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Phragmites australis: Genetic analysis reveals the promiscuous nature of the invasive reed

Friday, March 12th, 2010

Phragmites australis growing in a subestuary of Chesapeake Bay.

The non-native strain of Phragmites australis dominates many Chesapeake Bay wetlands. Photo Melissa McCormick.

Phragmites australis took its sweet time taking over East Coast wetlands. A non-native strain of the reed arrived in the U.S. around 1800, likely stowed away in the ballast material of European ships. For nearly two centuries the plant grew in relatively small pockets along the coast. Today it’s a poster child for invasive species. In some states along the Atlantic, it covers as much as a third of the tidal wetland acreage. Among other impacts, it challenges native plants for turf. The European strain has even out-competed North America’s native P. australis.
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Plants, climate change and the importance of being curious, an interview with Bert Drake

Thursday, February 25th, 2010

If you’re looking for a good conversation about science, history or life – talk to Bert Drake. He’s a plant physiologist and renaissance man who’s been with the Smithsonian Environmental Research Center for nearly four decades. Drake retired in January, but will continue his investigations as an emeritus scientist. We caught up with him before he took well-deserved vacation.

Wideshot of Drake on the boardwalk that winds through his marsh research station.

Drake's research unfolds at the Kirkpatrick Marsh, located in Maryland on a subestuary of the Chesapeake Bay.

How did you earn a living before you became a scientist?
I was a drummer in a jazz band, a ski guide, the host of a jazz radio program and a high school science teacher.

How did you get drawn to the world of plant physiology?
Nature has always fascinated me and science is about discovering how nature works. I grew up in northern Maine. My father was a barber, but loved the outdoors. I was outside year-round: skiing, canoeing, trapping animals, fishing and taking photos. I knew I wanted to do something connected with biology. I became a science teacher, but it wasn’t until I attended a summer course in ecology that I wanted to get inside a lab and practice science.

In science you almost always get an approximation of an answer because an experiment is only an approximation of reality.

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Wetlands on the rise, a conversation with biogeochemist Pat Megonigal

Tuesday, December 1st, 2009

Pat Megonigal is a biogeochemist here at the Smithsonian Environmental Research Center (SERC). The following is an interview with him about his recent research.

Smithsonian biogeochemist Pat Megonigal

Smithsonian biogeochemist Pat Megonigal

Climate change scenarios are driven largely by greater concentrations of carbon dioxide in the atmosphere. One common narrative includes faster-rising seas and the potential drowning of coastal regions. You recently published a paper in the Proceedings of the National Academy of Sciences that gives hope to some coastal wetlands. Tell us what you found.
PM: We conducted a study for two years on the Kirkpatrick Marsh, here on the Chesapeake Bay. We discovered that higher levels of atmospheric CO2 actually stimulated the surface elevation of saltwater marshes. The additional CO2 caused them to basically pop up, or rise in elevation, because the plants developed more roots. It’s kind of a silver-lining story.

How did you simulate climate change?
PM: We put out clear open-top chambers that are about two yards in diameter. They allow us to manipulate the atmosphere around a chunk of marsh. Then, in some of the chambers, we pumped in extra CO2; we raised it to a level that will be roughly what the whole world will be exposed to at the end of the century. And then we measured the changes in the soil’s elevation throughout the growing season.

When you think of measuring elevation, mountains come to mind, not soil. How did you measure the soil’s height?

PM: Well, we needed a stable point of elevation reference, so first we drove a steel rod about 20 feet into the ground. Then came the hard part. We had to design a tool that would give us not only precise, but multiple measurements of the soil elevation – both in and outside of our chambers. We came up with an instrument we dubbed the “monster arm.”

Technician Jim Duls measures the soil elevation with the 'monster arm.'

Technician Jim Duls measures the soil elevation with the 'monster arm.'

The monster arm?
PM: The technical name is “surface elevation table.” Basically it’s a long metal bar with 90 fiberglass pins running perpendicular through it. It looks like a big comb, but instead of the teeth being fixed in place, they can move up and down. So by gently placing the monster arm across the chambers we could measure where the top of each pin was in relation to the main crossbar. So if a pin rose 100 millimeters above the bar in April and in August it rose 102 millimeters, the soil elevation increased by two millimeters.

Your study showed that the marsh receiving the extra CO2 rose by an additional 3mm a year. Is that enough to keep pace with the rising sea level?
PM: It should help for a while, but we don’t know how much sea level rise a marsh can handle before it will disappear. We do know that rising sea level is one reason that some marshes in mid-Atlantic and around the world are disappearing right now. Our research indicates that some of these wetlands literally have an organic ability to fight back by building new soil. This is especially true for wetlands with brackish water, like Kirkpatrick Marsh. Saltier coastal wetlands won’t be able to accumulate as much soil because their plants are different and don’t respond to CO2 in the same way. But we’re now conducting a new experiment to look at sea-level rise and its effect on soil elevation. We think the pop-up effect we’ve observed will be even more pronounced when the water level rises. We’ll see!

‘Tidal Freshwater Wetlands’ gives an overlooked ecosystem its due

Tuesday, November 17th, 2009

Tidal Freshwater Wetlands book cover

Tidal Freshwater Wetlands

There are certain obstacles you have to embrace if you are going to edit a book about tidal freshwater wetlands. They include: mud, mosquitoes and leeches. Smithsonian plant ecologist Dennis Whigham has accepted all three and then some.

Whigham, along with colleagues Aat Barendregt from Utrecht University and Andy Baldwin from the University of Maryland, has edited the new book Tidal Freshwater Wetlands. It’s a weighty work containing more than 20 chapters written by more than 40 authors. For the first time ever, they have systematically peeled back the layers of these overlooked coastal ecosystems. The book explores how these wetlands work, the animal and plant life they support, and the threats they face.
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What one marsh tells us about rising CO2

Tuesday, October 27th, 2009

In the world of unassuming marshes, the Kirkpatrick Marsh stands apart. Smithsonian plant physiologist Bert Drake has studied this wetland for more than two decades. It’s located in Maryland, along the Rhode River, a sub-estuary of the Chesapeake Bay. Drake and his colleagues have used this community of grasses and sedges to explore whether plants have the potential to become a carbon source or a carbon sink. Watch the audio slideshow below, for a tour of the field experiment.

You can read more about Drake’s experiment on the Smithsonian Environmental Research Center’s Web site.