Wildfires in Alaska: Shifting landscapes and fire management strategies

What does a typical wildland fire season look like in Alaska?

Our large fires typically start in late May, and they usually die down in late July. However, we are seeing our fire seasons starting earlier. The official start of the Alaska season has moved a month earlier than previously, starting April 1. We are seeing more fire in the southwestern part of the state in recent years, particularly in the Yukon-Kuskokwim Delta tundra, attributed to warmer springs and earlier snowmelt.

We consider a large fire season to be over a million acres burned. So far in 2024 we’re below that, so it’s been more or less an average fire season. Fires in Alaska tend to be episodic. We’ll get some big fire years followed by a few years where we don’t get much of anything. For example, in 2022 we had a big fire year and then not so much in 2023.

Can you describe some of the key habitats impacted by fires in Alaska?

Most of Alaska’s fires are in the interior boreal forest that lies between the Brooks Range to the north and the Alaska Range to the south. The most common forest type is black spruce, which can be mixed with deciduous trees, primarily birch and aspen. One difference between the boreal forest in Alaska and Canada is that in Alaska we don’t have pine trees, while they do in Canada. Along with the forest are numerous wetlands, shrublands and tundra.

Fire has been the primary large scale disturbance agent here for about 5500 years – ever since black spruce came onto the landscape, which increases the flammability of the land. Fires do occur on the tundra in the north and to the west in Alaska, but tundra fires are less common.

How do wildland fires affect these habitats in Alaska?

Fire can create a shifting mosaic of different vegetation types across the landscape, with vegetation of different ages and stages of growth. What comes back after fire depends a lot on what was there before and how severe the fire was. The nature of this mosaic is going to change as fire occurrence changes. And as fire increases, you're going to have less mature forest on the landscape, less spruce trees, and an increase in younger successional types, which means vegetation is changing as plant communities are still establishing themselves. These successional communities can be dominated by different vegetation such as herbs, graminoids and shrubs. In some cases, you can even get a permanent change in the vegetation type.

Black spruce is easily killed by fire at low intensities. Despite this, black spruce is still considered a fire adapted species. They have serotinous cones, which means they need heat to open. The seeds are stored in the cones for years and they're clustered on the treetops where they have a better chance at avoiding direct flame, which can destroy them. When the fire comes through, the heat opens up the cones and they produce a large number of seeds that come down this freshly burned seed bed. Black spruce grows relatively slowly, but historically, black spruce sites usually revert back to black spruce over time, a process called self-replacement.

As wildland fires become more frequent and intense, how might that impact the Alaskan landscape?

A lot of changes to the landscape depend on how deeply fires burn. Fire isn't just killing the trees and above ground vegetation, it's consuming the forest floor and the organic layer of decaying plant parts beneath the surface, also called the duff layer. In boreal forest and tundra ecosystems, this duff layer can be quite thick – 40 centimeters or more – before you hit permafrost or mineral soil. When it’s really dry out, fire can completely consume this layer all the way down to the mineral soil. However, most of the time, it doesn’t reach that far down and what’s left is blackened duff, which is a really inhospitable seedbed for most plants. Most small seeds from birch, aspen or willows, for example, will dry out in burned duff and won’t be able to germinate. Black spruce actually has an advantage here because their seeds are relatively large compared to others, so they’ll get a toehold in the remaining duff. Birch, aspen, and shrubs can resprout even when their tops are burned if their roots are not killed by fire.

However, if most of the duff is burned up and more mineral soil is exposed, that's when the seeds from deciduous species like birch and willow come in and do well. They have a competitive advantage over the slow growing spruce seedlings, and the land will become deciduous. In these cases, black spruce can eventually come back and regain dominance. But this can take quite a bit longer – about 50 to 100 years.

So, as we get more fires and if we get more severe weather that promote deep burning such as droughts, we could see a shift towards more deciduous shrubs and trees in the landscape, and less of that black spruce replacement happening. We also see less resiliency in black spruce if there are re-burnings over short periods of time. It can take black spruce 30 years to produce a good quantity of seed. So if there’s a fire that occurs twice in the same spot within 30 years or so, it can mean black spruce doesn’t have enough time to re-establish itself. There’s been a couple of studies that have looked at satellite imagery and how vegetation is shifting across the landscape over time. While there is an increase in deciduous vegetation soon after fire in interior Alaska, spruce trees continue to repopulate disturbed areas over time for now.

What are the impacts from shifting vegetation in Alaska?

There are ramifications of shifting vegetation in terms of carbon storage. Most of the carbon in northern ecosystems is not stored in trees. It’s stored in layers of organic matter beneath the surface. Slow decomposition in black spruce forest promotes a buildup of thick layers beneath them where they can store massive amounts of carbon. However, deciduous vegetation doesn’t work the same way – they store carbon in their trunks, leaves, and branches rather than in their soil. So when you get more deciduous trees moving in, that carbon storage then moves from soil layers to above ground.

