Dr. Peter M. Groffman
Microbial Ecologist
Ph.D., 1984, University of Georgia

Dr. Groffman's research focuses on microbial processes in an ecosystem context. His objectives are to gain insight into 1) the role that microorganisms play in ecosystem functions related to nutrient cycling, water and air quality and soil carbon storage and 2) environmental regulation of microbes. Developing conceptual and practical ecosystem contexts for this work has required a large number of study sites and strong collaborations with other scientists.

Current Research

Exotic Earthworms & Northern Temperate Forests.
Earthworms effect microbial nitrogen cycling and ecosystem nitrogen retention. Earthworm invasion of north temperate forests will have large consequences for nutrient retention and uptake in these ecosystems. Read a general overview about this research, view the extended project summary, or see a list of scientific publications resulting from this work.

Human Accelerated Changes in Carbon & Nitrogen Dynamics.
Urban air pollution and land use change have altered watershed and soil C and N dynamics. In collaboration with the Baltimore Ecosystem Study, we are exploring the regulation of soil microbial processes in heavily human-dominated ecosystems.

Snow Depth & Soil Freezing as a Regulator of Microbial Processes.
In the northern hardwood forests in New Hampshire we are analyzing how soil freezing events cause root and microbial mortality, which can lead to increased rates of N and P mineralization and loss. Read about the ecological importance of snow in a Poughkeepsie Journal article or in the extended project summary, or see a list of scientific publications resulting from this work.

Base Cation Depletion: Organic Matter Quality & Microbial Processes.
We are analyzing how changes in soil base status can influence microbial physiology, organic matter quality, and microbial activity in northern hardwood forests at Hubbard Brook. You can view the gallery of images of the addition or read Dr. Groffman's research summary.

Selected Publications

• Groffman, P.M., J.P Hardy, C.T. Drisoll and T.J. Fahey. 2006. Snow depth, soil freezing and trace gas fluxes in a northern hardwood forest. Global Change Biology 12:1748-1760.
• Groffman, P.M., M.C. Fisk, C.T. Driscoll, G.E. Likens, T.J. Fahey, C. Eagar and L.H. Pardo. 2006. Calcium additions reduce nitrogen cycling in a northern hardwood forest. Ecosystems 9:1289-1305.
• Groffman, P.M., N.L. Law, K.T. Belt, L.E. Band and G.T. Fisher. 2004. Nitrogen fluxes and retention in urban watershed ecosystems. Ecosystems 7:393-403.
• Groffman P.M., P.J. Bohlen, M.C. Fisk and T.J. Fahey. 2004. Exotic earthworm invasion and microbial biomass in temperate forest soils. Ecosystems 7:45-54.
• Groffman, P.M., D.J. Bain, L.E. Band, K. T. Belt, G.S. Brush, J.M. Grove, R. V. Pouyat, I.C. Yesilonis and W. C. Zipperer. 2003. Down by the riverside: Urban riparian ecology. Frontiers in Ecology and Environment 6:315-321.