The historical photo collection at Northern Arizona University’s Cline Library will be a key tool in answering a very modern question over the coming months. Dating back to the late 1800s, the images will be used like a visual time machine to reveal the effects of changing climate – and land management – on northern Arizona’s plant communities.
Principal investigator Professor Tom Whitham says that comparing historical and contemporary photos will allow us to literally see how vegetation has changed over time.
Researchers will scour the archives to find the longest historical photographic sequences they can for locations along what’s called the Southwest Experimental Garden Array – a collection of 10 sites ranging from low to high elevations across northern Arizona.
Researchers use natural variations in temperature and moisture along that elevation gradient to mimic the effects of climate change on a range of plant species. The aim is to find plants with the genes best able to survive predicted changes to the environment.
At one riparian site along the Little Colorado River old photos have already shown that invaders like tamarisk and camelthorn have taken over from what was once native cottonwoods and willows.
Although the project has just begun, results from similar projects in other parts of the state suggest there’ll be some dramatic findings. A study in the Santa Catalina Mountains near Tucson has shown that alligator junipers now grow at elevations a thousand feet higher than they did just 50 years ago.
Earth Notes is produced by KNAU and the Sustainable Communities Program at Northern Arizona University.