
Jennifer D. Knoepp
Emeritus Research Soil Scientist(10 miles south of Franklin and west 3 miles from US-441)
Otto, NC 28763-9218
Fax: 828-369-6768
jennifer.knoepp@usda.gov
Current Research
High elevation ecosystem responses to acidic deposition in the southern Appalachian region; Loss of hemlock via hemlock woolly adelgid infestation and impacts on nutrient cycling; the potential of short rotation woody crop establishment on improving water quality in marginal farmlands of the Mississippi River Valley; impacts of land use changes in the southern Appalachians on ecosystem biogeochemical cycling; impacts of time, climate change, disturbance, and atmospheric deposition on stream chemistry in USFS EFRs across the U.S.
Research Interests
Forest soils, biological and environmental regulation of soil nitrogen transformations and biogeochemical cycles, nutrient transport within watersheds, long-term changes in soil carbon, nitrogen and available nutrients, effects of forest management practices and disturbance on soil carbon and nutrient transformations and availability.
Past Research
Examining the effects of elevation and vegetation gradients on forest nitrogen cycling; effects of prescribed burning on nutrient availability in xeric and mesic forests; structure and function of riparian soils and their role in regulating the movement of nutrients from hillslopes to streams; effects of forest management practices on soil carbon and nutrient cycling.
Why This Research is Important
Soil plays an important role in maintaining the ecosystem services provided by forests especially the headwater catchments present on National Forest lands, such as clean air and clean water. As a vital component of all ecosystems soils contain large pools of carbon and nutrients in forests. Disturbance of forests, by natural or anthropogenic impacts alters the cycling of both C and nutrients. Understanding the regulation of biogeochemical cycling by and within forest soils is essential to decision making by land managers.
Education
- Ph.D. in Forestry, 1987
- University of Missouri
- M.S. in Horticulture and Forestry, 1982
- University of Arkansas
- B.S. in Horticulture, 1980
- University of Arkansas
Professional Experience
- Research Soil Scientist, USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory
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1989—Current
- National Research Council Post-Doctoral Fellow, USEPA/CERL
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1987—1989
- Research Assistant, University of Missouri, School of Forestry, Fisheries, and Wildlife
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1982—1987
- Research Assistant, University of Arkansas, Department of Horticulture and Forestry
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1980—1982
- Laboratory Technician, Forestry Laboratory, University of Arkansas-Fayetteville, Department of Horticulture and Forestry
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1978—1979
Professional Organizations
- Soil Science Society of America, Fellow (2014—Current)
- University of Georgia, Adjunct Faculty (2012—Current)
- Virginia Polytechnic Institute and State University, Adjunct Faculty (2012—Current)
- Soil Science Society of America, Member (1982—Current)
- North American Forest Soils, Progam Chair (2008—2013)
- Soil Science Society of America, Chair - Forest, Range, And Wildland Soils Div (2006—2007)
Awards and Recognition
- Soil Science Society of America Fellow, 2014
- Fellow is the highest recognition bestowed by SSSA, an international scientific society whose more than 6,000 members are dedicated to advancing the field of soil science and fostering the transfer of knowledge and practices to sustain global soils.
Featured Publications and Products
- Knoepp, Jennifer D.; Coleman, David C.; Crossley, D.A., Jr..; Clark, James S. 2000. Biological indices of soil quality: an ecosystem case study of their use.
- Knoepp, Jennifer D.; Reynolds, Barbara C.; Crossley, D.A.; Swank, Wayne T. 2005. Long-term changes in forest floor processes in southern Appalachian forests.
- Walker, John T.; Vose, James M.; Knoepp, Jennifer; Geron, Christopher D. 2009. Recovery of Nitrogen Pools and Processes in Degraded Riparian Zones in the Southern Appalachians.
- Knoepp, Jennifer D.; Swank, Wayne T. 1994. Long-Term Soil Chemistry Changes in Aggrading Forest Ecosystems.
