10,000 Years in the Making
It has been suggested that the extinction of the Mammoth led to an increase in vegetation biomass which is then said to have given rise to the era of fire. Over the last 10 to 11,000 years, almost every ecosystem in British Columbia has evolved with its own unique fire regime. Because of this evolution, a significant proportion B.C.’s flora and fauna are adapted to or dependent on fire in some way or another.
Strategies in an Era of Fire
In the era of fire, some plant species have evolved to be fire resistant while others have become fire dependent, or fire tolerant. A few have not changed, so they are classified as fire intolerant.
Fire resistant plants have evolved strategies to resist the lethal effects of fire, such as thick bark that insulates living tissue from lethal temperatures.
Fire dependent plants require fire to perpetuate at least one stage of their life cycle, such as using fire to make sure their seeds germinate. Fire dependent wildlife needs the types of habitat that fire creates. Without fire, fire dependent plants and wildlife species disappear.
Fire tolerant plants can withstand being burned, and they recover quickly after the fire because of their ability to re-sprout from their roots. An example of a fire tolerant plant in is the iconic Trembling aspen tree.
Fire intolerant plants and wildlife are very sensitive to changes in their habitat caused by fire. Fire can cause fire intolerant species to decline or even disappear.
Animals aren’t resistant to or tolerant of fire per se; they are actually fairly flammable. However, their tolerance to fire is due to their avoidance strategies such as retreating to or living in habitats where the lethal effects of fire cannot physically harm them. Plants can also use avoidance strategies to tolerate living in fire prone regions by growing strictly in the habitats where fire cannot burn into very easily, such as riparian areas and rocky habitat.
What is a Fire Regime?
A fire regime is a combination of two factors.
1) The severity of the fire, which is measured by the amount of vegetation mortality caused by a fire and,
2) How often fire occurs.
Fire severity is controlled by the amount and type of combustible vegetation on the landscape and the sensitivity of that vegetation (i.e., resistant, tolerant or intolerant). How often fire occurs on the landscape is expressed as a “fire return interval” or “fire frequency.” Fire frequency is regulated by the interactions of climate and weather in the way that creates lightning – nature’s way of starting fires. Some ecosystems are more “lighting prone” than others, so they experience more frequent fires. Science also recognizes the use of fire by First Nations as contributing to the uniqueness of some of North America’s historical fire regimes. The other variables that help define a fire regime include the pattern, size, continuity and season of burning. All these factors work together to create unique fire regimes across the landscape at different points in time.
Generally, low severity fires that occur frequently create what are referred to as “Fire-Maintained Ecosystems.” Fire-maintained ecosystems are characterized by fire that is predominantly non-lethal to most of the vegetation in the ecosystem. On the other side of the coin, high severity fires that burn less frequently tend to be lethal to most of the vegetation, so they are often referred to as “Replacing Fires.” High levels of biodiversity are often correlated to ecosystems that experience mixed–severity fire regimes. Mixed-severity fire regimes are made up of a mixture of high and low severity fires at varying scales, patterns and timing across the landscape. The resulting pattern of mixed-severity fires is often referred to as a fire mosaic.
What is a Fire Mosaic?
Fire mosaic is the pattern of burned and un-burned vegetation distributed across a landscape after a fire. Mosaic fires create diverse patterns of vegetation, edge conditions and different micro climates which together provide habitats for a diversity of wildlife species. Ecotone gradients are a pattern of ecological communities where high levels of biodiversity are often found. An example of an ecotone gradient is where open grasslands and closed forests come together and where sub-alpine forest gives way to alpine habitats. Fire plays an important role in maintaining ecotone gradients because fire reverses the forest’s encroachment onto the grasslands or into the alpine.
The Importance of Fire to Biodiversity – The Bottom Line
Fundamentally, fire creates complexity on the landscape which allows for plant diversity. Plant diversity creates wildlife diversity. Diverse ecosystems are resilient ecosystems. Resilient ecosystems are better capable of resisting or recovering from stresses and disturbances.
Importance of Fire for Ungulates
Ungulate populations are driven by female adult survival and juvenile recruitment. The relationship between female adult survival and juvenile recruitment determines whether populations are increasing, stable or decreasing. External factors that regulate populations are grouped into “top down” and “bottom up” regulators.
