Southwest Wildfires Endanger Saguaros – The New York Times


ORO VALLEY, Ariz. – It started with a flash of lightning that swept the rugged Santa Catalina Mountains off Tucson’s coast. By the time firefighters got the fire under control, they had burned thousands of saguaros, towering cacti that can reach 60 feet in height and live 200 years.

For many in Arizona, where indigenous peoples learned to feed on tree-like saguaros, the loss was heartbreaking. A famous symbol of the Southwest. Some saguaros are still in their one-year scar. Great Horned Fire, their trunks sang up to their limbs, a testament to their reputation as masters of desert survival.

Still, Benjamin Wilder, an authority on saguaro and director of the University of Arizona’s Desert Laboratory in Tucson, said the lifespans of fire-damaged cacti will likely be shortened.

“I don’t think there are any more near misses when we get to the point where there are much bigger fires,” he said.

Wildfires are just one of the many threats facing saguaros that threaten not just cacti but the mesquite, ironwood and palo verde plants that protect them. At the same time, the unrestricted growth of invasive species, particularly the highly combustible buffelgrass, has fostered more competition for scarce water resources, while also fueling fast-moving — and hotter — fires.

Then there’s the urban sprawl of Arizona’s towns and cities. While the law generally protects saguaros from being cut – try this in Arizona and you can face it. years in jail — plant physiologists say all concrete in metro areas absorbs heat and clings to it. This creates higher nighttime temperatures than in the open desert, making it harder for saguaros to minimize water loss.

Taken separately, saguaros can be extremely resilient when mature, possibly able to react and adapt to any danger. But scientists warn that climate change could accelerate all threats simultaneously, balancing a striking set of challenges to the iconic saguaro. (How do we tell if people are new to Arizona? They pronounce the name of the cactus using a hard “g” instead of suh-wahr-ohs.)

Some disturbing signs are raising alarm bells for fans of the tallest cactus in the United States. Out of 10,000 saguaros studied in Saguaro National Park National Park Service report climate change and on the saguaro, only 70 were younger than 11 years old and were found almost exclusively in rocky foothill habitats.

“The establishment of young saguaros in almost all habitats has virtually stopped since the early 1990s,” the scientists who wrote the report said, noting that the depopulation of young saguaros occurred at a time when temperatures in the Sonoran Desert began to rise and the region increased. entered a prolonged drought.

Such findings are troubling for a plant that relies on creating favorable conditions that scientists describe as “Goldilocks.” Capable of dispersing hundreds of thousands of short-lived seeds each in their attempt to reproduce, Saguaros grow only in the northern parts of the Sonoran Desert – southern Arizona, southeastern California, and parts of Sonora State in northwestern Mexico.

In places with relatively low rainfall, it can take a century for a saguaro to sprout limbs that can give cacti a humanoid appearance; A saguaro in Arizona 78 sleeves is over a hundred years old and is known as Shiva, after the Hindu god.

Seeing the Saguaro as a person has its roots in the culture of the Tohono O’odham Nation, whose citizens live on both sides of the Mexican border. According to the oral tradition of the tribe, a mother left her child alone while she went to play buckle. a traditional game similar to field hockey.

Alone, the boy went to an anthill in the desert and then sank to the ground and came back as a tall saguaro. Relying on tradition that subverts the idea of ​​”food desert,” tribal citizens still use sun-bleached saguaro ribs, which are turned into a pole called a kuipad, to harvest the cactus’ red fruit, which is eaten raw and turned into syrup. or fermented into wine.

Jacelle E. Ramon-Sauberan, who teaches history and culture at Tohono O’odham Community College in Sells, Arizona, said the ritual involves both catching the fruit and symbolically opening the way for the harvest season. “We’re pulling the clouds down to bring the rains,” said Ms. Ramon-Sauberan.

As a keystone species, the saguaro is also of extraordinary importance to other life in the desert. Gila woodpeckers and gilded glowers dug holes in the saguaros for nests that could also house elven owls. Bighorn sheep and mule deer have been known to eat saguaro meat, which is a coveted water source in areas with low rainfall.

Saguaros, on the other hand, rely on less long-nosed bats and white-winged pigeons for pollination. Coyotes and desert tortoises feast on the fruit of the cactus, spreading the seeds in the dirt left on the desert floor.

But human-induced changes in the Sonoran Desert are disrupting the cycles of saguaros that have been sharpened for thousands of years. One of the biggest challenges involves buffelgrass, a drought-tolerant plant native to Africa, Asia, and the Middle East, which was deliberately brought to the arid regions of the United States in the 1930s for cattle feed and erosion control.

While rising temperatures may benefit saguaros by expanding the areas they can survive in, warmer weather could be a boon to buffelgrass, which is constantly spreading across the Southwest. Buffelgrass invasion increased Since the 1980s, patches have doubled every seven years.

Buffelgrass competes with species such as palo verde trees that provide shade protection for young, vulnerable, slow-growing saguaros—which can take about 10 years to grow an inch and a half. But more importantly, perhaps buffelgrass has transformed the relatively fireproof deserts into fire-prone meadows.

“Buffelgrass is in an ecosystem that isn’t really adapted to that, by filling in the spaces between saguaros, providing the fuel to carry larger fires,” said Don Swann, a wildlife biologist with Saguaro National Park.

As a precursor, an extraordinarily devastating wildfire last year, including the Bighorn Fire in the Santa Catalina Mountains and the Shrub Fire in the Tonto National Forest, killed thousands of saguaros and severely damaged many of the survivors. Relatively heavy monsoons have taken a breather this year, but officials in Arizona have struggled to contain nearly 20 statewide wildfires in recent weeks.

Meanwhile, some living in the shadow of the saguaro are mobilizing to protect the giant cacti. Some volunteers hand-dig buffelgrass in Tucson and surrounding areas; others spray the invaders with herbicides. A helicopter crew in Saguaro National Park air spray in some hard-to-reach places in the Rincon Mountains this week.

Patricia Estes, who heads the University of Arizona’s molecular and cellular biology lab, founded a volunteer group called the Catalina State Park Buffel Slayers six years ago. He said he got involved in digging for buffelgrass after learning how the invasive plant can wreak havoc in dry habitats.

“If you have a buffels fire on a street in Tucson, it will melt someone’s car or chain-link fence,” Estes said, adding, “For Saguaros, the biggest threat to climate change is not heat or drought. It is fire that goes in and burns extremely hot.”


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