Riparian Restoration with the San Carlos Apache Tribe

In this episode, we spoke with Roy Petrakis, a Geographer with the U.S. Geological Survey (USGS) Western Geographic Science Center. Roy’s expertise includes using remote sensing and GIS to understand how landscapes in the southwest are changing over time, including shifts in wildfire behavior, vegetation dynamics, and water availability. His research addresses wildfire and fuel treatments, climate variability, watershed management, and more.

He talked with us about the long-standing partnership between the San Carlos Apache Tribe and the USGS, where collaborative research supports land management decisions and riparian restoration efforts. From tracking invasive species like tamarisk to studying wildfire impacts and drought stress, Roy highlights how science and Indigenous knowledge come together to build more resilient ecosystems and support communities.

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Transcript

Sarah: Welcome to Come Rain or Shine podcast of the U.S. Geological Survey Southwest Climate Adaptation Science Center, or Southwest CASC 

Emile: and supported by New Mexico State University and the University of Arizona. We are your co-hosts, Emile Elias and 

Sarah: Sarah Leroy. Here we highlight stories to share the most recent advances in science, weather and climate adaptation, and innovative practices to support resilient landscapes and communities.

Emile: We believe that sharing some of the most innovative, forward thinking and creative scientific research and adaptation solutions 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.

Sarah: Riparian systems are critical to the human and ecological communities that interact with them. For the members of the San Carlos Apache Tribe in southeastern Arizona, this is particularly true as riparian systems provide immense cultural and natural values such as ceremonial grounds and recreation areas. However, the riparian areas within the San Carlos Apache Reservation are at risk of degradation due to climate change and land use.

The U.S. Geological Survey Western Geographic Science Center has had an ongoing relationship with the San Carlos Apache Tribe, aiming to provide essential research and data needed for management planning. So today we're speaking with Roy Petrakis, a geographer with the USGS, about his research with the San Carlos Apache Tribe. Welcome, Roy. Thank you for joining us today. Before we get into your research with the Tribe, specifically, I was wondering if you could just describe generally the type of research that you conduct with the USGS.

Roy: Well, thank you so much for having me today, Sarah, as part of the Come Rain or Shine podcast series. I'm very excited and perhaps a little bit nervous as well. But I just want to thank you for giving me and my team an opportunity to speak about our long term partnership that we have with the San Carlos Apache Tribe.

Absolutely. So I am a geographer with the US Geological Survey, Western Geographic Science Center, or WGSC, in Tucson, Arizona. My background is very much in geography, particularly using remote sensing and GIS or geographic information systems applications to answer environmental questions and challenges. Much of my work centers around using satellite remote sensing and GIS to understand how landscapes in the southwest are changing over time.

A lot of what I do involves tracking things like vegetation condition, wildfire behavior, surface water, and general land cover change. So sort of, in short, anything that helps to develop a clearer picture of how ecosystems respond to drought, climate variability, and then different land management practices as well. Wildfire is a big part of my research. For one relatively recent project that we actually had with the San Carlos Apache Tribe, that I had worked on, we spent time looking at how fuel treatments such as thinning or prescribed burning or even resource benefit burns, actually affect fire severity when a wildfire would then come through. So remote sensing gives us a great long term view or overview so we can see how vegetation recovers afterwards, and then where the risks may be increasing, tied to treatments on the landscape.

I also work on projects that map and monitor surface water in arid regions. Water is obviously a huge concern in the southwest. So being able to detect when and where water appears and how that shifts over certain years or decades can help land managers make better decisions. This kind of goes with our current areas as well, where we look at how these ecosystems are changing with environmental conditions, or restoration efforts and so on.

So in short, my work uses spatial data to help understand how environmental change and support those who are making decisions about land, water and fire management. And a lot of that ties directly into collaborative work with Tribes and other partners. 

Sarah: Yeah. Excellent. Roy, thanks. Yeah. And given everything that's going on, obviously in the region with warming temperatures, drought, very relevant research.

And I'm just curious, how did you get into this field of research? 

