Current Research

I study the effect of land management (forest, agriculture and urban land uses) on the terrestrial and aquatic cycling of nutrients, carbon, heavy metals (notably mercury) and water.

Currently I'm working on numerous studies to assess nutrient, carbon and mercury pools and processes in variety of ecosystems. Nutrient work includes studies related to Forestry Best Management Practices in riparian and wetland systems and work aimed at understanding the influence of strategically placed perennial vegetation in agricultural watersheds. Nutrient work also includes the effect of stream restoration on nutrient cycling. My carbon work includes studies looking at landscape level carbon pools and emissions across number of ecosystems including peatlands, and a variety upland vegetation types. The ecosystem carbon work also extends into characterizing the pools of coarse woody debris in forested riparian areas and streams. My mercury work is focused on two main efforts, one to characterize the mercury cycle under increased sulfate deposition and a second to understand the influence of prescribed fire on mercury cycling.

Why This Research is Important

The transport on nonpoint source pollutants including nutrients such as nitrogen and phosphorus are the number one concern regarding the impacts on aquatic ecosystems. This is demonstrated by the numerous issues surrounding the development of Best Management Practices for forest and agricultural systems and regulations that are being imposed by the Environmental Protection Agency (e.g. Total Maximum Daily Loads).

In the Lake States, mercury is of high concern because of its potential to bioaccumulate in the aquatic food chain. Understanding how management can lessen mercury inputs and/or increase storage in terrestrial systems is critical for human health and the fishing industry.

Investigating the landscape level influences on carbon storage and processing will lead to a better understanding of implications of climate change. One of the great uncertainties in climate modeling is the feedbacks that terrestrial systems have on atmospheric carbon, most notably on the green house gases carbon dioxide and methane. Our work is helping fill this important knowledge gap.

Education

• University of Minnesota, Ph.D. Soil Science 1996
• University of Minnesota, M.S. Soil Science 1993
• University of Wisconsin - Stevens Point, B.S. Soil Science 1990

Professional Experience

Professional Organizations

• Soil Science Society of America
• Society of Wetland Scientists
• American Water Resources Association
• Society of American Foresters
• Ecology and Biology Subject Area, Editorial Positions
• Society of American Foresters, Forest Science and Technology Board, Editorial Positions (2006 - Present)
• Wetlands, Associate Editor (2006 - Present)
• Ecosystems Restoration and Creation, Annual Conference Editorial Review Committee, Associate Editor (1997 - Present)

Featured Publications & Products

• Schulte, Lisa A.; Niemi, Jarad; Helmers, Matthew J.; Liebman, Matt; Arbuckle, J. Gordon; James, David E.; Kolka, Randall K.; O’Neal, Matthew E.; Tomer, Mark D.; Tyndall, John C.; Asbjornsen, Heidi; Drobney, Pauline; Neal, Jeri; Van Ryswyk, Gary; Witte, Chris. 2017. Prairie strips improve biodiversity and the delivery of multiple ecosystem services from corn soybean croplands.
• Kolka, Randy; Bridgham, Scott D.; Ping, Chien-Lu. 2016. Soils of peatlands: histosols and gelisols.
• Wilson, R. M.; Hopple, A. M.; Tfaily, M. M.; Sebestyen, S. D.; Schadt, C. W.; Pfeifer-Meister, L.; Medvedeff, C.; McFarlane, K. J.; Kostka, J. E.; Kolton, M.; Kolka, R.K.; Kluber, L. A.; Keller, J. K.; Guilderson, T. P.; Griffiths, N. A.; Chanton, J. P.; Bridgham, S. D.; Hanson, P. J. 2016. Stability of peatland carbon to rising temperatures.
• Kolka, Randy; Murdiyarso, D.; Kauffman, J. B.; Birdsey, Richard. 2016. Tropical wetlands, climate, and land-use change: adaptation and mitigation opportunities.
• Hagerty, Shannon B.; van Groenigen, Kees Jan; Allison, Steven D.; Hungate, Bruce A.; Schwartz, Egbert; Koch, George W.; Kolka, Randall K.; Dijkstra, Paul. 2014. Accelerated microbial turnover but constant growth efficiency with warming in soil.

