Timothy K. Kratz

Director, Trout Lake Station
Center for Limnology
University of Wisconsin-Madison
10810 County Highway N
Boulder Junction, WI  54512  USA

tkkratz@wisc.edu
Telephone:  715-356-9494
Fax: 715-356-6866

I am the director of the University of Wisconsin Trout Lake Station.  I welcome inquiries about the use of station facilities for research projects.  My research interests include the long-term, regional ecology of lakes; lake metabolism, including carbon dynamics in lakes, and the use of automated sensing systems to observe lake dynamics.  I am on the steering committee of the Global Lake Ecological Observatory Network (GLEON).

LTER Synthesis Book Published

Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes.

John J. Magnuson, Timothy K. Kratz, and Barbara J. Benson, editors

Oxford University Press, New York, 2005

 

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Education

B.S., Botany, University of Wisconsin-Madison, 1975.

M.S., Ecology and Behavioral Biology, University of Minnesota-Twin Cities, 1977.

Ph.D., Botany, University of Wisconsin-Madison, 1981.

Current Projects

North Temperate Lakes LTER Project

Humans, Lakes, and Riparian Zone Biocomplexity Project 

Global Lake Ecological Observatory Network

International Lake Metabolism Project

Selected Publications:

Kratz, T.K. and G.L. Jenson.  1977.  An ecological geographic division of Minnesota.  Minnesota Department of Natural Resources, Scientific and Natural Areas Section.  24 pp.

Friedman, R.M., C.B. DeWitt, and T.K. Kratz.  1979.  Simulating postglacial wetland formation: a quantitative reconstruction of Waubesa Marsh. Institute for Environmental Studies Report No. 106, University of Wisconsin-Madison. 60 pp.

Kratz, T.K., R.M. Friedman, and C.B. DeWitt.  1979.  A spatial simulation model of lake-edge wetland formation.  Institute for Environmental Studies Report No. 107, University of Wisconsin-Madison.  59 pp.

Kratz, T.K., M.S. Winkler, and C.B. DeWitt.  1981. Hydrology and chronology of a peat mound in Dane County, southern Wisconsin.  Trans. Acad. Wis. Acad. Sci. 69: 37-45.

Magnuson, J.J., C.J. Bowser, and T.K. Kratz.  1984.  Long-term ecological research on north temperate lakes (LTER).  Verh. Internat. Verein. Limnol. 22:533-535.

Kratz, T.K. and C.B. DeWitt.  1986. Internal factors controlling peatland-lake ecosystem development.  Ecology 67:100-107.

Kratz, T.K., J.J. Magnuson, C.J. Bowser, and T.M. Frost.  1986.  Rationale for data collection and interpretation in the Northern Lakes Long-Term Ecological Research Program.  In Rationale for Sampling and Interpretation of Ecological Data in the Assessment of Freshwater Systems.ASTM STP 894, B.G Isom, Ed.  American Society for Testing and Materials. Philadelphia. pp. 22-33. 

Lodge, D.M., T.K. Kratz, and G. Capelli.  1986.  Long-term dynamics of three crayfish species in Trout Lake, Wisconsin. Canadian Journal of Fisheries and Aquatic Science 43:993-998.

Brezonik, P.L., L.A. Baker, J.R. Eaton, T.M. Frost, P. Garrison, T.K. Kratz, J.J. Magnuson, W.J. Rose, B.K. Shepard, W.A. Swenson, C.J. Watras, and K.E. Webster.  1986.  Experimental Acidification of Little Rock Lake, Wisconsin.  Water, Air, and Soil Pollution.  31:115-121.

Kratz, T.K., T.M. Frost, and J.J. Magnuson.  1987.  Inferences from spatial and temporal variability in ecosystems: analyses of long-term zooplankton data from a set of lakes.  American Naturalist 129:830-846.

Kratz, T.K, R.B. Cook, C.J. Bowser and P.L. Brezonik.  1987.  Winter and spring pH depressions in northern Wisconsin lakes caused by increases in pCO2. Canadian Journal of Fisheries and Aquatic Science 44:1082-1088.

