Over the course of her study, Augspurger made nearly 600,000 observations of 43 plant species in Trelease Woods, a 60.5-acre remnant of old-growth forest in central Illinois. She noted 10 distinct developmental stages in the plants’ lives, including when they emerged in spring, how long it took them to mature, when the flowers opened and died, when the leaves began to lose their greenness and when the plants went dormant. Augspurger is a professor emerita of plant biology at the University of Illinois at Urbana-Champaign.

Augspurger stands next to a bur oak tree in an old-growth forest outside Urbana, Illinois. (Photo by Steve Buck)

By tracking these events and their relationship to average daily temperature and precipitation records, Augspurger and her colleague, Illinois Natural History Survey statistician and plant ecologist David Zaya, found that some shifts in the timing of plant seasonal life cycle events correlated with temperature trends.

The findings appear in the journal Ecological Monographs.

“We marked every major life cycle event in our plants from emergence until they went dormant,” Augspurger said. “And we did it for an intact community, a natural forest community.”