- Knoepp, Jennifer D.; Swank, Wayne T. 1997. Forest Management Effects on Surface Soil Carbon and Nitrogen.
- Knoepp, Jennifer D.; Swank, Wayne T. 1998. Rates of nitrogen mineralization across an elevation and vegetation gradient in the Southern Appalachians.
- Knoepp, Jennifer D.; Swank, Wayne T. 2002. Using soil temperature and moisture to predict forest soil nitrogen mineralization.
- Knoepp, Jennifer D.; Vose, James M.; Clinton, Barry; Hunter, Nark D. 2011. Hemlock infestation and mortality: impacts on nutrient pools and cycling in Appalachian forests.
- Knoepp, Jennifer D.; Vose, James M.; Swank, Wayne T. 2008. Nitrogen deposition and cycling across an elevation and vegetation gradient in southern Appalachian forests.
- Knoepp, Jennifer D.; Vose, James M.; Swank, Wayne T. 2004. Long-Term Soil Responses to Site Preparation Burning in the Southern Appalachians.
Publications
- Walker, John T.; Chen, Xi ; Wu, Zhiyong ; Schwede, Donna ; Daly, Ryan ; Djurkovic, Aleksandra ; Oishi, A. Christopher; Edgerton, Eric ; Bash, Jesse ; Knoepp, Jennifer ; Puchalski, Melissa ; Iiames, John ; Miniat, Chelcy F. 2023. Atmospheric deposition of reactive nitrogen to a deciduous forest in the southern Appalachian Mountains.
- Ulyshen, Michael ; Elliott, Katherine ; Scott, Joel ; Horn, Scott ; Clinton, Patsy ; Liu, Ning ; Miniat, Chelcy F.; Caldwell, Peter ; Oishi, Chris ; Knoepp, Jennifer ; Bolstad, Paul . 2022. Effects of Rhododendron removal and prescribed fire on bees and plants in the southern Appalachians.
- Baas, Peter ; Knoepp, Jennifer D.; Markewitz, Daniel ; Mohan, Jacqueline E. 2021. A rapid approach to determine soil carbon quality and its relationship to soil greenhouse gas emissions.
- Jackson, C Rhett; Cecala, Kristen ; Wenger, Seth ; Kirsch, Joseph ; Webster, Jackson ; Leigh, David ; Sanders, Jennifer ; Love, Jason ; Knoepp, Jennifer ; Fraterrigo, Jennifer ; Rosemond, Amy D. 2021. Distinctive connectivities of near-stream and watershed-wide land uses differentially degrade rural aquatic ecosystems.
- Brown, Cindi L.; Miniat, Chelcy F.; Knoepp, Jennifer D. 2021. Investigating the effect of lab bias on long-term stream chemistry data.
- Rustad, Lindsey E.; Knoepp, Jennifer ; Richter, Daniel D.; Scott, D. Andrew. 2020. Biogeochemical Cycling in Forest and Rangeland Soils of the United States.
- Hwang, Taehee ; Band, Lawrence E.; Miniat, Chelcy F.; Vose, James M.; Knoepp, Jennifer D.; Song, Conghe ; Bolstad, Paul V. 2020. Climate change may increase the drought stress of mesophytic trees downslope with ongoing forest mesophication under a history of fire suppression.
- Lee, Raymond M.; McGuire, Kevin J.; Strahm, Brian D.; Knoepp, Jennifer D.; Jackson, C. Rhett; Stewart, Ryan D. 2020. Revisiting the Hewlett and Hibbert (1963) hillslope drainage experiment and modeling effects of Decadal Pedogenic Processes and leaky soil boundary conditions.
- Caldwell, Peter V; Elliott, Katherine J.; Liu, Ning ; Vose, James M.; Zietlow, David R.; Knoepp, Jennifer D. 2020. Watershed‐scale vegetation, water quantity, and water quality responses to wildfire in the southern Appalachian mountain region, United States.