Roy: Yeah. So I mean that's a great question. And I kind of remember this actually pretty well that during my undergrad years at the University of Arizona, I had taken this introduction to GIS course - it was geography 400 something. And during that class, the professor had said something along the lines of, you know, GIS isn't widely used. Most of you probably won't use it in your careers. This is, you know, in 2005, 2007, something like that. And then I then went on to talk about how the benefits of the class, you know, we can still apply what we learn in whatever we do organization, data management, computer skills. And, you know, I was just thinking to myself, you know, GIS isn't for me, but I need these credits for my geography program.

But then I had graduated a year or so later, and I was looking for a job, and there was this opportunity to work with a US Geological Survey researcher doing, digitizing work of vehicle disturbances on a military base in these very dry, empty deserts of southeastern Arizona. So it was really simply mapping roads or disturbances caused by vehicles. And it was really heavy GIS type of work. 

So I applied, I needed a job, got the internship, and for the next year and a half, spent hours and hours and hours, just staring at an image and drawing lines and circles and polygons, all depending on how big and, you know, long these disturbances were.

And I loved it! Something about it was just so much fun being able to look at space and distance and impact on the landscape. And I think from that point on, I got more engaged with other topics like wildfire or land cover mapping, change detection, satellite remote sensing and so on. And that inspired my graduate program.

And then I came back to the USGS as a student contractor and continued on to my professional career. 

Sarah: Thanks for that. That's too funny that you had a class where the professor is like, you're never going to use this, and now that's like all you do and you love it. So that's great. Okay. So we're going to talk about your specific research with the Tribe in just a minute, but before we kind of, you know, dive into that, I wanted to talk about the relationship between the USGS and the Tribe – since I believe it's been ongoing for a long time. So I'm just curious how that relationship began. 

Roy: Yeah. And that's a really great question. Our team or science center, has had a relationship with the Tribe that began in 2004. At that time, Ed Pfeifer, who was with our science center, had traveled out to San Carlos to meet with Dee Randall, who was the San Carlos Apache Tribe Forest Resources program supervisor. And then we all kind of make this joke as we talk about it, but legend has it, they hit it off. You know, they were good friends. They had a good time talking and discussing science and so on.

And they ultimately developed a proposal to work together, where the USGS could provide scientific investigation into land management challenges that the Tribe was experiencing. So, in particular, at that time, Dee had presented a tribal fire plan to Ed, and was curious if science had supported these decisions or would support the decisions that he was making. Other topics introduced at that time included vegetation change such as drought and grass cover rehabilitation, fire impacts, restoration and water quality, quantity, all tied into watersheds and fire and drought.

It was very interdisciplinary, but was also very much focused on informing land management decisions for the Tribe. So ultimately the USGS science was used to address these land management concerns. And then over the next, at this point, 20 plus years or 22 years, we've built this established relationship with the Tribe that's built on engaging this partnership and trust with the Tribe in regard to data management products and releases.

So some of the early projects that our center was tasked with included mapping grassland condition and tipping points, using LIDAR data to assess burn severity, mapping woodland cover and encroachment as far back as 1935. So you can imagine being able to see the world from 90 years earlier and being able to see how it changed. And then, you know, a broad range of science kind of tied to those themes. 

So I then joined the Science Center, a student contractor, in November of 2015, and immediately began working on a project to quantify vegetation response to changing precipitation. So we could get a better understanding of how certain vegetation types may respond to drier or weather conditions, and how that might influence management decision making.

We then worked with the Tribe to quantify burn severity and post-fire vegetation response, tied to different fuel treatments that I had discussed previously, with the goal of developing results that would show benefits tied to this fire plan, and unknown challenges of certain field treatment applications. And then it kind of developed from there. So, most recently, we've been working with the Tribe to develop a watershed restoration field crew, consisting of Tribal members that go out and build small-scale natural infrastructure or nature-based solutions to help restore watershed function.

We've worked with the Tribe to develop, and I'll talk more about this later, but a tamarisk beetle monitoring program that helps to inform riparian management. So all these goals are designed around using scientific information from the USGS to help inform Tribal restoration priorities. 

Sarah: Yeah. Excellent. Thank you for that. And I wanted to, so you touched on already kind of your specific research with the Tribe, but I just wanted to talk about your research that's funded by the southwest CASC and a large part of that is focused on riparian restoration and the upper Gila watershed, obviously on the reservation. So could you describe that research and what you all found? 

