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November 1, 2024

Old rope swings hang from even older cottonwoods along the Middle Rio Grande in Albuquerque, New Mexico. The riverside forest, known as the bosque, has long been a shady oasis in the arid valley. “It’s where everyone would go,” said Shelby Bazan, who describes herself as a “born and raised Burqueña,” or native of Albuquerque. Her father grew up along the river in the ’70s, and both her parents remember summers when the river was alive with water and people. 

Myron Armijo, the governor of Santa Ana Pueblo, shares those memories. “The Rio Grande was our playground,” he said. “Once we got our chores done, then we would get out there and play, a lot of the time pretty much all day long.” Now, water diversions, development and climate change leave more sections of the river dry each year. “If you jump, you’re just going to hit the dirt,” said Bazan. Nobody has bothered to replace the old swings.  

Over the past two decades, restoration efforts large and small have removed introduced plants such as tamarisk and Russian olive, which can form impenetrable thickets, replacing them with native cottonwoods, willows and shrubs that support wildlife and are significant to the people with the deepest roots in the valley. “It means a lot to us, both traditionally, culturally,” Armijo said of the bosque.

But as the region warms — average temperatures since 2000 have been 1.8 to 2 degrees Fahrenheit higher than they were over the previous century — and the once-high water table drops, those who love the bosque have been forced to reconsider what can be realistically restored.

OVER MILLENNIA, the bosque’s mosaic of plant communities was maintained by a high water table, seasonal flooding and a meandering river channel. “You’d have grassy meadows, wetlands and understory shrubs over here; young cottonwoods over there; older cottonwoods over here,” said ecologist Kim Eichhorst, director of the community-science-based Bosque Ecosystem Monitoring Program (BEMP). 

By the 1990s, 150 years of water- and land-use decisions had destroyed or degraded much of this historic mosaic. “Channelization, levees to protect communities, impoundments to store water for irrigation purposes — that all changed the river,” said Glenn Harper, who’s worked for Santa Ana Pueblo for over 25 years and oversees its 142,000 acres of grassland, shrubland and woodland habitat. 

Cottonwoods that germinated in the 1930s and 1940s are now separated from the river and nearing the end of their lifespan. Without the seasonal floods that distributed seeds and nutrient-rich sediment, there are few young cottonwoods to replace them. At the same time, drier, hotter conditions have encouraged introduced plants, not only tamarisk and Russian olive but Siberian elm, Ravenna grass and many others. 

In response, many Middle Rio Grande communities — at Santa Ana and Sandia pueblos, in Albuquerque and elsewhere — began restoration efforts along the river to bring back the bosque. Though much of the initial work was spearheaded and funded by local communities, many of the projects now have government agency support. For example, Albuquerque’s industrialized South Valley is now home to Valle del Oro National Wildlife Refuge, thanks to a collaboration between the local community and the U.S. Fish and Wildlife Service. Though bosque restoration isn’t the refuge’s sole purpose, it is a part of its plans for the land. 

When Santa Ana Pueblo embarked on its ambitious bosque restoration plan, said Armijo, the tamarisk and Russian olive thickets under the mature cottonwoods were so dense that getting through them on horseback was impossible. After the pueblo’s Bosque Restoration Division cleared about 1,500 acres, the bosque began to resemble the open cottonwood forest that pueblo elders remembered from their youth. 

Since then, though, falling groundwater levels have stressed the aging cottonwoods, and many are dying or dead. “Climate change,” said Nathan Schroeder, Santa Ana Pueblo’s Restoration Division manager. “That’s where I feel like the deck keeps getting shuffled.” And because the roots of young trees can no longer reach the water table, the pueblo’s original plan for planting new cottonwoods among the old is no longer tenable.

AS CONVENTIONAL restoration approaches become less reliable, advocates are asking how to move forward. “What we really need is to recognize what the system can support,” said Eichhorst. Instead of trying to restore the bosque to what it was, she envisions a mix of dryland plants and smaller pockets of “wet-loving” plants, cottonwoods or otherwise, wherever water is sufficient.  

At the pueblo, the Restoration Division may plant some native drought-tolerant shrubs where it had planned to grow cottonwoods. Farther downstream in Albuquerque, said geographer and herbalist Dara Saville, some of these species are showing up on their own: “Now that the bosque is largely dry … you see the creeping in of plants from the mesa, from the foothills, from these higher, drier areas.” 

Saville, the founder of the nonprofit Yerba Mansa Project (YMP), doesn’t mind shrubs. “They’re key components of my concept of restoration, resiliency and ongoingness.” The bosque will continue, she said, but as it changes to adapt to new conditions, tenacious, shrubby plant species will likely become more common. And while shrubs can’t provide a shady refuge for people, they do offer food and shelter to wildlife, and some are sources of traditional foods and medicines. Along the Middle Rio Grande, project staff and volunteers have planted native species, such as yerba mansa, pale wolfberry, golden currant and willow baccharis, all of which have medicinal uses. 

Bazan, who works as a BEMP educator, said nonnative trees are another option: “If we don’t have the cottonwoods, would you rather have an exotic bosque that has Siberian elm that still provides shade — or would you rather have a native bosque, but of shrubs and dry grassland areas?” Though Siberian elms are classified as “noxious weeds” in New Mexico, their tolerance for a lower water table and their ability to provide habitat for local species such as porcupine have led restorationists to consider leaving them in place in some areas.

While the restoration projects are ecologically and culturally important, there are many competing uses for the Rio Grande’s water, including irrigation and the demands of an expanding urban population. Although riverside vegetation also uses river water, a new bosque mosaic is expected to use less water than extensive thickets of nonnative trees and shrubs. 

In the pueblo, however, the focus remains on native plants and wildlife. To support young cottonwoods and willows, the restoration division, in partnership with federal agencies, used excavators to lower sections of the riverbank and bring back some limited flooding. The bosque planted in this new floodplain over the past 15-plus years is luring endangered southwestern willow flycatchers, threatened western yellow-billed cuckoos and, according to this year’s survey, yellow warblers, Harper said. 

No matter its makeup, restoring and maintaining a more resilient bosque ecosystem will require cooperation and long-term maintenance. “It never ends,” said Harper. Eichhorst is encouraged by the region’s shared love of the bosque. “It isn’t something that’s just an older generation, but it’s something that younger students are actively participating in,” she said. “It’s not hopeless.”   

This story is part of High Country News’ Conservation Beyond Boundaries project, which is supported by the BAND Foundation. hcn.org/cbb