Herbaria aid climate change research

Haven't we been telling you that herbarium sheets are the foundation of all that is good and pure in the world? What is an herbarium sheet, you say? See this (then click on "store").



An old photograph shows that on Memorial Day, 1868, the deciduous trees in Lowell Cemetery in Massachusetts had yet to leaf out. On Memorial Day, 2005, they stood in full verdure. Leafing or flowering dates each year depend on temperature, and global warming has been driving those events earlier in many places. Plants take part in many ecological interactions—with their pollinators, for instance—that are precisely timed. Changes in their seasonal development may therefore bring on broader ecological disruptions. Records of past plant development are scarce, though, so analyzing trends in timing has been difficult.




Now Abraham J. Miller-Rushing and Richard B. Primack, both ecologists at Boston University et al. have compared dated historical photographs, as well as dated herbarium specimens, of plants in flower in eastern Massachusetts, with recent observations of the same species. The plants now flower about eleven days earlier than they did a hundred years ago, when the region was 4.5 Fahrenheit degrees cooler. Their findings echo independent estimates from other data, confirming that old photographs and herbarium specimens are reliable sources for climate-change research. (American Journal of Botany, in press, 2006)