- Knoepp, Jennifer D.; Adams, Mary Beth; Harrison, Robert ; West, Larry ; Laseter, Stephanie H.; Markewitz, Daniel ; Richter, Daniel D.; Callaham Jr., Mac A. 2019. History of forest soils knowledge and research.
- Knoepp, Jennifer D.; Adams, Mary Beth; Harrison, Robert ; West, Larry ; Laseter, Stephanie H.; Markewitz, Daniel ; Richter, Daniel D.; Callaham, Mac A. 2019. History of forest soils knowledge and research [Chapter 4].
- Knoepp, Jennifer D.; Markewitz, Daniel ; Callaham, Mac A.; Adams, Mary Beth; Laseter, Stephanie H.; West, Larry ; Robert Harrison, ; Richter, Daniel D. 2019. Long-term forest soils research: Lessons learned from the US experience [Chapter 19].
- Knoepp, Jennifer D.; Markewitz, Daniel ; Callaham , Mac A., Jr..; Adams, Mary Beth; Laseter, Stephanie H.; West, Larry ; Harrison, Robert ; Richter, Daniel D. 2019. Long-term forest soils research: lessons learned from the US experience.
- Osburn, Ernest D.; McBride, Steven G.; Aylward, Frank O.; Badgley, Brian D.; Strahm, Brian D.; Knoepp, Jennifer D.; Barrett, J. E. 2019. Soil Bacterial and Fungal Communities Exhibit Distinct Long-Term Responses to Disturbance in Temperate Forests.
- Baas, Peter ; Knoepp, Jennifer D.; Mohan, Jacqueline E. 2019. Well-aerated Southern Appalachian forest soils demonstrate significant potential for gaseous nitrogen loss.
- Webster, Jackson R.; Stewart, Rebecca M.; Knoepp, Jennifer D.; Jackson, C. Rhett. 2018. Effects of instream processes, discharge, and land cover on nitrogen export from southern Appalachian Mountain catchments.
- Veach, Allison M.; Stokes, C. Elizabeth; Knoepp, Jennifer ; Jumpponen, Ari ; Baird, Richard . 2018. Fungal communities and functional guilds shift along an elevational gradient in the southern Appalachian Mountains.
- Osburn, Ernest D.; Elliottt, Katherine J.; Knoepp, Jennifer D.; Miniat, Chelcy F.; Barrett, J.E. . 2018. Soil microbial response to Rhododendron understory removal in southern Appalachian forests: Effects on extracellular enzymes.
- Knoepp, Jennifer D.; See, Craig R.; Vose, James M.; Miniat, Chelcy F.; Clark, James S. 2018. Total C and N pools and fluxes vary with time, soil temperature, and moisture along an elevation, precipitation, and vegetation gradient in southern Appalachian forests.
- Fraterrigo, Jennifer M.; Ream, Kelsey ; Knoepp, Jennifer D. 2018. Tree mortality from insect infestation enhances carbon stabilization in southern Appalachian forest soils.
- Jackson, C. Rhett; Webster, Jackson R.; Knoepp, Jennifer D.; Elliott, Katherine J.; Emanuel, Ryan E.; Caldwell, Peter V.; Miniat, Chelcy F. 2018. Unexpected ecological advances made possible by long-term data: A Coweeta example.
- Baas, Peter; Knoepp, Jennifer D.; Markewitz, Daniel; Mohan, Jacqueline E. 2017. Areas of residential development in the southern Appalachian Mountains are characterized by low riparian zone nitrogen cycling and no increase in soil greenhouse gas emissions.
- Keiser, Ashley D.; Knoepp, Jennifer D.; Bradford, Mark A. 2016. Disturbance decouples biogeochemical cycles across forests of the southeastern US.
- Webster, J. R.; Knoepp, Jennifer; Swank, Wayne; Miniat, Chelcy. 2016. Evidence for a regime shift in nitrogen export from a forested watershed.
