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 an 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., K. Butterbach-Bahl, R. W. Fulweiler, A. J. Gold, J. L. Morse, E. K. Stander, C. L. Tague, C. Tonitto, and P. Vidon. 2009. Challenges to incorporating spatially and temporally explicit phenomena (hotspots and hot moments) in denitrification models. Biogeochemistry 93(1-2):49-77
• Groffman, P.M., J.P. Hardy, M.C. Fisk, T.J. Fahey, and C.T. Driscoll. 2009. Climate Variation and Soil Carbon and Nitrogen Cycling Processes in a Northern Hardwood Forest. Ecosystems 12(6):927-943
• Groffman, P.M. and R.V. Pouyat. 2009. Methane uptake in urban forests and lawns. Environmental Science & Technology 43(14):5229-5235. DOI:10.1021/es803720h.
• Groffman, P.M., C.O. Williams, R.V. Pouyat, L.E. Band and I.C. Yesilonis. 2009. Nitrate leaching and nitrous oxide flux in urban forests and grasslands. Journal of Environmental Quality 38(5):1848-1860
• Groffman, P.M., M.C. Fisk, C.T. Driscoll, G.E. Likens, T.J. Fahey, C. Eagar and L.H. Pardo. 2006. Calcium additions and microbial nitrogen cycle processes in a northern hardwood forest Ecosystems 9:1289-1305.