Come Rain or Shine

Assessing Climate Change Vulnerability of Navajo Nation Forests

July 06, 2022 USDA Southwest Climate Hub & DOI Southwest Climate Adaptation Science Center Season 3 Episode 7
Assessing Climate Change Vulnerability of Navajo Nation Forests
Come Rain or Shine
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Come Rain or Shine
Assessing Climate Change Vulnerability of Navajo Nation Forests
Jul 06, 2022 Season 3 Episode 7
USDA Southwest Climate Hub & DOI Southwest Climate Adaptation Science Center

Warming temperatures can exacerbate forest drought stress, reducing defenses to bark beetle outbreaks, wildfire, and tree diseases. Concern about losses within the forests of the Navajo Nation due to these stressors led to a partnership between the Navajo Forestry Department and a diverse group of scientists to assess the vulnerability of Navajo forests to climate change and develop strategies to promote forest resilience to drought and extreme fire behavior. Here we speak with Principal Investigator Dr. Margaret Evans, and forestry consultant Jaime Yazzie, to learn more about this project.

Relevant Links:

Forest Monitoring and Tree Ring Data to Inform Forest Management on the Navajo Nation

CASC Project Explorer: Forest Monitoring and Tree Ring Data to Inform Forest Management on the Navajo Nation 

Building Authentic Collaborations With Tribal Communities: A Living Reference for Climate Practitioners

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Come Rain or Shine affiliate links:
DOI Southwest CASC:
USDA Southwest Climate Hub:
Sustainable Southwest Beef Project (NIFA Grant #2019-69012-29853): 

Show Notes Transcript

Warming temperatures can exacerbate forest drought stress, reducing defenses to bark beetle outbreaks, wildfire, and tree diseases. Concern about losses within the forests of the Navajo Nation due to these stressors led to a partnership between the Navajo Forestry Department and a diverse group of scientists to assess the vulnerability of Navajo forests to climate change and develop strategies to promote forest resilience to drought and extreme fire behavior. Here we speak with Principal Investigator Dr. Margaret Evans, and forestry consultant Jaime Yazzie, to learn more about this project.

Relevant Links:

Forest Monitoring and Tree Ring Data to Inform Forest Management on the Navajo Nation

CASC Project Explorer: Forest Monitoring and Tree Ring Data to Inform Forest Management on the Navajo Nation 

Building Authentic Collaborations With Tribal Communities: A Living Reference for Climate Practitioners

If you’re enjoying this podcast, please consider rating us and/or leaving us a review on Apple Podcasts, Podcast Addict, or Podchaser Thanks!

Follow us on Twitter @RainShinePod

Never miss an episode! Sign up to get an email alert whenever a new episode publishes

Have a suggestion for a future episode? Please tell us!

Come Rain or Shine affiliate links:
DOI Southwest CASC:
USDA Southwest Climate Hub:
Sustainable Southwest Beef Project (NIFA Grant #2019-69012-29853): 

Sarah LeRoy: Welcome to Come Rain or Shine, podcast of the USDA Southwest Climate Hub and the USGS Southwest Climate Adaptation Science Center, or Southwest CASC. I'm Sarah LeRoy Science Applications and Communications Coordinator for the Southwest CASC. And I'm Emile Elias, Director of the Southwest Climate Hub. 

Here, we highlight stories to share the most recent advances in climate science, weather and climate adaptation and innovative practices to support resilient landscapes and communities. We believe that sharing some of the most innovative forward thinking and creative climate science and adaptation will strengthen our collective ability to respond to even the most challenging impacts of climate change in one of the hottest and driest regions of the world.

The contents of this podcast are for informational purposes only and should not be interpreted as endorsement for any of the products, technologies, or strategies discussed. 

Forests of the Navajo nation are experiencing an increasing likelihood of extreme conditions. Warming temperatures are exacerbating drought stress, which reduces defenses to bark beetle outbreaks, wildfire, and tree diseases.

Mutual concern about forest loss due to these stressors formed the foundation for a partnership between the Navajo Forestry Department and scientists from the University of arizona, Laboratory of Tree Ring research, Utah State University, and the National Oceanic Atmospheric Administration's National Center for Environmental Information.