- Knoepp, Jennifer D.; Vose, James M.; Jackson, William A.; Elliott, Katherine J.; Zarnoch, Stan. 2016. High elevation watersheds in the southern Appalachians: indicators of sensitivity to acidic deposition and the potential for restoration through liming.
- Singh, Nitin K.; Reyes, Wilmer M.; Bernhardt, Emily S.; Bhattacharya, Ruchi; Meyer, Judy L.; Knoepp, Jennifer D.; Emanuel, Ryan E. 2016. Hydro-climatological influences on long-term dissolved organic carbon in a mountain stream of the southeastern United States.
- Elliott, Katherine; Miniat, Chelcy F.; Knoepp, Jennifer; Crump, Michael A.; Jackson, C. Rhett. 2016. Restoration of southern Appalachian riparian forest affected by eastern hemlock mortality.
- Knoepp, Jennifer; Elliott, Katherine J.; Jackson, William A.; Vose, James M.; Miniat, Chelcy Ford; Zarnoch, Stan. 2016. Soil and stream chemistry relationships in high elevation waters.
- Knoepp, Jennifer D.; Taylor, Scott R.; Boring, Lindsay R.; Miniat, Chelcy F. 2015. Influence of forest disturbance on stable nitrogen isotope ratios in soil and vegetation profiles.
- Yanai, Ruth D.; Tokuchi, Naoko; Campbell, John L.; Green, Mark B.; Matsuzaki, Eiji; Laseter, Stephanie N.; Brown, Cindi L.; Bailey, Amey S.; Lyons, Pilar; Levine, Carrie R.; Buso, Donald C.; Likens, Gene E.; Knoepp, Jennifer D.; Fukushima, Keitaro. 2015. Sources of uncertainty in estimating stream solute export from headwater catchments at three sites.
- Baas, Peter; Mohan, Jacqueline E.; Markewitz, David; Knoepp, Jennifer D. 2014. Assessing heterogeneity in soil nitrogen cycling: a plot-scale approach.
- Webster, Jackson, R..; Swank, Wayne , T..; Vose, James , M..; Knoepp, Jennifer , D..; Elliott, Katherine , J. 2014. Bridging the gap between ecosystem theory and forest watershed management.
- Meyer, Judy L.; Webster, Jackson, R..; Knoepp, Jennifer , D..; Benfield, E.F. 2014. Dynamics of dissolved organic carbon in a stream during a quarter century of forest succession.
- Elliott, Katherine J.; Vose, James M.; Knoepp, Jennifer D.; Clinton, Barton D.; Kloeppel, Brian D. 2014. Functional role of the herbaceous layer in eastern deciduous forest.
- Adams, Mary Beth; Knoepp, Jennifer D.; Webster, Jackson R. 2014. Inorganic nitrogen retention by watersheds at Fernow Experimental Forest and Coweeta Hydrologic Laboratory.
- Knoepp, Jennifer, D..; Swank, Wayne , T..; Haines, Bruce L. 2014. Long- and short-term changes in nutrient availability following commercial sawlog harvest via cable logging.
- Swank, Wayne , T..; Knoepp, Jennifer , D..; Logic exception within f_get_listOfAuthors30(). Could not calculate fullname.; Logic exception within f_get_listOfAuthors30(). Could not calculate fullname.; Webster, Jackson, R. 2014. Response and recovery of water yield and timing, stream sediment, abiotic parameters, and stream chemistry following logging.
- Elliott, Katherine; Knoepp, Jennifer D.; Vose, James M.; Jackson, William A. 2013. Interacting effects of wildfire severity and liming on nutrient cycling in a southern Appalachian wilderness area.
- Block, Corinne E.; Knoepp, Jennifer D.; Fraterrigo, Jennifer M. 2013. Interactive effects of disturbance and nitrogen availability on phosphorus dynamics of southern Appalachian forests.
- Keiser, Ashley D.; Knoepp, Jennifer D.; Bradford, Mark A. 2013. Microbial communities may modify how litter quality affects potential decomposition rates as tree species migrate.
