Oils and other chemicals released by plants after a rainstorm may explain the feelings of euphoria and health benefits that follow a storm in the desert, research shows.
“The flora of the Sonoran Desert is one of the richest plants in the world, emitting aromatic volatile oils, and many of these aromas provide benefits to human health, wildlife and stress-reducing plants themselves,” said Gary Nabhan, a social research researcher. scientist at the Southwestern Center of the University of Arizona and chairman of the food and water security of the southwestern border areas.
Nabhan is the lead author of two new studies – one in International Journal of Environmental and Public Health Research and the other c Desert plants– which explain how volatile organic compounds that have evolved to protect plants from harmful solar radiation, heat waves, drought stress and predators can also have benefits for human health.
Desert monsoon season
Nabhan was inspired to explore the health benefits of desert scents after learning about “forest bathing”, an ancient practice that originated in the coniferous forests of East Asia and involves spending time in nature to help reduce stress. and improving overall well-being.
He was initially disappointed by the fact that the forests closest to him were thousands of feet high in the Catalina Mountains, which reached their highest point about an hour and a half away by car from downtown Tucson.
“But then I thought that some of these compounds are found in desert plants,” says Nabhan, “and we know we have great scents at certain times of the year, especially right after the monsoon thunderstorms.”
The southwestern monsoon season usually lasts from June 15 to September 30. About half of the average annual rainfall in the region falls during these three and a half months.
Nabhan and his associates, Eric Doherty, a former intern at Southwest Center, and Tammy Hartung, co-owner of Desert Canyon Farm in Canyon City, Colorado, identified 115 volatile organic compounds in 60 plant species in the Sonoran Desert that were released just before, during and after rain. Of these, 15 have shown in past studies that they offer tangible health benefits.
“Aromatic volatile organic compounds from desert plants can help in many ways to improve sleep, stabilize emotional hormones, improve digestion, increase mental clarity and reduce depression or anxiety,” says Nabhan.
“Their accumulation in the atmosphere just above the desert vegetation is what causes the smell of rain, which many people report. It also reduces exposure to harmful solar radiation in ways that protect the desert plants themselves, the wildlife that uses them as food and shelter, and the people who live among them.
Many desert plants produce more volatile oils in the summer to protect themselves from harsh conditions, Nabhan said.
“The production of oil compounds occurs during extreme droughts and severe heat waves, but they remain on the leaves until the onset of summer rains.
“We thought that during the summer rains these greasy and sticky substances are washed away in the air, but now there is some evidence that with the humidity and fierce winds that we get with the onset of rain, they are released into the atmosphere before the rain fallen and contribute to that incredible rush of anticipation you feel just before the first raindrop of a thunderstorm. From there, they travel into our lungs and blood for minutes. “
The creosote shrub is one of the most iconic plants in the Sonoran Desert and is often cited as the plant that gives the desert its familiar scent when it rains. One of the healing compounds that contributes to the familiar smell of creosote is trans-caryophyllene, which actually comes from a fungus that lives inside the plant, not the plant itself, Nabhan said.
Armed with his knowledge of desert plants, Nabhan is part of an initiative to create fragrant gardens to promote healing and prosperity in the Southwest.
In March, Nabhan and colleagues installed such a garden at the Sonoran Desert Inn and Conference Center in Ajo, Arizona. By late fall, they would like to complete another one at the base of Tumamok Hill, where many people go to train outdoors. The proximity of the hill to the hospital Carondelet St. Mary’s makes it an even more strategic place, says Nabhan, who envisions patients and their families reaping the health benefits of the garden.
“I would like to see these fragrant gardens around every hospital, public clinic and bed and breakfast – wherever someone comes to heal, relax and unwind,” says Nabhan. “These public gardens will not only produce nutritious food, but will offer residents, guests outside the city and tourists a powerful opportunity to feel how the desert smells of rain.”
Source: University of Arizona