Top down regulators represent consumers in the food web (i.e., natural predation, human hunting).
Bottom up regulators represent the resources available to a population (i.e., habitat and nutrition).
Two critical concepts regarding population regulation include:
- Predation or hunting might not be limiting population growth when poor nutrition is affecting the population.
- Conversely, predation or hunting may be very strongly impacting wildlife populations when the habitat is severely degraded.
Winter range has always been considered to be the factor limiting ungulate populations in British Columbia; however, summer range nutrition is reported in the scientific literature to play a very significant role in population dynamics. Spring and summer are critical times for adult females and their offspring. Their access to highly nutritious food is vital for their survival and collective ability to grow their population.
There are a number of reported negative population feedback mechanisms that are attributed to poor summer range nutrition including:
- Low pregnancy rates,
- Low offspring production,
- Poor female body condition and body mass,
- Low juvenile survival and,
- Increased vulnerability to predation and hunter harvest.
The bottom line – poor nutrition can lead to population declines and unstable populations.
Fire’s Influence on Nutrition
Fire has a significant influence over the nutrition available to grazing and browsing herbivores.
For example, decomposition of plant material in conifer forests is slow and, consequently, nutrient cycling is even slower. Nutrient cycling is important to herbivores because rapid nutrient cycling is linked to the palatability and quality of forage and browse. Fires tend to shift plant communities from conifer forests to deciduous-herb-grass habitats. Deciduous-herb-grass habitats tend to cycle nutrients much quicker than conifer forests. Consequently, deciduous-herb-grass habitats often produce some of the most nutritious food for herbivores including wildflowers, berry producing shrubs, aspen and lush herbaceous plants. Species that are depended on old growth like caribou, which rely on slow growing lichens, do not respond well to fire, so they tend to inhabit ecosystems where fire does not happen very often (i.e., fire intervals in the order of 100s to 1000s of years).
Ungulates prefer vegetation that regrows after a fire because it has higher digestibility and more crude protein than unburned vegetation. The high quality vegetation that grows after a fire explains why herbivores often seek out habitats renewing themselves after forest fires. The high nutritional value of the forage and browse typically only lasts about 5 to 7 years for grasses and 11 to 20 years for shrubs. But the importance of wildlife having perpetual access to new burns somewhere within their homes range is critical for many species. Stone’s Sheep in Northeastern B.C., for example, are reported to have higher lamb to ewe ratios and lower incidence of lungworm when they have access to burned habitats. This is why it is important to burn critical forage and browse habitats on a frequent basis (i.e., 7 to 15 years).
How do Ungulates Respond after a Big Fire?
For the most part, there is very little hard evidence in B.C. that shows how animals in this province respond to big landscape-scale fires. It’s just not something biologists have done a particularly good job at studying. However, in 2003, the Okanagan Mountain Park Fire burned approximately 25,000 ha (62,000 ac) of dry forest habitat south of Kelowna. 10 years prior to the fire, the Mountain Goats in Okanagan Mountain Park numbered around 8 animals. Ten years after the fire, the goat’s population grew to 85 animals (a whopping 962% increase). This increase is directly attributed to fire having improved habitat in the goats’ home range.
In wildlife management units MU 8-9 and 8-10 where the Okanagan Mountain Park Fire burned, the hunter harvest of mule deer and elk increased 32% and 144% respectively in the decade following the fire. This increase in harvest occurred with about a 15% decrease in the number of hunters and 15% decrease in the number of hunter days in those management units. There was no wildlife inventory data for deer and elk before and after the fire, so directly correlating increases in hunter harvest to increases in populations is not a firm conclusion; however, an increase in elk and deer abundance due to the fire can’t be discounted either.
Prior to the Okanagan Mountain Park Fire, there were no mountain sheep in the area. Between 2007 and 2009 a total of 53 sheep were transplanted to the burned habitat, and over the next 6 years, the herd size increased by an amazing 14%. It is likely the favorable habitat and nutritious forage created by the fire favored lamb survival, and that powered their population growth.
