Rachel Chelsea Nagy Defends Thesis on Amazon Land Use Change

September 11th, 2015 @

Rachel Chelsea Nagy, a student in the Brown-MBL Graduate Program in Biological and Environmental Sciences, successfully defended her Ph.D. dissertation entitled “Ecological and Biogeochemical Consequences of Land Use Change in the Brazilian Amazon” on August 6 at Brown University. Nagy, a student in the Ecology and Evolutionary Biology Department at Brown, was co-advised by MBL Senior Scientist and Ecosystems Center Director Chris Neill and Steven Porder, Associate Professor of Ecology and Evolutionary Biology at Brown.

This month, Nagy began a post-doctoral position with Jennifer Balch in the Dept. of Geography at the University of Colorado-Boulder. She is studying the links between fire distribution and anthropogenic activities across the United States.

Chelsea Nagy installing a temperature/ humidity logger to monitor microclimate conditions in riparian forests in the summer of 2013 on the Tanguro ranch in Mato Grosso, Brazil.

Chelsea Nagy installing a temperature/ humidity logger to monitor microclimate conditions in riparian forests in the summer of 2013 on the Tanguro ranch in Mato Grosso, Brazil.

Nagy’s doctoral research compared the structure, composition, and diversity of plant species in intact riparian forests (adjacent to rivers or streams) to riparian forests that were isolated by clearing for agriculture. She found that the size distribution, number of dead trees, mortality, biomass and carbon storage of altered riparian forests surrounded by agriculture were similar to that of intact riparian forests. However, riparian fragments had fewer seedlings and saplings that indicated reduced potential for forest regeneration. Agricultural fragments also had lower tree species diversity and a different species composition than intact riparian forests.

Nagy's other projects looked at carbon storage in agricultural soils and regrowing secondary forests. Her work showed that the widespread conversion of forests to intensive soybean production did not lead to large reductions in soil carbon despite relatively large changes in microclimate that accompany the land conversion. She developed a mass balance biogeochemical model to understand how different disturbance and land use practices, such as land clearing, shape nutrient limitation and biomass recovery in tropical secondary forests. Her model indicated that nitrogen limits growth of young secondary forests but that this limitation progresses to phosphorus as the forest ages. These results show the importance of retaining nutrients, particularly phosphorus, in order to fully recover from the disturbance of forest clearing.

Nagy’s doctoral committee also included Ed Rastetter, Senior Scientist at the MBL Ecosystems Center and Susan Trumbore, Professor of Earth System Science at the University of California, Irvine, and Director of the Max Planck Institute for Biogeochemistry.

Chelsea Nagy conducting a forest inventory of woody plants, seedlings, and saplings in Mato Grosso, Brazil

Chelsea Nagy conducting a forest inventory of woody plants, seedlings, and saplings in Mato Grosso, Brazil

Funding for Nagy’s doctoral research was supported by an EPA’s STAR graduate fellowship, a NSF grant to Chris Neill and Michael Coe (Woods Hole Research Center), with additional grant support from Steven Porder. Nagy also earned a Dissertation Development Grant (DDG) from the Dept. of Ecology and Evolutionary Biology at Brown and a Center for Latin American and Caribbean Studies (CLACS) award for research in Brazil.
Citations:

Nagy, R.C., Porder, S.; Neill, C., Brando, P.; Quintino, R.M., Nascimento, S.A. (2015). Structure and composition of altered riparian forests in an agricultural Amazonian landscape. Ecological Applications 25(6): 1725-1738.

2015 Summer Undergraduates

June 25th, 2015 @

The Ecosystems Center is mentoring a record number of undergraduate students this year! All of the students are working with Center scientists and are fully participating in laboratory exercises and activities. While some are working here on the MBL campus, others are working at the Toolik Field Station in Alaska, the Marshview Field Station in Plum Island, MA, and one will be off to the Tanguro Field Station in Brazil! It's shaping up to be a great summer!

Biological Discovery in Woods Hole REU Program
Jasmine Prat, University of California, Santa Barbara (Tang)

Brown-MBL LINK Awardees
Jonathan Ang, Brown University (Tang)
Lena Champlin, Brown University (Neill)
Jon Gewirtzman, Brown University (Tang)
Sarah Skelton, Brown University (Valiela)

Cornell University Visiting Undergraduate Intern
Jeanne Powell, Cornell University (Howarth)

Linton-Jefferson Fellow
Kassandra Baron, Washington & Jefferson College (Deegan)

National Science Foundation REUs
Lindsay Arick, University of Central Florida (Giblin)
Vanessa Cabrera, University of California, Santa Cruz (Neill)
Andrew Collins, University of New England (Deegan)
Emily Maness, University of Tampa (Conte)
Nathalie Moore, William & Mary (Deegan)
Levi Simmons, Utah State University (Shaver)
Kate Yuhas, University of Michigan (Shaver)

Naushon Island Summer Research Program
Luke O'Brien, Boston College (Neill)

Metcalf Summer for Undergraduate Research
Ruby An, University of Chicago (Vallino)
Eva Kinnebrew, University of Chicago (Neill)
Jonathan Michelsen, University of Chicago (Tang)
Caroline Owens, University of Chicago (Valiela)
Leonard Shaw, University of Chicago (Conte)

The Woods Hole Partnership Educational Program (PEP)
Camila Fishtahler, William & Mary (Tang)
Wyntin Goodman, University of Maryland, Eastern Shore (Foreman)

 

 

Toolik Field Station, North Slope, Alaska

June 17th, 2015 @

Research assistants for the Arctic Long-Term Ecological Research project collect water from lakes in the foothills of the Brooks Range. Since 1975, this project has tracked nutrient fluxes and water chemistry to study ecosystem dynamics in the rapidly changing Alaskan arctic.