Roy: Yeah, absolutely. So certainly for many years, the Tribe has discussed concerns with us regarding the riparian forests, which are immensely important for Apache Tribal culture, where native species are often used in ceremonies and everyday life, as well as just for the natural value of these very unique ecosystems.

So in general, riparian areas serve as vital habitats for a very disproportionate number of plant and animal species with respect to the amount of area that they cover. So these habitats are often provide a water source, vegetation, shelter or shade, and very diverse habitats that are very unique in this desert landscape that we live in. Now we define riparian as the forest or the vegetation that surrounds the river systems on the reservation.

So for the San Carlos Apache Reservation, there are two primary river systems, which are the Gila River, which flows from the Gila Mountains in New Mexico west into Arizona, and the San Carlos River, which flows south and connects with the Gila River at San Carlos Lake or at Coolidge Dam, a bit north of Tucson, east of Phoenix. Within the Tribe's riparian areas invasive tamarisk - also known as salt cedar - is a non-native plant that is typically present in the form of a tree or a large shrub. It's very widespread and has negatively impacted the larger ecosystem and forced Tribal members to travel further away for ceremonial gatherings and some other substantial impacts. In 2021, the WGSC developed a proposal to the Southwest CASC in conjunction with the Tribal Forest Resources program, who are co-principal investigators, to better understand the riparian vegetation condition and to measure its response to environmental conditions over time.

It was a really neat study. We had a lot of fun with the study, and I think we discovered some pretty important conclusions. Specifically, we used Landsat satellite imagery, which goes back nearly 50 years at this point, allowing for us to get a long-term continuous documentation of vegetation conditions, to measure vegetation response across three different climate periods, particularly a wetter period, which was from about the 1980s to the mid 1990s.

And then it dried out a little bit. So from the mid 1990s to the early 2010s, it was getting continuously drier. And then following that from the mid 2010s into the end of our study period, which at that point was 2023, we saw this very intense period of drought across the southwestern US. So the vegetation was very stressed throughout these conditions.

And we could see that some of the vegetation types actually had been more vulnerable to drought, one example being tamarisk - so this invasive, non-native plant, particularly in areas that have experienced periods of continuous flooding and then drought. So, for example, where the San Carlos reservoir and lake, it would fill up. And then when it would dry out, this tamarisk could fill in and be very dry for several years.

And these areas were showing high levels of stress. We had noticed that native vegetation, so trees like cottonwoods or willows, were actually increasing greenness a little bit, more so in the upper portion of the watershed, into New Mexico, but also in Arizona, also along the Gila River, San Carlos River, San Francisco River, and this was particularly tied to increased groundwater due to what we believe to be deeper roots. We weren't able to quite investigate the driver of that, but that was something that we found was interesting. 

And then lastly, we had reviewed this area, that had been restored by the Tribe and found that small scale restoration efforts had been successful and had increased not only riparian vegetation greenness, which is one of the metrics we could measure with remote sensing, but also likely led to an increase of native plants that were used for ceremonial gatherings.

So ultimately, this restoration was helping to retain and grow resources that were actively used for many benefits. So our role and in support of the Tribe was not necessary to make recommendations for restoration. You know, USGS isn’t a land management agency. But we had these objectives that were to help provide the Tribe and land managers, policymakers, even the public with impartial, relevant and timely scientific information that could support resilient communities along the riparian lands and sustainable land and water management.

So with the study, we could ultimately discuss adaptive management, guiding Tribal restoration efforts, and having a better understanding of the wildfire risks that were tied to changing environmental conditions. 

Sarah: Yeah. Thanks. So you just mentioned wildfire. So I wanted to bring up the fact that during the course of this project, you had identified wildfire as an expanding threat to the riparian ecosystem, and obviously is a growing challenge for the Tribe, for their management purposes.

And so I'm wondering if you could discuss how fire is changing on that landscape, and then also how you incorporated that into the research. 

