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Professor, students contribute to research published in Nature

O.A. Stevens traveled through North Dakota every summer, gathering plants and recording data from 1907 to 1961. In one summer alone, the noted botanist, recognized as a leading authority on North Dakota plants, collected 1,000 plant samples from western North Dakota. During his 67-year career as a professor at NDSU, Stevens fastidiously documented prairie plants.

Fast forward to 2012, when Steven Travers, assistant professor of biological sciences, and a team of students mined that data. Their efforts are now providing a wealth of information for climate change research published in early May in a major international science journal.

If you’ve noticed that spring seems to be arriving earlier, forcing blooms to burst and leaves to unfurl sooner than expected, these scientists may have found one of the reasons. The research team has shown that experiments underpredict how plants respond to climate change. The research, which included 22 institutions in the United States, Canada, Sweden, Switzerland and the United Kingdom, is being published in an advance online issue of the journal Nature at

Travers, along with graduate students Kelsey Dunnell, MS ’10, Horace, N.D.; Elise Boehm Maxson, Mauston, Wis.; and NDSU graduate Mathew Cuskelly, BS ’08, Manning, N.D.; are part of the research effort contributing to this worldwide study.

The research team analyzed 50 plant studies on four continents. The research results show that the shift in timing of flowering and leafing in plants, due to global warming, appears to be much greater than previously estimated in warming experiments.

“The data suggest that the advances in the start of spring worldwide could be much greater than previously estimated,” Travers said. “We know that plants are shifting the timing of flowering and leafing all over the world in response to climate change, with potentially important ecological effects, but we are basing predictions of how much timing is shifting and what future communities will look like on the outcome of artificial warming experiments over short periods of time.”

Travers adds, “Instead, our study found that plants are shifting more dramatically across the globe than predicted by the artificial experiments. Thus, to better understand the ecological consequences of climate change, we need to establish more long-term observatory networks of plants in the field and improve artificial warming experiments.”

These approaches, notes Travers, fit in with the research legacy of O.A. Stevens, for whom Stevens Hall is named.

These new research findings could have significant implications for predicting global models of future climate change. How plants respond to climate change plays an important role in water supply, crop pollination and ecosystems.

“I didn't know the data specific to this area regarding climate change before I came to NDSU,” Maxson said. “Also, I didn't realize that the species ranges were shifting as much as they are, which is fascinating.” Maxson is now participating in the Student Career Experience Program of the U.S. Fish and Wildlife Service. She works in the Rydell National Wildlife Refuge near Erskine, Minn., and Glacial Ridge National Wildlife Refuge near Mentor, Minn., while training to be a Fish and Wildlife Service biologist.

Dunnell also assisted Travers while he served as adviser for her master’s thesis. “I learned a lot about the effects that climate change is having on flowering phenology in the northern Great Plains,” Dunnell said. “Not only have spring temperatures increased, but growing seasons have lengthened significantly.” Dunnell currently works for the USDA Agricultural Research Service as a biological science technician and plans on pursuing her doctorate in plant pathology.

Known as phenology, plant experts study the timing of annual plant events, since they provide very visible and consistent responses to climate change. Ecologists use long-term historical records to track the leafing and flowering of plants. But ecologists often also have to use experiments in field plots to estimate how plants respond to temperature.

The research team created new global databases and then compared how sensitive the plants were to temperature, documenting the degree to which plants shift the timing of leafing and flowering with warming. Calculations were made from experiments and then compared to long-term monitoring records.

For more than two decades, scientists have used warming experiments to extrapolate future climate conditions. The approach rests on a critical but little-tested assumption that plant responses to experimental warming match the long-term responses to global warming. The group of researchers tested that assumption to assess how effective warming experiments are for long-term forecasting and prediction.

Researchers found that experiments underpredicted the plants’ responses to temperature by more than fourfold, when compared with long-term historical records. The group compared 1,634 species based on long-term observations and short-term warming experiments, with research results noted in the paper “Warming Experiments Underpredict Plant Phenological Responses to Climate Change.”

The results of the research show that using experiments and historical data may be providing a less than full picture of climate change. Improving the design of warming experiments is expected to be crucial, according to researchers involved in the study.

As it turns out, North Dakota’s normally cold winters provide an ideal research laboratory. “Fargo is a perfect place to study the impact of climate change on plants that have adapted to long, cold winters,” Travers said.

NDSU is recognized as one of the nation's top 108 public and private universities by the Carnegie Commission on Higher Education.

Student Focused. Land Grant. Research University.

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