With funding from the Southwest Climate Adaptation Science Center. The team is assessing the vulnerability of Navajo forests to climate change and developing strategies to promote forest resilience, to drought and extreme fire behavior. Today we're talking with the principal investigator on the project, Dr. Margaret Evans, who is an associate professor at the University of Arizona. We're also talking with Jaime Yazzie who worked on this project as a forestry consultant to lead the field collection after having completed her master's degree from Northern Arizona University in 2017. Welcome Margaret and Jaime. Thank you both for joining us today. Jaime, before we begin, would you like to introduce yourself?

 Jaime Yazzie: Yes, thank you. [Diné introduction] I am of the Cliff Dwelling and Honeycomb Rock People Clan, born for the Reed People. My maternal grandparents are One Walks Around Clan and my paternal grandparents are Chiricahua Apache. I’m originally from Genado and this is how I introduce myself as a Navajo woman. 

Sarah LeRoy: Thank you. Could you please give us just a brief overview of the project and its objectives and Margaret we'll start with you on this. 

Margaret Evans: Sure. Yeah. So our objective in this project, is to enhance the ongoing forest monitoring that is, is already going on on the Navajo nation. So the Navajo Forestry Department has a forest monitoring program that's been going on since the early 1970s.

So that means they have been monitoring the, the forest for about 50 years with a program that's called the continuous forest inventory or CFI. And our objective is to enhance that monitoring by adding tree ring sampling to a subset of the network of forest inventory plots that, that they have. So there's 272 of these forest inventory plots that are spread out throughout the forested lands of the Navajo nation.

And so what we've done is we've collected tree ring data in a subset of those of those forest inventory plots. And there's two things that we, that we use the tree ring data to, to get at. And one of them is how are the trees doing, in terms of how they're responding to climate variability and climate change trends in how climate is changing over the last several decades.

And then the second thing is to use those data, to look into the future. And use this data to, develop a forest management tool. It's called the Forest Vegetation Simulator. That's used as a decision support tool that will allow the foresters to look at, how is the growth of the trees gonna look going into the future for the next several decades based on data that were collected there at the Navajo nation that are so the, the models really tuned to the conditions of those Navajo forests.

I just wanna point out that the Navajo forestry department actually has one of the longest running forest monitoring programs in the US Southwest. So the US Forest Service also has its own monitoring network, which is called the Forest Inventory and Analysis Program. But those data go back to the 1980s and 1990s, and they've been a little bit less consistent about revisiting the plots and going back and remeasuring the trees. And so Navajo Forestry Department has one of the best data sets in the whole region. In terms of over the 50 years, since the plots were first installed, they've been visited about four times, so about every 10 to 15 years.

And it's very much like the US Census where, they come and knock on your door every 10 years and they ask how many people live here and of what age, gender, demographic information. So forest inventories are very much like a census. Where they go to this same place in the forest.

That's been permanently marked and mapped and, check on those individual trees. Are they still alive? Have they died? How much did they grow? Are there new births in the population, new trees that have reached the sort of minimum size threshold to be included in that inventory. And that gives us the demographic data that we need to be able to get an idea of.

What are the trends in terms of forest health? Is there regeneration happening? How much are the trees growing? Is there death, is there harvest. What kinds of things are going on. And that that's really important to get, get a handle on the status and trends of forests and forest health. 

Sarah LeRoy: Thank you for that added explanation and just taking a step back a little bit and thinking, for those of our listeners that aren't familiar with forestry practices, could you explain just in a general sense how you obtain tree ring data from a living tree and then what kind of information you can learn, from that data. Margaret. 

Margaret Evans: Yeah. So tree ring data is it's a really incredible source of data that, so the, the tool that's used to collect tree ring data is called an increment borer and it's a metal tube that has a very sharp end. And then there are these spiral metal threads that go from the sharp end up sort of like the threads on a, a screw, a metal screw.

And so, you press that sharp tip of the borer into the tree and you start turning the, clockwise, just like a screw. You start turning it into the tree and it bites through the bark and then goes into the wood. Inside the tube, there's a little bit of wood, sort of about the, the size of a pencil in terms of width that's inside the tube.

