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From: Eureka Alert
PROVIDENCE, R.I. [Brown University] — Global warming may exact a toll on salt marshes in New England, but new research shows that one key constituent of marshes may be especially endangered.
Pannes are waterlogged, low-oxygen zones of salt marshes. Despite the stresses associated with global warming, pannes are "plant diversity hotspots," according to Keryn Gedan, a graduate student and salt marsh expert at Brown University. At least a dozen species of plants known as forbs inhabit these natural depressions, Gedan said. The species include the purple flower-tipped plants Limonium nashii (sea lavender), the edible plant Salicornia europaea (pickleweed) and Triglochin maritima, a popular food for Brent and Canada geese as well as ducks and other migratory waterfowl.
Gedan and her adviser, Mark Bertness, chair of the Ecology and Evolutionary Biology Department at Brown, decided to find out how global warming may affect pannes. In a series of experiments published in Ecology Letters, the pair subjected plots of forb pannes to air as much as 3.3 degrees Celsius (about 6 degrees Fahrenheit) warmer than the surrounding area.
They found that the plants in the test plots responded initially by growing more but then began a rapid die-off. As they died, they were replaced by a salt marsh grass, Spartina patens. At two sites — Nag Creek (Prudence Island, Rhode Island), and Little River (Maine) — the forbs covered less than 10 percent of the plot, from 50 percent originally, in tests that spanned the summer from 2004 to 2006. At the third site, Drakes Island (Maine), the forb pannes cover decreased from 50 percent of the plot to 44 percent (a 12-percent decline) in just the summer of 2007.
The researchers believe the forbs disappeared due to changes in the plant-water balance in the zone. What that means, Gedan explained, is the warmer air causes the forbs to take in more water, thus making the area less waterlogged and more hospitable to an invasion by Spartina patens, which prefers less water-soaked conditions.
"The forbs basically engineer themselves out of their habitat by making it more favorable for their competitor," said Gedan, the paper's lead author.
In New England, pannes range from Connecticut, where they make up less than 10 percent of a salt marsh's area, to Maine, where they can comprise some 40 percent of the salt marsh ecosystem, according to Gedan.
The Brown experiments "demonstrate that New England salt marsh pannes are extremely sensitive to temperature increases and will be driven to local and regional extinction with the temperature increases expected to occur in New England over the next century," Bertness said.
The scientists are unsure how other variables associated with climate change, such as sea-level rise, may affect pannes. Gedan said higher sea levels would help pannes, because forbs fare well in areas inundated by water. On the other hand, she added, the higher concentrations of carbon dioxide also expected to occur would accelerate forbs' use of water, which may open them up to competition from other plant species.
"How all these things interact, we don't really know," Gedan said. "But we know that with [higher] temperatures, these changes happen rapidly."
From: Business News Wire - July 10, 2009
Rising Tides Exhibition on Display at San Francisco Ferry Building
SAN FRANCISCO--(BUSINESS WIRE)--WHAT: The San Francisco Bay Conservation and Development Commission (BCDC), the California state agency responsible for protecting San Francisco Bay, will announce the $10,000 Grand Prize winner for the Rising Tides Competition, a unique effort spearheaded by the agency to solicit innovative ideas related to future coastal development in light of a predicted four-foot-plus rise in sea level due to global warming. The competition has potentially far-reaching influence for shoreline design along coastal areas in the region and worldwide. More than 130 high-level entries from 18 countries were received in response to the design challenge.
WHEN: Tuesday, July 14 – 10 a.m.
WHERE: San Francisco Ferry Building (2nd Level)
WHO: BCDC Executive Director Will Travis; Jury Chairperson Marcel Stive (Scientific Director for the Water Research Centre in Delft, Holland); and possibly the grand prize award winner, if local
VISUALS: Exhibition of entries, display of winning entry, possible ceremonial offering of grand prize (if winner is local resident and present at the event)
The Rising Tides Exhibition is a free, public display at the San Francisco Ferry Building through Sunday, July 19, from 8 a.m. to 6 p.m. Major funding for the competition came from the National Oceanic and Atmospheric Administration (NOAA). Additional sponsors included the AIA San Francisco Chapter, the Port of San Francisco, Equity Office Management and BPS Reprographics.
The competition included an international panel of jurists, including Michael Sorkin (Professor of Architecture and Director of Graduate Program in Urban Design at the City College of New York), Walter Hood (University of California-Berkeley professor and principal of Hood Design in Oakland), Denise Reed (University of New Orleans professor whose research focuses on coastal marshes and sea-level rise), Marcel Stive (Scientific Director for the Water Research Centre in Delft, Holland) and Tracy Metz (veteran journalist with Dutch newspaper NRC Handelsblad).