A giant undertaking: Transplanting thousands of saguaros to help restore ecosystems in the Altar Valley

The Sonoran Desert’s signature succulent may feel like a permanent part of the landscape, but according to the U.S. National Parks Service, saguaro reproduction has been on the decline since the early 1990s. Prolonged drought, climbing temperatures and loss of habitat make it difficult for saguaro seedlings to recruit and reach maturity. That’s a problem for a species that can take 70 years to reach reproductive age – as old saguaros die off, there may not be young plants to replace them.

The saguaro population of Southern Arizona’s Altar Valley is getting a boost, though, thanks to a restoration effort led by researchers in the University of Arizona School of Natural Resources and the Environment (SNRE). Funded in large part by a $3 million America the Beautiful Challenge grant from the National Fish and Wildlife Foundation, the multi-year project will transplant young saguaros across the landscape as one of several complementary strategies to improve overall ecosystem function in the region.

“Saguaros are what we call a keystone species,” said Aaron Flesch, an SNRE research scientist specializing in wildlife ecology and conservation and the principal investigator of the grant. “They’re tremendously important in the environment. More than a hundred vertebrates and countless insects depend on saguaros for their survival.”

The effort will combine saguaro transplantation with the installation of erosion control structures, seeding of native grasses and construction of nest boxes for native birds, which researchers believe will help address several ecological issues at once.

“Erosion and chronic drought are problems that folks in the region – and across the planet – are grappling with,” said Elise Gornish, a professor in SNRE whose work focuses on the logistics of ecological restoration. “Instead of putting a band-aid on the issue, we propose a series of treatments that are mutually supporting and address a series of different challenges at the same time.”

Working from the ground up

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Erosion and prolonged drought have degraded the landscape across the Altar Valley, resulting in the loss of native plant and wildlife populations. Gornish, Flesch and their partners led by Altar Valley Conservation Alliance plan to combat these forces using some surprisingly simple tools: rocks, seeds, nest boxes and saguaros.

“When you’re working on a large-scale project, your approach has to be reasonably inexpensive and logistically simple,” Gornish said. “We’ve successfully deployed a lot of these tools in other projects in the area, so the ranchers and land managers we’ll be working with know they’re effective.”

She explained that the project team will install rocks in eroded uplands and streams to act as erosion breaks – and as tiny nurseries.

“Wind and water carry a lot of organic material like seeds and soil across a landscape,” she said. “When they hit rocks, the force of the wind or rain reduces for just a second, and they drop anything they’re carrying. That means you can get really nice nursery conditions around rocks: a high concentration of organic material, seeds, and even a little bit of shading on the soil surface.”

The team will also spread seeds of fast-growing native plant species to slow erosion, contribute more organic matter to soils, reduce wildfire risk by competing with invasive species like buffelgrass, and provide high-protein forage for grazing cattle.

Gornish noted that seeding can often be complicated by the presence of small, granivorous animals.

“When you throw down a bunch of seed, all the animals that live near there are going to want to eat it,” she said. “If they eat your seeds, you can’t get growth out of the plants. That’s where the saguaros and next boxes come in – they provide necessary nesting cavities for predatory birds to keep those populations under control.”

Predatory bird species like gilded flickers, kestrels, and small owls require nesting cavities high up in trees and saguaros. In the Altar Valley, those aren’t always easy to come by.

“In the short term, we’re erecting nest boxes to address the cavity limitation,” Flesch said. “But the long-term strategy is to plant saguaros to support these predators. If we can help them get established in areas where they once occurred, it could create a trophic cascade that will help restore these desert grassland ecosystems.”

Salvaging saguaros

Flesch’s team began transplanting saguaros in early 2026 as part of a pilot effort on Bureau of Land Management and Pima County lands. In their first season, they planted approximately 600 salvaged or donated young saguaros across the Altar Valley.

“We were able to salvage about 50 five- to six-foot-tall plants from power line rights-of-way, thanks to the Western Area Power Administration,” he said. “The rest were one- to two-foot, nursery-grown plants donated by Pattern Energy.” 

Transplanting hundreds of young saguaros is no small feat. Their root systems need careful excavation, transportation requires significant coordination of equipment and workforce, and planting sites need to have appropriate protection from the desert’s harsh weather.

“When saguaros self-plant, they depend on nurse trees to act as a buffer against swings in temperature, provide some extra moisture and shade, and offer some protection from wildlife,” Flesch said. “We’re planting smaller saguaros under nurse trees, installing shade cloth, doing some hand-watering and mulching, and even using metal mesh to protect them from getting munched on or trampled.”

Rooted in collaboration

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This kind of watershed-scale restoration work demands extensive collaboration between scientists, conservation groups, and ranchers and land managers.

“In the Altar Valley, we have longstanding, trusting relationships with the local community,” Gornish said. “We’re fortunate to work with this decades-old group called the Altar Valley Conservation Alliance, who are all working together to make the environment more sustainable for ranching, wildlife, and the people living there.”

The research team is working with a broad coalition of public and private partners, including Pima County, Tucson Bird Alliance - who is designing and building nest boxes - Pattern Energy, the Western Area Power Administration, and local community members.

The project will also create more than 20 paid positions and offer experiential learning opportunities to U of A students, developing a workforce with in-demand skills in restoration ecology.

“Ecological restoration is one of the fastest-growing industries on the planet,” Gornish said. “This project will help develop a workforce with marketable skills in all areas of dryland restoration, from deploying the treatments to monitoring.”

Playing the long game

The Altar Valley project will include several years of monitoring to assess the effects of the treatments over time.

“Our current grant provides funding for four years, which gives us enough time to see how our saguaro transplants are surviving, how many of the nest boxes are being used, how much of the seed has germinated,” Gornish said. 

She said the team’s ultimate goal is to survey the saguaros every five years to gather valuable information about the health of the individual plants and to develop best practices for saguaro transplantation writ large. 

“Any time you’re dealing with saguaros, you’ve got to be thinking about the long game,” Flesch said. “When you’re dealing with these dryland ecosystems, you have to be thinking about success in terms of decades.”