Researchers at the University of Arizona's Tumamoc Hill have digitized 106 years of growth data on individual plants, making the information available for study by people all over the world.

Knowing how plants respond to changing conditions over many decades provides new insights into how ecosystems behave.

The permanent research plots on Tumamoc Hill represent the world's longest-running study that monitors individual plants, said co-author Larry Venable, director of research at Tumamoc Hill.

Some of the plots date from 1906 – and the birth, growth and death of the individual plants on those plots have been periodically recorded ever since.

The century-long searchable archive is unique and invaluable, said Venable, a UA professor of ecology and evolutionary biology who has been studying plants on Tumamoc since 1982.

"You can see the ebb and flow of climate, and you can see the ebb and flow of vegetation," he said.

Lead author Susana Rodriguez-Buritica said, "Long-term data sets have a special place in ecology."

The records have allowed scientists to estimate life spans for desert perennials, some of which are very long-lived, Venable said.

In addition, data from the plots on Tumamoc Hill reveal changes in the Sonoran Desert and have been important to key advances in the science of ecology.

For example, the Tumamoc plant censuses helped overturn the long-standing idea that plant communities progress through a series of steps to a stable collection of species known as a climax community.

"The desert wasn't progressing toward a climax community," he said. Instead of being in synch, each species and plot was changing to its own rhythm.

Rodriguez-Buritica, a postdoctoral research associate in the UA department of ecology and evolutionary biology, Venable and their co-authors Helen Raichle and Robert H. Webb of the U.S. Geological Survey and Raymond M. Turner, formerly of USGS, have published a description of their data in the Ecological Society of America’s journal Ecology and archived the data set with the society.

 

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The title of their paper is, "One hundred and six years of population and community dynamics of Sonoran Desert Laboratory perennials." The National Science Foundation, the USGS and the U.S. National Park Service funded the archiving.

Landmark research on the physiology and ecology of desert plants has been conducted on Tumamoc Hill ever since the Carnegie Institution of Washington established the Desert Laboratory there in 1903 to study how plants cope with living in the desert.

The first permanent plots, generally 33 feet by 33 feet (10 meters by 10 meters), were established in 1906 by Volney Spalding; nine of his original plots remain to this day. Additional plots were established by Forrest Shreve in the 1910s and 1920s. Two more plots were added in 2010. Currently, there are 21 plots.

For every perennial plant within each plot, the ecologists recorded the species, the area the plant covered and its location. Even seedlings were identified and mapped.