Giant cactus collapses in record heat in US

Record high temperatures in Arizona, combined with a lack of monsoons, put the saguaro cacti at the Desert Botanical Garden under great stress.

A cactus collapsed in the botanical garden. Photo: KVOA

Kimberlie McCue, director of science at the botanical garden, said the saguaro cactus was likely "fairly normal" or slightly soft before it collapsed suddenly, suggesting it was rotting from the inside due to heat-related stress, CNN reported on July 28.

Every February, the Desert Botanical Garden takes an inventory of its saguaros and assesses the condition of each one. McCue says that since 2020, when record temperatures have stressed many saguaros, she and her colleagues have seen more and more cacti die at the garden. The current record heat has pushed some previously affected plants to the brink, causing them to shed branches or even collapse. The evening of July 26 ended a record 16-day streak of temperatures above 90 degrees Fahrenheit in Phoenix. The city experienced temperatures above 111 degrees Fahrenheit again on July 27.

Cacti perform many essential functions at night. That’s when they regasify, absorbing carbon dioxide for photosynthesis during the day. But as Phoenix experiences record-breaking heat at night, the conditions are stifling and stressful for saguaros, leading to dehydration and increased vulnerability to disease and insects. Saguaros are well adapted to hot, dry environments, but they do have their limits, McCue said.

Phoenix is ​​one of nine cities in the United States with at least a million people living in neighborhoods with temperatures several degrees warmer than the surrounding area. In Tucson, temperatures still hover above 100 degrees, but the local saguaro doesn’t face the same stress because it’s less affected by the urban “heat island” effect. The biggest threat to saguaros, says Erik Rakestraw, curator of plants at the Arizona-Sonora Desert Museum, is that as temperatures rise over time, it will be harder for new generations of cacti to grow.

An Khang (According to CNN )

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