00:17:59

Hosts: Anna Reser and Leila McNeill

Guest: Valerie Trouet

Rate. Review. Subscribe.

In this episode, dendrochonologist Valerie Trouet of the Laboratory of Tree-Ring Research at the University of Arizona talks with Anna and Leila about her new book, Tree Story: The History of the World Written in Rings. She talks about the fascinating science of tree-rings and what they can tell us climate patterns and ecosystems.

Show Notes

Valerie Trouet

Tree Story: The History of the World Written in Rings

Transcript

Transcription by Julia Pass

Anna:  Hi, everyone. Anna here. I wanted to jump in at the beginning of this episode just to let you know that it's gonna be a little bit different. Today we have an interview with Dr. Valerie Trouet, who is an associate professor in the Laboratory of Tree-Ring Research at the University of Arizona. We talked to her about her wonderful new book, Tree Story. We hope you enjoy this interview. We had a really great time talking to Dr. Trouet and learning about the science of tree rings.

Leila:   Today we're talking with Valerie Trouet. She is an associate professor at the Laboratory of Tree-Ring Research at the University of Arizona and author of the new book Tree Story: The History of the World Written in Rings, which is coming out with Johns Hopkins University Press. This book takes us through an exploration of the familiar, I guess, practice of counting tree rings and how this practice can tell us much more than just a tree's age. Dr. Trouet, welcome to the show.

V. Trouet:        Well, thank you so much for having me.

Anna:  Let's jump right in. Can you start by telling us a little bit about yourself and how you came to be a dendrochronologist and a little bit about what that science involves?

V. Trouet:        Sure. My name is Valerie. I'm Belgian originally, so if you hear an accent, that's 'cause my mother tongue is Dutch. I did all of my education, including a PhD, in Belgium and then moved to the US afterwards. And I'm now a professor in the Laboratory of Tree-Ring Research, which is a department of its own at the University of Arizona. I moved there in 2011.

V. Trouet:        I became a dendrochronologist pretty haphazardly. I think that's the case for most of my colleagues. I don't think anyone as a kid grows up and thinks like, "Ooh, I wanna be a dendrochronologist when I grow up." When I was looking for a topic for my master's dissertation, my master's thesis, I was very much an idealist at the time. So I was studying environmental engineering, and I wanted to do something that would improve the situation of the world. And my idea of doing that at the time was going to Africa.

V. Trouet:        So I really wanted to go to Africa, and there was this one topic that was available that was set in Tanzania that involved dendrochronology. And so I was like, "All right. If it allows me to go to Tanzania, I'll do dendrochronology." I'd never heard of it before. I went on a long field work trip to Tanzania, came back, and when the samples that me and one of my colleague students at the time—who's now also a dendrochronologist, by the way—when the samples finally arrived in Belgium and we started looking at the wood under the microscope, that's when the dendrochronology bug really bit me.

V. Trouet:        I really like looking at wood under a microscope. It's gorgeous. It's really beautiful. And then doing dendrochronology, the actual act of—we don't just count the tree rings, but we match the patterns that we see in tree rings from different trees. And the process is called cross-dating. It's really a lot like putting a puzzle together. You're trying to match pieces from a puzzle together. So you can just spend hours doing it without getting bored. At least I could.

V. Trouet:        So that, really, the combination of the beauty of the wood and then the process of puzzling and the process of doing all that, coming up with new scientific discoveries, it was really very exciting to me. And so I continued on to do a PhD dissertation on the same topic, and then I've never done anything else. I've been a dendrochronologist ever since. Yeah. That's the story.

Leila:   Well, this book in particular is somewhat unusual in that it really reads like a memoir. And we enjoyed the descriptions of your research and travels and adventures. But we wanted to ask why write about dendrochronology in such a personal way?

V. Trouet:        There's a couple of reasons. Thanks for the question. One is that I've done quite a bit of outreach. So I give public talks and I speak to the media every now and then. And what struck me or what people often tell me is that when I talk about anecdotes, when I provide anecdotes or stories about my research, that's what really captures their attention and that's what keeps them attentive to what I'm saying. And so I realized that through telling stories and anecdotes, that's a really good way of bringing the science to a broader audience, which is the intention of this book. It's not a academic book. It's a broad audience book.