And then you start rotating the other direction, counterclockwise that breaks that piece of wood that's inside the tube. You take it out of the tree and then you have this little piece of wood. That's really just kind of like a pencil. It could be a very, very long pencil if it's a large tree. And you've gone all the way to the center of the tree.

That's a very, very long pencil. Or if it's a small tree, then it's a short pencil, but it's, it's a piece of wood that if you've done it right, it goes all the way to the pith of the tree, which is, the very center of the tree and the earliest growth rings. And it gives you a piece of wood that, that gives you the, the material to look at those growth rings. Those annual growth rings year after year, the tree puts on wood and that increment core, that little piece of wood then gets mounted onto another piece of wood, sanded to a very fine Polish, a very smooth surface. And then we look at it under a microscope, we identify the rings, we assign a year of formation to the, to each ring, and then they get measured using a microscope and a measuring stage.

And so by hand there's a person, sort of turning a little, a little dial and the measurements are made in micrometers. So very, very precise measurements of the width of the rings. And it allows us to look at how much the tree is growing in every single year. And generally, and especially in this dataset every year of the entire tree's life.

Jaime, do you wanna add anything? 

Jaime Yazzie: Yes. So the tree rings can tell us how old the tree is. And it's useful for dating historical events in the life of the tree. And our work is mainly focused on tree growth as an indicator of forest health, but there's a lot of other uses of dendrochronology such as dating when wildfires have happened, reconstructing fire history, reconstructing climatic conditions, whether you're looking at climate through precipitation or temperature, it can record insect outbreaks as well as earthquakes and diseases. So it's really good indicator for the condition of the forests. 

Sarah LeRoy: Thank you for that explanation. And so I'm wondering Jaime how treeing data is specifically helpful to your analysis in this project? 

Jaime Yazzie: Yes. So there's a lot of things that the tree rings are useful for first, they allow us to look at the effective climate variation on tree growth. Answering the question, what is the effect of warmer temperatures, warmer drought, and we're using tree growth as an indicator of forest health.

The forest inventories that have been done every 10 to 15 years, don't provide the kind of data needed to detect year to year variation in temperature precipitation that affect forest health. And second, they allow us to look at long-term trends we've collected over just about a thousand tree cores within our field seasons and some of the oldest cores date back to the 1500s, 1600s.

And so it's a long time series all the way to now to 2021 when we ended the field season. And so when we core tree, we go all the way to the center to make sure that we can date it back to how the tree has been doing, every year throughout the most of its life. Do you wanna add anything, Margaret?

Margaret Evans: Yeah, just again, emphasizing the thing that's really special about tree rings is that it gives us the ability to look at growth in every single year of the tree's life. And then we can associate that with the climate records in terms of how much did it rain? What was the temperature like? We have monthly climate data products for the entire North American continent for every location.

And so we can correlate with statistical models, how much the tree grew in terms of the width of that growth ring. And how much winter precipitation there was or cool season precipitation, which turns out to be a really critical variable that drives variation and growth across the whole us Southwest.

But we also see, temperature, temperature variability also affects the growth of the trees and that's something that, like Jaime was saying the forest inventory data, if you measure once every 10 years or 15 years, the only thing you can look at is average precipitation across that whole 10 year or 15 year period and how much the tree has grown over that same interval.

So the tree ring data enhance and, augment that already ongoing forest monitoring by allowing us giving us that annual resolution information about how trees are responding to that inter-annual variability. 

Emile Elias: Thanks Margaret. And you mentioned the CFI or the continuous forest inventory plots used by the Navajo Forestry Department, since I think you said the 1970s, so a long term record of locations.

And it seems like for this project you were working on a selection. Of those continuous forest inventory plots. And so I'm curious about how you selected those and the range of variability between those plots and how representative you think those conditions might be for the broader forest.

Margaret Evans: Yeah, that's a great question. We put a lot of thought and effort into trying to make sure that the sample that we're taking is very representative and unbiased with respect to the range of variability of forest conditions that are out there on the Navajo nation. So that means elevation variability. These forests are found from about 7,000 to about 9,000 feet in elevation.

