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| Dana Royer,
assistant professor of earth and environmental science, presented his
research on leaf economics at the Geological Society of America in October.
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| Posted11.01.06 |
New Method Gives Insight into Plant Characteristics During Global
Warm-Up, Says Professor
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Many scientists have long believed a major clue
to rapid global warming is locked in leaf fossils that are millions of years
old. Dana Royer, assistant professor of earth and environmental science, has
just found a key.
Royer and colleagues have generated a reliable method to ascertain from
fossils from the Eocene period, 34 million to 56 million years ago, the leaf
mass per unit of leaf area, an important trait that is related to “leaf
economics.” His findings were highlighted at the annual meeting of the
Geological Society of America (GSA), which was held in Philadelphia from
October 22-25.
“The early Eocene was a period when the planet experienced intense warming,”
Royer says. “Quantify the leaf economics of that time allows us to see how
plants and the environment around them responded to a warm-up and compare
that with what’s happening now.”
Which brings us back to leaf economics, or more precisely, what kind of
leaves the plants had and how quickly they grew. In essence, plants tend to
be relatively quick or slow growing. Quick-growing plants tend to have a low
leaf mass per area. They are typified by thinner leaves, a higher
photosynthetic rate and use more nutrients. They also tend to have faster
lifecycles and be more susceptible to insect damage. Plants with a high leaf
mass per area tend to be slow-growing and have thicker leaves that are more
resistant to insect damage. They also display slower photosynthetic rates,
use fewer nutrients and longer lifecycles.
Obtaining these types of measurements is simple enough in present day, but,
in all but a few examples, has been difficult to generate in the fossil
record.
Royer and his co-investigators were able to solve this puzzle by relating
leaf mass to the width of the petiole, the thin stalk that connects the leaf
to the branch. Heavier leaves require thicker petioles for reasons of
support. In fossils, petiole width and leaf area can therefore be measured
to estimate leaf mass per area. They tested their methods on Eocene fossils
from sites in Washington and Utah.
Royer hopes that this new method will open up a new area of inquiry into the
fossil record that can provide important data for helping us understand the
effects of climate change today.
“It’s always a best case scenario when you can find something from the
geological record that helps us learn something new and useful about our own
world,” Royer says.
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By David Pesci, director of Media Relations |
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