Douglas-fir, geoducks make strange bedfellows in studying clim...( NEWPORT Ore. Scientists are compari...)

NEWPORT, Ore. Scientists are comparing annual growth rings of the Pacific Northwest's largest bivalve and its most iconic tree for clues to how living organisms may have responded to changes in climate.

Analyzed by themselves, the rings from a single tree or mollusk may sometimes reflect conditions that are either favorable or unfavorable for growth. When scientists look at numerous individuals of the same species, however, the consistency of the ring patterns allows them to build a model and compare that to known climatic measurements.

But when you add in a second species and compare the growth rings of geoducks and Douglas-firs, for example the reliability of the data increases significantly, according to Bryan Black, a dendrochonologist at Oregon State University. Black has been applying tree-ring techniques to the growth increments of long-lived marine and freshwater species.

"When we associate rings from one species with known sea surface temperatures, we can account for almost 50 percent of the variability in the instrument records," Black said. "But when we add the data from a second species, we can increase that number to 70 percent or more. And that's important because it is allowing us to go back and create more accurate models of sea surface temperatures and at time scales more than twice the length of the instrument measurements.

"Each species brings its own 'perspective' of past climate, such that their combination provides a more accurate account," Black added.

Results of the study are being published in the professional journal, Palaeogeography, Palaeoclimatology, Palaeoecology. Other authors include Carolyn Copenheaver of Virginia Tech, David Frank of the Swiss Federal Institute for Forest, Snow and Landscape Research, and Matthew Stuckey and Rose Kormanyos of OSU's Hatfield Marine Science Center.

Sea surface temperatures are an important factor in analyzing the effects of climate change,
'/>"/>