It's also species composition, slope aspect, biophysical variables that really, strongly influence what kind of vegetation you see. And so we put a lot of thought and effort into using previous forest inventory data also to capture variability in forest stand conditions like the density of trees which varies on the landscape also, and also the sort of average size of trees.

I'm gonna pass it over to Jaime because she led the field campaigns both in 2019 and 2021. So she actually visited every single one of these plots. So she can speak a little bit more specifically to what they look like. 

Jaime Yazzie: Yes. So a lot of these plots, they're very different in sort of the forest types, elevation, the slope that we covered. The Navajo forest is sort of compartmentalized between three different regions. You have the Defiance plateau, you have the Chuska and Lukachukai mountains, as well as sort of like the Tsaile region that's connecting these two mountains. And throughout this, the, the plots are really defined by within the lower elevation.

You see a Ponderosa dominated forest, including one of the largest stands of old growth pine in the Southwest and the associated tree species with this range from Pinion Pine to Gamble Oak, two different types of Juniper and in the higher elevation, these tend to be in the Chuska and Lukachukai mountains. The forest type is often Ponderosa dominant, but we do see many, many types of mixed conifer forests with variations in Douglas fir, Cork bark fir, Quaking And so within these two mountains, they're very different in that, the lower elevation we have more open stands, a little bit more dryer conditions and in the higher elevation stands, it's very cool, receives more precipitation and often a little bit more denser than the Ponderosa pine dominated stand.

Emile Elias: Thanks, Jaime. And to add on to that question, I'm wondering about the relationship between climate stress and elevation. So were trees at lower elevations more impacted by certain things as opposed to other trees at higher elevations? 

Jaime Yazzie: So, well, we have seen everywhere across through this data collection, negative effects of inter-annual variation and temperature of the previous fall and current spring.

And collectively a positive effect of the cool season precipitation. From our initial field season in 2019, there is a potential trend that we noticed being that lower elevation forest stands are more sensitive to temper variation. And high elevation stands are less sensitive to temporal variation.

But with the second field season, we worked hard to strengthen the sampling at high elevation, sort of to fill in some gaps that we noticed in 2019 under the guidance of the Navajo Forestry Department. And through that, we're hoping once that's added to the overall analysis, we'll be able to have a better understanding on the relationship and the differences, according to the elevational trends.

Emile Elias: Thanks Jaime, and Margaret, did you have anything to add around the relationship of climate stress and elevation? 

Margaret Evans: Yeah, just a little bit. I wanted to kind of put this in context also in terms of longer term trends, which is, one of the strengths of the tree ring data. We get these time series data that are decades long and what we know actually also from tree ring data but separate studies is that the last 20 years has been some of the most extreme drought conditions of the last 1200 years. So more than a thousand years. There's a studies by a Denver climatologist named Park Williams, where he's used tree ring data to reconstruct drought conditions over the last 1,200 years. 

And just this last year looking, adding in the 2021 data, when they did a reanalysis, this 20 year period of the 21st century is the most extreme drought that we've seen in Southwestern North America for more than a thousand years. So there are drought conditions throughout this region across the whole Southwestern US or Southwestern North America that have emerged pretty strongly in the last 20 years.

And we do see an effect of that trend. Looking at the tree ring time series data. So we see reduced basal area increment, reduced growth, trends in declining growth that are not due to the changing size of the trees and not due to the changing competitive conditions. And so this is a really unique data set where we have all of that contextual information about not just isolated trees, but trees in a forest context where we can control for the effect of the tree size and the forest stand conditions.

And we're able to say that there's declining growth that is, caused by this trend of drought. 

Emile Elias: Thanks Margaret. And I wonder if you can define for us basal area increment how that's measured and what that is. 

Margaret Evans: Sure. Yeah. So if you think about a tree like the, the stem of a tree or the, the forestry word is bole B O L E.

