Michael Keller
International Institute of Tropical Forestry, Rio Piedras, Puerto Rico

Contact Information:
Complex Systems Research Center
Morse Hall Telephone: 603-862-4193
University of New Hampshire Facsimile: 603-862-0188
Durham, NH 03824, USA E-mail: michael.keller@unh.edu

I study the effects of land use change and agricultural intensification in Central and South America on the function of ecosystems and the control of atmospheric chemistry and composition. My research ranges from the biological controls of trace gas emissions at the organismal level to the estimation and modeling of regional and global trace gas and carbon budgets. Over the past two decades, I have lived and worked in Brazil, Panama, Costa Rica, and Puerto Rico as well as in the United States. I currently serve as lead scientist for the NASA sponsored LBA-ECO component of the Brazilian led Large Scale Biosphere Atmosphere in Amazonia (LBA) and the Co-Chair of the LBA International Science Steering Committee. LBA-Ecology is designed around the question "How do tropical forest conversion, regrowth, and selective logging influence carbon storage, nutrient dynamics, trace gas fluxes and the prospect for sustainable land use in the Amazon region?" In order to answer this question together with my colleagues in LBA-ECO, I combine in situ measurements with regional models and remotely sensed observations of biological and social systems in the Amazonian environment.

Education

Ph.D. 1990. Department of Geological and Geophysical Sciences, Princeton University.

A.B. summa cum laude, 1982. Harvard College. Department of Geology.

Employment

Research Scientist (GS-15), International Institute of Tropical Forestry, US Forest Service, 1992 -

Visiting Research Professor, University of New Hampshire, 1997 -

Post-Doctoral Fellow, National Center for Atmospheric Research, 1990 to 1992

Post-Doctoral Fellow, Botany Department, University of Wyoming, 1989 to 1990.

Graduate Fellow, National Center for Atmospheric Research, 1988 to 1989.

Research Assistant, Department of Geological Sciences, Princeton University, 1984 to 1988
Research Intern, World Wildlife Fund, Manaus, Brazil, 1983 to 1984

Professional Leadership Activities

Project Scientist for the NASA LBA ECO Project of the "Large Scale Biosphere-Atmophere Experiment in Amazonia" (LBA). The Project Scientist coordinates the scientific activities of over 300 scientific and technical personnel participating in LBA Ecology. 1996 to present

Co-Chair of the International Scientific Steering Committee for LBA. 1998 to present.

Member of the Editorial Board, Nutrient Cycling in Agroecosystems. 1998 to 2001.

Co-Convenor of the "Biosphere-Atmosphere Trace Gas Exchange in the Tropics (BATGE)" activity of the International Global Atmospheric Chemistry Program (IGAC) of International Geosphere-Biosphere Program (IGBP). 1993 to 1998.

Languages: English, Spanish, Portuguese, French (reading only).

Publications

Keller, M. In Press. Conversion of tropical forests to pasture and soil-atmosphere exchange of the trace gases nitrous oxide, nitric oxide, and methane. Notes from the Underground: Soil Processes and Global Change, edited by E. Holland.

Keller, M., M. Palace, and G.E. Hurtt. 2001. Biomass in the Tapajos National Forest, Brazil: Examination of Sampling and Allometric Uncertainties. Forest Ecology and Management 154: 371-382.

Erickson, H., E.A. Davidson, and M. Keller. 2001. Former land-use and tree species affect nitrogen oxide emissions from a tropical dry forest. Oecologia 130: 297-308.

McSwiney, C.P., W.H. McDowell, and M. Keller. 2001. Distribution of nitrous oxide and regulators of its production across a tropical rainforest catena in the Luquillo Experimental Forest, Puerto Rico. Biogeochemistry 56:265-286.

Nobre, A.D., M. Keller, P.M. Crill, and R.C. Harriss. 2001. Short-term nitrous oxide profile dynamics and emissions response to water, nitrogen and carbon additions in two tropical soils. Biology and Fertility of Soils 34: 363-373.

Erickson, H.E., M. Keller, and E.A. Davidson. 2001. Nitrogen Oxide Fluxes and Ecosystem Nitrogen Cycling during Postagricultural Succession and Forest Fertilization in the Humid Tropics. Ecosystems 4: 67-84.

Weitz A.M., E. Linder, S. Frolking, P.M. Crill, and M. Keller. 2001. N2O emissions from humid tropical agricultural soils: Effects of soil moisture, texture, and nitrogen availability. Soil Biology and Biochemistry 33: 1077-1093.

