A conversation with Dr. Tyler Hoecker, who studies forest ecology and the changing dynamics of fire as the climate warms. This episode was recorded in August of 2023.

Glacier Conservancy: https://glacier.org/headwaters Frank Waln music: https://www.instagram.com/frankwaln/ Stella Nall art: https://www.instagram.com/stella.nall/

Climate change in Glacier: https://www.nps.gov/glac/learn/nature/climate-change.htm Dr. Hoecker’s research: https://www.sciencedirect.com/science/article/abs/pii/S0378112721009051

---

TRANSCRIPT:

---

Lacy Kowalski: Headwaters is supported by the Glacier National Park Conservancy.

Peri Sasnett: This is Headwaters, a show about how Glacier National Park is connected to everything else. My name is Peri, and I'm talking to you from the dense forests of northwest Montana. This episode is an interview that my co-host Daniel did with forest ecologist Dr. Tyler Hoecker about how wildfires exacerbated by climate change are upending our forests. This episode is part of a series of conversations we've been having with a wide variety of climate change experts. These episodes don't have to be listened to in any order, each one stands on its own. And they all focus on a particular aspect of the way the world is being altered by the burning of fossil fuels. Over the past century and a half, human activity has released enough greenhouse gases to warm the Earth's climate over one degree Celsius, with only more warming on the way. Throughout 2023, Daniel sat down with experts to talk about how that warming is altering Glacier National Park, our lives and our futures. [drum and synth beat starts to play] I find fire fascinating, so I think this conversation was one of my favorites. I feel like I've heard most of the usual stories about wildfire so many times, so I was really excited to hear about Dr. Hoecker's research on how forests are responding to climate change. It felt like a new angle. I learned a lot, and I hope you do too.

[beat concludes]

Daniel Lombardi: So, Dr. Tyler Hoecker, welcome to Headwaters.

Tyler Hoecker: Thanks so much for having me.

Daniel: It feels pretty good that we're talking today, or auspicious or bad, on like just this week the smoke really rolled into the park. We have several new fires burning right around us. It's very much fire season, so it's a good time to have this conversation. Will you introduce yourself and talk about kind of your job and the work you're doing right now?

Tyler: Sure. So I'm Tyler Hoecker. I'm a research scientist at the University of Montana in Missoula. And right now I'm doing research trying to understand how climate change is changing fire activity across the western U.S. and trying to project how fires and forests might change into the future.

Daniel: How did you get into fire stuff, like how did that become the path for you?

Tyler: I think everybody is sort of drawn to fire, in a, in a weird way, you know, fires are pretty important, has been an important like catalyst, you know, for civilization. And so I think it's sort of just a compelling thing.

Daniel: It's kind of a universal concept, that fire and flames draw your eye and like draw you in.

Tyler: Absolutely. Absolutely. It's hard to think about forests in the West without thinking about fire. I remember as an undergrad, I took a a forest ecology and policy class, and we went to a community fire meeting. And I just remember being really fascinated by the process. And it was clear to me pretty quickly that it was really important at shaping forests in the West. And so I was really interested in understanding it. And, you know, it's sort of interesting to think back on that. You know, that was 2010. And, you know, I think fire scientists probably understood what was what was unfolding in terms of fire in the West. But I don't think anybody would have been able to really predict, you know, what's happened in the last 13 years since in terms of the amount of area burned every year. And, yeah, the types of fire events that we're seeing every summer now.

Daniel: Yeah. So let's jump into some fire ecology. At one point I was hiking up Mt. Brown and it was kind of in the fall, early fall, the fireweed was blooming and like the sun was rising and kind of glowing through it. And there was the cloud layer was like fog all in the forest. And so I was walking through that and it had burned, you know, like a year before. So everything is charred and crisp and like pretty black. There's no living trees. But in that morning light, it was so beautiful. And for me it was kind of like a pivot point. This, like black backed woodpecker, flew down and landed on the tree in front of me and was feasting on beetles that like the fire-killed trees. And I was like, Oh my gosh, like fire is not ugly. The aftermath of fire can be really beautiful. And I knew intellectually that it's also ecologically important. So maybe we can start with something like that. Like why, why is fire important in a place like Glacier National Park?