So the trunk of a tree, if you were to cut it down, it's a circle and the area of that circle, or remember PI R squared is sort of the spacial footprint of a tree. And so one way to think about the growth of a tree is how much has that footprint gotten larger. How much has the diameter or the radius of the stem of the tree increased from one year to the next?

And the tree ring data allows to make those calculations of how much the radius or the diameter of the tree has increased in every single year. And so, we express it in terms of basal area, rather than you know, there's a number of different ways to measure tree growth. If you're looking at just radial or diameter increments, that's a linear dimension.

It's just a measurement like on a ruler. If you look at area, then it's, it's a, it's in inches squared or, centimeters squared. So it's to the second power and then there are other metrics that, that have to do with volume. So thinking about the, the tree as a whole three dimensional organism, which is really what it is, it's three dimensional, but we're limited in our ability to, to observe and measure the growth of a three dimensional organism.

So we, we talk about basal area as one way to measure the growth of the tree. 

Emile Elias: So thanks for bringing up the drought, the drought conditions that have been especially severe over the last two decades and how that relates to some of the trends you're seeing. And I'm wondering if the drought or your results impact the forest management approaches in different areas within Navajo forests.

Jaime Yazzie: So right now, the Navajo Forestry Department operates under a 10 year management plan. This is currently under development. So the past management plans combined even and uneven age silvicultural treatments. And, currently at this time, there is limited forest management. They do manage alternative programs, such as issuing wood permits for tribal citizens to harvest firewood, poles and other wood products for cultural, provisional, and subsistence uses. These programs have certain regulations regarding tree conditions, tree size and species. For example, 50% of Dine households use firewood as the main source of heating. So dead and downwood is collected for personal use or resell. Another example is that poles are, marched by the forestry departments and then cut down by tribal citizens to use for traditional structures, cabins, fences, posts, and homes.

And with this project, our hope is that, this can be incorporated into the future 10 year management plan and that we can provide a tool, a basis that can really help make those decisions for forest management. 

Emile Elias: Thanks, Jaime. Margaret, your project focuses on competition for trees of different sizes.

And I'm wondering how you went about calculating competition at the tree level. 

Margaret Evans: Sure. Yeah. So going back to that measurement, the idea of basal area, which is sort of like the spatial footprint of a tree, our measurement of competition was to look at the total basal area of live trees that are larger than the trees that we're focusing on.

So for any, any individual tree, it's got some trees that are smaller than it. And some trees that are larger than it. And so when we measure competition, we're focusing on the trees that are larger than that particular tree. So those are trees that are gonna block light and they may also have a deeper rooting system or a more extensive rooting system to be able to extract or exploit soil moisture resources.

So those are two of the things that trees are gonna be competing with each other for is light. And then water. And so if you have more neighbors that are taller than you, you're gonna be experiencing more competition, more competitive pressure for those resources for light and soil moisture. And that just sort of reflects those sort of general principle in, in ecology and in population dynamics.

That competition tends to be asymmetric. So if you're a smaller tree, you're, you're gonna have a harder time competing against larger trees. So we add up the spacial footprint of all of a tree's neighbors that are taller than that tree. That's and we call it basal area larger than so for every single tree, it's got a unique value of basal area larger than, and we find really consistently that there's a negative effect of the basal area of trees larger than, the, the tree that you're looking at on growth.

And so, combined with the climate effects that we're seeing we see negative effects of warmer than average temperatures. And we see negative effects of increased competition from trees larger than a focal tree. And so those are two stresses together that are affecting negatively affecting the growth of the trees.

Sarah LeRoy: Thanks Margaret. So, yeah. So building on that, so you just mentioned, some of your results indicate that these large tall trees are vulnerable to hotter drought and that trees and these dense forest stands, they face, as you mentioned, these two stresses combined competition and climate. Where smaller trees are, less productive with these larger trees around. So I'm curious, and Jaime talked a little bit about this with the Navajo Forestry Department planning for their ten year plans, but you know, how might these findings be used to inform forest planning and management decisions for the Navajo Forestry Department? 

Margaret Evans: Sure. Yeah. So there's maybe two points that I should emphasize.