Publications

• Quigley, K.M. ; Wildt, R.E. ; Sturtevant, B.R. ; Kolka, R.K. ; Dickinson, M.B. ; Kern, C.C. ; Donner, D.M. ; Miesel, J.R. . 2019. Fuels, vegetation, and prescribed fire dynamics influence ash production and characteristics in a diverse landscape under active pine barrens restoration.
• Pischke, Erin C.; Berry, Z. Carter; Kolka, Randall K.; Salcone, Jacob ; Córdoba, Diana ; Shinbrot, Xoco ; López Ramirez, Sergio Miguel; Jones, Kelly W.; Congalton, Russell G.; Manson, Robert H.; Von Thaden Ugalde, Juan José; Selfa, Theresa ; Avila Foucat, V. Sophie; Asbjornsen, Heidi . 2019. Lessons learned about collaborating across coupled human-natural systems research on Mexico's Payments for Hydrological Services Program.
• Fernandez, Christopher W.; Heckman, Katherine ; Kolka, Randall ; Kennedy, Peter G. 2019. Melanin mitigates the accelerated decay of mycorrhizal necromass with peatland warming.
• Noh, Nam Jin; Shannon, Joseph P.; Bolton, Nicholas W.; Davis, Joshua C.; Van Grinsven, Matthew J.; Pypker, Thomas G.; Kolka, Randall K.; Wagenbrenner, Joseph W. 2019. Temperature responses of carbon dioxide fluxes from coarse dead wood in a black ash wetland.
• Kolka, Randall K.; Riggs, Charlotte E.; Nater, Edward A.; Wickman, Trent R.; Witt, Emma L.; Butcher, Jason T. 2019. Temporal fluctuations in young-of-the-year yellow perch mercury bioaccumulation in lakes of northeastern Minnesota.
• McPartland, Mara Y.; Kane, Evan S.; Falkowski, Michael J.; Kolka, Randy ; Turetsky, Merritt R.; Palik, Brian ; Montgomery, Rebecca A. 2019. The response of boreal peatland community composition and NDVI to hydrologic change, warming and elevated carbon dioxide.
• Murdiyarso, Daniel ; Lilleskov, Erik ; Kolka, Randy . 2019. Tropical peatlands under siege: the need for evidence-based policies and strategies.
• Miesel, Jessica R.; Kolka, Randy ; Townsend, Phil . 2018. Chapter 10 - Wildfire and fire severity effects on post-fire carbon and nitrogen cycling in forest soil (Project NC-EM-F-14-1).
• Iversen, Colleen M.; Childs, Joanne ; Norby, Richard J.; Ontl, Todd A.; Kolka, Randall K.; Brice, Deanne J.; McFarlane, Karis J.; Hanson, Paul J. 2018. Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat.
• Bertolet, Brittni L.; Corman, Jessica R.; Casson, Nora J.; Sebestyen, Stephen D.; Kolka, Randy K.; Stanley, Emily H. 2018. Influence of soil temperature and moisture on the dissolved carbon, nitrogen, and phosphorus in organic matter entering lake ecosystems.
• Lilleskov, Erik ; McCullough, Kevin ; Hergoualc’h, Kristell ; del Castillo Torres, Dennis ; Chimner, Rodney ; Murdiyarso, Daniel ; Kolka, Randy ; Bourgeau-Chavez, Laura ; Hribljan, John ; del Aguila Pasquel, Jhon ; Wayson, Craig . 2018. Is Indonesian peatland loss a cautionary tale for Peru A two-country comparison of the magnitude and causes of tropical peatland degradation.
• Bolton, Nicholas; Shannon, Joseph; Davis, Joshua; Grinsven, Matthew; Noh, Nam; Schooler, Shon; Kolka, Randall; Pypker, Thomas; Wagenbrenner, Joseph. 2018. Methods to Improve Survival and Growth of Planted Alternative Species Seedlings in Black Ash Ecosystems Threatened by Emerald Ash Borer.
• Woerndle, Glenn E.; Tsz-Ki Tsui, Martin ; Sebestyen, Stephen D.; Blum, Joel D.; Nie, Xiangping ; Kolka, Randall K. 2018. New Insights on Ecosystem Mercury Cycling Revealed by Stable Isotopes of Mercury in Water Flowing from a Headwater Peatland Catchment.
• Corman, J. R.; Bertolet, B. L.; Casson, N. J.; Sebestyen, S. D.; Kolka, R. K.; Stanley, E. H. 2018. Nitrogen and Phosphorus Loads to Temperate Seepage Lakes Associated With Allochthonous Dissolved Organic Carbon Loads.
• Kolka, Randall K.; D'Amato, Anthony W.; Wagenbrenner, Joseph W.; Slesak, Robert A.; Pypker, Thomas G.; Youngquist, Melissa B.; Grinde, Alexis R.; Palik, Brian J. 2018. Review of ecosystem level impacts of emerald ash borer on black ash wetlands: What does the future hold.
• Chen, Zichong; Griffis, Timothy J.; Baker, John M.; Millet, Dylan B.; Wood, Jeffrey D.; Dlugokencky, Edward J.; Andrews, Arlyn E.; Sweeney, Colm; Hu, Cheng; Kolka, Randall K. 2018. Source partitioning of methane emissions and its seasonality in the U.S. Midwest.
• Kolka, Randall ; Trettin, Carl ; Tang, Wenwu ; Krauss, Ken ; Bansal, Sheel ; Drexler, Judith ; Wickland, Kimberly ; Chimner, Rodney ; Hogan, Diana ; Pindilli, Emily J.; Benscoter, Brian ; Tangen, Brian ; Kane, Evan ; Bridgham, Scott ; Richardson, Curtis . 2018. Terrestrial wetlands.
• Shannon, Joseph; Van Grinsven, Matthew; Davis, Joshua; Bolton, Nicholas; Noh, Nam; Pypker, Thomas; Kolka, Randall. 2018. Water Level Controls on Sap Flux of Canopy Species in Black Ash Wetlands.
• Warren, Matthew; Hergoualc'h, Kristell; Kauffman, J. Boone; Murdiyarso, Daniel; Kolka, Randall. 2017. An appraisal of Indonesia's immense peat carbon stock using national peatland maps: uncertainties and potential losses from conversion.
• Comas, Xavier; Terry, Neil; Hribljan, John A.; Lilleskov, Erik A.; Suarez, Esteban; Chimner, Rodney A.; Kolka, Randy K. 2017. Estimating belowground carbon stocks in peatlands of the Ecuadorian p ramo using ground-penetrating radar (GPR).
• Olson, J. C.; Marcarelli, A. M.; Timm, A.L.; Eggert, S.L.; Kolka, R.K. 2017. Evaluating the Effects of Culvert Designs on Ecosystem Processes in Northern Wisconsin Streams.
• Powers, Matthew; Kolka, Randall; Bradford, John; Palik, Brian; Jurgensen, Martin. 2017. Forest floor and mineral soil respiration rates in a northern Minnesota red pine chronosequence.
• Haynes, Kristine M.; Kane, Evan S.; Potvin, Lynette; Lilleskov, Erik A.; Kolka, Randall K.; Mitchell, Carl P.J. 2017. Gaseous mercury fluxes in peatlands and the potential influence of climate change.
• Haynes, Kristine M.; Kane, Evan S.; Potvin, Lynette; Lilleskov, Erik A.; Kolka, Randy; Mitchell, Carl P. J. 2017. Mobility and transport of mercury and methylmercury in peat as a function of changes in water table regime and plant functional groups.