Veldkamp, E., A.M. Weitz, and M. Keller. 2001. Management Effects on Methane Fluxes in Humid Tropical Pasture Soils. Soil Biology and Biochemistry 33: 1493-1499.

Keller, M., A. M. Weitz, B. Bryan, M. M. Rivera, and W. L. Silver. 2000. Soil-atmosphere nitrogen oxide fluxes: effects of root disturbance. Journal of Geophysical Research 105: 17,693-17,698.

Liu, S., W.A. Reiners, M. Keller and D.S. Schimel. 2000. Simulation of nitrous oxide and nitric oxide emissions from tropical primary forests in the Costa Rican Atlantic Zone. Environmental Modelling & Software 15:727?743.

Davidson, E.A., Keller, M., Erickson, H.E., Verchot, L.V. and Veldkamp, E. 2000. Testing a conceptual model of soil emissions of nitrous and nitric oxides. Bioscience. 50:667-680.

Crill, P.M., Keller, M., Weitz, A.M., Grauel, B., and Veldkamp, E. 2000. Intensive field measurements of nitrous oxide emissions from a tropical agricultural soil. Global Biogeochemical Cycles. 14: 85-95.

Silver W., Neff, J.C., McGroddy, M., Veldkamp, E., Keller, M. and Oliveira Jr., R.C. 2000. Effects of soil texture on belowground carbon and nutrient storage in a lowland Amazonian forest ecosystem. Ecosystems 3:193?209.

Weitz, A.M., Keller, M., Linder, E. and Crill, P.M. 2000. Spatial and temporal variability of nitrogen oxide and methane fluxes from a fertilized tree plantation in Costa Rica. Journal of Geophysical Research. 104:30,097-30,107.

Perez, T., Trumbore, S.E., Tyler, S.C., Davidson, E.A. , Keller, M., and De Camargo, P.B. 2000. Isotopic variability of N2O emissions from tropical forest soils. Global Biogeochemical Cycles. 14: 525-535.

Silver, W., Lugo, A.E. and Keller, M. 1999. Soil oxygen availability and biogeochemistry along rainfall and topographic gradients in upland wet tropical forest soils. Biogeochemistry 44:301-328.

Veldkamp, E. Davidson, E.A., Erickson, H.E., Keller, M. and Weitz, A.M. 1999. Soil nitrogen cycling and nitrogen oxide emissions along a pasture chronosequence in the humid tropics of Costa Rica. Soil Biology and Biochemistry. 31: 387-394.

Keller, M. and Lerdau, M.T. 1999. Isoprene emission from tropical canopy leaves. Global Biogeochemical Cycles 13: 19-29.

Liu, S., Reiners, W.A., Keller, M., and Schimel, D.S. 1999. Model simulation of changes in nitrogen trace gas emissions with the conversion of tropical rain forests to pastures in the Costa Rican Atlantic Zone. Global Biogeochemical Cycles 13: 663-677.

Verchot, L., Davidson, E.A., Cattanio, J.H., Ackerman, I.L., Erickson, H.E., and Keller, M. 1999. Land use change and biogeochemical controls of nitrogen oxide emissions from soils in Eastern Amazonia. Global Biogeochemical Cycles, 13: 31-46.

Chestnut, T.J., Zarin, D.J., McDowell, W.H. and Keller, M. 1999. A nitrogen budget for late-successional hillslope tabonuco forest, Puerto Rico. Biogeochemistry, 46: 85-108.

Weitz, A.M., Veldkamp, E., Keller, M., Neff, J. and Crill, P.M. 1998. Nitrous oxide, nitric oxide, and methane fluxes from soils following clearing and burning of tropical secondary forest. Journal of Geophysical Research 103: 28,047- 28,058.

Mosier, A.R., Delgado, J.A., and Keller, M. 1998. Methane and nitrous oxide fluxes in an acid oxisol in Western Puerto Rico: Impact of tillage, liming, and fertilization. Soil Biology and Biochemistry. 30:2087-2098.

Reiners, W.A.,Keller, M., and Gerow, K. 1998. Estimating rainy season nitrous oxide and methane fluxes across forest and pasture landscapes in Costa Rica. Water Air and Soil Pollution 105:117-130

Veldkamp, E., Keller, M. and Nuñez, M., 1998. Effects of pasture management on N2O and NO emissions from soils in the humid tropics of Costa Rica. Global Biogeochemical Cycles. 12: 71-79.