Swanson, F.J., T.K. Kratz, N. Caine, and R.G. Woodmansee.  1988.  Landform effects on ecological features and processes.  Bioscience 38:92-98.

Kratz, T.K.  1988.  A new method for estimating horizontal growth of the peat mat in basin-filling peatlands.  Canadian Journal of Botany 66:826-828.

Carpenter, S.R., T.M. Frost, D.M. Heisey, and T.K. Kratz.  1989. Randomized intervention analysis and the interpretation of whole-ecosystem experiments.  Ecology 70:1142-1152.

Kratz, T.K., and V.M. Medland.  1989.  Relationship of landscape position and groundwater input in northern Wisconsin kettle-hole peatlands.  pages 1141-1151 In Sharitz, R. R., and J. W. Gibbons (eds.), Freshwater Wetlands and Wildlife.  DOE Symposium Series No. 61.  USDOE Office of Scientific and Technical Information, Oak Ridge, Tennessee.

Magnuson, J. J., B. J. Benson, and T. K. Kratz.  1990.  Temporal coherence in the limnology of a suite of lakes in Wisconsin, U.S.A.  Freshwater Biology 23:145-159.

Adams, M. S., T. W. Meinke, and T. K. Kratz.  1990.  Primary productivity in three northern Wisconsin lakes.  Verh. Internat. Verein. Limnol. 24:432-437.

Marin, L. E., T. K. Kratz, and C. J. Bowser.  1990.  Spatial and temporal patterns in the hydrogeochemistry of a poor fen in northern Wisconsin.  Biogeochemistry 11:63-76.

Carpenter, S.R., T.M. Frost, J.F. Kitchell, T.K. Kratz, D.W. Schindler, J. Shearer, W.G. Sprules, M.J. Vanni, and A.P. Zimmerman. 1991.  Patterns of primary production and herbivory in 25 North American lake ecosystems.  Pages 67-96 In  Cole, J. J., G.M. Lovett, and S.E.G. Findlay (eds.), Comparative Analyses of Ecosystems: Patterns, Mechanisms, and Theories.  Springer-Verlag.  New York.  375 pp.

Magnuson, J.J., T.K. Kratz, T.M. Frost, B.J. Benson, R. Nero, and C.J. Bowser.  1991.  Expanding the temporal and spatial scales of ecological research and comparison of divergent ecosystems: roles for LTER in the United States.  pp 45-70 in Risser, P. G. (ed.) Long-term Ecological Research.  Wiley & Sons.

Kratz, T. K., T. M. Frost, J. E. Elias, and R. B. Cook.  1991.  Reconstruction of a regional, 12000-year silica decline in lakes by means of fossil sponge spicules.  Limnology and Oceanography 36:1244-1249.

Kratz, T. K., B. J. Benson, E. Blood, G. L. Cunningham, and R. A. Dahlgren.  1991.  The influence of landscape position on temporal variability in four North American ecosystems.  American Naturalist 138:355-378.

Frost, T. M., S. R. Carpenter, and T. K. Kratz.  1992.  Choosing ecological indicators:  effects of taxonomic aggregation on sensitivity to stress and natural variability.  p 215-227 in:  Ecological Indicators, D. H. McKenzie (ed.)  Elsevier Applied Science Publishers, Essex England.

Carpenter, S.R., T.M. Frost, J.F. Kitchell, and T.K. Kratz.  1993.  Species dynamics and global environmental change: a perspective from ecosystem experiments.  pp. 267-279 in Kingsolver, J., P. Kareiva, and R Huey (eds.) Biotic Interactions and Global Change.  Sinauer, Sunderland, Massachusetts.

Turner, M. G., W. H. Romme, R. H. Gardner, R. V. O'Neill, and T. K. Kratz.  1993.  A revised concept of landscape equilibrium: disturbance and stability on scaled landscapes.  Landscape Ecology 8:213-227.

Adams, M. S., T. W. Meinke, and T. K. Kratz.  1993.  Primary productivity of three Wisconsin lakes, 1985-1990.  Verh. Internat. Verein. Limnol. 25:406-410.