• Timm, A.; Higgins, D.; Stanovick, J.; Kolka, R.; Eggert, S. 2017. Quantifying fish habitat associated with stream simulation design culverts in northern Wisconsin.
• Hobbs, Trevor; Lynch, Jason; Kolka, Randy. 2017. Site-specific critical acid load estimates for forest soils in the Osborn Creek watershed, Michigan.
• Van Grinsven, Matthew J.; Shannon, Joseph P.; Davis, Joshua C.; Bolton, Nicholas W.; Wagenbrenner, Joseph W.; Kolka, Randall K.; Grant Pypker, Thomas. 2017. Source water contributions and hydrologic responses to simulated emerald ash borer infestations in depressional black ash wetlands.
• Anwar, Usman; Schulte, Lisa A.; Helmers, Matthew; Kolka, Randall K. 2017. The Effect of Five Biomass Cropping Systems on Soil-Saturated Hydraulic Conductivity Across a Topographic Gradient.
• Dymond, Salli F.; Bradford, John B.; Bolstad, Paul V.; Kolka, Randall K.; Sebestyen, Stephen D.; DeSutter, Thomas M. 2017. Topographic, edaphic, and vegetative controls on plant-available water.
• Davis, Joshua C.; Shannon, Joseph P.; Bolton, Nicholas W.; Kolka, Randall K.; Pypker, Thomas G. 2017. Vegetation responses to simulated emerald ash borer infestation in Fraxinus nigra dominated wetlands of Upper Michigan, USA.
• Riggs, Charlotte E.; Kolka, Randall K.; Nater, Edward A.; Witt, Emma L.; Wickman, Trent R.; Woodruff, Laurel G.; Butcher, Jason T. 2017. Yellow perch (Perca flavescens) mercury unaffected by wildland fires in northern Minnesota.
• Adkins, Joshua; Barton, Christopher; Grubbs, Scott; Stringer, Jeffrey; Kolka, Randy. 2016. Assessment of streamside management zones for conserving benthic macroinvertebrate communities following timber harvest in eastern Kentucky headwater catchments.
• Gerken Golay, Michaeleen; Thompson, Janette; Kolka, Randall; Verheyen, Kris. 2016. Carbon, nitrogen and phosphorus storage across a growing season by the herbaceous layer in urban and preserved temperate hardwood forests.
• Hill, Brian H.; Jicha, Terri M.; Lehto, LaRae L.P.; Elonen, Colleen M.; Sebestyen, Stephen D.; Kolka, Randy. 2016. Comparisons of soil nitrogen mass balances for an ombrotrophic bog and a minerotrophic fen in northern Minnesota.
• Puhlick, Joshua J.; Fraver, Shawn; Fernandez, Ivan J.; Weiskittel, Aaron R.; Kenefic, Laura S.; Kolka, Randy; Gruselle, Marie-Cecile. 2016. Factors influencing organic-horizon carbon pools in mixed-species stands of central Maine, USA.
• Dymond, S.F.; D'Amato, A.W.; Kolka, Randy; Bolstad, P.V.; Sebestyen, Stephen; Bradford, J.B. 2016. Growth-climate relationships across topographic gradients in the northern Great Lakes.
• Timm, Anne; Hallerman, Eric; Dolloff, Andy; Hudy, Mark; Kolka, Randall. 2016. Identification of a barrier height threshold where brook trout population genetic diversity, differentiation, and relatedness are affected.
• Psarska, Sona; Nater, Edward A.; Kolka, Randy. 2016. Impacts of invasive earthworms on soil mercury cycling: Two mass balance approaches to an earthworm invasion in a northern Minnesota forest.
• Witt, Emma L.; Barton, Christopher D.; Stringer, Jeffrey W.; Kolka, Randy; Cherry, Mac A. 2016. Influence of Variable Streamside Management Zone Configurations on Water Quality after Forest Harvest.
• Hanson, P. J.; Gill, A. L.; Xu, X.; Phillips, J. R.; Weston, D. J.; Kolka, Randy; Riggs, J. S.; Hook, L. A. 2016. Intermediate-scale community-level flux of CO2 and CH4 in a Minnesota peatland: putting the SPRUCE project in a global context.
• Puhlick, Joshua J.; Weiskittel, Aaron R.; Fernandez, Ivan J.; Fraver, Shawn; Kenefic, Laura S.; Seymour, Robert S.; Kolka, Randall K.; Rustad, Lindsey E.; Brissette, John C. 2016. Long-term influence of alternative forest management treatments on total ecosystem and wood product carbon storage.
• Kim, Dong-Gill; Taddese, Habitamu; Belay, Abrham; Kolka, Randy. 2016. The impact of traditional fire management on soil carbon and nitrogen pools in a montane forest, southern Ethiopia.
• Sebestyen, Stephen; Kolka, Randy. 2016. Thirty-year results from a paired-catchment study of upland flowpath responses to forest cover conversion in northern Minnesota.
• Kolka, Randy; Mitchell, Carl; Nater, Ed. 2016. Watershed cycling of mercury and controls on methylmercury production in Northern Minnesota landscapes.
• Asbjornsen, Heidi; Mayer, Alex S.; Jones, Kelly W.; Selfa, Theresa; Saenz, Leonardo; Kolka, Randall K.; Halvorsen, Kathleen E. 2015. Assessing impacts of payments for watershed services on sustainability in coupled human and natural systems.
• Potvin, Lynette R.; Kane, Evan S.; Chimner, Rodney A.; Kolka, Randall K.; Lilleskov, Erik A. 2015. Effects of water table position and plant functional group on plant community, aboveground production, and peat properties in a peatland mesocosm experiment (PEATcosm).
• Ontl, Todd A.; Cambardella, Cynthia A.; Schulte, Lisa A.; Kolka, Randall K. 2015. Factors influencing soil aggregation and particulate organic matter responses to bioenergy crops across a topographic gradient.
• Comas, X.; Terry, N.; Warren, M.; Kolka, R.; Kristiyono, A.; Sudiana, N.; Nurjaman, D.; Darusman, T. 2015. Imaging tropical peatlands in Indonesia using ground-penetrating radar (GPR) and electrical resistivity imaging (ERI): implications for carbon stock estimates and peat soil characterization.
• Ross, D.S.; Bailey, S.W.; Briggs, R.D.; Curry, J.; Fernandez, I.J.; Fredriksen, G.; Goodale, C.L.; Hazlett, P.W.; Heine, P.R.; Johnson, C.E.; Larson, J.T.; Lawrence, G.B.; Kolka, R.K.; Ouimet, R.; Pare, D.; Richter, D. deB; Schirmer, C.D.; Warby, R.A. 2015. Inter-laboratory variation in the chemical analysis of acidic forest soil reference samples from eastern North America.
• Desai, Ankur R.; Xu, Ke; Tian, Hanqin; Weishampel, Peter; Thom, Jonathan; Baumann, Dan; Andrews, Arlyn E.; Cook, Druce D.; King, Jennifer Y.; Kolka, Randall. 2015. Landscape-level terrestrial methane flux observed from a very tall tower.
• Babcock, Chad; Finley, Andrew O.; Bradford, John B.; Kolka, Randy; Birdsey, Richard; Ryan, Michael G. 2015. LiDAR based prediction of forest biomass using hierarchical models with spatially varying coefficients.