One is that our role in terms of university scientists is to provide technical support and not to tell anyone what to do. We can provide sort of the, the technical information about, here's what we're seeing from the data in terms of the effect of climate variability and climate trends on the growth of the trees and changing stand density and the negative effects of stand density on the growth of the trees.

But it's, it's up to Navajo Forestry Department to decide what to do in terms of management. The Navajo Nation is a sovereign nation. It's up for Navajo people to decide, what they want to see in terms of what's done on the forests. So the university partners, our role is to provide technical support and technical advice, information, but not, not to tell anyone what to do.

So what the data are telling us very clearly is that, we have these two negative impacts happening at the same time, we have warming temperatures and mega drought conditions that have emerged over the last 20 years across the Southwest that are negatively affecting the trees at the same time that you have high density in, in some stands, not all stands, but some forest stands and that's especially in forest stands that may have been harvested in the past. So there's, a history of commercial forestry on the Navajo nation that goes back to, from the 1960s until the 1980s. And so there were, places where big old trees were cut. And then you have young trees that are growing up, you know, recovery, the, the forest recovery, following that harvest.

And in some of those stands, you have very dense conditions. And those are the places that we worry about in terms of the competition, the effects of drought and competition happening at the same time in those stands, and also the risk of high severity fire in some of those high density, forest stands.

So. Our data are telling, telling us that, that things like silvicultural treatments, where the forest stand is thinned. So reducing the density of trees, reducing the number of trees can mitigate some of that climate stress, the foresters, Navajo Forestry Department can't control. The future climate that's, that climate just happens.

And so one of the few things that foresters can do is thinning treatments to reduce the amount of the density of the forest stand and the, the, the amount of competition pressure between trees. So that's one of the few options that foresters do have, is to do thinning treatments, to, to reduce some of that stand density.

Sarah LeRoy: Thanks Margaret. And so Jaime, I'm wondering if you could speak to the role of the Navajo Forestry Department in this project. For example, were they a part of the research development or data collection? How were, how were they a partner for this project? 

Jaime Yazzie: Yes. So this project wouldn't have been possible without the permission of the Navajo Forestry Department.

And at the very beginning, the principal investigators, Margaret Evans, Chris Guiterman, and Justin DeRose. They collaborated with the Navajo Forestry Department leadership with proposal development, the funding application, and really guiding how our goals and objectives are set up and posing, what are the research questions?

This is super important because research partners, academic researchers need to be very intentional about how projects are set up with tribal nations. And myself as an indigenous scholar, there are a number of ethical guidelines and protocols that need to be followed in order to produce actionable science that is valuable to tribal communities and tribal managers.

So with, with any project, it was, it was very important for me to emphasize the ethics that needed to be presented for this project. And so, at the very beginning, the Navajo Forest Department has been a part of this project and throughout the process of it, as I led a two person filled crew for two filled seasons, this was done under the guidance of the Navajo Forest Department Research and Development crew members.

They really provided the assistance with sampling tree sampling. And not only that, it is super difficult to find these CFI plots and their help made it a success because we would not have been able to locate these plots in sufficient time. There are GPS points for these plots, but when these plots were first set up GPS systems did not exist.

And so the coordinates unfortunately do not indicate the right point to get to these plots. So we really had to rely on Navajo Forestry Departments, maps, and records. And a lot of times the directions from the 1970s are not the exact ones we could follow. They were very reliable, but there were times where some of the roads were impassable and the Navajo Forestry Department has put a tremendous amount of effort into helping us get the sampling done. We were going into basically the winter season at the end of each season. And additionally, going forward, Navajo Forestry Department's involvement, their engagement has stretched to advising on our data interpretation and evaluation, and continually is the vocal point of how our outcomes will be developed and our outreach strategies as well. 

Emile Elias: Jaime, thanks for that, and especially thank you for bringing up the ethical guidelines in working with indigenous nations. We include links in our episode descriptions. So we will include any links that you might like to provide and some links that we have as well so that others, as they move forward can continue to think about knowledge co-production and working ethically with indigenous nations.

So thanks for that. And if I'm not mistaken, you have a new job now in the tree ring lab and a new role in the project. And so Jaime, can you tell us about your new position and how this project helped you in getting to where you are now? 