Kratz, T. K.  1993.  Assessing how freshwater systems will respond to global change:  where are we?  Review of Firth, P, and S. G. Fisher (eds.) 1992. Global climate change and freshwater ecosystems.  Springer-Verlag, New York.  Ecology 74:1292-1293.

Kratz, T. K. 1993.  Review of Barron, J. (ed.) Biogeochemistry of a Subalpine Ecosystem:  Loch Vale Watershed.  1991. Ecological Studies Series 90.  Springer-Verlag, New York.  Arctic and Alpine Research 25:418-419.

Brezonik, P. L., J. G. Eaton, T. M. Frost, P. J. Garrison, T. K. Kratz, C. E. Mach, J. H. McCormick, J. A. Perry, W. A. Rose, C. J. Sampson, B. C. L. Shelley, W. A. Swenson, and K. E. Webster.  1993.  Experimental acidification of Little Rock Lake, Wisconsin:  chemical and biological changes over the pH range 6.1 to 4.7.  Canadian Journal of Fisheries and Aquatic Science 50:1101-1121.

Kratz, T. K., J. J. Magnuson, T. M. Frost, B. J. Benson, and S. R. Carpenter.  1994.  Landscape position, scaling, and the spatial and temporal variability of ecological parameters: considerations for biological monitoring.  pp.  217-231 in S. L. Loeb and A. Spacie (eds.) Biological Monitoring of Freshwater Ecosystems:  Interpretation and efficacy to assess environmental quality.  CRC Press, Ann Arbor, MI.

Cole, J. J., N. F. Caraco, G. W. Kling, and T. K. Kratz.  1994.  Carbon dioxide supersaturation in the surface waters of lakes.  Science 265:1568-1570.

Carpenter, S.R., T.M. Frost, A.R. Ives, J.F. Kitchell, and T.K. Kratz.  1994.  Complexity, cascades, and compensation in ecosystems.  pp. 197-207 in M. Yasuno and M.M. Watanabe (eds.).  Biodiversity:  Its Complexity and Role. Global Environmental Forum, Tokyo, Japan.

Frost, T. M., S. R. Carpenter, A. R. Ives, and T. K. Kratz.  1995.  Species compensation and complementarity in ecosystem function.  pp 224-239 in Jones C. G., and J. H. Lawton (eds.), Linking Species and Ecosystems.  Chapman and Hall, New York.  387 pp.

Kratz, T.K., J.J. Magnuson, P. Bayley, B.J. Benson, C. W. Berish, C.S. Bledsoe, E.R. Blood, C.J. Bowser, S.R. Carpenter, G.L. Cunningham, R.A. Dahlgren, T.M. Frost, J.C. Halfpenny, J.D. Hansen, D. Heisey, R.S. Inouye, D.W. Kaufman, A. McKee, and J. Yarie.  1995.  Temporal and spatial variability as neglected ecosystem properties:  lessons learned from 12 North American ecosystems.  pages 359-383 In  Rapport, D. and P. Calow (eds.)  Evaluating and Monitoring the Health of Large-Scale Ecosystems.  Springer-Verlag.

Webster, K. E., T. K. Kratz, C. J. Bowser, J. J. Magnuson, and W. J. Rose.  1996.  The influence of landscape position on lake chemical responses to drought in northern Wisconsin, USA.  Limnology and Oceanography 41:977-984.

Hope, D., T. K. Kratz, and J. L. Riera.  1996.  The relationship between PCO2 and dissolved organic carbon in the surface waters of 27 northern Wisconsin lakes.  Journal of Environmental Quality 49:1442-1445.

Kratz, Timothy K., Katherine E. Webster, Carl J. Bowser, John J. Magnuson, and Barbara J. Benson.  1997. The influence of landscape position on northern Wisconsin lakes.  Freshwater Biology 37:209-217.

Kratz, T.K., J. Schindler, D. Hope, J. L. Riera, and C. J. Bowser.  1997.  Average annual carbon dioxide concentrations in eight neighboring lakes in northern Wisconsin, USA.  Verh. Internat. Verein. Limnol. 26:335-338.

