Drew Peltier, assistant professor in the School of Life Sciences, is only half joking when he tells you the reason he is in his field is because he couldn’t find a real job. Growing up in California, around some of the largest organisms on Earth — redwood trees — was also a big influence.

“It’s hard not to stand at the base of a tree like that, where it’s too tall to even see the top, and not think that’s something important to preserve,” says Peltier. 

After graduating with his bachelor’s degree in environmental science, his options for working in the field seemed limited. It became clear he would likely need a graduate degree to be able to contribute to research and knowledge about the effects of climate change the way he really wanted.   

This path led him back to school and to higher education in general, where he saw research as an opportunity to move the needle on what we know about how climate change affects trees. This would eventually land him at UNLV in January 2024. 

“Las Vegas and the surrounding areas are the perfect experimental laboratory to learn about the limits of tree physiological tolerance to extreme climates,” says Peltier, “and my research shows many tree species are exceptionally drought resilient, but we need to take care of our urban trees.”

In a desert climate, trees become very important for shading homes, cleaning the air of pollution, and generally helping to cool the city. This makes UNLV an ideal place to study how trees respond to drought and heat.

Living in a world where the consequences of climate change are becoming more and more apparent, the work Peltier is doing is vitally important to better understand how trees are affected by extreme weather events over time. 

Las Vegas isn't known for its redwoods. What brought you to UNLV?

UNLV is a great place to study forest responses to drought. We are really right at the hottest, driest, southern boundary of a lot of forest types and species in the Western U.S. That is, the sky island forests around Las Vegas are the perfect experimental laboratory to learn about the limits of tree physiological tolerance to extreme climates. 

My work also uses radiocarbon dating from what’s called the atmospheric bomb-spike. The bomb-spike was basically a “bookmark” in time, caused by nuclear bomb-testing in the atmosphere in the 1950s and 1960s, much of which was conducted about 70 miles from Las Vegas at the Nevada Test Site. 

Those bombs added what’s called radiocarbon to the atmosphere, and the incorporation of that radiocarbon into plant tissues allows us to track the age of sugars through long-lived trees. This has shown that coast redwood trees use 50- to 100-year-old sugars to support recovery from fire. 

We plan to do a lot more radiocarbon dating and recently received an award, which will help to increase our capacity for doing these sorts of tests. Our Delta-14C Investigation of Carbohydrates in Ecosystems (DICE) lab will allow us to do more radiocarbon dating internally instead of having to outsource it to another lab.

Las Vegas is a great place to be for this kind of research, and I am looking forward to collaborating with some folks at the Nevada Test Site as we continue this work.

Tell me about your research – what is the Peltier Lab here at UNLV working on?

My lab is focused on understanding how trees are responding to climate change in a variety of ways. Trees can’t move; they need to tolerate whatever conditions come their way. So much of my research is focused on resilience — resilience to droughts, resilience to fire, resilience to heat waves. We are interested in understanding how trees can deal with such poor conditions and still grow, survive, and reproduce. 

We study the mechanisms of tree mortality (or survival) under climate change and drought. We study how tree rings integrate past climate conditions like rain or heat (memory). We also study how trees can store energy (sugars) for exceptionally long periods of time, saving up for emergencies essentially.

Research in the lab focuses on trees across the Western U.S., from tiny pinyon pine to the tallest and largest trees on earth, like coast redwood and giant sequoia.

What excites you about the research you are doing?

Trees are just so cool! Anyone in Las Vegas can go on a hike on Mt. Charleston and visit trees that are older than the United States. Trees are just incredibly resilient, and their long lives mean they have seen a lot.

Because they are so long-lived, they also do some things pretty slowly. For example, we know drought conditions can leave multi-year to decade-long legacies in tree growth. 

That is, trees “remember” extreme wet and dry conditions for many years. This is bad news because it means more frequent droughts are really stressing trees out. But, it also means that trees have physiological capacity to “remember” the good times, like pluvials or wet periods, for a long time, too.

We keep seeing evidence that trees can survive drought for a really long time, waiting for a rainy year to help them recover. I continue to be surprised at how trees can just stick it out in extreme environments like the deserts around Las Vegas. 

How can research like yours help us to understand tree growth and the effects of climate change better?

Yes, this is really an important question to me. I am the UNLV principal investigator of the Southwest Climate Adaptation Science Center, and we are focused on producing actionable science that can help people and communities in the Southwest adapt to climate change. Our center just received funding for another five years to continue this work, our second time successfully renewing this support. 

A key thing my research shows is that trees really are responding to climate very slowly, and if we can bring down carbon emissions in the coming years and decades, many forests will probably recover. That is, if we take major steps now we can preserve forest ecosystems across the West that are so valuable.

But, there are limits. It is extremely clear at this point that we need to rapidly transition to alternative energy, like solar and wind, as soon as possible. 

Luckily, Las Vegas is really poised to be a leader in climate adaptation, as a true desert city. Las Vegas is the driest major city in the U.S., but we also get so many clear days during a year that the potential for solar energy generation is very high. And, Las Vegas is making a lot of positive changes in water management that are going to be very important moving into a drier future.

I look forward to seeing an entirely solar-powered Las Vegas, as long as we can responsibly deploy solar across the valley and minimize impacts to wildlife and regional ecosystems.