- Argerich, A.; Johnson, S.L.; Sebestyen, S.D.; Rhoades, C.C.; Greathouse, E.; Knoepp, J.D.; Adams, M.B.; Likens, G.E.; Campbell, J.L.; McDowell, W.H.; Scatena, F.N.; Ice, G.G. 2013. Trends in stream nitrogen concentrations for forested reference catchments across the USA.
- Elliott, Katherine J.; Vose, James M.; Knoepp, Jennifer D.; Jackson, William. 2012. Effects of wildfires and liming of pine-oak-heath communities in the Linville Gorge Wilderness, western North Carolina.
- Knoepp, Jennifer D.; Vose, James M.; Michael, Jerry L.; Reynolds, Barbara C. 2012. Imidacloprid movement in soils and impacts on soil microarthropods in southern Appalachian eastern hemlock stands.
- Block, Corinne E.; Knoepp, Jennifer D.; Elliott, Katherine J.; Fraterrigo, Jennifer M. 2012. Impacts of Hemlock Loss on Nitrogen Retention Vary with Soil Nitrogen Availability in the Southern Appalachian Mountains.
- Elliott, Katherine J.; Vose, James M.; Knoepp, Jennifer D.; Clinton, Barton D. 2012. Restoration of shortleaf pine (Pinus echinata) - hardwood ecosystems severely impacted by the southern pine beetle (Dendroctonus frontalis).
- Webster, Jackson R.; Benfield, Ernest F.; Cecala, Kristen K.; Chamblee, John F.; Dehring, Carolyn A.; Gragson, Ted; Cymerman, Jeffrey H.; Jackson, C. Rhett; Knoepp, Jennifer D.; Leigh, David S.; Maerz, John C.; Pringle, Catherine; Valett, H. Maurice. 2012. Water quality and exurbanization in southern Appalachian streams.
- Yamashita, Youhei; Kloeppel, Brian D.; Knoepp, Jennifer; Zausen, Gregory L.; Jaffe', Rudolf. 2011. Effects of watershed history on dissolved organic matter characteristics in headwater streams.
- Clinton, Barton , D..; Vose, James , M..; Knoepp, Jennifer , D..; Elliott, Katherine , J..; Reynolds, Barbara , C..; Zarnock, Stanley , J. 2010. Can structural and functional characteristics be used to identify riparian zone width in southern Appalachian headwater catchments?.
- Knoepp, Jennifer D.; Elliott, Katherine J.; Clinton, Barton D.; Vose, James M. 2009. Effects of prescribed fire in mixed oak forests of the southern Appalachians: forest floor, soil, and soil solution nitrogen responses.
- Walker, John T.; Vose, James M.; Knoepp, Jennifer; Geron, Christopher D. 2009. Recovery of nitrogen pools and processes in degraded riparian zones in the southern Appalachians.
- Knoepp, Jennifer D.; Clinton, Barton D. 2009. Riparian zones in southern Appalachian headwater catchments: Carbon and nitrogen responses to forest cutting.
- Elliott, Katherine J.; Vose, James M.; Knoepp, Jennifer D.; Johnson, Dale W.; Swank, William T.; Jackson, William. 2008. Simulated effects of sulfur deposition on nutrient cycling in class I wilderness areas.
- Knoepp, Jennifer d.; Vose, James M. 2007. Regulation of nitrogen mineralization and nitrification in Southern Appalachian ecosystems: separating the relative importance of biotic vs. abiotic controls.
- Knoepp, Jennifer D.; DeBano, Leonard F.; Neary, Daniel G. 2005. Chapter 3: Soil Chemistry.
