Saguaro National Park in the Sonoran Desert •

Saguaro National Park in the Sonoran Desert

Today’s Image of the Day from NASA Earth Observatory features Saguaro National Park, which was founded to protect the saguaro cactus (Carnegiea gigantea).

Growing up to 60 feet in height, the saguaro is the largest cactus in the United States, and an icon of the American West. It has spiny, branching arms.

The saguaro grows exclusively in the Sonoran Desert across southern Arizona, southeast California, and western Sonora, Mexico. State laws protect the cactus from harvesting or destruction.

The national park covers about 145 square miles of the Sonoran Desert around Tucson, Arizona. The park is split into two sections: the eastern Rincon Mountain District and the western Tucson Mountain District.

Today’s photograph is focused on the western district, which was once the site of 137 mining sites. Copper, lead, silver, and molybdenum were mined here from the mid-1800s to the early 1900s. 

The saguaro cactus grows very slowly. Given the right conditions, these plants can live to be 200 years old. 

According to NASA, the saguaro is particularly sensitive to temperature range and water abundance, and highly variable or extreme weather can stress the plants and limit reproduction. 

Climate monitoring in Saguaro National Park shows that the region is receiving less rainfall in the winter, but more in the summer. With an abundant amount of rainfall, the cacti can weigh up to 4,800 pounds. However, recent drought conditions threaten the survival of young saguaros.

Experts will continue to seek out improved methods for monitoring the saguaro cactus populations. According to NASA, some recent studies have used such machine learning to survey and map populations of saguaro, which cast shadows that can be identified in imagery. 

The natural color image was captured on September 21, 2021, by the Operational Land Imager (OLI) on Landsat 8.

Image Credit: NASA Earth Observatory 

By Chrissy Sexton, Staff Writer

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