A forest and fire ecologist discusses her research on how to reduce the damage being done to BC’s forests by fires.
BY LATE AUGUST there had been over 1100 forest fires in BC during 2017. With 1 million hectares burned, it was officially a record-breaking season. In the previous ten years, the largest area lost was in 2014 when 339,168 hectares went up in smoke. One would have to go back to 1958’s record of 855,000 hectares burned to come anywhere close. This fire season also resulted in the longest state of emergency in BC’s history.
Interestingly, between 2006 and 2016 the average annual number of fires was 1,844. So this year’s 1000 (and rising) fires were, on average, a lot bigger than previous years. And the outlook does not look any better. Natural Resources Canada’s Canadian Forest Service predicts a potential doubling of the amount of area burned in Canada by the end of this century, compared with amounts burned in recent decades.
One of the more than 1000 wildfires in BC in 2017
Besides the devastation to forests and wildlife this summer, over 45,000 people were evacuated from their homes. While residents of the Interior bore the brunt of the unpleasant and sometimes tragic consequences, even those of us on BC’s coast experienced numerous smoky days, with attendant health issues.
And, of course, there’s an impressive impact on BC’s economy. In 2014, when less than one-third of the area burned, direct costs were $300 million. So this year’s direct costs will be significantly higher. And then there’s all the indirect costs, from health care through impacts on tourism, small business, and agriculture.
BC, of course, is not alone. Heat waves and droughts have led to horrific wildfires in Italy, France, Spain and especially Portugal. In California, 100 million trees are expected to be casualties of their drought and rising temperature. A changing climate has being identified as increasing the intensity of these events.
A recently published meta-analysis by 63 scholars in Nature Ecology and Evolution found that trees in droughty conditions shut pores that let in carbon dioxide in order to conserve moisture. That also blocks the water transport within the tree, leading to dehydration and carbon starvation—in other words, dead, dry trees that don’t absorb atmospheric carbon and easily catch fire.
Forest fires themselves are a significant contributor to greenhouse gas emissions. They function as a “feedback loop”—warmer, drier conditions caused by climate change produce more forest fires, which release carbon and thereby contribute to climate change. Forests fires are one factor reducing the ability of BC forests to act as carbon sinks (logging and insect outbreaks also contribute). According to the federal government’s Forest Service, in the past Canada’s forests absorbed about one-quarter of the carbon emitted by human activities, but in some recent years they have become carbon sources, emitting more than they absorb.
Is there anything we, or our elected governments can do to lessen wildfires and their impact?
Focus interviewed forest and fire ecologist Jill Harvey about the situation. Harvey, who graduated from UVic in 2017 with a PhD in geography and whose research was published in July in two peer-reviewed journals, looks both to the past and the future.
“The mechanisms driving global climate change and ecosystem response are numerous,” she says. “Therefore, the research questions I ask target understanding changing disturbance regimes and tree growth-climate responses. Looking back into the past and into the future, my research examines both the causes and consequences of environmental change in temperate forests with a special interest in the outcomes for forest structure, ecosystem function and management implications.”
Focus caught up with Harvey (via email) in Greifswald, Germany, where she is doing postdoctoral research at the Institute for Botany and Landscape Ecology. She is there to gain international expertise in advanced tree-ring and climate science approaches, which she will bring back to Canada.
Q. What does your research show about the history of forest fires in British Columbia?
A. Historically, many sites in the Cariboo Forest Region burned every 15 to 25 years between 1600 and 1900 AD. These fires consumed fine fuels and maintained open forests. In the last 100 years, very few of these sites recorded a single fire. Effective and widespread fire suppression has resulted in denser forests throughout much of the Cariboo, providing more fuel for fires.
For example, one of my research sites near Hanceville burned in mid-July in the Hanceville Fire Complex, which is over 200,000 hectares in size and only 25 percent contained [on August 21]. At that site, nine historic fires were recorded between 1769 and 1896, with fire occurring about every 16 years. No fires have burned at that site for over 120 years. All the fuel that has accumulated over the past 120 years is supporting the fire that is burning right now.
Q. How did you conduct your recent research?
A. The fires that are burning in the Cariboo Forest Region are intense due to the accumulation of fuels over the past century. As I mentioned, fires prior to the 20th century were more frequent and generally less severe. These lower intensity fires oftentimes “scarred” mature Douglas-fir trees, but did not cause the tree to die. These living Douglas-fir trees, that can reach over 500 years of age, are recorders of past fire activity. Fire scars are preserved in the chronology of the tree’s life recorded annually as tree rings. Using principles of dendrochronology, tree-ring science [done by tree core sampling], I am able to date the year of the fire and sometimes even the season that the fire occurred in. When you compile the fire records from multiple trees at a site you can gain a pretty clear picture of the history of fire activity at site. And when you compile many sites across a region, you can identify years of widespread fire activity—like we are experiencing this summer.