What About Da Bears?
Huckleberries are fire tolerant, and fire creates the conditions for huckleberry plants to thrive, expand and persist on the landscape by preventing forests from overgrowing huckleberry patches. The most nutritious huckleberries for bears grow in full sunlight. Since the early 1900s, the Flathead grizzly bear population management unit (GPMU) in Southeastern B.C. has had the shortest fire return intervals (i.e., most frequent fire) and the highest percentage of the land base burned by fire on an annual basis compared to other units in Southeastern B.C. Because of the unique fire regime in the Flathead and the abundance of huckleberry plants, huckleberry production is a strong bottom up regulating factor for grizzly bears in the Flathead. The graph below shows how grizzly bear adult female density, over the years, has increased with increasing berry production and has decreased with decreasing berry production.
The New Frontier of Fire Research in B.C.
In 2017, the Elephant Hill Fire in Southcentral B.C. burned over 191,000 ha (472,000 ac). A wildlife research project led by Dr. Adam Ford from the University of British Columbia-Okanagan campus and Dr. Sophie Gilbert from the University of Idaho, in cooperation with the B.C. Wildlife Federation and Habitat Conservation Trust Foundation, is studying the effects of the Elephant Hill Fire on mule deer population dynamics. It’s an exciting time for wildlife science and the future of effin big habitat burns in B.C. (hint hint).
An Obvious Question is, “Won’t Nature Take Care of it if We Just Let Fires Burn?”
The year 1850 is the date where the fire history record, as recorded in the rings of ancient fire survived trees, shows that the European colonization of western North America began to disrupt the natural fire regimes. 1940 is the date recognized where the post-war fire suppression effort began to exacerbate the disruption of natural fire regimes that was started by early settlers. The overall influence of humans on natural fire cycles is one of decreasing the frequency and size of fires on the landscape and increasing the severity of fires when they occur.
The Pacific Decadal Oscillation (PDO), an El Niño-like warm phase of the Pacific Ocean that lasts much longer than El Niño (20 to 30 years vs. 1 to1.5 years) is known to influence fire behavior as well as some ungulate populations in North America. The PDO ceased to be a dominant natural influence on fire cycles in B.C. after 1940 due to modern fire suppression that prevented fires during PDO season from growing to historical sizes. For example, after 1940 in Southeastern B.C., there have been very few landscape fires greater than 500 sq. km (200 sq. mi). The influence of the PDO still persists today, and the oscillation of this ocean current created peak fire seasons in B.C. in 1960, 1985 and 2000; however, the area burned during those years was much lower than the area burned prior to 1940 due to modern fire suppression that limited fires from growing to their historic sizes.
Since 1850 and more so since 1940, ecosystems have been accumulating more biomass in the absence of natural fires. The result of this biomass accumulation, or fuel loading as it is most often called, is that some ecosystems are experiencing fire severities at levels that the ecosystems are not adapted to. Un-natural catastrophic fire can cause the reduction of ecosystem resilience, loss of wildlife habitat and loss of biodiversity. Ecosystems subject to un-natural catastrophic fires might not ever recover to their former conditions or functions. So conservationists have to be very cautious about advocating for a “let it burn policy” in wildfire management because of the potential negative consequences that un-natural fire regimes can have on ecosystem resilience.
Historically, B.C. experienced some very large fires. In fact, the second largest fire recorded in North America, the Wisp Fire, burned between 1.4 and 1.7 million ha (3.5 to 4.2 million ac) in 1950 between Ft. St. John and northern Alberta. In 1958, the Ketch Fire burned about 225,000 ha (556,000 ac) in the Ketchika Valley in Northern B.C. For comparison, 2017, which is touted as the worst fire year in British Columbia’s history, burned a total of 1.2 million ha (297 million ac), which is still smaller than Wisp Fire. Setting aside economic damage to homes, businesses and infrastructure, 2017 was by no means a record year for area burned. Instead, 2017 was maybe just a little bit closer to the typical fire years pre-1850.