- Ellison, Aaron M.; Bank, Michael S.; Clinton, Barton D.; Colburn, Elizabeth A.; Elliott, Katherine; Ford, Chelcy Rae; Foster, David R.; Kloeppel, Brian D.; Knoepp, Jennifer D.; Lovett, Gary M.; Mohan, Jacqueline; Orwig, David A.; Rodenhouse, Nicholas L.; Sobczak, William V.; Stinson, Kristina A.; Stone, Jeffrey K.; Swan, Christopher M.; Thompson, Jill; Holle, Betsy Von; Webster, Jackson R. 2005. Loss of foundation species: consequences for the structure and dynamics of forested ecosystems.
- Elliott, Katherine J.; Knoepp, Jennifer D. 2005. The effects of three regeneration harvest methods on plant diversity and soil characteristics in the southern Appalachians.
- Elliott, Katherine J.; Vose, James M.; Clinton, Barton D.; Knoepp, Jennifer D. 2004. Effects of Understory Burning in a Mesic Mixed-Oak Forest of the Southern Appalachians.
- Hubbard, Robert M.; Vose, James M.; Clinton, Barton D.; Elliott, Katherine J.; Knoepp, Jennifer D. 2004. Stand restoration burning in oak-pine forests in the southern Applachians: effects on aboveground biomass and carbon and nitrogen cycling.
- Clinton, Barton D.; Vose, James M.; Knoepp, Jennifer D.; Elliott, Katherine J. 2003. Stream nitrate response to different burning treatments in Southern Appalachian Forests.
- Johnson, D.W.; Knoepp, Jennifer D.; Swank, Wayne T.; Shan, J.; Morris, L.A.; D.H. van Lear, David H.; Kapeluck, P.R. 2002. Effects of forest management on soil carbon: results of some long-term resampling studies.
- Knoepp, Jennifer D.; Vose, James M. 2002. Quantitative comparison of in situ soil CO2 flux measurement methods.
- Vose, James M.; Swank, Wayne T.; Clinton, Barton D.; Knoepp, Jennifer D.; Swift, Lloyd W. 1999. Using stand replacement fires to restore southern Appalachian pine-hardwood ecosystems: effects on mass, carbon, and nutrient pools.
- Knoepp, Jennifer D.; Tieszen, Larry L.; Fredlund, Glen G. 1998. Assessing the vegetation history of three Southern Appalachian balds through soil organic matter analysis.
- Knoepp, Jennifer D.; Swank, Wayne T. 1997. Long-term effects of commercial sawlog harvest on soil cation concentrations.
- Knoepp, Jennifer D.; Swank, Wayne T. 1995. Comparison of Available Soil Nitrogen Assays in Control and Burned Forested Sites.
- Knoepp, Jennifer D.; Swank, Wayne T. 1993. Site preparation burning to improve southern Appalachian pine-hardwood stands: nitrogen responses in soil, soil water, and streams.
Research Highlights
- A Tale of Nitrogen Retention From Two Watersheds (2014)
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Because elevated nitrogen loading can impair terrestrial and aquatic ecosystems, understanding the origins, retention, and export of nitrogen from forested watersheds is crucial. Forest Service scientists at Fernow Experimental Forest and Coweeta Hydrologic Laboratory analyzed long-term watershed studies to demonstrate the important effects of atmospheric deposition, history of disturbance, and biological inputs on the ability of a forest to keep nitrogen out of streams.
- Changes in Water Quality Last More Than 30 Years After Clear Cutting (2016)
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Evidence from 36 years of data following experimental clear-cut logging at Coweeta Hydrologic Laboratory, N.C., suggests that forest disturbance in the southern Appalachian mountains can cause elevation of nitrogen in streamflow. These elevated nitrogen levels an last decades or perhaps longer.
- Sensitivity of Southern Appalachian Watersheds to Acidic Deposition (2016)
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High-elevation forested watershed streams remain acidic even though acid deposition has declined. Land managers have long sought to identify and restore watersheds remaining impacted by chronic acid deposition. Forest Service scientists studied high-elevation southern Appalachian watersheds across a gradient of acidic deposition to identify measurements that could be used to index stream acid neutralizing capacity and pH, and to estimate the lime required to restore watersheds.