Roy: Yeah. So wildfire is a very interesting natural phenomenon. We had not considered wildfire when we had originally proposed our study to the Southwest CASC and at that time - you know, riparian wildfire is natural, it occurs and has occurred fairly widely in riparian ecosystems of the southwest. But at the time of the research, it really had not been a dominant feature on these riparian areas. So typically, riparian wildfires are localized, small-scale due to various factors, such as spatial limitations of riparian lands, can't really spread all that far. They're very moist microclimates, with active groundwater, active surface water, and riparian ecosystems, they certainly can consist of higher severity and have substantial impacts for surrounding human environments, but are largely not necessarily impactful and do have a lot of positive benefits, helping to maintain ecological balance and removing dense understory of forests. 

However, in this study, we really began to observe this large expansion of riparian wildfire, in our study sites. So, for example, in 2021, the Bottom Fire burned roughly 6,000 acres of the Gila River bottom from the San Carlos Lake, almost to Bylas, Arizona.

So it was a very large distance of land that had burned. It was a very large fire that a few areas of very high fire severity. And it was impactful to the overall ecosystem. Many, many areas just burned out completely. So I think from there, wildfire became certainly an expanding threat in the riparian ecosystems on the Tribal lands, to the people of the Tribe as well.

So tied to our study specifically, we noticed that increased wildfire was one of several stressors affecting the riparian zones across the upper Gila River watershed and on the reservation. We then quantified wildfire impacts by analyzing spectral data from Landsat imagery. So we could look at greenness. We could look at wetness conditions of the vegetation, to detect shifts in these vegetation conditions. And then this allowed us to get a better understanding of the spatial properties of wildfire as a disturbance. 

So the Bottom Fire was not the only fire that actually burned during that study period. And several burned further east all the way towards the city of Safford, Arizona. Some conclusions that we were able to make were that despite a regional trend toward overall greening, areas in the lower watershed had exhibited elevated stress closely associated with these recent wildfire events and disturbances. 

We found that small scale restoration efforts conducted in fire impacted zones had actually shown improvements in vegetation greenness, suggesting that post-fire restoration - like planting native vegetation or just managing fuels - can effectively enhance riparian recovery. And I think what was really positive and was kind of a hopeful result, was that this supported the notion that wildfire acts as both a risk and as an opportunity.

Obviously, it contributes to degradation of the system. But it also provided this critical window for restoration interventions that could promote resilience and habitat recovery. So I think unfortunately, we hadn't really planned for a wildfire as a major function of this research project and we certainly hope to shape any future research, a bit more on, you know, what could potentially lead to fire conditions and so on.

But, it potentially, it became an important aspect of the study in the end, which was a really interesting sort of add on that we weren't expecting. 

Sarah: Yeah, it was nice that you were able to kind of pivot a little bit, and incorporate that into the study because we cannot predict wildfires. Obviously. And the timing worked, I guess, for your research. And then thinking beyond this, and you already touched on this a little bit about the Tamarisk's leaf beetle, but this project that we were just discussing led to further research by the team. And like you said, focus specifically on the invasive tamarisk and then the arrival of the beetle. So could you describe that project a bit? 

Roy: Yeah, absolutely, Sarah. So one of the primary conclusions of the phase one study was that tamarisk, as we've kind of discussed here, was potentially showing more drought stress than native vegetation species.

So it represented this species of concern for the Tribe. There was this growing need to better understand where tamarisk was in riparian forests. And more precisely, how would it respond to drought and other environmental conditions and more of this sort of real time way, you know, what would happen in current conditions? And then further tied into the topic of tamarisk, which you had asked about, was the tamarisk leaf beetle.

So just for a brief background on the beetle, the tamarisk leaf beetle was introduced in 2001 as a biocontrol agent by the US Department of Agriculture to assist in invasive tamarisk control efforts, so the beetle originally came from areas in Asia, Europe and Africa, and four species were introduced at different locations across the western U.S. based on their environmental preferences, and so on.

So what the beetle would do is it would defoliate the plant, essentially eating the foliage or the leaves on the plant, and then repeated defoliation could theoretically kill the plant. So from a restoration perspective aiming to restore the natural and native plant habitat, the beetle offered an opportunity to assist in removing invasive and non-native tamarisk vegetation. So for our project, the primary objectives were ultimately to map the location of tamarisk and other riparian vegetation types, and then to analyze each of these types’ responses to environmental conditions.