That thick organic mat also acts as insulation for permafrost. When fire comes in and burns deeply into it, the permafrost is more vulnerable to thaw. Some of this permafrost has been holding carbon for millennia. So when permafrost begins to thaw, it releases greenhouse gases into the atmosphere over a much longer period than what’s released through smoke during a wildfire. This leads to a feedback mechanism where an increase in greenhouse gases leads to more climate warming, which leads to more fires and permafrost thaw. Globally, permafrost holds at least two times the amount of carbon that’s currently in the atmosphere. Some of that permafrost is thawing just from climate change alone, and fires will then exacerbate that. A lot of global climate models don’t account for permafrost thaw and the greenhouse gases that it will release. This is a really big concern that I don’t think is getting enough attention in the media.

There are studies looking at how quickly deciduous vegetation can sequester carbon to see if it could offset the losses from the burned organic matter. It may not help insulate permafrost, but it does suck up carbon at a faster rate. Deciduous vegetation is also less flammable, but it can burn when conditions are right. Firefighters are noticing that deciduous plants aren’t always acting as a natural firebreak like they had in the past.

As wildland fires intensify, are there changes to fire management in Alaska?

In Alaska, federal policy called for suppression of wildfires from about 1940 to the mid-eighties. Alaska tried to suppress fires, but it quickly became apparent that you can’t get them all – total fire suppression doesn’t work. Recognizing that fire is a natural part of forest ecosystems, what they did was divide the state of Alaska into four different initial attack options: Critical, Full, Modified, and Limited depending on risk to values. Initial attack is when action is taken to control a fire within around 72 hours after ignition; this time frame has the best chance for successful suppression.

Critical areas occur around communities and villages where life and property are at risk. Full suppression areas tend to be adjacent to communities or areas with human and cultural value around them, and it’s not quite as critical to get the fire out quickly, but you still get there as soon as possible. In Limited management areas, fires are allowed to play their ecological role, but they are monitored and specific sites will be protected as needed but there is generally not an attempt for more widespread control of the fire. Most of the state is in Limited management. Modified management is treated like Full suppression early in the season until around mid-July in interior Alaska, when it’s treated as Limited because there’s less chance of a fire getting really big after that time period.

As fire occurrence increases, some land managers are rethinking this fire management approach for their area. While fire is a natural part of the ecosystem in Alaska, at what point might fire be detrimental?

One example is a pilot project that was instigated in 2023. The refuge manager of the Yukon Flats National Wildlife Refuge in northeast Alaska changed the fire management option on some areas of the refuge due to human health and carbon sequestration concerns. There are quite a few villages within that area where people are exposed to a lot of smoke, and it’s a remote region with no roads so they can’t easily escape poor air quality. But we’re also looking at it from a climate change standpoint. The smoke and greenhouse gas emissions from the fires themselves can be massive. But in this area, we also have a lot of Yedoma permafrost – around 4 million acres - which stores very old organic matter from the Pleistocene epoch and it’s also ice rich, meaning it's more susceptible to rapid thaw. So, looking at these different factors, we changed some of the Yedoma areas from the Limited to the Modified management option to protect permafrost. This region is about 1.6 million acres, so it’s a very large area.

Implementing fire suppression as a climate solution is a novel concept for our modern fire management. Before, fire in this region would only be suppressed if it posed a threat to humans or property. There were stipulations involved in enacting this change. First is recognizing that life and property are always going to come first for fire protection. Also, we don't want to send firefighters to really remote locations where it would be hard to extract them if they were injured, so these areas were excluded. We only looked at areas that hadn't burned since about 1989, so fairly mature forests with a thick organic mat. Another stipulation is that only fires ignited in the Yedoma would be initial attacks; fires moving into the area would not be suppressed. This is still an experiment now – we're looking to see how it works. We have limited resources, and it’s expensive to respond to remote fires. But if you look at the emissions saved, the expense may not be so different from climate measures being taken in other places.

Ultimately, people are thinking about boreal fire management differently. The idea is that this wouldn't be a permanent change, but that it will play a role in reducing carbon emissions and essentially buys us time while we aim to reach our climate goals.

How are you involved in CAFF and the ArcticFIRE project?

I am a U.S. representative on the steering committee for the ArcticFIRE project. It's been a really interesting project. A lot of initial discussion involved mapping fire locations for different Arctic nations and Indigenous Permanent Participants. Alaska and Canada have good fire perimeter mapping databases, and we weren't sure what other countries have those. Such databases are really useful for documenting change. Gwich'in Council International initiated and leads the project, so there’s a strong Indigenous fire management component to it.

One of the goals is to increase the awareness of fire in Arctic nations. I think it's been successful in that Arctic Council now has picked up this important issue, and there’s work being done also in the Emergency Prevention, Preparedness and Response Working Group’s Circumpolar Wildland Fire project. There’s a lot of different directions this work can go in, and a lot of great potential for collaboration with others.