From 2006 to 2016, wildfires in B.C. burned a total of 12,000 to 370,000 ha per year (30,000 to 914,000 ac). Some notably large scale fires have burned during this time period; however, the majority of fires during this ten year span ranged from 5 to 250 ha in size (12 to 600 ac). The average fire size during the 2006 to 2016 period was only 75 ha (185 ac). So on average, wildlife is not benefiting from the kinds of fire disturbances on the land that they need. 2006 to 2016 is also a period where we have seen dramatic declines in many wildlife species in the province.
Looking at the sizes of the home ranges of the largest wildlife species in B.C., as reported in the literature, the average upper home range size for all these species combined is somewhere in the range of 500 sq. km (75 to 190 sq. mi). The lower end is somewhere around 200 sq. km. In the face of modern fire suppression, nature is no longer able to create fires at a scale important to the survival of fire dependent wildlife and plant species.
The Next Obvious Question is, “Doesn’t Clearcutting Take the Place of Fire?”
In classical forestry education, students were taught that most forests in B.C. originated from stand replacing fire regimes. After stand replacing fires, the new forests establish over a short period of time and grow into what Foresters call “even-aged” forests. Clearcutting causes forests to also establish and mature into even-aged forests, especially when they are artificially planted right after logging is finished. Classical forestry theory often suggests that clearcutting mimics or is a substitute for natural stand replacing wildfire. So the premise in forest management is to put out wildfires, log the timber and all will be good for biodiversity.
Twenty or 30 years after logging, it can be hard to discern if you are standing in an old logging block or in an old natural burn; however, that’s where the similarity ends. Even with natural replacing fires, there is still a tremendous amount of habitat structure and diversity left immediately after the fire. “Snag forests,” the type of habitat left after a forest fire, provide valuable habitat for many wildlife species including moose, bears, furbearers, rodents, insects and many species of birds including woodpeckers. To the moose, these standing dead forests provide enough visual cover that allows them feed on the regrowth and not been seen as easily as they would if they were in the middle of salvage logged block. A moose’s long legs are an adaption for living in deep snow and in wet habitats, but they are also thought to be an adaptation to living in old burns where the dead standing trees eventually fall over and become crisscrossed. The ability to live in the tangled old burns may be a strategy of moose to avoid predators. Old burns are a type of fortified moose sanctuary. This type of important moose habitat is lacking in B.C. because of our obsession with giving burnt trees rides to sawmills.
Wildlife habitat burns and forestry silviculture burns were well-used land management tools between 1980 and 1994 in B.C. At its peak, the use of prescribed fire approached 50% of the total area burned by wildfire even during some of the worst fires seasons. Between 1970 and 2000, prescribed fire use even exceeded the total area burned by wildfire. 1970 to 2000 was an era where land managers were managing the landscape with fire. Fear about using prescribed after the severe 1985 fire season began to erode political and public support for prescribed fire as a land management tool, so land managers chose the option that protected their careers. Less fire became a good thing.
The possible correlation between the decline in the use of prescribed fire on the landscape and the amount of property loss due to wildfires after 2000 is an interesting one to look at more closely. Progress is being made by the province on a number of policy and funding initiatives with respect to restoring the use of prescribed fire as management tool, but progress is not moving remotely fast enough to keep up with what wildlife need. Significant work still needs to be done to reduce liabilities (perceived and real) around the use of prescribed fire by the forest industry and government agencies. Too many folks are scared of prescribed fire.
What about Ecosystem Restoration? We Hear A Lot About it.
Southeast B.C. has one of the most aggressive habitat restoration programs in the entire province. The program is aimed at restoring fire-maintained ecosystems in the Rocky Mountain Trench, yet over the last 20 years, the program has only managed to reach about 40% of the area identified as needing to be burned. Species like elk in the Rocky Mountain Trench that should have benefited from 20 years of habitat restoration have declined nearly 50% between 2008 and 2018. Not a great outcome for the province’s poster child in ecosystem restoration.