1 Toolik North Slope

Photo by Sarah Nalven (click for larger image)

 

Fazendo Tanguro, Mato Grosso, Brazil

June 17th, 2015 @

A rainstorm approaches a soybean field in Amazonian Brazil. Ecosystems Center scientists conduct experiments on this working farm to study how agricultural practices alter water and nutrient cycles.

Neill Amazon soybean field

Photo by Chris Neill (click for larger image)

Plum Island Estuary, Rowley, MA

June 17th, 2015 @

Saltmarsh Pickleweed, Salicornia europaea, near the MBL's Marshview Field Station, home of the Plum Island Ecosystem Long Term Ecological Research project. This project aims to understand the response of coupled watershed, marsh and estuarine systems to changes in climate, land use and sea level.

PIE LTER

Photo by David S. Johnson (click for larger image)

Harvard Forest, Petersham, MA

June 17th, 2015 @

Soil warming plots located at the Harvard Forest. Established in 1991, this long term project warms the soil to 5 degrees C above ambient temperature and measures changes in soil processes.

11 HF Soil Warming

Photo by Audrey Barker Plotkin (click for larger image)

Waquoit Bay, Falmouth, MA

June 17th, 2015 @

A Semester in Environmental Science student uses a dip net to collect organisms in Waquoit Bay. Back in the laboratory, students build a food web using gut contents and stable isotopes. They then consider how local policy decisions, such as increasing the nitrogen load to the estuary, will alter these food webs.

4 Waquoit Bay

Photo by Sarah Nalven (click for larger image)

Sargasso Sea, Bermuda

June 6th, 2015 @

The recovery of the 500m sediment trap from the Oceanic Flux Program (OFP) mooring in the Sargasso Sea near Bermuda.  At 37 years and running, the OFP is the longest running oceanographic time-series recording temporal variability of particle flux from the surface to the deep ocean resulting from the interplay between physical, biological and chemical processes.

OFPtrapcomesonboardApr15_FullSize

Photo by Alice Carter (click for larger image)

 

Winter Impressions

March 12th, 2015 @

Even though the winter conditions have been unusually harsh this year, Ecosystems Center scientists carry out monthly water sampling campaigns in the watersheds contributing to Plum Island Sound. This effort is part of the Plum Island Ecosystems Long-Term Ecological Research project that studies the coupling between ecosystems upstream and the estuary downstream. This winter not only the freshwater is frozen over, but even the salt marsh areas and tidal creeks.

OLYMPUS DIGITAL CAMERA

Sam Kelsey and Tyler Messerschmidt, Ecosystems Center Research Assistants, preparing to take water samples. Photo: Inke Forbrich

Frozen_TidalCreek

Frozen tidal creek in salt marsh. Photo: Inke Forbrich.

OLYMPUS DIGITAL CAMERA

Ipswich River dam in Ipswich: sampling site for the PIE LTER project. Photo: Inke Forbrich.

 

Peregrine Falcon Visits MBL

March 11th, 2015 @

A peregrine falcon, the world's fastest bird—and quite simply one of the planet's most awe-inspiring raptors—made its second appearance at MBL on the same cliff-like perch on the Lillie Building on the afternoon of March 9. It had spent parts of two previous days there on February 26 and 27.

Local photographer and bird enthusiast Mike Schanbacher of Woods Hole climbed into the old library stacks and took this picture (click photo for full resolution).

Photo: Mike Schanbacher

Photo: Mike Schanbacher

Peregrines follow their waterfowl and shorebird foods sources along the east coast in winter. It no doubt had its eye on the small flock of Mallards that are eeking out a living in the small remaining patch of open water in Eel Pond. The ledges on the back of the Lillie Building are the nearest thing Woods Hole has to peregrines' preferred habitats. "The nearest thing to a cliff in Woods Hole," said MBL Marine Resources Manager David Remsen, who originally spotted the bird.

Schanbacher commented that it's appropriate that this majestic bird sits within stone's throw of the life-sized bronze statue of Rachel Carson that was dedicated in Woods Hole's Waterfront Park on June 12, 2013. I agree.

Rachel Carson, a marine biologist who worked at MBL from 1925-1929, authored Silent Spring, a 1962 best-seller that documented the damage that persistent chemical pesticides did to birds and the environment. One of the chief culprits—DDT—was banned by in US in 1972.

We in Woods Hole reap the rewards of what former MBL Director Gary Borisy called Rachel Carson's journalistic "kicking the hornet's nest."

Peregrine falcons, because they sit atop coastal food chains, were among the most vulnerable of all birds to DDT, which accumulated in their fatty tissues and caused their eggshells to become thin and breakable. Eastern US peregrines were extinct when Carson penned Silent Spring. Ospreys suffered a similar same fate, although their numbers did not drop to zero. Both species have recovered. The US Fish and Wildlife Service removed peregrine falcons from the endangered species list in 1999.

While this bird's visit to Lillie is a chance to see a peregrine up close, thanks to Silent Spring and subsequent scientific investigations into pesticides in the environment, it's now possible to find peregrines cruising the Falmouth and Cape Cod coastlines.

Thanks, Rachel.


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