Weitz, A.M., Veldkamp, E., Keller, M., Neff, J. and Crill, P.M. 1998. Nitrous oxide, nitric oxide, and methane fluxes from soils following clearing and burning of tropical secondary forest. Journal of Geophysical Research 103:28047-28058.

Veldkamp, E. and Keller, M., 1997. Fertilizer induced nitric oxide emissions from agricultural soils. Nutrient Cycling in Agroecosystems, 48: 69-77.

Lerdau, M.T. and Keller, M., 1997. Isoprene emission from trees in a sub-tropical dry forest. Plant, Cell, and Environment, 20:569-578.

Keller, M., Melillo, J.M., de Mello, W.Z., 1997. Trace gas emissions from ecosystems of the Amazon Basin. Ciencia e Cultura, 49:87-97.

Veldkamp E. and Keller, M., 1997. Nitrogen oxide emissions from a banana plantation in the humid tropics. Journal of Geophysical Research. 102:15,889-15,898.

Weitz, A.M, Grauel W.T., Keller, M., and Veldkamp, E. 1997. Calibration of time domain reflectometry technique using undisturbed soil samples from humid tropical soils of volcanic origin. Water Resources Research, 33:1241-1249.

Erickson, H.E., and Keller, M., 1997. Tropical land use change and soil emission of nitrogen oxides. Soil Use and Management. 13:278-287.

Valdés?González, J,. Rossi, F., Quesada, J. Marenco, H., Wright, J., Núñez, M., and Keller, M. 1997. Tropospheric ozone in San José, Costa Rica. Ingeniería y Ciencia Química. 16: 65?66.

Keller, M, Clark, D.A, Clark D.B., Weitz, A.M. and Veldkamp, E., 1996. If a tree falls in the forest... Science, 273:201.

Neff, J., Keller, M., Holland, E., Weitz, A., and Veldkamp, E., 1995. Fluxes of nitric oxide following clearing and burning of a tropical rain forest. Journal of Geophysical Research, 100:25913-25922.

W. F. J. Parsons and Keller, M. 1995. Controls on nitric oxide emissions from tropical pasture and rain forest soils. Biology and Fertility of Soils, 20:151-156.

M. Keller and Stallard, R.F. 1994. Methane emission by bubbling from Gatun Lake, Panama. Journal of Geophysical Research , 99: 8307-8319.

M. Keller and Matson, P. A. 1994. Evaluating the effects of tropical land use changes on atmospheric composition. pp. 103-118 in R. G. Prinn (ed.) Global Atmospheric-Biospheric Chemistry, Plenum Publishing Company, New York.

M. Keller and Reiners, W. A. 1994 Soil-atmosphere exchange of nitrous oxide, nitric oxide, and methane under secondary succession of pasture to forest in the Atlantic lowlands of Costa Rica. Global Biogeochemical Cycles, 8:399-409.

Keller, M. 1994. Controls on soil-atmosphere fluxes of nitrous oxide and methane: Effects of tropical deforestation. pp. 121-138 in R.G. Zepp (ed.) Climate Biosphere Interaction: Biogenic Emissions and Environmental Effects of Climate Change, John Wiley and Sons, New York.

W. A. Reiners, Bouwman, A. F., Parsons, W. F. J., and Keller, M. 1994. Tropical rain forest conversion to pasture: Changes in vegetation and soil properties. Ecological Applications, 4: 363-377.

M. Keller, Veldkamp, E., Weitz, A.M., and Reiners, W.A. 1993. Pasture age effects on soil-atmosphere trace gas exchange in a deforested area of Costa Rica. Nature, 365: 244-246.

W. F. J. Parsons, Mitre, M. E., Keller, M. and Reiners, W. A. 1993. Nitrate limitation of N2O production and denitrification from tropical pasture soils. Biogeochemistry, 22: 179-193.
Keller, M., Galbally, I., Bär, M., Davidson, E., Fitzjarrald, D., Harris, G., Johansson, C., Matson, P., Nobre, C., Sanhueza, E., and Stewart, J., 1992. Tropical land use change and trace gas emissions. Ecological Bulletin (Copenhagen), 42:156-163.

Keller, M., Jacob, D.J., Wofsy, S.C., and Harriss, R.C. 1991. Effects of tropical deforestation on global and regional atmospheric chemistry. Climatic Change, 19:139-158.

