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KEEPING RECORDS: A FAMILY TRADITION OF SCIENCE AND SENSITIVITY

by Nina Leopold Bradley

In 1935, when Aldo Leopold purchased his Sand County farm, "our refuge from too much modernity," he and his family began keeping records of seasonal events on the site. As we became more and more familiar with the place, we found more to anticipate and to record in our journal. At that time, of course, climate change was not a part of our thinking. However, with the advent of possible global warming in the subsequent decades, our phenological tradition took on a substantial scientific direction.

Aldo Leopold observed that the events comprising the annual cycle recur year after year in a regular order. He wrote, "A year to year record of this order is a record of the rates at which solar energy flows to and through living things. They are the arteries of the land. By tracing their responses to the sun, phenology may eventually shed some light on that ultimate enigma, the land's inner workings."

After twelve years of observation, Aldo Leopold published a scientific paper in Ecological Monographs, "A phenological record for Sauk and Dane counties, Wisconsin 1935-45." In the paper, he compared 328 seasonal events at two stations that were 33 miles apart. His primary findings were

• Spring events during the decade 1935-1945 were two weeks earlier than the same events at the same station in l88l-l885 (Trelease 1884).
• Events at the northern station occurred three days later in spring than at the southern station. The difference in phenology between the two stations was least in early spring and greatest in midsummer.
• Some plants showed little variability in date of first bloom, perhaps suggesting that their phenology is governed more by photoperiod than by weather.
• Bird migration responded to changes in temperature much more quickly than did flowering of plants.

Our data also showed that timing of 20 of the events showed no statistically significant change, therefore suggesting that some species are changing their life cycles in response to climate change while others are not.

Terry Root (2003) has written, "in response to global warming, some species are moving north in the northern hemisphere and some are moving south in the southern hemisphere; and they are moving up in elevation." She has stated that "morphological traits in species have changed in response to global warming: egg sizes and body sizes have changed; there have also been genetic changes in several insect species."

If the climatic warming trend continues over the coming decades, stress to biological systems will surely result. Some plant and animal species may be able to adjust their life histories in response to the changing climate. Many species, however, are evidently not able to respond. It is apparent that climate change is already disrupting ecological communities.

Keeping records of phenological events is an enjoyable and interesting hobby. It also has the merit of sharpening one's sensitivity to the seasonal progressions. Over time, these records can become useful data, necessary to monitoring long-term change.

"Keeping records enhances the pleasure of the search, and the chance of finding order and meaning in these events" (Leopold 1949). With 80 years of hindsight, my father's work takes on new relevance.

Literature Cited

Bradley, N., C. Leopold, J. Ross, and W. Huffaker. 1999. Phenological changes reflect climate change in Wisconsin. Proceedings of the National Academy of Sciences 96.

Leopold, A., and S. Jones. 1947. A phenological record for Sauk and Dane counties, Wisconsin 1935-1945. Ecological Monographs 17:81-122.

Root, T. 2003. Fingerprints of global warming on wild animals and plants. Environmental Review 10(3).

Trelease, W. 1884. When the leaves appear. University of Wisconsin Experiment Station.

The Aldo Leopold Foundation received a 2003 SCB Distinguished Service Award in recognition of their support for a program of diverse ecological research and restoration that has resulted in ecologically sound land management, educational training, and numerous scientific publications.

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