A Career on Fire

Mountains in the desert – who's heard of them? 

If you were a bird flying over Southern Arizona, you would notice that the sandy desert landscape is punctuated every so often by groups of tall mountains rising up. These mountain ranges are known as the Madrean Sky Islands.  

In A Natural History of the Santa Catalina Mountains, Arizona, the authors state, “A mountain range in this region is defined as a Sky Island if it is high enough to include oak woodland habitat and is isolated in a ‘sea’ of dryland below....”  

To the North of Tucson proper lie the Santa Catalina Mountains, which provide a popular backdrop in photographs of the city. They turn pink in the glow of the evening light. Nestled among this range is Mount Lemmon, a well-loved destination for tourists, outdoor adventurers and urban-weary Tucsonans alike. A well-maintained highway takes visitors all the way to the summit, which is heavily developed with human structures including housing, restaurants and shops, a ski lift, astronomical observatories and research facilities. 

As one might expect, this development comes at a cost to the surrounding ecosystems. 

Fire is a natural and important part of many ecosystems. But Mount Lemmon is classified as a wildland-urban interface, where fire is often suppressed for fear of damage to human structures. This leads to a heavier accumulation of vegetative fuels, causing the rare fires the ecosystem gets to burn at a high intensity. 

“So, when you exclude fire, the main thing that happens is that the fuels build up. That’s the primary thing,” says Don Falk, a professor in the University of Arizona’s School of Natural Resources and the Environment. “And then once the fuels build up, then when a fire occurs, good luck trying to stop it. It’s going to be very difficult.” 

When the Catalinas burn, they burn hot. It can be distressing for locals, although  Mount Lemmon residents have developed strategies  to live with this problematic fire regime and protect their structures when a large fire does occur. 

In contrast, the Rincon Mountains to the East of Tucson are extremely remote. Their lack of development allows them to maintain what Falk calls “a continuous fire regime,” which is closer to an ideal situation. Fires burn more frequently at a lower intensity in the Rincons, and they typically do not experience a stand-replacing fire. 

“If people want to get to them, they have to hike really long distances,” says Molly Hunter, an associate professor in the University of Arizona’s School of Natural Resources and the Environment. “You know, compared to the Catalinas where there’s people everywhere because it is so accessible.” 

Hunter says it’s a difference of the Rincons having fires every 3 to 8 or 10 years versus the Catalinas having fires every 10, 15 or 20 years. 

Jose Iniguez, a research ecologist with the U.S. Forest Service, is familiar with fire ecology in the Sky Islands, having spent summers living in the mountains in the 1990s. 

Iniguez is from Nogales, Sonora, Mexico, and moved with his family to Nogales, Arizona, on the other side of the border at age 10. He recalls exploring these mountains with friends as a teenager. He graduated from Nogales High School and went on to get a bachelor’s degree in forestry from Northern Arizona University in Flagstaff in 1996. 

This led him to get a job with the Rocky Mountain Research Station, which belongs to the Forest Service. He contributed to a project looking at vegetation used by the Mexican Spotted Owl. Upon graduating, he began working for them again and traveled to various mountain ranges in the Sky Islands to measure vegetation factors such as tree density, type and size. 

Iniguez continued working with Rocky Mountain Research Station to collect data for his master’s degree, which he completed in 2000. Working as a scientist for the Forest Service’s research branch requires a PhD, so the Rocky Mountain Research Station offered to support Iniguez in this endeavor. 

At the time, his primary focus was plant ecology and he had not yet become completely immersed in his passion for fire. That was about to change, as his employer’s educational support came with a few stipulations. He was required to study fire on a landscape scale and leave Flagstaff to attend a different university. 

After weighing a few options, Iniguez chose the University of Arizona in Tucson. There, he found a home at the world-famous Laboratory of Tree-Ring Research with mentor Thomas Swetnam. He studied dendrochronology – the study of tree rings – with a specialty in fire regimes of the Rincon and Santa Catalina Mountains of Tucson. 