Keller, M., Mitre, M.E., and Stallard, R.F., 1990. Consumption of atmospheric methane in tropical soils: Effects of agricultural development. Global Biogeochemical Cycles, 4:21-27.

Keller, M., Jacob, D.J., Wofsy, S.C., and Harriss, R.C. 1991. Effects of tropical deforestation on global and regional atmospheric chemistry. Climatic Change, 19:139-158.

Keller, M., 1990. Biological Sources and Sinks of Methane in Tropical Habitats and Tropical Atmospheric Chemistry. Cooperative Thesis No. 126. National Center for Atmospheric Research, Boulder, Colorado, 216 pp.

Bakwin, P.S., Wofsy, S.C., Fan, S.-M., Keller, M., Trumbore, S.E. and da Costa, J.M. 1990. Emission of nitric oxide (NO) from tropical forest soils and exchange of NO between the forest canopy and atmospheric boundary layers. Journal of Geophysical Research, 95:16755-16763.

Trumbore, S.E., Keller, M., Wofsy, S.C., and da Costa, J.M., 1990. Measurement of soil and canopy exchange rates in the Amazon rain forest using 222Rn. Journal of Geophysical Research, 95:16865-16873.

Robertson, G.P., Andreae, M.O., Bingemer, H.G., Crutzen, P.J., Delmas, R.A., Duyzer, J.H., Fung, I., Harriss, R.C., Kanakidou, M., Keller, M., Melillo, J.M., and Zavarzin, G.A., 1989. Trace gas exchange and the chemical and physical climate: Critical interactions. pp. 303-320 in Andreae, M.O. and Schimel, D.S. (eds.) Exchange of Trace Gases between Terrestrial Ecosystems and the Atmosphere, John Wiley and Sons, New York.

Kaplan, W.A., Wofsy, S.C., Keller, M., and da Costa, J.M., 1988. Emission of NO and deposition of O3 in a tropical forest system. Journal of Geophysical Research, 93:1389-1395.

Keller, M., Kaplan, W.A.,Wofsy, S.C. and da Costa, J.M., 1988. Emissions of N2O from tropical forest soils: Response to fertilization with NH4+, NO3-, and PO43-. Journal of Geophysical Research, 93:1600-1604.

Keller, M. Kaplan, W.A. and Wofsy, S.C., 1986. Emissions of N2O, CH4, and CO2, from tropical forest soils. Journal of Geophysical Research, 91:11791-11802.

Keller, M., Goreau, T.J., Kaplan, W.A., Wofsy, S.C. and McElroy, M.B., 1983. Production of nitrous oxide and consumption of methane by forest soils. Geophysical Research Letters, 10:1156-1159.

Contracts and Grants:

January 2002. "Ecosystem Respiration and Trace Gas Exchange in Undisturbed and Selectively Logged Forests in the Brazilian Amazon Region." Keller is Principal Investigator. National Aeronautics and Space Administration; $2,300,000; 3 years.

July 2001. "Amazon Forest Selective Logging and Phenology from Imaging Spectroscopy." Keller is Co-Investigator with Dr. Greg Asner, University of Colorado. National Aeronautics and Space Administration; 3 years.

October 1999. "Evaluation of EO?1 Hyperion and ALI for Detection and Biophysical Characterization of Selective Logging in Amazonia." Keller is Co-Investigator with Dr. Greg Asner, University of Colorado. National Aeronautics and Space Administration; 2 years.

July 1998. "Soil Biogeochemistry of Carbon, Nutrients, and Trace Gases in the Amazon Region of Brazil: Field and Model Studies of Natural and Managed Conditions." Keller is Principal Investigator. National Aeronautics and Space Administration; $1,254,000; 3.5 years.

May 1997. "Tropical Biogeochemistry and NASA LBA?Ecology Science Support" Keller is Principal Investigator. National Aeronautics and Space Administration; $565,000; 4.5 years.

July 1994, "Land Management in the Tropics and Its Effects on the Global Environment;" Keller was Co-Investigator with Dr. Brad Weiner and 12 additional investigators from the University of Puerto Rico; National Aeronautics and Space Administration; $316,000 (Keller's portion of $3.3 million total grant); 5 years.

May 1994, "Development of a Center for Tropical Atmospheric Sciences in Puerto Rico;" Keller was Co-Investigator with Dr. Juan Gonzalez and 22 additional investigators from the University of Puerto Rico; $210,000 (Keller's portion of $4.5 million total grant); National Aeronautics and Space Administration; 3 years.

