A bird’s-eye view from an airplane window can provide observers with a sampling of how dramatically the environment changes from one place to another. Few people, however, get the opportunity to appreciate how much one location can change through time. Those temporal changes may determine the diversity of plants that survive and thrive in any individual location, says Peter Adler, assistant professor of Wildland Resources at Utah State University.
“All plants need the same resources–water, nutrients and light,” Adler says. “You’d think if one plant was better at capturing these resources, it would take over the world. If things were constant, maybe one species would take over the world. Clearly, that doesn’t happen.”
Imagine your garden, lawn or perhaps a nearby meadow. Why do tomatoes grow in abundance one year but don’t do so well the next? What helps dandelions destroy your lawn in some years but not others? And what determines which plant species pop up and persist in a rural grassland when no direct human intervention is involved?
Is it weather? Competition for resources with other plants? Adler believes it’s probably both. Using decades of historical data, Adler is teasing apart the interacting effects of climate and competition on plant populations.
“Range scientists have been trying to sort out the importance of competition and climate for years,” Adler says. “I use long-term datasets to build computer models. Thanks to some new statistical techniques, we can better explain why plant populations grow in some years and shrink in others.”
Adler came upon the historical data while working on his doctorate at Colorado State University. His professor at the time, Bill Lauenroth, was archiving records of vegetation taken annually in Hays, Kansas from 1932-1972. These hand-written maps show the location of every individual plant in a series of permanent plots scattered across the prairie.
Nearly 35 years later, Adler leads a team of faculty and student researchers bent on discovering ecological trends based on that information. That involves more than looking at data taken from old papers. Adler’s team uses cutting-edge software and technology to analyze these data.
“You can see if there are trends just by plotting the recorded data,” Adler says. “What we want to do now are some virtual experiments where we step outside the historical data and explore future scenarios.”
But why look at antiquated information from a spot of prairie hundreds of miles away from Utah? Why not monitor local grasslands or shrublands?
Adler is gathering similar historical datasets from Idaho, Utah, Montana and New Mexico. Like the Kansas data, the Idaho and New Mexico datasets are especially valuable thanks to the consistency with which the data were kept–records were made of vegetation on the same plots each year. Adler also plans to conduct new field experiments at these sites to test the predictions coming out of his computer models.
What Adler can take from comparisons among these datasets and experiments, he believes, is a serious look into questions of how climate change may alter our local ecosystems. For example, could the predicted increase in extreme events, such as severe storms and droughts, actually increase species diversity? Maybe, maybe not, but Adler believes that careful analysis of historical events can offer important insights into future climate change.
“This is a retrospective analysis, just the first step of forecasting ecological effects of climate change,” Adler says. “You couldn’t collect this kind of information in forests. They don’t change very fast. But grasslands can change quickly following a drought or a series of wet years.”
From scouring the Kansas data, Adler has seen dramatic changes in the density and variety of plant species from year to year. As this research progresses, he hopes to better understand what accounts for such variability.
“To understand how all these native plants persist over time, you have to play these kinds of games,” Adler says.
In addition to shedding light on climate change, this research could be a boon to ranchers, who rely on certain types of vegetation so their animals can graze. What if there’s not enough food on the grasslands one year? What if a poisonous plant has a boom year? For ranchers, it is important to be able to predict those scenarios based on weather patterns.
“If you knew in advance, maybe there are some things you can do to take advantage of those conditions,” Adler says.
Adler hopes his work will serve as a legacy to the researchers who originally collected the data. The work is painstaking, to say the least–those Kansas researchers spent long hours on their knees under the hot sun, staring at grass. But Adler believes the work was well worth it.
“We now have the tools to extract amazing information out of the historical data,” Adler says. “We can use the past to learn about the future.”
Picture column from top to bottom: dry year at Hays, KS plot; wet year at Hays, KS plot; research site in ID; Adler at UT site; Adler and colleague at UT site.