Lab Members

Joaquin Chaves - Post doc

I am an ecologist with broad interests in coastal and terrestrial systems. My work has concentrated in understanding how the fluxes of bioactive elements, such as C, N, P, and water influence ecosystem function.  Originally trained as an oceanographer, I completed M.S. and Ph.D degrees in Biological Oceanography at the University of Rhode Island with Dr. Scott Nixon. Before coming to Dr. Porder’s lab at Brown, I was a post-doctoral scientist with Dr. Christopher Neill at the Ecosystems Center of the Marine Biological Laboratory in Woods Hole, MA. Prior to pursuing post-doctoral experience in the United States, I taught at the School of Chemistry at Universidad Nacional de Costa Rica, in Heredia, Costa Rica.
My graduate research work led me to combine observational studies with budgetary and modeling approaches to assess the fluxes of nitrogen through estuarine embayments in Central America and the Northeast coast of the United States. My post-doctoral work at the MBL brought me inland, to the middle of the Brazilian Amazon, where my research laid at the interface of hydrology and biogeochemistry.  My work focused on understanding how land use cover change, the clearing of forest for cattle pastures, alters water and elemental fluxes from small catchments. Understanding nutrient transfers from land to water is particularly important in tropical regions, where forests are undergoing more rapid rates of conversion to agriculture than any other biome. I combined End Member Mixing Analysis (EMMA) and other statistical techniques to identify the water sources that contribute to streamflow. I combined these approaches with analyses of stable isotopes to investigate how each water source affects export and retention of nitrogen in these small Amazon catchments.

My current research at Brown University focuses on how hydrological mechanisms and pathways may contribute to the larger set of geologic processes (e.g. uplift, erosion) that affect soil age and the availability of phosphorus in tropical landscapes.  A fundamental question in our project is how does soil residence time vary between locations in different erosional environments and how that, in turn, affects soil fertility. We are exploring these questions in two contrasting tropical settings: the Guyana Shield in Venezuela and the Coto Brus Valley in southwestern Costa Rica, which occupy the extremes of erosion and uplift rates, and presumably, soil ages. We hope to contribute to the understanding of factors that affect the nutrient status of tropical forest and how these systems are going to respond to global change.

Shelby Hayhoe - Graduate Student in the Brown/MBL program and the Department of Ecology and Evolutionary Biology (co-advised by Chris Neill)

I am interested in biogeochemical cycling, how this cycling affects ecosystem functioning, and what, then, happens with anthropogenic land use changes.  I did my undergrad research in rural Iowa, an area that has seen some of the most rapid and complete land use change in the world, looking at nutrient loading in stream and lake systems.  I have also worked in Brazil, a region under immense development pressure, for Chris Neill of MBL, who was looking at nutrients and hydrologic flowpaths in small streams, comparing catchments in tropical forest and pasture.  Most recently, however, I worked as a consultant, conducting sampling of impaired waterbodies in Minnesota as well as working on hazardous material clean ups.  My dissertation work will focus on the effects of forest and pasture conversion to intensive soybean agriculture in Brazil. 

Lindsay McAlpine - Undergraduate (Environmental Science Major).

I'm an undergraduate concentrator in Environmental Science with a focus in Ecosystems and Design. I will be doing my senior thesis research on the impact of garlic mustard, an invasive species, and the efforts to control its spread in the Berkshire Hills region. I will be more specifically looking at the success or failure of the Nature Conservancy's efforts to control garlic mustard with herbicides and the economic efficiency of this control measure.

Deborah Lipson - Undergraduate Student (Environmental Science Major).

I am an Environmental Science concentrator focusing on the built environment and carbon sequestration. My thesis project aims to describe and quantify the fate of carbon in soils and aboveground biomass when orestland is converted into residential areas in the greater Seattle area. I've spent the past summer in Seattle collecting data, which primarily involved taking soil cores from forests and suburban backyards. When I'm not digging up peoples backyards to look for carbon, I work with Brown's climate change and sustainability activism organization emPOWER and am a member of the Brown women's golf team.

Lindsay Hagamen - Undergraduate Student (Environmental Science Major).

I am an undergraduate concentrating in Environmental Science. I am interested in how changes in land use practices impact ecosystem functioning and how appropriate land management strategies can help sustain ecosystem services, especially at the intersection between forested and agricultural landscapes. My senior thesis focuses on how the conversion of forests to pasture and to intensive agriculture (primarily sugar cane and rice) is impacting nutrient levels in small, fresh water streams in the lowlands of northwestern Costa Rica.