June 1993, "Nitrous Oxide Emissions from Tropical Agricultural Soils: Intensive Field Experiments and Development of a Process Model;" Keller was Principal Investigator.; $560,000; National Aeronautics and Space Administration; 4 years.
June 1993, "Testing a Simple Conceptual Model of Soil Emissions of NO and N2O Across a Broad Range of Forest Types and Pastures Within the Tropical Forest Biome;" Keller was Co-Investigator with Dr. Eric Davidson (Woods Hole Research Center); $286,366 (Keller's portion of $480,000 total grant); National Aeronautics and Space Administration; 3 years.

July 1992, "Biogeochemistry and Atmospheric Interactions in Tropical Forests: Responses to Global Change;" Keller; $554,076; Keller was the principal investigator. Environmental Protection Agency; 3 years.

Courses Taught:
Tropical Forest Ecology (University of Puerto Rico, 1993) - team teaching in a semester long course, I contributed lectures related to ecosystem productivity, nutrient cycling, and the fluxes of trace gases.

Curso de Operações de Sitios Experimentais [Course on the Operation of Experimental Sites] (Instituto Nacional de Pesquisas da Amazônia, 1998) - course development and team teaching for a two week intensive field course on observational methods for micrometeorology, carbon and trace gas flux measurements. I lectured and taught laboratory sessions on gas measurement and gas handling techniques and I advised individual projects.

Integration of Modeling in the Large-Scale Biosphere-Atmosphere Experiments in Amazonia (Centro de Prevenção do Tempo e Estudos Climáticos, 2000) - course development, coordination, and team teaching for a two week intensive course on ecological modeling. I lectured on general principles of ecological modeling, taught practical sessions on modeling with Stella and advised individual projects.

Doctoral Student Advisory Committees:
Jason Neff (Stanford University, 1999)
Claire McSwiney (University of New Hampshire, 1999)
Antje Weitz (University of New Hampshire, 2000)
Evilene Lopes (University of New Hampshire, in progress)
Michael Palace (University of New Hampshire, in progress)
Marcel Franz (Universidade Federal Fluminense, in progress)

Outside Examiner on Doctoral Dissertations:
Roel Plant (Wageningen Agricultural University, 1999)
Eric Duchemin (Université du Québec à Montréal; 2000)
Luanne Beverly Otter (University of Witwatersrand, 2000)
Reinaldo Imbrozio Barbosa (Instituto Nacional de Pesquisas da Amazônia, 2001)

Licenciatura Thesis Advisor:
Martin Mitre (Universidad de Panamá, 1988)
Marvin Nuñez (Universidad de Costa Rica, 1992)

Bachelor of Science Thesis Advisor:
Jillana Robertson (University of New Hampshire, in progress)

Peer Reviews for Journals : Biogeochemistry, Bioscience, Biotropica, Chemosphere, Ecological Applications, Ecological Monographs, Ecology, Ecosystems, Environmental Science and Technology, Global Biogeochemical Cycles, Interciencia, Journal of Ecology, Journal of Geophysical Research, Journal of Tropical Ecology, Limnology and Oceanography, Nature, Nutrient Cycling in Agroecosystems (Member Editorial Board) , Soil Biology and Biochemistry, and Tellus

Peer Reviewer and Panelist for Government Agencies and Programs: NASA Terrestrial Ecology, NASA Land Use and Cover Change, NASA Hydrometeorology, NSF Division of Environmental Biology, USDA National Research Initiative Competitive Grants Program, US EPA, NERC (United Kingdom), Inter-governmental Panel on Climate Change (IPCC)

Honors and Awards
National Center for Atmospheric Research, Advanced Study Program Post-Doctoral Fellowship, 1990-1992.
National Center for Atmospheric Research, Advanced Study Program Pre-Doctoral Fellowship, 1988-1989.
Elected to Sigma XI Scientific Research Society, 1986.
Smithsonian Tropical Research Institute, Short Term Fellowship, 1985.
National Science Foundation Graduate Fellowship, 1984-1987.
Princeton University Hess Prize for the outstanding new graduate student in Geological and Geophysical Sciences, 1984.
Elected to Phi Beta Kappa Academic Honor Society, 1982.

Membership in Professional Societies
American Geophysical Union 1983 - present
Sigma Xi Research Society 1986- present