• Kristensen, Terje; Naesset, Erik; Ohlson, Mikael; Bolstad, Paul V.; Kolka, Randall. 2015. Mapping above- and below-ground carbon pools in boreal forests: The case for airborne lidar.
• Miesel, Jessica R.; Hockaday, William C.; Kolka, Randy; Townsend, Philip A. 2015. Soil organic matter composition and quality across fire severity gradients in coniferous and deciduous forests of the southern boreal region.
• Palik, Brian J.; Haworth, Brooke K.; David, Andrew J.; Kolka, Randall K. 2015. Survival and growth of northern white-cedar and balsam fir seedlings in riparian management zones in northern Minnesota, USA.
• Coleman Wasik, J.K.; Engstrom, D.R.; Mitchell, C.P.J.; Swain, E.B.; Monson, B.A.; Balogh, S.J.; Jeremiason, J.D.; Branfireun, B.A.; Kolka, R.K.; Almendinger, J.E. 2015. The effects of hydrologic fluctuation and sulfate regeneration on mercury cycling in an experimental peatland.
• Romanowicz, Karl J.; Kane, Evan S.; Potvin, Lynette R.; Daniels, Aleta L.; Kolka, Randy; Lilleskov, Erik A. 2015. Understanding drivers of peatland extracellular enzyme activity in the PEATcosm experiment: mixed evidence for enzymic latch hypothesis.
• Gottfried, Gerald J.; Ffolliott, Peter F.; Brooks, Kenneth N.; Kolka, Randall K.; Raish, Carol B.; Neary, Daniel G. 2014. Contributions of studies on experimental forests to hydrology and watershed management Chapter 14.
• Chimner, Rodney A.; Ott, Cassandra A.; Perry, Charles H.; Kolka, Randall K. 2014. Developing and evaluating rapid field methods to estimate peat carbon.
• Hill, Brian H.; Elonen, Colleen M.; Jicha, Terri M.; Kolka, Randall K.; Lehto, LaRae L.P.; Sebestyen, Stephen D.; Seifert-Monson, Lindsey R. 2014. Ecoenzymatic stoichiometry and microbial processing of organic matter in northern bogs and fens reveals a common P-limitation between peatland types.
• Smith, Tomorra E.; Kolka, Randall K.; Zhou, Xiaobo; Helmers, Matthew J.; Cruse, Richard M.; Tomer, Mark D. 2014. Effects of native perennial vegetation buffer strips on dissolved organic carbon in surface runoff from an agricultural landscape.
• Seifert-Monson, L.R.; Hill, B.H.; Kolka, R.K.; Jicha, T.M.; Lehto, L.L.; Elonen, C.M. 2014. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland.
• Mazur, M.; Mitchell, C.P.J.; Eckley, C.S.; Eggert, S.L.; Kolka, R.K.; Sebestyen, S.D.; Swain, E.B. 2014. Gaseous mercury fluxes from forest soils in response to forest harvesting intensity: A field manipulation experiment.
• Dymond, Salli F.; Kolka, Randall K.; Bolstad, Paul V.; Sebestyen, Stephen D. 2014. Long-term soil moisture patterns in a northern Minnesota forest.
• Handler, Stephen; Duveneck, Matthew J.; Iverson, Louis; Peters, Emily; Scheller, Robert M.; Wythers, Kirk R.; Brandt, Leslie; Butler, Patricia; Janowiak, Maria; Shannon, P. Danielle; Swanston, Chris; Barrett, Kelly; Kolka, Randy; McQuiston, Casey; Palik, Brian; Reich, Peter B.; Turner, Clarence; White, Mark; Adams, Cheryl; D'Amato, Anthony; Hagell, Suzanne; Johnson, Patricia; Johnson, Rosemary; Larson, Mike; Matthews, Stephen; Montgomery, Rebecca; Olson, Steve; Peters, Matthew; Prasad, Anantha; Rajala, Jack; Daley, Jad; Davenport, Mae; Emery, Marla R.; Fehringer, David; Hoving, Christopher L.; Johnson, Gary; Johnson, Lucinda; Neitzel, David; Rissman, Adena; Rittenhouse, Chadwick; Ziel, Robert. 2014. Minnesota forest ecosystem vulnerability assessment and synthesis: a report from the Northwoods Climate Change Response Framework project.
• Pérez-Suárez, Marlín; Castellano, Michael J.; Kolka, Randall; Asbjornsen, Heidi; Helmers, Matthew. 2014. Nitrogen and carbon dynamics in prairie vegetation strips across topographical gradients in mixed Central Iowa agroecosystems.
• Zhou, X.; Helmers, M.J.; Asbjornsen, H.; Kolka, R.; Tomer, M.D.; Cruse, R.M. 2014. Nutrient removal by prairie filter strips in agricultural landscapes.
• Kolka, Randy; Sturtevant, Brian; Townsend, Philip; Miesel, Jessica; Wolter, Peter; Fraver, Shawn; DeSutter, Tom. 2014. Post-fire comparisons of forest floor and soil carbon, nitrogen, and mercury pools with fire severity indices.
• Kastendick, Douglas N.; Palik, Brian J.; Zenner, Eric K.; Kolka, Randy K.; Blinn, Charles R.; Kragthorpe, Joshua J. 2014. Regeneration responses in partially-harvested riparian management zones in northern Minnesota.
• Vose, James M.; Swank, Wayne T.; Adams, Mary Beth; Amatya, Devendra; Campbell, John; Johnson, Sherri; Swanson, Frederick J.; Kolka, Randy; Lugo, Ariel E.; Musselman, Robert; Rhoades, Charles. 2014. The role of experimental forests and ranges in the development of ecosystem science and biogeochemical cycling research.
• Vose, James M.; Swank, Wayne T.; Adams, Mary Beth; Amatya, Devendra; Campbell, John; Johnson, Sherri; Swanson, Frederick J.; Kolka, Randy; Lugo, Ariel E.; Musselman, Robert; Rhoades, Charles. 2014. The role of experimental forests and ranges in the development of ecosystem science and biogeochemical cycling research Chapter 17.
• Jackson, C. Rhett; Thompson, James A.; Kolka, Randall K. 2014. Wetland soils, hydrology and geomorphology.
• Golay, M.E.G.; Thompson, J.R.; Mabry, C.M.; Kolka, R.K. 2013. An investigation of water nutrient levels associated with forest vegetation in highly altered landscapes.
• Cole, Jason A.; Johnson, Kristopher D.; Birdsey, Richard A.; Pan, Yude; Wayson, Craig A.; McCullough, Kevin; Hoover, Coeli M.; Hollinger, David Y.; Bradford, John B.; Ryan, Michael G.; Kolka, Randall K.; Wieshampel, Peter; Clark, Kenneth L.; Skowronski, Nicholas S.; Hom, John; Ollinger, Scott V.; McNulty, Steven G.; Gavazzi, Michael J. 2013. Database for landscape-scale carbon monitoring sites.
• Laacouri, Aicam; Nater, Edward A.; Kolka, Randall K. 2013. Distribution and uptake dynamics of mercury in leaves of common deciduous tree species in Minnesota, U.S.A..
