Broad Research Interests

  • Top-down controls of ecosystem biogeochemistry
  • Nutrient and greenhouse gas cycling in wetlands
  • Intersection of biodiversity and ecosystem function
  • Bird-window collisions and conservation

Waterfowl herbivory effects on methane emission and nitrogen cycling

mass ducks closeA focus of my dissertation was on the effects of aquatic herbivores (ducks and swans in this case) on the emission of the greenhouse gas, methane, and on export of nutrients (nitrogen and phosphorus) from freshwater wetlands.  Broadly speaking, I am interested in how biodiversity influences ecological processes related to climate change and nutrient pollution, and in identifying mitigation opportunities.

Tundra SwanMattamuskeet National Wildlife Refuge attracts a spectacular mega-flock of hundreds of thousands of ducks, geese and swans each winter.  Successful management of breeding habitats has led to population increases in recent years, but because of development along the East Coast of the US, quality wintering habitat has become limited.  Waterfowl on the Atlantic Flyway are forced to concentrate at remaining premium habitats, such as at Mattamuskeet where up to 5 to 10 percent of entire populations congregate in some years.

Flock of Ducks FlyingHow do high densities of these birds affect the emission of methane?  My research has shown that emergent wetland plants play an important role in transporting oxygen into wetland sediments which mitigates methane emissions.  When plant roots and tubers are decimated by grazing birds during winter, their regrowth in spring is sparse and retarded, leading to less methane oxidation and higher emissions. This study is published in the journal, Ecology (see publications page).

Organic matter amendments and greenhouse gas emissions from restored wetlands

P1150027As a research assistant at the Duke University Wetland Center I worked at a restored wetland in Charles City County, Virginia to study how amending soils with compost impacts the emission of greenhouse gases.  We found that  compost amendments increased carbon dioxide emission, but lead to no change in the emission of methane. These results are published in my dissertation and in the journal Wetlands (see publications page).

In order to generate reliable methane data I had to design a remote rod sampling system for the estimation of static chamber trace gas flux.  This was a significant cost-saving methodological innovation that has been published in my dissertation and in the journal, Wetlands Ecology and Management (see publications page).

Bird-window collisions project

Scarlet TanagerI have been working with Natalia Ocampo-Penuela and Duke instructor, Nicolette Cagle on a project to understand and ultimately prevent bird-window collisions on Duke’s campus.  We have completed 5 seasons of migration carcass surveys.  See more about this project here: Bird Collision Project at Duke University

After finding that Duke University’s buildings kill more birds than any other participating institution, I wrote and presented a resolution demanding bird-friendly facilities on campus.  The Duke Graduate and Professional Student Council unanimously passed the resolution and after local and regional press coverage, the administration took action to make Duke University a bird-friendly campus. Co-authors and I published an article in the journal PeerJ (see publications page).