“He worked with me during his dissertation work, and that was really important in studying the detailed history of the mountain ranges in Southern Arizona, and learning about the role of both high severity fire and low severity fire,” says Thomas Swetnam, University of Arizona Professor Emeritus of Dendrochronology. 

Swetnam says that Iniguez – whom, along with other colleagues and friends, he refers to as “Pepe” - has also contributed to the field an improved understanding of the variety of fire types that occur on a landscape, as well as establishing that some of Southern Arizona’s mountain ranges have been affected by high severity burns. 

Swetnam believes that fire is neither a wholly good nor wholly bad influence, and says that Iniguez’s explorative work rides this same wave. 

Iniguez earned his doctorate from the University of Arizona in 2006. Aside from the Mexican Spotted Owl, some other wildlife-focused research he’s done has been on tropical birds that find their way into Southern Arizona. The birds are native to Mexico and other tropical regions, and Iniguez’s team studied what type of vegetation they use when found in the Sky Islands. 

Outside of its native home, the elegant trogan is only found in the Santa Rita, Huachuca and Chiricahua Mountains of Southern Arizona – all of which are south of Interstate 10. People travel from all across the United States to see it. Iniguez has seen it once and describes it as an “amazingly beautiful bird,” speaking of its impressive colors. 

“It’s not your average bird, that’s for sure,” he says with a laugh. 

Someone that has inspired Iniguez professionally is Aldo Leopold, conservationist and author of A Sand County Almanac. Leopold was both a scientist and someone who wrote eloquently about many of the things Iniguez observed in nature. Leopold was unique for the way that he viewed fire during that time period, as he was one of very few people in the 1920s and 1930s who believed that fire is a natural part of ecosystems. 

“So to me, he was a pioneer, and he saw something that others didn’t, and so I think that really inspired me,” Iniguez says. 

Another inspiring factor of Leopold’s work is how he gave life to the concept of wilderness: places where roads are not constructed, and nature is allowed to run its course. The culture in which Iniguez grew up did not really include the concept of wilderness. It was something he learned to appreciate upon visiting the Gila Wilderness, which was established in 1924 at the suggestion of Aldo Leopold. According to the  Forest Service website , it was the first place in the world to be designated as wilderness and is located in western New Mexico with the Aldo Leopold Wilderness as its neighbor. 

Iniguez believes the healthiest and most beautiful forests of the American Southwest are the Gila Wilderness and Saguaro National Park, which he credits to them being wilderness areas restored by frequent fires rather than mechanical thinning. Saguaro National Park is split up between the West and East sides of Tucson, with the East side going into the Rincon Mountains. 

“One of the things that [Leopold] inspires is this idea that just because we’re scientists, it doesn’t mean that we have to think things in terms of numbers. We can also appreciate things for their beauty and for other values.” 

Iniguez feels that his work with the Forest Service is important because he is in charge of managing land that is owned by everyone. Having grown up in Mexico, where picnics and river excursions were always on land owned by someone, the idea of public lands was something that drew him to forestry. 

Another factor that inspired him about forestry was the concept of sustainability. He is motivated by the desire to manage forests in such a way that they are preserved for the enjoyment of future generations. 

But Iniguez is also worried about some challenges that stand in the way of this goal. His concern is that forests are not currently being managed for sustainability, and as a result, we lose forest.  

“I would hate to be the generation that lost this forest,” he says, punctuating his statement with nervous laughter. 

This is exemplified by a possible trend debated by scientists, which Iniguez calls “type conversion” - with “type” referring to the type of vegetation. The idea is that a high intensity burn can convert a forest into a grassland. Iniguez believes this is already happening to some extent on Mount Lemmon. 

Iniguez recalls being on Mount Lemmon a few years ago and staring down into an area that he previously admired for its mixed conifer forest, which included some Douglas fir. The area experienced a high severity burn and every tree died. Afterwards, the forest began its new life in the form of aspen and oak. 