Magnuson, J.J., T.K. Kratz, T.F. Allen, D.E. Armstrong, B. J. Benson, C.J. Bowser, D.W. Bolgrien, S.R. Carpenter, T.F. Frost, S.T. Gower, T.M. Lillesand, J.A. Pike, and M.G. Turner.  1997.  Regionalization of long-term ecological research (LTER) on north temperate lakes. Verh. Internat. Verein. Limnol. 26:522-528.

Kratz, T.K., P.A. Soranno, S.B. Baines, B.J. Benson, J.J. Magnuson, T.M. Frost, and R.C. Lathrop.  1998.   Interannual synchronous dynamics in north temperate lakes in Wisconsin, USA.  Pages 273-287 In George, D.G., J. G. Jones, P. Puncochar, C. S. Reynolds, and D. W. Sutcliffe (eds.)  Management of Lakes and Reservoirs during Global Climate Change.  Kluwer Academic. 

Kratz, T. K., B. Bojanovsky, V. Drabkova, and V. Straskrabova.  1998.  International networks of lake sites: report of working group 4.  Pages 307-320 In George, D.G., J. G. Jones, P. Puncochar, C. S. Reynolds, and D. W. Sutcliffe (eds.)  Management of Lakes and Reservoirs during Global Climate Change.  Kluwer Academic.

Frost, T.M., P.K. Montz, and T.K. Kratz. 1998. Zooplankton community responses during recovery from acidification:  limited persistence by acid-favored species in Little Rock Lake, Wisconsin.  Restoration Ecology 6:336-342.

Frost, T. M., T. K. Kratz, and J. J. Magnuson.  1999.  Focus on Field Stations:  Center for Limnology Trout Lake Station, University of Wisconsin.  Bulletin of the Ecological Society of America 80:70-73.

Frost, T. M., P.K. Montz, T.K. Kratz , T. Badillo, P.L. Brezonik, M.J. Gonzalez, R.G. Rada, C.J. Watras, K. E. Webster, J.G. Wiener, C.E. Williamson, and D. P. Morris.  1999.  Multiple stresses from a single agent:  diverse responses to the experimental acidification of Little Rock Lake, Wisconsin.  Limnology and Oceanography 44:784-794.

Riera, J. L., J. E. Schindler, and T. K. Kratz.  1999.  Seasonal dynamics of carbon dioxide and methane in two clear-water and two bog lakes in northern Wisconsin, USA.  Canadian Journal of Fisheries and Aquatic Sciences 56:265-274.

Soranno, P. A., K. E. Webster, J. L. Riera, T. K. Kratz, J. S. Baron, P. Bukaveckas, G. W. Kling, D. White, N. Caine, R. C. Lathrop, and P. Leavitt.  1999. Spatial variation among lakes within landscapes: ecological organization along lake chains.  Ecosystems 2:395-410.

Gergel, S. E., M. G. Turner, and T. K. Kratz.  1999.  Dissolved organic carbon as an indicator of the scale of watershed influence on lakes and rivers.  Ecological Applications 9(4):1377-90.

Lathrop, R. C. and T. K. Kratz.  1999.  Long-term ecological research on Wisconsin lakes affected by human activities, p. 67-71.  In: P. Bijok and M. Prus [eds.] Long term ecological research - examples, methods, perspectives for Central Europe.  Proceedings of the ILTER Regional Workshop, 16-18 September 1998, Madralin, Poland.

Baines, S. B., K. E. Webster, T. K. Kratz, S. R. Carpenter, and J. J. Magnuson.  2000.  Synchronous behavior of temperature, calcium and chlorophyll in lakes of northern Wisconsin.  Ecology 81:815-825.

Bolgrien, D. W., and T. K. Kratz.  2000.  Lake shore riparian areas.  Pages 207-217 in  Verry, E. S., J. W. Hornbeck, and C. A. Dolloff (eds.)  Riparian Management in Forests of the Continental Eastern United States.  Lewis Publishers, Washington D.C.

