The Hawai'i Air Nataional Guard fights wildfire in Maui's Upcountry on August 9, the day after the first blaze was reporteds. Human activity plus fuel overloads from non-native grasses on the dry side of the island make conditions ideal for wildfire, says fire scientist Chreighton Litton. (U.S. National Guard image by Air Force Master Sgt. Andrew Jackson)

On Tuesday, August 8, 2023, a wildfire whipped from the dry grasslands adjacent to the historic town of Lāhainā on Maui, Hawai’i, into the town’s streets, killing more than 100 people. The death toll continues to grow. 

Fire scientists say a combination of factors created ideal conditions for a devastating wildfire: warmer and drier conditions propelled by climate change, the spread of invasive plant species, and a rise in the number of human activities that can create a spark. 

The Daily Yonder talked to Creighton Litton, a professor of forest ecology and management in the Department of Natural Resources and Environmental Management at the University of Hawai’i at Manoa on O‘ahu. Litton spoke about the changing firescape of Hawai’i, which communities are most at risk, and how local and state policy should be responding. 

This conversation has been edited for length and clarity. 

Claire Carlson, Daily Yonder: Can you talk about the role of fire in Hawai’i’s ecosystem historically?

Creighton Litton: Yeah, for sure. I think it’s important for people to understand that in Hawai’i, as in most terrestrial ecosystems in the world, wildfires are a natural disturbance, that is, they were occurring in the Hawaiian Islands long before humans arrived. 

Creighton Litton (Source: University of Hawaii at Manoa Facebook)

When we think about natural disturbances like wildfires, we like to think about what are referred to as regimes or wildfire regimes. And what that really means is understanding the details of wildfire as a natural disturbance. So in what ecosystems did they occur, how intense were they? And one of the big ones that we think about is how frequently did they recur? That’s referred to as the mean fire return interval, which is just on average, how long does it take for fire to return to the same place in a given ecosystem type?

And so if we think about natural fire regimes in Hawai’i prior to humans inhabiting these islands, we know from some work that was done in the past using charcoal and charcoal dating that wildfires did occur. But in wetter ecosystems, they would’ve occurred quite infrequently. So, on the order of 700 to 1,000-year mean fire return interval, which means that the same area is going to burn on average every 1,000 years. There’s some other work that folks like Kealohanuiopuna Kinney have done that shows that in drier areas, in some native montane grassland shrubland areas, it would have burned probably much more frequently, perhaps on the scale of a couple of decades in terms of a mean fire-return interval.

And so I think the key points are that fire is a natural disturbance, but naturally fire would have occurred pretty infrequently [in Hawai’i]. And it’s thought that they would’ve been relatively small in scale and would not have burned huge, vast areas due to a lack of fuel loads, especially fine fuels, that are associated with things like grasses. We do have native grasses in Hawai’i, but they’re not widespread like the invasive grass ecosystems that we have today.

Daily Yonder: So in West Maui where the Lāhainā fire took place, is that region where it would’ve been more common to see fires in those couple of decades timeline that you just mentioned?

Litton: Possibly. That’s another thing that a lot of people have is this image of all of Hawai’i being a tropical rainforest. That’s not true. You know, due to our dominant wind and climate regimes, the windward – the eastern and northern sides of our islands – tend to get much, much more rain. 

But Lāhainā is on the leeward side of an island. So it’s in the rain shadow, and so it would’ve naturally been a very dry area. When you think about where fires would’ve occurred more frequently in the past prior to humans, it becomes really important to think about what the ignition source would’ve been. 

Today, well over 95% of the fires that start in Hawai’i are ignited by humans or by human activities. So prior to humans, the two things that would have started fires were lava and lightning. Lava would’ve been restricted to the younger islands where there’s volcanic activity. Historically, [lava-ignited fires] would have been pretty infrequent. 

The Maui community of Lahaina is close to fallow agricultural lands with dry, non-native grasses. The fires in the grasslands ignited the town. More than 100 people died in the fires. (Photo by State Farm via Flickr)

We do have lightning in Hawai’i, but we don’t have nearly as much lightning as you get in places like the fire-prone Western states in the mainland United States. And in particular, we don’t have a lot of dry lightning. That is, we don’t have a lot of lightning that is not accompanied by rain that would keep a fire from igniting and spreading. It does happen. We do have recent records of fires in these non-native grasslands being started by lightning.

I have never seen any evidence for these low elevation coastal areas like Lāhainā in terms of what their natural fire regime might have been. I don’t think we know enough about the distribution and the frequency of lightning in the state to be able to say anything definitive, but my guess is that those high elevation areas would have had more dry lightning than low elevation areas. And so that might not necessarily be the case for areas like where the town of Lāhainā is located.

 Daily Yonder: You mentioned that a lot of the fires Hawai’i sees today are ignited by humans. Is that someone throwing a cigarette butt out or is it kind of a variety of human activities?

Litton: Yeah, it’s a variety of human activities. I don’t have the statistics right at hand. Arson is certainly part of it, but I don’t think they’re the majority. 

We’ve been able to collect a kind of a database of fire ignitions. And if you look at that database of fire ignitions in the past couple of decades, you’re essentially mapping the road network on the islands. Which means that these fires are being caused primarily along roadways by things like people throwing cigarettes out of their car, or another one that you hear quite frequently is just being pulled over on the side of the road and your car’s catalytic converter, if it’s in contact with dry fuels from grasses on the side of the road, can ignite fires that way as well. The military also starts a lot of fires in the state with live fire training activities. And they will sometimes burn outside of those areas into the surrounding forest and at times communities. So it’s really a mixed bag of what’s causing those ignitions. 