Jaime Yazzie: Yes. So I currently work as a scientific analyst on the project. And my main role right now is to analyze the last field season data.

So the 2021 tree ring data that we collected and incorporate that with the 2019 data. I graduated from NAU in 2017 with my master's in forestry. And there I worked with the Navajo Forest Department using the forest vegetation simulator to really provide predictions of forest conditions over a hundred years.

And that really provided me with a good basis of understanding the forest conditions and as well as connecting, not only with tribal forest managers, but also the tribal community. And really understanding what are the community values and needs. And after, after that project, I've worked as a forestry consultant, as well as a coordinator with different tribal environmental programs and public universities.

And all these have really strengthened my knowledge of tribal sovereignty, environmental policies and tribal self-determination. And as a Dine woman, my main passion is to really be to uphold the responsibility I have to my tribal community. and I'm from Ganado Arizona. And, I grew up within Woodlands, surrounded by pinion, pinon pine, and different junipers.

And so those are really the main things that push me to, to study and to continue my work as an indigenous scholar and create actionable science that benefits tribal communities and decision makers, so that we can you know, build on our relationship with the landscape and continue with that responsibility we have to our homeland. 

Emile Elias: Thank you and congratulations. And also, congratulations are in order for Dr. Evans being recently promoted to associate professor. And so my question for you along with the congratulations is what's next, what's next with this project and, and for you as you move forward in your research. 

Margaret Evans: Yeah. I just wanna brag a little bit on Jaime here because she did such an incredible job leading the two field seasons. So the first one was in 2019 before COVID and then the second one was in 2021 just last year, so still during COVID. Both of these field seasons were incredibly successful. The total number of plots that we now have sampled is 56.

We have a thousand trees for which we have tree ring time series that go all the way to the birth of the tree. In those 56 plots, every single tree greater than five inches in, in diameter was diameter at breast height was, was cord. So we have these tree cores for all of the trees in the plot or in a subplot.

And as Jaime was saying, it's really challenging to do this work. I mean, these are really rugged landscapes, Jaime and her crew of one her assistant in each year, Gabriel Sam, Gabe Sam in 2019 and Toby Showa in 2021. They toughed it out under conditions going into November and December when daytime temperatures are below freezing, navigating through a maze of unpaved roads throughout the Defiance and Defiance plateau.

And the Chuska Lukachukai mountains is incredibly tough work to do and always, just keeping a masterful control of the data and getting every single piece of data and all of it in these digital data collection systems and the physical samples and organized everything. Jaime's new role is now analyzing the data that she generated and working with scripts in R and a GitHub repository, sort of open source, reproducible science. It's not open source in the sense that the data are, sovereign property of the Navajo Forestry Department. So it's not open source in that sense, but the scripts for, you know, for doing the analyses are all reproducible and, you know, version controlled in GitHub.

So she's been doing a ton of ramping up on all of these technical sides of statistical modeling, data management, open source data, data reproducible science, data science. So a whole bunch of like really cool and useful data science and forestry skills that hopefully these are skills that, that she'll be able to, we hope apply, in a position within the Navajo Forestry Department, if such a position were to open up.

So that's, a lot of, a lot of skills building going on there associated with this project. In terms of what we are hoping to do in the future, we've mentioned the, the forest vegetation simulator a couple of times there. So that's a management tool that foresters use across the, the US and actually around the world in other countries also.

So it's a forest growth and yield model, a stand level growth and yield model that was created by the US Forest Service. And it's used by managers throughout the federal forest forested land systems, but also by state foresters, tribal foresters by all kinds of forest managers. And what we're doing is this really innovative thing, which is to bring the climate sensitivity information that's treeing data into the forest vegetation simulator. So that that simulator is going to, when it makes projections of what the forest is gonna look like in 40 years, that's gonna take into account how climate is changing in the next 40 years.

According to future climate scenarios from the IPCC and other kinds of climate products. So that's kind of the next big challenge is integrating these tree ring data and the forest inventory data into the forest vegetation simulator. 