• Wickland, Kimberly P.; Krusche, Alex V.; Kolka, Randall K.; Kishimoto-Mo, Ayaka W.; Chimner, Rodney A.; Ogle, Stephen; Srivastava, Nalin. 2013. Inland wetland mineral soils.
• Olson, D.M.; Griffis, T.J.; Noormets, A.; Kolka, R.; Chen, J. 2013. Interannual, seasonal, and retrospective analysis of the methane and carbon dioxide budgets of a temperate peatland.
• Hernandez-Santana, V.; Zhou, X.; Helmers, M.J.; Asbjornsen, H.; Kolka, R.; Tomer, M. 2013. Native prairie filter strips reduce runoff from hillslopes under annual row-crop systems in Iowa, USA.
• Fissore, Cinzia; Giardina, Christian P.; Kolka, Randall K. 2013. Reduced substrate supply limits the temperature response of soil organic carbon decomposition.
• Golay, Michaeleen Gerken; Manatt, Robert; Mabry, Catherine; Thompson, Janette; Kolka, Randall. 2013. Restoration of herbaceous woodland plants: persistence, growth, and reproductive success of local and non-local propagules.
• Fissore, Cinzia; Giardina, Christian P.; Kolka, Randall K. 2013. The effects of substrate supply on the temperature sensitivity of soil carbon decomposition.
• Ontl, Todd A.; Hofmockel, Kirsten S.; Cambardella, Cynthia A.; Schulte, Lisa A.; Kolka, Randall K. 2013. Topographic and soil influences on root productivity of three bioenergy cropping systems.
• Wu, J.Y.; Thompson, J.R.; Kolka, R.K.; Franz, K.J.; Stewart, T.W. 2013. Using the storm water management model to predict urban headwater stream hydrological response to climate and land cover change.
• Powers, Matthew D.; Kolka, Randall K.; Bradford, John B.; Palik, Brian J.; Fraver, Shawn; Jurgensen, Martin F. 2012. Carbon stocks across a chronosequence of thinned and unmanaged red pine (Pinus resinosa) stands.
• Kolka, R. K. 2012. Effects of fire and fuels management on water quality in eastern North America.
• Kastendick, Douglas N.; Zenner, Eric K.; Palik, Brian J.; Kolka, Randall K.; Blinn, Charles R. 2012. Effects of harvesting on nitrogen and phosphorus availability in riparian management zone soils in Minnesota, USA.
• Miesel, Jessica; Goebel, P.; Corace, R.; Hix, David; Kolka, Randall; Palik, Brian; Mladenoff, David. 2012. Fire effects on soils in Lake States forests: A compilation of published research to facilitate long-term investigations.
• Gabriel, Mark; Kolka, Randy; Wickman, Trent; Woodruff, Laurel; Nater, Ed. 2012. Latent effect of soil organic matter oxidation on mercury cycling within a southern boreal ecosystem.
• Risch, Martin R.; DeWild, John F.; Krabbenhoft, David P.; Kolka, Randall K.; Zhang, Leiming. 2012. Litterfall mercury dry deposition in the eastern USA.
• Jurgensen, Martin; Tarpey, Rachel; Pickens, Jim; Kolka, Randy; Palik, Brian. 2012. Long-term effect of silvicultural thinnings on soil carbon and nitrogen pools.
• Coleman Wasik, Jill K.; Mitchell, Carl P.J.; Engstrom, Daniel R.; Swain, Edward B.; Monson, Bruce A.; Balogh, Steven J.; Jeremiason, Jeffrey D.; Branfireun, Brian A.; Eggert, Susan L.; Kolka, Randall K.; Almendinger, James E. 2012. Methylmercury declines in a boreal peatland when experimental sulfate deposition decreases.
• Palik, Brian; Martin, Michelle; Zenner, Erik; Blinn, Charles; Kolka, Randall. 2012. Overstory and regeneration dynamics in riparian management zones of northern Minnesota forested watersheds.
• Brooks, Robert T.; Eggert, Susan L.; Nislow, Keith H.; Kolka, Randall K.; Chen, Celia Y.; Ward, Darren M. 2012. Preliminary assessment of mercury accumulation in Massachusetts and Minnesota seasonal forest pools.
• Kolka, Randy; Steber, Aaron; Brooks, Ken; Perry, Charles H.; Powers, Matt. 2012. Relationships between Soil compaction and harvest season, soil texture, and landscape position for aspen forests.
• Helmers, Matthew J.; Zhou, Xiaobo; Asbjornsen, Heidi; Kolka, Randy; Tomer, Mark D.; Cruse, Richard M. 2012. Sediment removal by prairie filter strips in row-cropped ephemeral watersheds.
• Mitchell, Carl P.J.; Kolka, Randall K.; Fraver, Shawn. 2012. Singular and combined effects of blowdown, salvage logging, and wildfire on forest floor and soil mercury pools.
• Parsekian, Andrew D.; Slater, Lee; Ntarlagiannis, Dimitrios; Nolan, James; Sebestyen, Stephen D.; Kolka, Randall K.; Hanson, Paul J. 2012. Uncertainty in peat volume and soil carbon estimated using ground-penetrating radar and probing.
• Guy, A.C.; DeSutter, T.M.; Casey, F.X.M.; Kolka, R.; Hakk, H. 2012. Water quality, sediment, and soil characteristics near Fargo-Moorhead urban areas as affected by major flooding of the Red River of the north.
• Kolka, Randall K.; Sebestyen, Stephen D.; Bradford, John B. 2011. An evolving research agenda at the Marcell Experimental Forest. Chapter 3..
• Grigal, David F.; Bates, Peter C.; Kolka, Randall K. 2011. Ecosystem carbon storage and flux in upland/peatland watersheds in northern Minnesota. Chapter 9..
• Witt, Emma L.; Barton, Christopher D.; Stringer, Jeffrey W.; Bowker, Daniel W.; Kolka, Randall K. 2011. Evaluating Best Management Practices for ephemeral channel protection following forest harvest in the Cumberland Plateau - preliminary findings.
• Kolka, Randall K.; Rabenhorst, Martin C.; Swanson, David . 2011. Histosols.
• Powers, Matthew; Kolka, Randall; Palik, Brian; McDonald, Rachel; Jurgensen, Martin. 2011. Long-term management impacts on carbon storage in Lake States forests.
• Sebestyen, Stephen D.; Dorrance, Carrie; Olson, Donna M.; Verry, Elon S.; Kolka, Randall K.; Elling, Art E.; Kyllander, Richard. 2011. Long-term monitoring sites and trends at the Marcell Experimental Forest. Chapter 2..
• Kolka, Randall K.; Mitchell, Carl P.J.; Jeremiason, Jeffrey D.; Hines, Neal A.; Grigal, David F.; Engstrom, Daniel R.; Coleman-Wasik, Jill K.; Nater, Edward A.; Swain, Edward B.; Monson, Bruce A.; Fleck, Jacob A.; Johnson, Brian; Almendinger, James E.; Branfireun, Brian A.; Brezonik, Patrick L.; Cotner, James B. 2011. Mercury cycling in peatland watersheds. Chapter 11..
• Andrews, Danielle M.; Barton, Christopher D.; Kolka, Randy; Rhoades, Charles C.; Dattilo, Adam J. 2011. Soil and water characteristics in restored canebrake and forest riparian zones.