Benson, B. J., J. D. Lenters, J. J. Magnuson, M. Stubbs, T. K. Kratz, P. J. Dillon, R. E. Hecky, and R. C. Lathrop.  2000.  Regional coherence of climatic and lake thermal variables of four lake districts in the Upper Great Lakes Region of North America.  Freshwater Biology 43:517-527.

Kratz, T. K., and T. M. Frost.  2000.  The ecological organization of lake districts:  general introduction.  Freshwater Biology 43:297-299.

Riera, J. L., J. J. Magnuson, T. K. Kratz, and K. E. Webster. 2000.  A geomorphic template for the analysis of lake districts applied to the Northern Highland Lake District, Wisconsin, USA.  Freshwater Biology 43:301-318.

Webster, K. E., P. A. Soranno, S. B. Baines, T. K. Kratz, C. J. Bowser, P. J. Dillon, P. Campbell, E. J. Fee, and R. E. Hecky.  2000.  Structuring features of lake districts: geomorphic and landscape controls on lake chemical responses to drought.  Freshwater Biology 43:499-516.

Magnuson, J. J., and T. K. Kratz.  2000. Lakes in the landscape: approaches to regional limnology. Verh. Internat. Verein. Limnol. 27:74-87.

Kratz, T. K., B. P. Hayden, B. J. Benson, and W. Y. B. Chang.  2000. Patterns in the interannual variability of lake freeze and thaw dates. Verh. Internat. Verein. Limnol. 27:2796-2799.

Watras, C.J., K.A. Morrison, R.J.M. Hudson , T.M. Frost, T.K. Kratz.  2000.  Decreasing mercury in northern Wisconsin: temporal patterns in bulk precipitation and a precipitation-dominated lake.  Environmental Science and Technology 34:4051-4057.

Riera, J, P. R. Voss, S. R. Carpenter, T. K. Kratz, T. M. Lillesand, J. A. Schnaiberg, M. G. Turner, M. W. Wegener.  2001.  Nature, society and history in two contrasting landscapes in Wisconsin, USA: interactions between lakes and humans during the twentieth century.  Land Use Policy 18:41-51.

Hamilton, D. P., C. M. Spillman, K. L. Prescott, T. K. Kratz and J. J. Magnuson. 2002. Effects of atmospheric nutrient inputs and climate change on the trophic status of Crystal Lake, Wisconsin. Verh. Internat. Verein. Limnol. 28:467-470.

Watras, C.J., K.A. Morrison, and T.K. Kratz. 2002.  Seasonal enrichment and depletion of Hg and SO4 in Little Rock Lake: relationship to seasonal changes in atmospheric deposition. Canadian Journal of Fisheries and Aquatic Sciences 59:1660-1667.

Kratz, T. K.,  D. W. Bolgrien, S. Giblin, and J. O'Leary. 2002.  Human influences on the spatial distribution of coarse woody debris in lakes in northern Wisconsin, USA.  Verh. Internat. Verein. Limnol. 28:545-548.

Kratz, T. K.,  L. A. Deegan, M. E. Harmon, and W. K. Lauenroth.  2003. Ecological variability in space and time: insights gained from the US LTER program.  Bioscience 53:57-67.

Hanson, P. C., D. L. Bade, S. R. Carpenter, and T. K. Kratz. 2003. Lake metabolism: relationships with dissolved organic carbon and phosphorus. Limnology and Oceanography 48:1112-1119.

Yannarell, A. C., A. D. Kent, G. H. Lauster, T. K. Kratz, and E. W. Triplett.  2003 Temporal patterns in bacterial communities in three temperate lakes of different trophic status. Microbial Ecology 46: 391-405.

Magnuson, J. J., B. J. Benson, and T. K. Kratz. 2004. Patterns of coherent dynamics within and between lake districts at local to intercontinental scales. Boreal Environment Research 9:359-370.

Wilson, K. A, J. J. Magnuson, D. M. Lodge, A. M. Hill, T. K. Kratz, W. L. Perry, and T.V. Willis. 2004.   A long-term rusty crayfish (Orconectes rusticus) invasion: dispersal patterns and community change in a north temperate lake.  Canadian Journal of Fisheries and Aquatic Science 61:2255-2266.