Emile Elias: Thanks Margaret. We like to end our podcasts and our conversations on a hopeful note.

And so I like to ask people we get to speak with what gives them hope. So what, from your work on this project, or from anything really gives you hope. And I'll start with Margaret for this question. 

Margaret Evans: Sure. Yeah. I think the thing that makes me most hopeful is the, the people that I've been able to work with on this project have all been so passionate and so concerned about forest health and the future and the forested lands of the Navajo nation.

And that's true for the university partners. Jaime mentioned Justin DeRose, who's at Utah State University, Chris Guiterman, who was at the beginning of this project in, in the tree ring lab at the U of A, but has transitioned into a position at NOAA. The university partners and also everyone in Navajo Forestry, we're all, we're bonded by our shared concern about what's happening to these forests and we want to quantify it and we wanna be able to help have conversations about what can we do, what can be done.

Those are, as I said before, deliberative conversations that need to be had on the Navajo Nation by Navajo communities about what do Navajo people want to do about the challenges these stresses that, that the forests face. And what are the choices as a society that Navajo people want to, to, to make in terms of forest management to address those challenges. We had one day in particular last fall during the 2021 field season.

Where we had, I think it was 11 people together in the field. And this included, I think it was three or four people from Navajo Forestry Department Jaime and her assistant, Toby Showa, myself, my postdoc Kelly, and three people from Navajo Fish and Wildlife Department. I might be forgetting a couple of people.

We had about a dozen people. We all were wearing our masks and our helmets, but we were out there together collecting data and sharing meal together, talking about what's happening with climate change, what's happening on the Navajo nation. What are people thinking? And that just really was an amazing experience to, to be able be out in the woods together. And, and I also have to say really just, as someone who is a descendant of European immigrants to this country, there's a lot, there's a legacy here of displacement and violence against the first peoples of, of North America. And, just a little bit trying to heal some of the damage and the, the wrong that's been done.

In terms of colonial settlement of North America or of the United States there's a lot of work that needs to be done to build. Build relationships, build bridges, heal the wounds and, try to make things if not right, then at least move them in the right direction. 

Emile Elias: Thanks, Margaret.

And the same question to you, Jaime, what gives you hope for the future? 

Jaime Yazzie: Yes. So, as Margaret was saying, we had a really amazing day with not only Navajo Forestry but Navajo Fish and Wildlife, and our engagement with these departments within the division of natural resources is really inspiring because we're not only ensuring that we can provide information about forest health, but we're also ensuring that these findings and these outcomes are accessible to the tribal community, to tribal managers. And this is super important because for tribes, for tribal nations, there's a long history of, of silence and erasure of indigenous people.

And for, for us to be able to have full autonomy over our forests, over our landscapes, over our seascapes, and to be able to manage the land and really, through different strategies. Whether that is utilizing information from Western science or indigenous knowledge, to be able to make informed decisions that will be put forth for a sustainable future for the tribal communities.

And what gives me hope is just building on these relationships and ensuring that there's, there's reciprocity at all these bridges that we're building. And not, not just with the people, but with the forest so that we can address this huge challenge of a changing climate. But yeah, that's, that's really what gives me hope.

Emile Elias: Jaime Yazzie and Dr. Margaret Evans, thank you so much for joining us today and thank you for the work that you do on behalf of Navajo forests. 

Margaret Evans: Thank you. I I'm just gonna add one tiny thing. I just, I have to say it's Jaime who gives me hope. Honestly, just younger people, younger scientists and their passion and I'm so impressed with everything that Jaime does and yeah, that's what gives me hope.

Sarah LeRoy: We’d like to give a shout-out to our listener, Connie Barlow. She sent us some great feedback about the podcast and also provided us with some excellent suggestions for future topics, so thank you Connie.

Emile Elias: Thanks for listening to Come Rain or Shine, podcast of the USDA Southwest Climate Hub and the USGS Southwest CASC. If you liked this podcast, don't forget to rate or review it and subscribe for more great episodes. A special thanks to our production crew, Skye Aney and Reanna Burnett. If you want more information, have any questions for the speakers or would like to offer feedback, please reach out to us via our websites.