V. Trouet:        The other aspect of that is that tree rings lend themselves to that so well. They're a very approachable science. Everyone or most people have looked at the rings in trees as a kid and counted them and figured out that that's a way to determine how old a tree is. So there's a concept there that most people are familiar with. I'm not talkin' about some far-flung galaxy or about some obscure enzyme. It's something very tangible that people are familiar with. And so we can start from that and then build on that to come to the exciting, really profound scientific insights that we can get starting from that familiar concept.

V. Trouet:        And I guess a third reason why is that it's a female voice. I'm a woman scientist. There's not that many books written by women scientists. And I think also talkin' about what that experience is like, to be a scientist and to do scientific research, it is important to bring that voice out there.

Anna:  That kind of leads me right into my next question, which is about being a woman scientist and being a woman dendrochronologist in particular. I think we often find that sometimes field sciences are sort of more stratified by gender, and I just wonder for your field if there's a kind of, with all of the sort of hiking and going to remote places to sample trees, is there kind of an aspect of risk or ruggedness that kind of makes dendrochronology one of these sort of manly sciences? I don't know if that's reaching, but could you just talk a little bit about?

V. Trouet:        I think it's in our field, as it is in many other fields, in that there's actually quite a lot of women, or it's fairly evenly distributed in the early career stage. So PhD students, master's students, postdocs, there's quite a lotta women. Also because there's a few important applications of tree-ring science, right? One is ecology. The other one is climatology. And for those, those involve extensive fieldwork. But then the third important application is archaeology and art history. So we use the rings in trees to date archaeological material or paintings or shipwrecks and so forth. And that traditionally is a field where there's very good female representation.

V. Trouet:        But as in many academic fields, and I'm experiencing this now as someone who's in a more senior position as an associate professor, representation of women declines as you go up the ranks. Let's put it that way. So there's fewer and fewer women in those more leadership positions. Yeah. In my book I mostly describe field campaigns in more remote areas.

V. Trouet:        That being said, I've often been the only woman on a team of men. For instance, when I was in Siberia for 10 days, which was pretty rough [unclear 08:48], that's true. But you can also do dendrochronology in your backyard, right, or in the forest, in your campus forest or the park in the city where you live in. So there is an aspect of it that can also happen closer to home, and it's less adventurous but more easily combinable with other aspects of life. Let's put it that way.

Leila:   I love that idea, that you said this is something you can do in your own backyard, that you could do it anywhere. But one of the things that in the book that I was most interested in is how the science kind of sits at the nexus of all these other fields. And you just mentioned some of them, like archaeology, and then other ones that you might not expect, like astronomy. What's it like to work in such a deeply interdisciplinary field, and how do you think that this affects how dendrochronology is done today?

V. Trouet:        Yeah. Very good question again. To me it's very exciting because it means that you can meander in your choice of topics and you can change. So for instance, I came in from an environmental engineering, kind of a forestry background then started studying the climate of the past with tree rings, so I kinda veered in that direction. And now more and more I realize like, "Oh, we're in a unique position with this climate history that we're putting together to also look at how climate has influenced human history." So I'm moving a little bit in that direction. So you're really not limited to any topic, which makes it continuously exciting. You don't easily get bored as a dendrochronologist.

V. Trouet:        The other aspect of that is that I mentioned I'm a professor in the Laboratory of Tree-Ring Research. So we're a department of our own. There's about 12 faculty who all specialize in dendrochronology and tree-ring science. But some of us are archaeologists. Some of us are chemists. Some of us are hydrologists. Some of us are forest ecologists. Some of us are climatologists like myself. So it's really a mixture of bringing together these various fields that really creates a ground for deep thought. Let's put it that way. And to be fair, it's also a nexus that is really relevant for our human system as we're moving forward, right? This combination between forest ecology and climatology and human ecology, the combination of the three is very powerful. It's a very important topic to study moving forward.