• Goychuk, Denys; Kilgore, Michael A.; Blinn, Charles R.; Coggins, Jay; Kolka, Randall K. 2011. The effect of timber harvesting guidelines on felling and skidding productivity in northern Minnesota.
• Richardson, Murray C.; Mitchell, Carl P. J.; Branfireun, Brian A.; Kolka, Randall K. 2010. Analysis of airborne LiDAR surveys to quantify the characteristic morphologies of northern forested wetlands.
• Bradford, John B.; Weishampel, Peter; Smith, Marie-Louise; Kolka, Randall; Birdsey, Richard A.; Ollinger, Scott V.; Ryan, Michael G. 2010. Carbon pools and fluxes in small temperate forest landscapes: Variability and implications for sampling design.
• Maher, Ryan M.; Asbjornsen, Heidi; Kolka, Randall K.; Cambardella, Cynthia A.; Raich, James W. 2010. Changes in soil respiration across a chronosequence of tallgrass prairie reconstructions.
• Kolka, Randall K.; Giardina, Christian P.; McClure, Jason D.; Mayer, Alex; Jurgensen, Martin F. 2010. Partitioning hydrologic contributions to an 'old-growth' riparian area in the Huron Mountains of Michigan, USA.
• Zhou, Xiaobo; Helmers, Matthew J.; Asbjornsen, Heidi; Kolka, Randy; Tomer, Mark D. 2010. Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion.
• Merten, Eric C.; Hemstad, Nathaniel A.; Kolka, Randall K.; Newman, Raymond M.; Verry, Elon S.; Vondracek, Bruce. 2010. Recovery of sediment characteristics in moraine, headwater streams of northern Minnesota after forest harvest.
• Merten, Eric; Hemstad, Nathaniel; Eggert, Susan; Johnson, Lucinda; Kolka, Randall; Vondracek, Bruce; Newman, Raymond. 2010. Relations between fish abundances, summer temperatures, and forest harvest in a northern Minnesota stream system from 1997 to 2007.
• Weishampel, Peter; Kolka, Randall; King, Jennifer Y. 2009. Carbon pools and productivity in a 1-km2 heterogeneous forest and peatland mosaic in Minnesota, USA.
• Bradford, John B.; Weishampel, Peter; Smith, Marie-Louise; Kolka, Randall; Birdsey, Richard A.; Ollinger, Scott V.; Ryan, Michael G. 2009. Detrital carbon pools in temperate forests: magnitude and potential for landscape-scale assessment.
• Bradford, John; Weishampel, Peter; Smith, Marie-Louise; Kolka, Randall; Birdsey, Richard A.; Ollinger, Scott V.; Ryan, Michael G. 2009. Detrital carbon pools in temperate forests: magnitude and potential for landscape-scale assessment.
• Gabriel, Mark C.; Kolka, Randy; Wickman, Trent; Nater, Ed; Woodruff, Laurel. 2009. Evaluating the spatial variation of total mercury in young-of-year yellow perch (Perca flavescens), surface water and upland soil for watershed-lake systems within the southern Boreal Shield.
• Wells, Gail; Hayes, Deborah; Krause, Katrina; Bartuska, Ann; LeVan-Green, Susan; Anderson, Jim; Gough, Tivoli; Adams, Mary; Schuler, Thomas; Kolka, Randy; Sebestyen, Steve; Kenefic, Laura; Brissette, John; Stout, Susan; Kanoti, Keith; Swanson, Fred; Greene, Sarah; Herring, Margaret; Ritchie, Martin; Skinner, Carl; Lisle, Tom; Keppeler, Elizabeth; Reid, Leslie; Wohlegemuth, Peter; Kitchen, Stanley; McCaughey, Ward; Guldin, Jim; Bragg, Don; Shelton, Michael; Loftis, David; Greenberg, Cathryn; Murphy, Julia. 2009. Experimental forests and ranges : 100 years of research success stories.
• Witt, Emma L.; Kolka, Randall K.; Nater, Edward A.; Wickman, Trent R. 2009. Forest fire effects on mercury deposition in the boreal forest.
• Steil, Jeremy C.; Blinn, Charles R.; Kolka, Randy. 2009. Foresters' perceptions of windthrow dynamics in northern Minnesota riparian management zones.
• Witt, E.L.; Kolka, R.K.; Nater, E.A.; Wickman, T.R. 2009. Influence of the forest canopy on total and methyl mercury deposition in the boreal forest.
• Sumner, Jaclyn, P..; Vepraskas, Michael J.; Kolka, Randall K. 2009. Methods to evvaluate normal rainfall for short-term wetland hydrology assessment.
• Mitchell, Carl P. J.; Branfireun, Brian A.; Kolka, Randall K. 2009. Methylmercury dynamics at the upland-peatland interface: Topographic and hydrogeochemical controls.
• Pelster, David E.; Kolka, Randall K.; Prepas, Ellie E. 2009. Overstory vegetation influence nitrogen and dissolved organic carbon flux from the atmosphere to the forest floor: Boreal Plain, Canada.
• Fissore, Cinzia; Giardina, Christian P.; Kolka, Randall K.; Trettin, Carl C. 2009. Soil organic carbon quality in forested mineral wetlands at different mean annual temperature..
• Perry, Charles H. (Hobie); Amacher, Michael C.; Cannon, William; Kolka, Randall K.; Woodruff, Laurel. 2009. The distribution of mercury in a forest floor transect across the central United States.
• Fissore, Cinzia; Giardina, Christian P.; Swanston, Christopher W.; King, Gary M.; Kolka, Randall K. 2009. Variable temperature sensitivity of soil organic carbon in North American forests.
• Schulte, Lisa; Asbjornsen, Heidi; Atwell, Ryan; Hart, Chad; Helmers, Matt; Isenhart, Tom; Kolka, Randy; Liebman, Matt; Neal, Jeri; O’Neal, Matt; Secchi, Silvia; Schultz, Richard; Thompson, Jan; Tomer, Mark; Tyndall, John. 2008. A targeted conservation approach for improving environmental quality.
• Mitchell, Carl P.J.; Branfireun, Brian A.; Kolka, Randall K. 2008. Assessing sulfate and carbon controls on net methylmercury production in peatlands: An in situ mesocosm approach.
• Barton, Christopher D.; Andrews, Danielle M.; Kolka, Randall K. 2008. Evaluating hydroperiod response in restored Carolina Bay Westlands using soil physicochemical properties.
• Bradford, John B.; Weishampel, Peter; Smith, Marie-Louise; Kolka, Randall; Hollinger, David Y.; Birdsey, Richard A.; Ollinger, Scott; Ryan, Michael. 2008. Landscape-scale carbon sampling strategy-lessons learned. Chapter 17.
• Kolka, Randall; Weishampel, Peter; Froberg, Mats. 2008. Measurement and importance of dissolved organic carbon. Chapter 13.
• Weishampel, Peter; Kolka, Randall. 2008. Measurement of methane fluxes from terrestrial landscapes using static, non-steady state enclosures. Chapter 12.