We use this term hydro climatological conditions. But we were really looking at just patterns and measurements of hydrology such as surface flow, high flows, low flows, then climatological variables like precipitation and temperature. And then an additional objective of this project was to assist the Tribe in developing a monitoring program for the tamarisk leaf beetle on their lands.

So thanks to support from the Southwest CASC, we were able to develop this training, with employees from the Tribe in June 2024. And then the Tribe has been actively monitoring for beetles since that summer. 

Sarah: Excellent. So this is a good segue, because you're talking about how the Tribe is involved in the project, and they've been involved in this research from the start.

And you mentioned this earlier, but several Tribal partners are actually, you know, PI’s on the project. Co-Investigators in the research. So could you talk a little bit more about how you have engaged with the Tribe throughout the research process? And then also, you know, how that engagement contributed to developing useful products like that training for your partners? 

Roy: Yeah, absolutely.

So, both of these riparian themed-projects that were supported by the Southwest CASC and really all of the projects that we have had with the Tribe beginning in 2004 have been direct partnerships with Tribal employees and programs. So co-investigators, co-principal investigators, and to speak more directly on the two riparian projects, we involved members of the Tribe to better understand precisely what their concerns were.

So this was primarily led by in-person meetings, often traveling to meet with Tribal employees and to really listen to what their concerns were regarding riparian vegetation. So, for example, in the phase one study, we had developed a series of four different case studies that had focused on restoration sites, wildfire, historic management of the riparian lands and so on.

And, and these case studies were specifically mentioned by Tribal employees as areas of interest. For the second project, which was more directly focused on tamarisk and the tamarisk beetle, we worked with employees to identify primary research areas and to involve Tribal members in the development of the beetle monitoring program, as I had previously discussed. So these are examples how we really directly involved the Tribe, you know, shaping project objectives and study sites based on Tribal management needs.

And then we can provide the scientific analysis with remote sensing, with GIS, with aerial imagery modeling, as well as spatial and statistical analyses. That can then answer these concerns that the Tribe has regarding their lands. 

Sarah: So I yeah, I'm just curious if you know how - I mean, you talked a little bit about this already, but if you have some more specific examples of how your partners with the Tribe have actually used the research that you've developed in their planning purposes.

Roy: Yeah, absolutely. So, unfortunately, our Tribal partners are unable to join us today. But they are very, very much still engaged in the project. And so this is an ongoing relationship and an ongoing partnership. And so I can't speak for them specifically regarding their management, decision making and planning, but we do provide all results from our study to our Tribal partners.

This includes map documents, written reports, statistical analyses and graphs and so on. And then the Tribe can then make these management decisions, such as prescribed burning, for example, clearing and or planting in certain areas, and so on, to address their own current resource management objectives. Some examples of how they might be using these results in this study - some restoration objectives that were introduced to us during the phase two project development included identifying areas of tamarisk for removal, so that tied into mapping where it was, what its condition was, trying to identify, areas that may be showing more stress, identifying areas for increased fire risk where, you know, we know it's been really dry. We know these areas are very dry. And how can that be tied into fire based on previous fire history and so on? 

Monitoring vegetation conditions for endangered bird species is certainly very important for the Tribe. So we can get an indication of, you know, areas that might have mixed vegetation with native and non-native vegetation, large cottonwood stands, and so on. And then ultimately helping to prepare the riparian vegetation for future environmental conditions.

So we provide the Tribe with this information and then allowed for them to make decisions based on where that restoration objective needs to be applied. 

Sarah: Yeah. Great. Okay. So I want to kind of switch gears a little bit away from the specific research. But we have asked this question a few times and gotten some interesting responses, but about field work.

And so, you know, many people who are doing field research have some harrowing stories, sometimes about something that happened in the field. And so I'm wondering if you have any fun or interesting stories, from the field that you want to share? 

Roy: Yeah, I, I love this question. We've had a lot of really fun and engaging field trips with our Tribal partners.

You know, we've been very fortunate to have explored quite a bit of the reservation, 1.8 million acres. So it's a very large area. I mean, we've seen some really cool things in our time, but I think, you know - well probably one of the more fun and, and even terrifying experiences, was on a field trip to visit a restoration site along the Gila River.