“I was in the grieving process of lamenting that we had lost that mixed conifer forest and thinking how bad that was, right?” he says. 

But nearby, a couple were photographing and gazing at the same sight. The trees’ colors were in full autumn splendor. 

“And they come up to me and they say, ‘isn’t it beautiful?’” Iniguez recalls. “And I thought, oh my God, these people are looking at the same thing I’m looking at, but they’re not looking at what it used to be. They’re looking at what it is right now.” 

Similarly, many Summerhaven residents told him they had a better view from their house after the fire due to trees being cleared out. 

Iniguez uses this story as an example of a lesson in perspective on the good things that can come out of a fire in spite of its chaos. 

Just recently, Iniguez finished up a project researching how fire management practices have changed in response to a policy change in 2009 that allowed a combination of suppression and letting it burn for ecological benefit, as opposed to the old policy that required managers declare one strategy or another for a fire. The research involved taking a look at every fire in the western United States larger than 10 acres and using data from weather stations to classify them based on the when and where of the burns. 

Next up, he would like to start analyzing comparative data from 1996 and 2015 to see how fire effects vegetative factors such as tree density and how this can impact bird populations. Some thoughts Iniguez has ahead of this project are that fire can promote a diversity of landscape types, which allows for diverse habitat types and, in turn, a diverse bird community. He believes diversity is important when it comes to tackling climate change and other threats. 

Although the Rincons are seen as overall having a more ideal fire regime than the Catalinas, Iniguez breaks down some of the complexities that exist among the Rincons. 

The mountain range’s ecosystems can be separated into Rincon Peak and Mica Mountain. Rincon Peak has seen fire-free intervals lasting 40 to 50 years, which Iniguez says is unusual. The resulting fuel buildup means that Rincon Peak actually mirrors the trend we are seeing across the Western United States: fire is excluded from the system, and it’s an issue. The lack of fire on Rincon Peak stems, in part, from natural causes. Its landscape has a tricky structure for fires. 

“They’ve had lightning ignitions up there, and the fire just doesn’t take,” Iniguez says. “It’s just a very kind of isolated mountain range with a lot of rocks and a lot of, you know...it’s very kind of dissected landscape, very heterogenous landscape. So fires never go very far.” 

It also resembles the problematic fire regime of the Catalinas. With some hesitation, Iniguez says that Rincon Peak is still better off than the Catalinas. But he also says it’s inevitable that Rincon Peak will burn sometime in the 30 to 50 years ahead. 

Mica Mountain, on the other hand, personifies the healthier fire regime that characterizes the Rincon Mountains overall. Its ponderosa pine forest is met with more frequent, recurring fires. As a result, the forest is clean and open with fewer trees. This is largely due to the mountain range’s lack of roads, which encourages a more hands-off approach. Managers typically do not ascend these mountains to suppress fire. 

Many ecosystems that have strayed from the ideal, healthy fire regime like this one have historic fire suppression to blame. This natural regime of the past ended around the same time that the Forest Service gained management jurisdiction over the Catalinas and the Rincons. Due to Mount Lemmon’s highway and the overall development and high visitation rates of the Catalinas, the Forest Service adopted a strategy of aggressive suppression of every single fire that ignited. 

The issue is that, after fire suppression dominated management strategies for about 100 years, there is now a massive amount of vegetative fuels lying around. Iniguez says that his generation inherited this issue from previous generations, and he laments that the trend is still continuing to some extent. 

“And so anytime there’s a fire out there and we go and suppress it, we’re just passing the buck to the next generation,” he says.  

In the 1970s, land managers began reversing this harmful pattern by allowing fire to add itself back into the equation. 

Iniguez explains that these fires allowed to burn for the health of the ecosystem have fallen under a number of jargon terms, including “prescribed natural fire” and “wildland fire use.” Currently, they are called “managed fires,” meaning that they are managed for resource benefit. 

