Climate-Ready Trees: Planting Smarter for a Warmer (and hopefully shadier) Future

Stacked bigtooth maple leaves in the Manzano Mountains this October. While native to New Mexico, bigtooth maple trees tend to thrive in cooler temperatures and higher elevations. Photo credit M. Thompson

Question:

I am updating the Valencia County Extension Master Gardener brochure on trees. How do I access the new recommended trees for climate change? I would like to include them in the brochure.

- Zena K., Los Lunas

Answer:

The final report, entitled “Climate-Ready Trees: Tree Species Selection Guidelines for the Albuquerque Metro Area,” has just been released and is accessible online at https://www.nature.org/newmexicotrees. There you can read about this great project and others led by Sarah Hurteau, the Albuquerque Urban Conservation Program Director for the New Mexico chapter of The Nature Conservancy. Hurteau was inspired by a similar project performed by researchers at the USDA Forest Service and University of California-Davis and published in 2018. With funding from the National Fish and Wildlife Foundation, Wells Fargo, Nusenda Foundation, Avalon Trust, Enterprise Bank & Trust, and other private donors, Hurteau and her team invited local tree experts to assess over 130 tree species for their long-term viability in the Albuquerque area. Over the next 30 years, high temperatures in the Albuquerque area are expected to resemble the current high temperatures in Las Cruces or El Paso, and in 80 years, by 2100, closer to the highs currently experienced in Tucson.

I selected the following excerpts from the 46-page Climate-Ready Trees report. Please note that even though the report focuses on trees recommended for the Albuquerque area specifically, the broader concepts can and should be applied to Farmington, Raton, Clovis, Carlsbad, Lordsburg, and everywhere in between.

“Albuquerque is facing increasingly extreme climatic events, compounded by the city’s urban heat island effect. As a large metropolis in an already arid environment, Albuquerque urgently needs creative strategies to mitigate and adapt to climate change.

“Urban trees are a cost-effective, nature-based solution to mitigating climate change and improving the livability in cities and towns. Albuquerque’s estimated 1.5 million urban trees are quietly benefitting human and wildlife inhabitants, providing air and water pollution removal, carbon sequestration, carbon storage, building energy savings, heat mitigation, reducing stormwater runoff, and improving physical and physiological health and wellbeing for residents.

“Yet, the tree canopy in Albuquerque is rapidly declining. Poor tree species and planting site selection, limited capacity for proper tree care, weak policies to protect mature trees, and tree canopy age are major factors in the decline. Climate change is amplifying the urban heat island effects with increasing temperatures and altered precipitation patterns, which will greatly affect Albuquerque’s urban trees. Tree species that practitioners have been planting for years are no longer viable options. Sun scorch, drought stress, new pests, disease and other tree health problems are increasingly prevalent.

“The last major tree planting campaign in New Mexico took place nearly a century ago. Many of the largest shade trees in Albuquerque today are the Siberian elms (Ulmus pumila, now considered an invasive species) planted during that campaign that alone account for 25% of Albuquerque’s canopy cover. Roughly 60% of Albuquerque’s trees are younger or smaller stature trees with a trunk diameter of six inches or less that contribute limited shade. Albuquerque faces a crisis where a majority of the shade-producing tree canopy could be lost over the next decade. [Again, this crisis is not unique to Albuquerque. Urban trees are failing across the state and globally.]

“The Nature Conservancy is part of a concerted effort in Albuquerque to reverse the tree canopy decline by supporting thoughtful tree plantings resilient for the century to come. An alliance of public agencies and non-profit organizations is addressing the tree stewardship and climate challenges. Each organization brings a unique area of expertise and influence that is necessary for a holistic and robust approach to meeting the needs of both the community and the community forest. The alliance’s efforts have built a strong foundation that has empowered the City of Albuquerque’s Mayor Keller to adopt a goal to plant 100,000 trees by 2030, one tree for every child in Albuquerque. The Nature Conservancy’s role in this effort has been to convene stakeholders and find science-based solutions that use data and analysis to inform projects and ensure long-term success…

“The purpose of the Climate-Ready Trees for Albuquerque project was to develop a list of urban adapted tree species that can survive both current conditions and the climatic challenges over the next century… This report is intended to serve as a guideline to increase the tree species diversity and resiliency of Albuquerque’s community forest. Outcomes of this project and report:

• Provide the first step in making the Albuquerque community forest more resilient to climate change, more specifically increasing temperatures and decreasing precipitation.
• Provide a resource for use in tree selection and site selection.
• Highlight the variety of trees available to help diversify our future community forest.
• Encourage nursery industry partners to start planning for future tree needs of their customers and introduce new species into the propagation pipeline.
• Inspire more people to plant trees and engage in The Nature Conservancy’s tree awareness and tree planting campaigns.
• Continue to foster community stewardship of trees and guide people to plant the right tree in the right place at the right time.”

In addition to cold and heat tolerance, the team rated trees on their tolerance to different soil textures, drought, and other important characteristics, like pest and disease susceptibility, allergen issues, wildlife habitat, and more. The final report includes several lists of recommended trees for site-specific locations. For example, there’s a list for “Xeriscaped Public Recreation, Residential, or Commercial Places” and a separate list for “Restricted Growing Areas,” like 4- to 6-foot-wide medians.

Several people from other parts of the state have already asked me how they can use this resource to select trees for their areas. As you scan the lists, you’ll likely see at least a few trees that are currently thriving in your area. If you’re in Las Cruces, you’ll recognize Chinese pistache, crape myrtle, Texas mountain laurel, chaste tree, and honey mesquite, just to name a few. Cross check the ones you’re interested in with the species on publicly available tree lists for the Tucson and Yuma areas to be sure they’re going to be heat hardy in the warmer decades to come.
Visit the blog version of this column at Desert Blooms for links to more resources (aka “tree sources”).

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

Links:

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook page.

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