Anna:  Yeah. So I wanted to ask you more about that, about working in climate science. And obviously that's a very politicized place to be, and I'm just curious about your experience doing this kind of work. And, I don't know, I'm sure you've received some pushback about your findings or stuff like that.

V. Trouet:        I must admit I've been fairly lucky so far, as in the pushback has been fairly limited by, let's say, well-known climate deniers who just push back on every single study that comes out regarding science. But it's not been very open into the public sphere, which I'm very grateful for because especially, again, as a woman and climate scientist, you're very vulnerable to attacks from climate deniers or climate skeptics. It can be quite vile. But personally I've not experienced that, knock on wood. Maybe because I'm working with wood I've been lucky in that way.

V. Trouet:        But I do describe in the book. The famous example of that happening is when my colleague Malcolm Hughes and his colleagues Michael Mann and Ray Bradley brought out or published what's now called the "hockey sticks" or "tree-ring-based" reconstruction of temperature over the last 1,000 years that shows that the most recent year at that point in time, the year 1998, was the warmest year over the last 1,000 years. That study was published in 1999, and it got a huge amount of pushback that's really unleashed climate deniers because it was such a prominent study. It was part of the IPCC report at the time. It was on all the media. It was on TV and so forth. So that really created a very strong climate denial pushback, even as far as in the US Senate. So I do describe that story in my book. But personally I've been not as subject to such strong pushback so far.

Leila:   Well, before we wrap up, I wanted to ask just one question. What is something in the field or in your research personally that you're most excited about at the moment?

V. Trouet:        One of the applications of tree-ring research that I'm really passionate about is how we can use tree rings to look at forest fires in the past. So fire history. So I've done a lot of that work in California, and it's really told us the story of fires in the American West that without tree rings, we wouldn't know that story. We wouldn't know that in the past there used to be frequent ground fires that we've then put out in the beginning of the 20th century. So even, I mean, there's a photo in the book as well that just shows—it's such a beautiful—you can see the scars in the wood that those fires left. You can date them using dendrochronology.

V. Trouet:        And so you can really come up with fire history in a very extensive and detailed way, to the extent that we've been, as I mentioned, able to put together the fire history for the American West but also look at how climate influences those fires, how land use change has influenced these fires. For instance, how the fires in California changed after the Gold Rush, how they changed after the establishment of the missions, how they changed after the establishment of the Forest Service, and so forth. So I think that really, as we were talkin' about the nexus between ecology, climatology, and human history, and I think the study of forest fires through dendrochronology really puts those three aspects together beautifully.

Anna:  Well, is there anything that we didn't talk about that you really wanted to cover?

V. Trouet:        I think one last thing is that I haven't really talked about that, but with tree rings, we study the past. But trees also play a really important role for our future, right? They capture CO2 out of the atmosphere, so they're one of the solutions to mitigating manmade climate change. And I think there's an important role for tree rings there as well, to see how much carbon can we capture, how can we use trees as a solution. And I think that's a beautiful thing as well, that it allows us not only to look at the past, but also to look at what might come in the future.

Anna:  All right. Well, I think that's a great place to wrap up and a really nice kind of sentiment to wrap up on. Dr. Trouet, thank you so much for joining us today, and congratulations on the publication of your book.

V. Trouet:        Thank you so much.

Anna:  Like our episode today? Please leave us a rating and review on Apple Podcasts so that new listeners can find us. If you have questions about the interview, tweet us at @ladyxscience or use the hashtag #ladyscipod. For show notes, episode transcripts, to sign up for our monthly newsletter, read articles and essays, pitch us an idea, and more, visit ladyscience.com.

Anna:  And we are an independent magazine, and we depend on support from our readers and listeners. You can support us through a monthly donation with Patreon or through one-time donations. Just visit ladyscience.com/donate. And until next time, you can find us on Facebook at @ladysciencemag and on Twitter and Instagram at @ladyxscience.

Image credit: Weathered growth rings at Aztec Ruins National Monument, Michael Gäbler, 2010 (Wikimedia Commons | CC BY 3.0)