Falk echoes this sentiment of fire’s ability to be beneficial. 

“And the key thing here is allowing fire to stay in the system,” he says. 

Iniguez describes himself as someone that “breathe[s] and think[s] fire constantly.” His experience in the field has led him to develop some opinions on how these forest fuel loads should be managed following a century of suppression. One option is mechanical thinning, which involves going into the forests and cutting a certain number of trees. This opens up the ecosystem and reduces the risk of it experiencing a high severity fire. 

“Then there’s others of us, including myself, that are more kind of up to the idea of allowing fire itself to go into the systems and thin the forest themselves,” Iniguez says. 

The two methods differ in several ways, including the cost. According to Iniguez, mechanical thinning can cost $500 to $1,000 an acre, whereas fire as a management tool presents a more cost-efficient method at $100 to $200 an acre.  

However, there are advantages to both methods, as mechanical thinning allows managers to accomplish more specific goals – right down to the number of trees they want per acre. Fire, on the other hand, does not allow for this level of detail. Some trees will be killed in the process. There is also the unfortunate possibility of a fire escaping managers’ control, damaging public perception of fire. 

“And there’s certain, you know, kind of political ramifications associated with that,” Iniguez says. 

Iniguez disagrees with those who believe mechanical thinning is a realistic way to solve the issue of huge fuel loads, saying that there is simply too much land for managers to handle this way.  

And in the case of Mount Lemmon, mechanical thinning is blocked by both topography and legality. The majority of Mount Lemmon is designated wilderness. Its topography is too steep for machines, compared to the gentler landscapes of Flagstaff and Mount Graham. Such machines are also not legally allowed in designated wilderness areas. 

Rather than mechanical thinning, Inigiuez is a firm believer in burning on what he calls the “shoulder” season. 

In the American Southwest, fire season peaks in May and June of each year. The “shoulder” is defined as the time period either before or after this. A midsummer fire will burn at a high severity, whereas a shoulder burn has a lower severity due to the vegetative fuels being wet. Shoulder burns play a role in Mica Mountain’s success. 

Another issue facing ecosystems right now is climate change. Managers are concerned as to how the ecosystems will be able to adapt and cope with the changes ahead. Iniguez believes that plant species diversity presents a way for ecosystems to protect themselves from the effects of climate change. He compares it to diversifying one’s portfolio in the stock market. 

The Sky Islands surrounding Tucson boast impressive biodiversity. If you drive the highway up Mount Lemmon, which lies in the Catalinas, you will start out seeing a desert ecosystem at the bottom that brings to mind those of Mexico. By the time you reach the summit, the ecosystem will have transitioned to a forest that more closely resembles those of Canada. 

Iniguez discusses how this biodiversity can provide strength. He brings up the contrasting example of Northern Arizona’s forests, which basically have ponderosa pine as their only species. 

“So if that one species gets an insect outbreak then, or goes down because of drought, then we are screwed,” he says with concern. 

But if the ponderosa pine were to meet one of these dreadful fates in the Sky Islands, which Iniguez says are home to 6 or 7 different species of pine trees, there would be more options. The ponderosa could be replaced by another type of pine, such as pinyon or white. 

When considering the future, Iniguez sees projected drought. That, combined with the fuels produced by forests, reinforces his belief that fire is both necessary and inevitable. 

“We are the richest country in the world and we have proven that we cannot stop fires,” he says. “Fires are gonna happen.” 

The choice, he says, is whether we want it to be high or low severity fires. 

What Iniguez wants for the future is for people to “learn to live with fire.” This means that smoke will be present, and he says we will need to develop ways to help those for whom this presents a health concern. He reiterates the importance of avoiding fires in May and June, when fire season is at its peak. 

If Iniguez and his colleagues in the Forest Service are successful, he hopes that by 2050 perceptions will have changed and people will understand fire’s important role in the ecosystem.