Field Notes

Ancient pollen sheds light on current environmental issues

Shinya Sugita uses fossil records of pollen to study the history of vegetation and climate.

"I love counting pollen," says Sugita, assistant professor in the Department of Ecology, Evolution, and Behavior. "It's very relaxing."

Sugita is a palynologist, a scientist who studies ancient pollen grains and other microfossils found in sediment beneath lakes and bogs. Based on their observations, palynologists can paint a portrait of the vegetation at various times and places of our planet"s past. They can then correlate those changes with known changes in other variables such as climate and the presence of humans to create a clearer picture of how external forces shape ecosystems.

Sugita got into this field in the late 1970s as a way to combine two big interests of his history and ecology. At the time it seemed to be basic science at its best knowledge for the sake of knowledge. But as global climate change began to attract attention, so did palynology. Because the fossil pollen record shows how vegetation changes as climate changes, it's useful for testing models attempting to predict how future climate might affect future vegetation. "Over the last 10 to 15 years paleorecords have become more important as people try to understand change in the environment," Sugita says.

Results from palynological studies are also drawing interest from the emerging field of conservation biology, which seeks to preserve or recreate aspects of nature in their natural state. "Paleodata help tell us what to conserve," Sugita says. "In Europe, Japan, this country, people are interested in what were the natural conditions before."

As interest in their field has grown, palynologists have faced a bit of a challenge. Traditionally they have been a qualitative bunch, observing but not applying a whole lot of mechanistic thinking to their observations. Consequently, the discipline was short on the quantitative rigor public policymakers need to extrapolate from a picture of what was to predict what might be.

Fortunately, Sugita was a bit of a renegade in this regard. As a postdoctoral student working with now-professor emeritus Margaret Davis in the 1990s, he developed an elaborate computer model that takes the many variables involved in pollen distribution, from pollen weight and shape to prevailing winds and topography, and creates from them a corrective lens that transforms historical pollen data into a comparatively clear picture of the past.

In 1997 Sugita took his model to Sweden to evaluate, "the history and impact of human activities on vegetation over the last 5,000 to 7,000 years." As part of that effort he and his European colleagues obtained funding from the Nordic Research Council in Norway to enhance the userfriendliness of his computer program and train Ph.D. students from 10 European countries to use it.

Mary K. Hoff