Stephen Sebestyen

Title: Research Hydrologist
Unit: Center for Research on Ecosystem Change
Previous Unit: Ecology & Management of Riparian/Aquatic Ecosystems
Address: Northern Research Station
1831 Hwy 169 East
Grand Rapids, MN  55744-3399
Phone: 218-326-7108
E-mail: Contact Stephen Sebestyen

Jump to Publications

Education

• PhD (2008) State University of New York College of Environmental Science & Forestry, Forest and Natural Resources Management, Syracuse, NY.
• MS Cornell University (2000), Department of Natural Resources (Program in Biogeochemistry & Global Change), Ithaca, NY.
• B.S. Susquehanna University (1997), Department of Geological and Environmental Sciences, Selinsgrove, PA.

Civic & Professional Affiliations

• American Association for the Advancement of Science
• American Geophysical Union
• Ecological Society of America
• International Association of Hydrological Sciences

Current Research

My scientific interests focus on understanding how hydrological and biogeochemical processes interact in ecosystems. I study how source variation and landscape processes affect the flow of water and solutes through the environment at a range of settings in the USA and abroad using traditional hydrological analyses, high-frequency chemical sampling, and isotopic tracers.
I am Forest Hydrologist with the USDA Forest Service in Grand Rapids, MN. I devote a portion of my time to research at the Marcell Experimental Forest (MEF). I am initiating a comprehensive research program that builds upon the 50 year legacy of research at this site - a series of research watersheds that were established to study the ecology and hydrology of peatlands and uplands in northern forests. Using the extensive resources at the field site, I pursue research related to the effects of nitrogen pollution on ecosystem functions, carbon cycling in peatlands, understanding how climate variability affects northern forests, and quantifying the effects of landscape disturbance on fluxes of water and solutes from peatland ecosystems.
I currently work on several other catchment studies. At the Sleepers River Research Watershed in northeastern Vermont, I have been exploring how sources of stream nitrate, dissolved organic nitrogen (DON), dissolved inorganic carbon (DIC), and dissolved organic carbon (DOC) vary among events, seasons, and years.
I am also interested in lake and wetland ecosystems to understand how the direction, magnitude, and variability of groundwater seepage influences biogeochemical cycles. In previous studies, I explored the effects of lakeshore seepage on pore water biogeochemistry, plant communities, and brook trout redds in lakes of the Adirondack Mountains of New York.

Why is This Important

1. The flow of water transfers energy and matter from the atmosphere and terrestrial landscapes to lakes, streams, wetlands, and coastal zones. My scientific interests center on understanding how water and reactive chemicals are transported and transformed in the environment. With an emphasis on catchment science, I study hydrological and biogeochemical cycles to identify ways to effectively maintain water quality and ecosystem productivity. I use multiple approaches (hydrologic, biologic, geochemical, biogeochemical, and isotopic) across range of temporal, spatial, climatic, and ecological settings to study such issues as atmospheric pollutant deposition, forest health, ecosystem acidification, nutrient enrichment of surface waters, and ecosystem response to climate change.
2. The variation of stream nutrient concentrations over event and seasonal time scales reflects complex biogeochemical and hydrological processes that affect ecosystem functions, but more fundamentally, relates to the availability of biologically-essential substances that fuel life cycles in catchments, headwater streams, and downstream water bodies.
3. In landscapes where human activities enrich nutrient availability and affect land use / land cover, my work highlights the need to consider multiple elements and interactions of water and nutrient cycles in the context of coupled hydrological and biogeochemical cycles that control surface water chemistry. For example, I study how the nutrient enrichment of ecosystems by human activities directly affects the forms and concentrations of nitrogen in streams. Understanding the linkages between atmospheric sources of nitrogen to forests and streams helps to inform scientists, land managers, and legislators who seek to protect the valuable natural resources provided by forests.

Future Research

With future projects and collaborations, I will pursue research that:

• quantifies rates of terrestrial and aquatic biogeochemical transformations to definitively pinpoint the landscape processes that affect water chemistry.
• determines how sources, transformations, and transport processes interact to control nutrient availability within ecosystems.
• quantifies how short-term processes that occur at discrete locations and times (the "hotspots" and "hot moments" of biogeochemical processes) are important when considered at the ecosystem level.
• considers how to "scale up" understanding of hydrological and biogeochemical processes from plot level studies and point monitoring locations to larger landscape units.
• establishes monitoring and experimental (manipulative) studies to identify how the timing, release, and cycling of solutes in catchments is affected by climatic and land use / land cover changes.

Featured Publications

Additional Online Publications

Other Publications by Stephen Sebestyen *