Kent, A. D., S. E. Jones, A. C. Yannarell, J. M. Graham, G. H. Lauster, T. K. Kratz, and E. W. Triplett. 2004. Annual patterns in bacterioplankton community variability in a humic lake.  Microbial Ecology 48:550-560.

Hrabik, T. R., B K. Greenfield, D. B. Lewis, A. I. Pollard, K. A. Wilson, and T. K. Kratz. 2005. Landscape scale variation in taxonomic diversity in four groups of aquatic organisms:  the influence of physical, chemical, and biological properties.  Ecosystems 8:301-317.

Lenters, J. D., T. K. Kratz, and  C. J. Bowser.  2005.  Effects of climate variability on lake evaporation: results from a long-term energy budget study of Sparkling Lake, northern Wisconsin (USA). Journal of Hydrology 308:168-195.

Porter, J., P. Arzberger, H. Braun, P. Bryant, S. Gage, T. Hansen, P. Hanson, F. Lin, C. Lin, T. K. Kratz, W. Michener, S. Shapiro, and T. Williams.  2005.  Wireless sensor networks for ecology.  Bioscience 55:561-572.

Magnuson, John J., Timothy K. Kratz, and Barbara J. Benson. 2006. Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes. Oxford University Press, New York, 400pp. 

Magnuson, J. J., T. K. Kratz, and B. J. Benson. 2006.  The challenge of time and space in ecology.  Pages 3-16 in Magnuson, J. J., T. K. Kratz, and B. J. Benson (eds.) Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes. Oxford University Press, New York. 400pp.

Kratz, T. K., K. E. Webster, J. L. Riera, D. B. Lewis, and A. I. Pollard.  2006.  Making sense of the landscape: geomorphic legacies and the landscape position of lakes.  Pages 49-66 in Magnuson, J. J., T. K. Kratz, and B. J. Benson (eds.) Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes. Oxford University Press, New York. 400pp.

Magnuson, J. J., T. K. Kratz, B. J. Benson and K. E. Webster. 2006.   Coherent dynamics among lakes.  Pages 89-106 in Magnuson, J. J., T. K. Kratz, and B. J. Benson (eds.) Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes. Oxford University Press, New York. 400pp.

Riera, J. L., T. K. Kratz, and J. J. Magnuson. 2006.   Generalization from intersite research.  Pages 107-120 in Magnuson, J. J., T. K. Kratz, and B. J. Benson (eds.) Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes. Oxford University Press, New York. 400pp.

Frost, T. M., J. M. Fischer, P. L. Brezonik, M. J. Gonzalez, T. K. Kratz, C. J. Watras, and K. E. Webster.  2006.  Pages 168-186 in Magnuson, J. J., T. K. Kratz, and B. J. Benson (eds.) Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes. Oxford University Press, New York. 400pp.

Magnuson, J. J., B. J. Benson, T. K. Kratz, D. E. Armstrong, C. J. Bowser, T. W. Meinke, P. K. Montz, and K. E. Webster.  2006.   Origin, Operation, Evolution, and Challenges. Pages 280-322 in Magnuson, J. J., T. K. Kratz, and B. J. Benson (eds.) Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes. Oxford University Press, New York. 400pp.

Benson, B. J., T. K. Kratz, and J. J. Magnuson.  2006.  Synthetic summary and prospective.  Pages 325-333 in Magnuson, J. J., T. K. Kratz, and B. J. Benson (eds.) Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes. Oxford University Press, New York. 400pp.

Kratz, T. K., S. MacIntyre, and K. E. Webster.  (in press).  Causes and consequences of spatial heterogeneity in lakes.  In Lovett, G., C. Jones, M. G. Turner, and K. Weathers (eds.). Ecosystem Function in Heterogeneous Landscapes.   Proceedings of the 10th Cary Conference.

Watras, C. J., K. A. Morrison, O. Regnell, and T. K. Kratz.  (in press). The methylmercury cycle in Little Rock Lake during experimental acidification and recovery.  Limnology and Oceanography.