I then link the years when fires burned to historical records of climate to see what kind of climate conditions are associated with different types of fires. For example, I found that fires that burned in forests next to expansive grasslands are associated with wet, cool springs. Wet, cool springs promote the growth of fine fuels, an important prerequisite to the spread of fire in fuel limited environments (eg. grasslands). In years when widespread fires burned at many sites across the Cariboo Forest Region, I found that multiple years of drought preceded these large fire years.
Q. What changed so much 120 years ago?
A. Around the end of the 19th century and towards the 1950s, European settlement in the Cariboo Forest Region increased. As it is now, fire was dangerous in areas where people lived, cattle grazed, and transportation corridors were constructed. Fires were suppressed and care was taken not to set fires. As stewards of the landscape, Indigenous people of the region had used fire effectively and carefully, thinning forests and promoting vegetation diversity. Indigenous burning was discouraged and forbidden in the early 20th century. Fires were perceived to “destroy” forests.
That is the irony we are facing now. The measures that we have taken for over 100 years to “protect” our forests by suppressing fires, have actually predisposed forests to more intense, and much more damaging fires.
Q. What does your research show about the way a forest fire changes ecology?
A. I conducted an intensive survey of historical patterns of fire severity in the Churn Creek Protected Area, which is located in the Cariboo Forest Region. Many of my plots were in forested areas next to grasslands. When I collected data in 2013 and 2014 for this study, these forests were incredibly dense with many young trees in the understory. I sampled hundreds of these young trees and when I got back to the lab and determined the age of these trees—almost all of them established in the late 1800s over a 20-year period. Prior to the late 1800s, frequent fire in these grassland-adjacent forests eliminated seedlings and kept forests open, encouraging the growth of native grass communities and promoting habitat for many animal species. Now, these dense forests have changed the composition of the herbaceous understory and eliminated habitat for multiple ungulate and bird species.
Q. Given your research and that of others, how should forest management practices change in BC?
A. Considering the costs associated with fighting the fires of 2017 [potentially $1 billion] and the fact that scientists have already confirmed that more fire is expected in the future, more funding should be directed to fire management and research that reduces fire risk. Today’s forest management plans should continue to enhance practices such as thinning dense forests and using prescribed fire to reduce fuel loads. We also should consider expanding these activities in the province to include larger areas. Increased research directed at prescribed burning approaches, smoke dispersal and the effects of fire is crucial. If fires are to be more frequent in the future, we need to use the fires of this summer to improve our understanding of the ecological effects of fire. These insights would allow us to improve the resilience of both the forests and communities of BC.
Q. What does climate change mean for the future of BC’s fires?
A. Climate projections for the next 50 to 100 years clearly and consistently show an increase of one to three degrees Celsius or even more. Future drier and warmer climates will undoubtedly lead to more fires in the province and for longer periods of time. If we do not reduce the fuel load now, we can expect more intense fires across multiple locations in the future.
Q. So we can’t necessarily reduce the number of fires, but we could work on reducing their intensity?
A. Yes, I think that we can reduce the intensity with which fires burn in targeted areas, such as areas around communities. Efforts to thin forests can be focused in these settings to inhibit the spread of fire towards people’s homes and property.
Q. Wasn’t reducing the fuel load and prescribed burning recommended, among other measures, after the 2003 fire season when 260,000 hectares burned with costs of $700 million? Were these not done—or not enough?
A. Yes, prescribed burning and thinning were recommended following the 2003 fire season and these treatments were conducted in some regions. However, I do think that more can be done going forward, especially after this summer.
Q. I understand the area burned annually in Canada is 2.5 times larger than the area harvested. Does that mean we should allow more logging?
A. No, I don’t think we should log more! Many of the large fires that burn every year are in the northern boreal forests of Canada where it is very difficult and oftentimes unnecessary to suppress the fire (no people or communities nearby). Fire is also a very important part of the ecology of boreal forests and in these environments trees are generally not targeted for logging. The tree species and/or sizes are currently considered unsuitable.
Q. What in your mind is the best path forward? Is there any good news about BC forests and fire?
A. We cannot simply hope that a fire year like 2017 won’t happen again. It will happen again, and it will likely happen more frequently. We must use this summer as a catalyst for change in forest management practices and research.
There are many stakeholders to consider when we plan our path forward after this summer. We must first consider those directly affected by the fires of 2017 and hear their stories and collectively recover from a very difficult time.
We need to critically review how we manage our forests and look back to the 2003 fire year and see if we have made progress.
We need to integrate insights from historical fire perspectives, Indigenous land management practices, and fire behaviour and meterology science.
Immediate resources for directly reducing fire risk such as forest thinning and prescribed fire are essential.
Fire-related research needs to occur at all scales, and across all involved disciplines. The 2017 fires present an exciting opportunity for fire ecologists to examine what happens next. Understanding how landscapes recover after a fire will help us develop appropriate management strategies important for the reforestation. We also need to look at how other forest agencies, such as in the US and Australia, are managing forests and fire and provide opportunities for inter-interagency and international collaboration between managers and scientists.
Leslie Campbell is the editor of Focus.