• Mitchell, Carl P.J.; Branfireun, Brian A.; Kolka, Randall K. 2008. Spatial characteristics of net methylmercury production hot spots in peatlands.
• Fissore, Cinzia; Giardina, Christian P.; Kolka, Randall K.; Trettin, Carl C.; King, Gary M.; Jurgensen, Martin F.; Barton, Christopher D.; McDowell, S. Douglas. 2008. Temperature and vegetation effects on soil organic carbon quality along a forested mean annual temperature gradient in North America.
• Tarpey, Rachel A.; Jurgensen, Martin F.; Palik, Brian J.; Kolka, Randy K. 2008. The long-term effects of silvicultural thinning and partial cutting on soil compaction in red pine (Pinus resinosa Ait.) and northern hardwood stands in the northern Great Lakes Region of the United States.
• Landman, George B.; Kolka, Randall K.; Sharitz, Rebecca R. 2007. Soil seed bank analysis of planted and naturally revegetating thermally-disturbed riparian forests.
• Steber, Aaron; Brooks, Ken; Perry, Charles H.; Kolka, Randy. 2007. Surface compaction estimates and soil sensitivity in Aspen stands of the Great Lakes States.
• Jeremiason, Jeff D.; Engstrom, Daniel R.; Swain, Edward B.; Nater, Edward A.; Johnson, Brian M.; Almendinger, James E.; Monson, Bruce A.; Kolka, Randy K. 2006. Sulfate Addition Increases Methylmercury Production in an Experimental Wetland.
• ​Kolka, Randall K.; Thompson, James A. 2006. Wetland geomorphology, soils, and formative processes.
• Svec, J.R. ; Kolka, R.K. ; Stringer, J.W. . 2005. Defining perennial, intermittent, and ephemeral channels in Eastern Kentucky: Application to forestry best management practices.
• Thompson, James A.; Kolka, Randall K. 2005. Soil carbon storage estimation in a forested watershed using quantitative soil-landscape modeling.
• McClure, J. M.; Kolka, R. K.; White, A. 2004. Effect of forest harvesting best management practices on coarse woody debris distribution in stream and riparian zones in three Appalachian watersheds.
• Kolka, Randy K.; Smidt, Mathew F. 2004. Effects of forest road amelioration techniques on soil bulk density, surface runoff, sediment transport, soil moisture and seedling growth.
• Abnee, Amanda C.; Thompson, James A.; Kolka, Randall K.; D'Angelo, Elisa M.; Coyne, Mark S. 2004. Landscape Influences on Potential Soil Respiration Rates in a Forested Watershed of Southeastern Kentucky.
• Giese, Laura A. B.; Aust, W. M.; Kolka, Randall K.; Trettin, Carl C. 2003. Biomass and carbon pools of disturbed riparian forests.
• Giese, Laura A.B.; Aust, W.M.; Kolka, Randall K.; Trettin, Carl C. 2003. Biomass and carbon pools of disturbed riparian forests.
• Svec, J. R.; Kolka, R. K.; Stringer, J. W. 2003. Defining perennial, intermittent and ephemeral channels in eastern Kentucky: application to forestry best management practices.
• Verry, E. S.; Kolka, R. K. 2003. Importance of Wetlands to Streamflow Generation.
• Birdsey, R.; Hollinger, D.; Heath, L.; Hoover, C.; Kolka, R.; Smith, M. L.; Ryan, M. 2003. Pilot Studies for Enhanced Forest Land Measurement.
• Kolka, R. K.; Trettin, C. C.; Nelson, E. A.; Barton, C. D.; Fletcher, D. E. 2002. Application of the EPA Wetland Research Program Approach to a floodplain wetland restoration assessment.
• Smidt, Mathew F.; Kolka, Randall K. 2001. Alternative skid trail retirement options for steep terrain logging.
• Kolka, R. K.; Grigal, D. F.; Nater, E. A.; Verry, E. S. 2001. Hydrologic cycling of mercury and organic carbon in a forested upland-bog watershed.
• Kolka, Randy K.; Nelson, E. A.; Trettin, C. C. 2000. Conceptual assessment framework for forested wetland restoration: the Pen Branch experience.
• Dulohery, C. J.; Kolka, Randy K.; McKevlin, M. R. 2000. Effects of a willow overstory on planted seedlings in a bottomland restoration.
• Kolka, Randy K.; Singer, J. H.; Coppock, C. R.; Casey, W. P.; Trettin, C. C. 2000. Influence of restoration and succession on bottomland hardwood hydrology.
• Grigal, D. F.; Kolka, Randy K.; Fleck, J. A.; Nater, E. A. 2000. Mercury budget of an upland-peatland watershed.
• Nelson, Eric A.; Dulohery, Neil C.; Kolka, Randall K.; McKee, William H., Jr. 2000. Operational restoration of the Pen Branch bottomland hardwood and swamp wetlands - the research setting.
• Barton, Christopher; Nelson, Eric A.; Kolka, Randall K.; McLeod, Kenneth W.; Conner, William H.; Lakly, Michelle; Martin, Douglas; Wigginton, John; Trettin, Carl C.; Wisniewski, Joe. 2000. Restoration of a severely impacted riparian wetland system - The Pen Branch Project.
• Giese, Laura A.; Aust, W. Michael; Trettin, Carl C.; Kolka, Randall K. 2000. Spatial and temporal patterns of carbon storage and species richness in three South Carolina coastal plain riparian forests.
• Kolka , Randy K.; Nater, E. A.; Verry, Elon S,. 1999. Atmospheric Inputs of Mercury and Organic Carbon into a Forested Upland/Bog Watershed.
• Kolka, Randall K.; Nater, E.A.; Grigal, D.F.; Verry, E.S. 1999. Atmospheric Inputs of Mercury and Organic Carbon into a Forested Upland/Bog Watershed.
• Kolka, R. K.; Grigal, D. F.; Verry, E. S.; Nater, E. A. 1999. Mercury and Organic Carbon Relationships in Streams Draining Forested Upland/Peatland Watersheds.
• Kolka, Randall K.; Grigal, D.F.; Verry, E.S.; Nater, E.A. 1999. Mercury and Organic Carbon Relationships in Streams Draining Forested Upland/Peatland Watersheds.
• Kolka, Randall K.; Trettin, Carl C.; Nelson, E.A. 1998. Development of an Assessment Framework for Restored Forested Wetlands.
• Kolka, Randall K.; Wolf, Ann T. 1998. Estimating actual evapotranspiration for forested sites: modifications to the Thornthwaite Model.
• Kolka, Randall K.; Nelson, Eric A.; Bonar, Ronald E.; Dulohery, Neil C.; Gartner, David. 1998. The Pen Branch Project: Restoration of a Forested Wetland in South Carolina.
• Kolka, Randall K.; Trettin, Carl C.; Nelson, E.A.; Conner, W.H. 1998. Tree Seedlings Establishment Across a Hydrologic Gradient in a Bottomland Restoration.
• Kolka, Randy K.; Grigal, D.F.; Nater, E.A. 1996. Forest soil mineral weathering rates: use of multiple approaches.

