Two University of Arizona graduate students have each earned a highly competitive and prestigious fellowships awarded by the U.S. Environmental Protection Agency.
Henry Adams and Daniel Griffin, both UA doctoral candidates, are among 121 master's and doctoral students across the nation to be named EPA STAR fellows, which which supports some of the nation's top students in environmental studies. Griffin is a graduate student in the School of Geography and Development.
The agency will offer this year's class of fellows up to $37,000 annually for a three-year period to cover tuition and fees, a research allowance and stipend.
"It's a handsome award, and the benefit to me is that it is effectively funding my graduate studies," said Griffin.
"That is really wonderful, and it also provides some validation that the type of work I am involved in is salient," Griffin added.
Griffin, a dendrochronologist researching the southwestern region's summer monsoon history, is part of a broader research effort at the UA to create the first systematic network of monsoon-sensitive tree-ring records.
However, this work demands a study of "latewood," the darker orb that forms during the summer monsoon months.
Researchers have long studied the total amount of wood formed each year and also "earlywood," the lighter diameter band in every cross section of a tree's bark, which forms during the spring.
But, for the first time, Griffin and other researchers are independently measuring both earlywood and latewood on samples archived at the UA's Laboratory of Tree-Ring Research, where Griffin also is a graduate student.
"Latewood width provides a proxy record for past monsoon rainfall patterns," he said, adding that less forms during summers with a dry monsoon, while more latewood is produced during wet monsoons.
He and his colleagues have been collecting new tree-ring samples from mountain ranges across Arizona and New Mexico.
In evaluating latewood, Griffin – who previously helped develop blue oak tree-ring chronologies in California – will attempt to explain monsoon variability in the Southwest over a 500-year period.
"Humans have also thrived in this region for thousands of years but, in recent decades, we have placed unreasonable demands on the natural environment," Griffin said. "As we start to think about more holistic and sustainable water resource management, we must consider all the elements."
For every week over the next two years, Griffin will measure tree growth at two locations in the Santa Catalina Mountains to help advance what is known about how earlywood and latewood formation corresponds to the variability of moisture during the winter and monsoon seasons.
Griffin also will analyze archived tree-ring collections at the UA, expanding their evaluation to include latewood measurements.
His project, "Tree-ring reconstructions of North American monsoon variability in the southwestern U.S.," is being supervised by Connie Woodhouse, an associate professor in the UA School of Geography and Regional Development.
Griffin, who is also affiliated with the UA's Climate Assessment of the Southwest, CLIMAS, and the Institute of the Environment, intends for his work to inform researchers attempting to understand how trees respond to and use monsoon rainfall.
"It's amazing to me that I am able to do this research in Arizona, where people have studied tree rings and climate for 100 years," said Griffin, who earned his undergraduate and master's degrees from the University of Arkansas. "It's perhaps serendipitous for me to be here and to be doing this work with my heroes."
Griffin intends for his work to be useful for regional stakeholders and decision makers and plans to work through CLIMAS.
"As we start to think more about water resources management, the monsoon turns out to be very important on the demand side," he said, noting that monsoon timing and characteristics also influence the fire season and the general health of ecosystems.
"For the first time, we will be able to get specific information about the monsoon season for the last 500 years and determine what long-term relationship exists between the monsoon and winter climate variability."
By La Monica Everett-Haynes and Monique Padia, University Communications, October 22, 2010