The photo below shows prescribed burns (red) that were planned for the Galton Range in Southeastern B.C. The Galton’s have historically sustained amazing mule deer and bighorn sheep herds for hundreds of years. Now the Galton’s are mostly covered by dense forest. Like many herds of mule deer and sheep, the Galton sheep and deer populations have dwindled. Sheep have declined about 40% in the last 10 years alone. The proposed habitat burns for the Galton’s total a mere few hundred hectares. It’s a drop in the bucket compared to the hundreds of thousands of hectares that these ungulate’s home ranges cover. I call these types of habitat enhancement projects for large ranging mammals “micro burns.” When I look at the home range size of most large mammals combined with the fact these species need access to large burns within their home ranges, it is clear that our thinking on habitat enhancement burning needs to be on a scale that is meaningful to wildlife and not simply at a scale that suggest that wildlife managers are doing “something.”
In the photo above, the orange shaded area represents the size of the 2003 Okanagan Mountain Park Fire. This shows you what an effin big habitat burn really looks like in comparison to the micro burns that were planned for the area. If we want resilient ecosystems to help recover dwindling wildlife populations and to protect biodiversity, we need effin big burns not micro burns!
My Key Take Home Messages are:
- Habitat biologists need to change their paradigm and execute prescribed burns in the order of 100-500 sq. km per wildlife population unit. Ditch the micro burns!
- Prescribed fire objectives need to be linked to wildlife population objectives.
- Habitat biologists need to focus on enhancing plant nutrition and to understand optimal fire regimes that make high quality nutrition available to herbivores on a perpetual basis.
- Habitat biologists need to expand burning away from winter range and into spring/summer calving and lambing areas to ensure the best forage surrounds the most critical natal and pre-natal habitats.
- Habitat biologists need to be measuring success of habitat burns by monitoring wildlife population metrics rather than tallying the total area burned.
- Forest managers need to accept that some fire-killed “snag forests” are off limits to salvage logging in order to restore diversity on the landscape, especially for moose. (I can hear the gasps now).
When I tell wildlife and fire managers what size habitat burns should really be, they get a little freaked out. In the southern half of the province, safely executing habitat burns on a big scale likely won’t happen in one single burn – that’s the reality of our situation given where most of our population and infrastructure is located. But if habitat biologists were dedicated to burning habitat at a meaningful scale for wildlife, and they staggered a series of systematically inter-connected burns over a 5 year time frame, I think our fire management experts in B.C. and the nail biting land managers could handle that. There is a saying that every new idea goes through 3 stages – resistance, discussion and then adoption. Most of what I have written about here is not new, so I hope we are able to get passed stage 1 fairly quickly. Wildlife is disappearing while they wait for us to figure this fire thing out. The time for effin big fires is right now.
What Can Conservationists do to Help Advocate for Effin Big Fires on the Landscape?
- Always be engaging your local habitat biologists to help them identify critical areas for habitat burns (draw really big circles on their maps).
- Demand habitat biologists responsible for prescribed burns either go big or go home.
- Demand that habitat biologists demonstrate how habitat burns are linked to firm population objectives (no wishy washing stuff).
- Become familiar with your local Wildfire Center’s Fire Management Plan because it should show areas where the fire management objectives call for “modified responses” – aka let-burn-but-keep-an-eye-on-it approach. Hold fire managers accountable to letting fire burn where the objective is to let it burn. Tell them there will be no sneaking in to put out fires in those areas just because fire crews are on overtime.
- Help support habitat projects and contribute third party funding to effin big habitat burns. Boycott funding for micro burns.
- Engage your local politicians and government decision makers to educate them about the benefits of effin big burns. Help build their confidence in B.C.’s wildfire management experts’ abilities to execute effin big habitat burns. Tell them effin big habitat burns help protect communities from nasty wildfires. Tell them effin big fires will increase wildlife populations which will help get them re-elected.
- Use social media and local newspapers to praise habitat burns (yes even micro burns).
- Counter people who are complaining about smoke from habitat burns and tell them it’s the sweet smell of biodiversity. Super Natural B.C. = smoke once and while.
- Be like a woodpecker looking for a grub deep inside a dry snag and relentlessly pound away on all the above items. The future of healthy wildlife populations depends on your hammering away at making effin big habitat burns a reality. Failure here is not an option folks.
I Will Leave You with One Final Thought
- Responsible stewardship of wildlife should not involve an obsession with top down regulators when so many habitats in B.C. are skewed from their natural states.