Las Vegas Faces New Threats to Iconic Desert Plants as Heat Intensifies.
LAS VEGAS — On a scorching stretch of West Charleston Boulevard, Norm Schilling, a local horticulturist, stopped his truck to visit an old friend: his favorite tree. This African sumac, saved decades ago by Schilling after a brutal winter left its branches frozen and lifeless, is now facing a new challenge—months of relentless heat that have dried out its branches and caused clusters of its foliage to die back.
It’s a puzzling issue. The Southwest is no stranger to extreme heat, and desert plants are known for their resilience. Yet, experts say that as climate change drives more frequent, intense, and prolonged heatwaves, even these hardy species, including iconic saguaro cacti and agave, are struggling.
“We saw damage to plants this summer that had never shown heat stress before,” Schilling said. During a drive around Las Vegas, he pointed out the toll the heat has taken.
On a quiet residential block, a mock orange shrub showed signs of sunburn, with bleached spots where the sun had damaged its shiny leaves. Nearby, a pair of mulberry trees were drying out, likely due to insufficient water to combat the heat. Around the corner, a large juniper tree exhibited signs of severe decline, with dead, brown leaves clinging to withered branches—a clear indication of recent heat damage.
“That juniper is probably close to 40 or 50 years old. It’s a magnificent specimen, but she’s going to die,” Schilling lamented, patting and kissing its rough trunk. A few blocks away, a group of gopher spurge, normally a dependable and common species in the Valley, appeared burnt, their yellowed branches splayed in all directions. “Some of these plants are just at the point where they’re not going to recover,” he said.
This summer, Las Vegas has broken several heat records, including the highest temperature in its recorded history—120 degrees Fahrenheit on July 7. A record streak of seven consecutive days at or above 115 F followed. June, July, and August saw consistent triple-digit temperatures with little relief, even at night.
“The heat we’re seeing now is a new paradigm. It’s like the ground is shifting beneath our feet,” Schilling observed.
Across the Southwest, ecologists are working to understand how different species are coping with the ongoing heat onslaught and to determine just how hot is too hot for desert plants and trees.
Kevin Hultine, director of research at the Desert Botanical Garden in Phoenix, is studying the effects of heat stress on the Sonoran Desert ecosystem. He and his team have been tracking a rise in saguaro cactus mortality that began in 2020 during a severe, prolonged drought and has continued since.
“Summer of 2020 was our hottest on record until last year, and we saw a major die-off,” Hultine said. “It has been constant ever since, and then obviously 2023 increased the pace even more.”
Last year, Phoenix experienced its hottest summer in recorded history, with 31 consecutive days of temperatures at or above 110 F. Stark images emerged of saguaro cacti that had dropped their signature arms or toppled over entirely. This year has brought little relief; July was the city’s second-hottest on record, and Hultine reported that some cacti and agave are still struggling, though the situation is slightly less dire.
Hultine is still investigating the exact causes of the saguaro die-off, including whether the primary threat comes from individual heatwaves or the cumulative effects of multiple extreme summers. With long-lived plants like cacti, the full extent of the problem may not be immediately apparent.
“It’s possible that we’re looking at this exponential curve of mortality, but it could take years before we know,” he said.
Schilling believes repeated exposure to extreme heat is a major issue. The Southwest is no longer experiencing many cooler years between record-setting ones, and consistently high nighttime temperatures leave plants and trees with less time to recover.
Krista Kemppinen, a senior scientist at the Center for Biological Diversity in Tucson, Arizona, pointed out that the combination of extreme heat and drought is particularly damaging to the desert ecosystem.
Although it’s unlikely that saguaros are headed for extinction, Kemppinen said, the heat stress observed so far is a serious concern. “They’re one of the hardiest plants in the desert—they are very robust,” she noted. “The fact that they seem to be responding so negatively to extreme heat events and climate change is particularly worrisome.”
While saguaros receive significant attention due to their status as a symbol of the Sonoran Desert, there are hundreds of lesser-known species across the region with smaller populations that could be even more severely impacted as climate change intensifies.
The recent heat stress and die-offs have caused horticulturists like Schilling to reconsider what they thought they knew about desert ecosystems. The changing landscape has also motivated him to raise awareness about climate change among his clients and community. He is now collaborating with local nonprofits and government agencies to enhance climate resilience across the Las Vegas Valley.
“We need to figure out how we exist in this environment and make it not only a healthy place to live,” Schilling said, “but also one that is beautiful and sustainable and nourishing to our soul.”