Tyler: So one of the things that I like to, to maybe start by kind of acknowledging or stating is that fire, in seasonally dry places, is inevitable. I mean, it's important to think about the benefits and the risks and things like that. And it's also important to acknowledge that it's inevitable. And it's just it is. And it will always, it will always happen in seasonally dry places.

Daniel: Yeah. So like, this place gets dry. There's lots of things growing here -- trees -- it's going to burn.

Tyler: Exactly. And so that means that everything that we see when we look at forests in fire-prone places are shaped by fire. Right? And so the species that we see, that's the forest structure or kind of the age of the trees and the way that they're arranged on the landscape in a place like Glacier, that that is driven primarily by fire and the history of fire.

Daniel: The animals and the trees that have lived here for millions of years have lived here with fire for billions of years. They always have coexisted.

Tyler: Exactly. But the biggest thing is that fires create what we call, like heterogeneity. You know, the opposite of homogeneity. Heterogeneity is variation in species composition, in structure and physical structure of a vegetation. And that heterogeneity confers resilience, right? And so a forest and an ecosystem that's heterogeneous, that's diverse and variable is going to be more resilient to future disturbances, to different pressures and stresses to insects and pathogens to drought.

Daniel: So would you say, when you say that fire creates heterogeneity in an ecosystem, in Glacier National Park, it kind of sounds like you're saying fire creates complexity.

Tyler: Absolutely.

Daniel: Okay. And that creates complexity means different habitats, which means that allows for biodiversity for more kinds of life to live in one place.

Tyler: Absolutely. So biodiversity basically emerges from complexity. Right? A complex system has more niches, has more opportunities for different types of organisms, and that creates a richer system.

Daniel: Compared to, say, a cornfield or like a forest that's all just one kind of -- lodgepole pine say. You know, it's just all one tree. So only certain kinds of birds, only certain kinds of animals are going to live there. You start mixing that up, you burn it and different trees start growing, then you're getting more complexity. You're getting more biodiversity.

Tyler: Yep.

Daniel: That's cool.

Tyler: Yeah.

Daniel: Not every tree in the forest has the same adaptations to fire. Some trees are adapted where they like a little bit of fire. Others, they only grow in places that probably aren't going to burn. So maybe you could break that down a little bit. Like, what are the strategies for trees? What are your options?

Tyler: Right. So trees or plants, you know, have these, as you described them, quirks, right. These characteristics. And in, and in sort of the ecology world we call those traits, but I think makes more sense to call like a strategy. So basically your options are to avoid fire, to be a species that can either hang out for a long period in the understory and during a long fire free period, or can tolerate cool, wet sites where fire is less common and happens never or very infrequently. So those are species like subalpine fir, Engelmann spruce, western red cedar, western hemlock. Those are trees that grow in regions or in microclimates that tend not to burn very often or tend to burn very infrequently. And so there's a long fire-free interval in which they can establish and become dominant.

Daniel: So if you're familiar with the park, then like somewhere like the Fish Creek campground or the Avalanche area. These are like little pockets in the landscape where a creek goes through the middle, they get a lot of rain right there, they get a lot of snow. And so you have a lot of cedar and hemlock, these forests that are really dense and dark and mossy, you can just feel that it doesn't feel like fire comes through there very often.

Tyler: Exactly. Yeah. And so the other strategy or another strategy is to resist fire, and to survive fire as an individual. So those are species like ponderosa pine, western larch, and they have things like thick bark. They drop their lower branches, so that there aren't ladder fuels that would carry flame to the crown. They have rot-resistant wood, so that when their trunk is scarred by fire, that exposed wood doesn't rot. Hmm.

Daniel: And then there's all kinds of species that are-- there's all kinds of other strategies, too.

Tyler: Yeah. And so there's there's maybe sort of a third strategy around what we might say, fire embracing, or fire resilient.

Daniel: Fire loving.

Tyler: Yeah, fire loving. And ...

Climate and the Future of Forests with Dr. Tyler Hoecker