Over the last five years, a simple observation from a Desert Botanical Garden researcher sparked a fascinating project.
Wendy Hodgson, Herbarium Curator Emerita and Senior Research Botanist, noticed that after rainstorms, a group of smaller saguaros on South Mountain seemed to swell and take up water, while the larger ones didn’t appear to respond as much. Were the big saguaros still alive and functioning—or were they standing relics of the desert?
To find out, Garden researchers teamed up with Central Arizona Conservation Alliance’s Program Director Challie Facemire, who connected them with Donald Domann, City of Phoenix Parks Supervisor, South Region. With his help, they obtained permits to begin monitoring saguaros across the site.
Over the past year, Garden researchers have been measuring each plant’s volume and surface area to estimate how much water they absorb after rain events. They also track their photosynthetic activity and, more recently, have added thermal imaging to capture temperature data.
The results so far have been encouraging: initial data show that the saguaros in the tested site are responding to rainfall and reveal which months are the most photosynthetically productive for them. Moving forward, researchers hope to expand this monitoring across South Mountain to gain a fuller picture of saguaro health throughout the preserve.