But the thing that they all have in common is that there is a human factor, an anthropogenic ignition source for almost all of the wildfires that we have in Hawai’i , particularly today.

 Daily Yonder: What communities have you found to be most at risk? At the Daily Yonder we write about rural communities specifically, and there are some unique challenges, especially in responding to rural fires. I guess I’m kind of setting up your answer here, but have you found there to be certain communities where it can be harder to respond to or they may be exposed to a higher wildfire risk in Hawai’i?

Litton: I think I would answer that question by thinking about the distribution of non-native grasslands in the state. Almost all of these fires are starting in non-native grasslands. Unfortunately, they’ll often burn from these non-native grasslands that are found at lower elevations up into the forest ecosystems above them. And in that respect, they sort of knock the forest back a little bit with each fire and expand the coverage of grassland. 

Some of Lisa Ellsworth‘s work on lands where they stopped live fire military training and therefore took the fire ignition source out of those systems showed that [those lands] were able to revert back to woody ecosystems over relatively quick timescales. In one to two decades, you can go from essentially a non-native grassland to non-native, but at least a non-native woody ecosystem that has smaller fine fuel loads that carry those fires.

So that’s a kind of a long-winded way to get back to addressing your question. So I think where these non-native grasslands come from primarily is abandoned agricultural land. We had large-scale agriculture in Hawai’i in the past that was primarily sugarcane, and to a lesser extent, pineapple plantations. The market for sugarcane and pineapples moved to other places in the world. And so those agricultural industries went out of business, and it resulted in a lot of fallow agricultural land that were allowed to revert to non-native grasslands. And that’s where most of these fires start. 

So communities like Lāhainā that are surrounded by these fallow abandoned agricultural lands that have very high fuel loads are the areas that are the most prone to these sorts of fires that interact with urban environments. That’s gonna be primarily on leeward sides of the island, which are also the areas that get the driest. And so yes, I think it’s true that in general, rural communities have less of a capacity to be able to respond to wildfires when they happen. But what happened with the fire in Lāhainā shows very clearly that, you know, you don’t have to be in a rural area to be in danger of these sorts of fires. You just have to be in an area that’s in close association with this abandoned agricultural land and buildup of non-native grasslands.

 Daily Yonder: Are there efforts to plant native grasses, for example, in those fallow agricultural lands?

Litton: I don’t know that native grasses would be the best thing to put in there. Assuming that we’re going to continue to have ignitions, which I think is a safe bet because we’re going to continue to have humans and human activities in Hawai’i, if you put native grasses on [fallow agriculture lands] and you get a drought or you just get the dry part of the season, they’re going to dry out and produce fine fuels, creating a similar fire problem. 

So when you think about protecting communities from fire, you’ll hear people talk about the WUI, the wildland urban interfaces. That’s where a lot of management, fire management and preventative management, happens. Some of that is just simply reducing fuel loads, whether that’s weeding the grasses so that they don’t produce a lot of fuel loads, whether it’s using herbicides to keep the grasses out of there in the first place, that’s an important technique. 

But another one that I think we could and should do more of in the state is along the lines of green breaks. That’s not just reducing these fuel loads that carry fires, but it’s putting species and managed ecosystems in place that are much, much less likely to burn. You need to think about species that are adapted to the areas that you’re trying to restore that have relatively high moisture contents, live biomass moisture, as well as ideally live fuel moisture content. 

Those are the sorts of species and the sorts of managed ecosystems that are going to be able to, if not stop a fire, at least slow it down so putting the fire out or controlling or managing it would be a lot easier to do.

 Daily Yonder: That makes sense. Switching gears a little bit: You’re in Hawai’i right now watching the recovery efforts begin in Lāhainā. Is there anything that you’re seeing that is something that could be improved upon or something to learn from in responding to future fires like this in Hawai’i? There have been lots of challenges that have been brought up already by the media, but I’m wondering if you yourself have seen any challenges that you think could be responded to better?

Litton: I think we need to, as a state and as counties, allocate a lot more resources, money and people to wildfire prevention and wildfire management. The wildfire problem in Hawai’i, as we’ve talked about, is largely a human problem. The ignition sources are largely human ignition sources. The fuels that are driving these wildfires are due to human introductions of these species and abandonment of agricultural land and letting these lands be overtaken with these non-native grasses. 

So I hope that this will be a little bit of a wake up call for the state that this is a natural resource management issue that we need to be giving a lot more attention to so that these sorts of impacts to communities are greatly mitigated moving forward. 

It’s also been pretty well established that these fires are detrimental to most native species and most native ecosystems. And so they do have an important role to play in our ongoing biodiversity crisis, loss of biodiversity in Hawai’i. Most of our [native] species are found nowhere else. And so if we lose a species in the state of Hawai’i, then it’s a pretty good chance that we lose that from the whole planet. 

I think the big take-home lesson for me in terms of trying to mitigate the negative impacts of wildfires on communities is that we need to be allocating more resources. We need to understand the scale of the issue, and we need to be allocating resources that are proportionate to the scale of the problem.

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