And this was in the spring of 2023. And that winter had been very wet, in New Mexico and so on. And the Gila River had experienced these very, very large flows, consistent large flows. So a lot of the areas in the riparian forest were muddy and so on. So we went to finally go check it out, and we went with one of our principal investigators with the Tribe, and we headed down to this tamarisk and willow forest, and found this again, very muddy ground that had probably just been underwater a couple days earlier.

We're looking around and we see some really cool tracks. We see bobcat, probably coyote, some bird tracks, and then right in front of us was this just massive mountain lion claw print. And it was so cool. And it was so fresh. I mean, it was still bubbling out of the ground. We still saw these air bubbles popping out.

So it was probably from just a few minutes prior. And it was really cool and really terrifying at the same time. So it was just a great experience. And we obviously, you know, we made it out unharmed, fortunately. But just to know that that area remains so wild, and is important for the local wildlife, that that just makes it a fun experience.

Sarah: So you when you're telling that story and you said you saw this big mountain lion and then paw print, I thought you definitely were saying you saw a mountain lion at first. And I'm like, oh my God, that's terrifying. But I'm glad you only saw the paw print! Probably still really scary. And I'm guessing you were all looking around trying to make sure you weren't watched.

Yeah, that's a, that's a good story. Okay, so again, switching gears a little bit, I want to talk about hope. You know, we like to ask all of our participants about where they find hope for the future. And so I just want to ask you what gives you hope. 

Roy: Yeah. Well I certainly hope to not see a mountain lion in the wild.

So I think that's hopeful. But to answer your question, more directly, you know, thinking about hope and I think there's a lot that does. And I think the first example that comes to mind is working with the Tribe and the Tribal members, Tribal employees is really such a pleasure. Our partners have prioritized protecting the natural and cultural value of the riparian ecosystem for the community, and working to protect areas or even certain vegetation types that would provide significant value.

So there's this really ingrained mindset of working hard to both better understand the world, you know, the riparian habitat that's around them, but also to build resilience, to build sustainable communities that plan to use and engage with the world around them. So I think that that gives me a lot of hope. And it's not just on Tribal lands.

I think riparian ecosystems across the southwest have been greatly impacted in recent decades by drought, invasive species, expanding urbanization, agricultural water use, and so on. Wildfire, various factors that impact these systems. But what you can see is that there's science - small scale local restoration projects designed around protecting these environments and retaining their value for us, for humans and the many other animal and plant species that call them home, you know, is really constantly ongoing.

So there's several great nonprofit groups, science based organizations, researchers, that, that support this work. And I think there's a really bright future for riparian forests throughout the West because of the hard work of these individuals. 

Sarah: Great. Thanks. And so last question, what is one thing that you'd like listeners to remember from our conversation today? 

Roy: Yeah, absolutely.

I mean, I think, one is always really, really hard. And I'm going to try to do one, but I'm pretty sure it'll turn into more. But, you know, it's important to work with Tribes. I think that's very important to have that understanding of the world. That was a big impact on this study and, and beyond.

I think listening to partner needs is really important, and really shaping our science, and even your own science to meet those needs, you know, so I if I was to say one thing, I, I've already said two, I'm pretty sure, I think it would just be to have this growing appreciation for riparian ecosystems, of the western/southwestern US.

They're vital ecosystems for plants and animals. They cover such a small area but have such a big impact. So it's important to take care of these ecosystems and to care for the world around us. So I think that's kind of a takeaway. 

Sarah: Yeah. Thanks, Roy. I do think that was three things. But that's quite all right. We can end with the three things that people should remember.

Well thanks. This is a great conversation day. I always enjoy talking with you about your research. So yeah. Thanks, Roy. 

Roy: Thank you so much, Sarah. It was a pleasure to be part of this podcast series. And yeah, thank you for your time and thank you for the support from the Southwest CASC on these studies.

Emile: Thanks for listening to Come Rain or Shine podcast of the USGS Southwest CASC, New Mexico State University and the University of Arizona. 

Sarah: 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, Reanna Burnett and Lauren White. If you want more information or have any questions for the speakers or would like to offer feedback, please reach out to us via our website.