research undertaken by Aitken and others is to ensure that B.C.’s forests of tomorrow will be suited to their environments and will be healthy enough to withstand whatever threats may be in store.
In the remote reaches of Surrey, sandwiched between industrial parks and farmland, sits a non-descript 3,600-square-metre facility that at first glance is indistinguishable from nearby warehouses. The Tree Seed Centre, operated by the Ministry of Forests, Lands and Natural Resource Operations, is ground zero in the province’s reforestation efforts; every one of the two hundred million seedlings planted on Crown land annually passes through its doors.
Outside the centre, metal racks bearing lumpy burlap sacks extend the length of a corrugated tin wall. The sacks—each bearing a tag with a hand-written registration number (identifying where the cones were collected, when and by whom)—contain an assortment of cones, collected from around the province and representing B.C.’s dominant tree species: fir, hemlock, larch, pine, spruce and cedar. Each seed will be tracked through SPAR, the province’s Seed Planting and Registration database, as it is processed in the centre, shipped to a nursery and finally planted in the wild.
If the climatic projections and genetic profiling underway today prove accurate, the seedlings arriving at the centre today will one day populate healthy forests that are resilient in the face of whatever diseases or infestations the future may have in store. If not, it won’t necessarily mean the death of B.C. forests: new trees will continue to rise, filling in the bare patches left by the most recent infestation, disease or wildfire. But the cycle of devastation and regrowth will likely be repeated with increasing frequency, leaving a patchwork quilt of unhealthy trees. Either way, we can be sure of one thing: the forests our grandchildren walk in will be very different from those we grew up with.