Research Highlights

Highlight	Title	Year
NRS-2017-2	Incorporating ecosystem services into Midwest agriculture Science-based Trials of Rowcrops Integrated with Prairie Strips (STRIPS) is transforming the way farmers conduct agriculture in the Midwest. STR ...	2017
NRS-2016-155	Largest Climate Change Experiment on the Planet: SPRUCE The Spruce and Peatland Responses Under Climatic and Environmental Change Experiment (SPRUCE) is stretching scientists’ ability to manipulate ...	2016
NRS-2012-32	Prairie Strips Lead to Better Environmental Health and Greater Socioeconomic Vitality Forest Service scientists help Midwestern farming communities understand how to transform strategic portions of the agricultural landscape into ...	2012
NRS-2016-162	Scaling Up Ecosystem Impacts of the Pagami Creek Fire in Northern Minnesota Quantifying fire severity is critical to understanding the ecosystem impacts of wildfire. Forest Service research demonstrates the magnitude of ...	2016
NRS-2016-163	Sustainable Northern Conifer Forest Management Stores More Carbon than Exploitative Harvesting An important part of climate change mitigation is carbon storage in forests and wood products. Yet managers are often uncertain about which mana ...	2016
NRS-2015-175	“Smart Forests” Digital Environmental Sensors and Telecommunications Take Research to New Levels Scientific breakthroughs of the 21st century will be powered by tools that help researchers collect and manipulate massive datasets, visualize t ...	2015