After a long stretch of dry weather and searing heat, the monsoon made its long-anticipated arrival this week. Monsoon storms have been dramatic, bringing much needed precipitation to Tucson and the surrounding desert.
George Montgomery, curator of botany at the Arizona-Sonora Desert Museum, says the brief but heavy summer rains are vital to the desert. Many native plants such as palo verde and ironwood trees and ocotillo cactus respond in dramatic fashion to the moisture by sprouting new leaves.
“With these first rains, the leaves pop out and start growing within hours,” Montgomery says. “Within a day and a half it will be in full leaf.”
Montgomery says the area around Tucson is lush as far as deserts go because of how plants have evolved to maximize their ability to respond to the fleeting rains. “Shallow roots are the major adaptation that has evolved for taking advantage of the quick rains that don’t soak in deep,” he says.
Monsoon rains have always played an important role in shaping the ecology of the Sonoran desert. Likewise, for early inhabitants of the area, the monsoon rains had a way of dictating the rhythm of life. The predictability of the monsoon rains helped native inhabitants know when to plant essential crops.
Murray DeArmond, master gardener Arizona Cooperative Extension of Pima County, says the monsoon provides modern urban gardens with needed moisture. “When that storm came in on July 4, that was a huge relief for us,” he says.
DeArmond says the sometimes violent nature of the summer monsoon rains can damage trees, and it's important to prune damaged branches.
The national weather service says Tucson had a strong start to the monsoon, and a favorable pattern could be repeated anytime during the months of July, August and September.