Current Research

I conduct research on artificial regeneration (i.e., planting) of oak (Quercus) and American chestnut (Castanea dentata) to restore and/or sustain these important species. This research is unique and innovative because the genetic heritage is known for all material, and seedlings are highly characterized prior to planting. I examine the effects of seedling quality and factors that affect field performance after planting. I also study the effect of silvicultural treatments, including prescribed burning, herbicide, and commercial timber operations, to develop the most effective and economically efficient prescriptions that can be used to regenerate oak and American chestnut species. Our most current research is testing how planted white oak seedlings (Q. alba) perform in and around small gaps (0.5-1 acre) that will later be expanded, compared to trees planted in the more traditional two-age regeneration harvests. 

Research Interests

• Artificial regeneration of white oak (Quercus alba) and northern red oak (Q. rubra)
• Restoration of American chestnut (Castanea dentata) in upland hardwood forests
• Silviculture in upland hardwood forests

Past Research

I used tree-rings to reconstruct stand history and tree-climate interactions. The study of tree-rings (i.e., dendrochronology) is a robust and powerful tool that can assist managers in understanding natural processes that led to current forest conditions. Tree-ring research can also be used to predict responses to future man-made disturbance, natural disturbances, or changes in climatic conditions.

Why This Research is Important

OAK RESTORATION RESEARCH: Oaks are highly valued species for wood products, as a hard-mast food source for wildlife, and for ecosystem resiliency and diversity. We can sustain or restore oak species through active forest management. Commercial forest management, herbicides, and prescribed fire can be used to improve the oak component by increasing available light and controlling non-oak species, but the challenge is developing practical prescriptions for various site types. Tree planting of oak seedlings can supplement natural oak regeneration when it is lacking or when large oak reproduction is needed immediately. Planting can be cost prohibitive and ineffective if seedling quality is poor or if planting is not coupled with the proper silvicultural treatment(s). Seedlings can be improved through cultural practices, and genetic selections are currently being tested. Locally adapted seedlings should be used for planting, but testing of seed sources for planting in warmer and drier environments should also be conducted.

AMERICAN CHESTNUT RESEARCH: American chestnut (Castanea dentata) was once a keystone tree species in the eastern United States and was highly valued for its wood, edible nuts, and aesthetics. The tree has been virtually extirpated by exotic pathogens from Asia, most notably, the chestnut blight (Cryphonectria parasitica). Advancements in genetic breeding for resistance to blight are being achieved from partner organizations, but prescriptions have not been widely accepted for planting and maintaining chestnut in natural forest communities where it once thrived. Technological advancements in commercial nursery production are in the early testing stages for this species. Early results indicate strategies for success in planting American chestnut are similar to oak species: use high-quality seedlings, protect from animal browse, plant in high-light environments, and reduce hardwood competition. American chestnut appears to have fast growth after overcoming planting shock and is competitive with most native tree species; however non-native pests including root rot caused by Phythophthora cinnamomi, have negatively impacted planting success. 

TREE-RING RESEARCH (DENDROCHROLOGY): The study of tree-rings allows us to understand how past disturbances and climate conditions created the stand conditions we see today. Managers can use this information to improve stand resiliency and adaptability to climate change, exotic pests, and other disturbances. Through analysis of tree rings, historical documents, and stand inventory data, we have discovered that many oak forests are shifting towards non-oak species. These predicted changes will result in decreased ecological diversity and function, and forests will be less valuable to wildlife species if no management action is taken. 

Education

• Oklahoma State University, Ph.D. Plant Science 2003
• The University of Tennessee, M.S. Forestry 1999
• The University of Tennessee, B.S. Forest Resource Management 1996

Professional Organizations

• National Museum of Forest Service History, Member (2020 - Current)
• The Forest Guild, Member (2017 - Current)
• University of Tennessee, Adjunct Faculty (2007 - Current)
• Natural Areas Association, Member (2004 - Current)
• Society of American Foresters (SAF), Member (1997 - Current)

Featured Publications & Products

• Clark, Stacy; Schlarbaum, Scott; Clark, Joseph. 2019. Restoring a forest icon: could returning the American chestnut remodel our wildlife landscape.
• Clark, Stacy L.; Schweitzer, Callie J. 2019. Oak symposium: sustaining oak forests in the 21st century through science-based management.
• Clark, Stacy L.; Schlarbaum, Scott E.; Crane, Barbara S.; Pinchot, Cornelia C.; Schaberg, Paul G.; Thomas-Van Gundy, Melissa . 2020. Restoration of the American chestnut will require more than a blight-resistant tree.
• Clark, Stacy L.; Schlarbaum, Scott E.; Saxton, Arnold M.; Baird, Richard . 2019. Eight-year blight (Cryphonectria parasitica) resistance of backcross-generation American chestnuts (Castanea dentata) planted in the southeastern United States.
• Clark, Stacy; Schlarbaum, Scott. 2019. Artificial regeneration in the Southern Appalachians.
• Clark, Stacy L.; Schlarbaum, Scott E. 2018. Effects of acorn size and mass on seedling quality of northern red oak (Quercus rubra).
• Schweitzer, Callie; Clark, Stacy L.; Gottschalk, Kurt W.; Stringer, Jeff; Sitzlar, Robbie. 2014. Proactive restoration: planning, implementation, and early results of silvicultural strategies for increasing resilience against gypsy moth infestation in upland oak forests on the Daniel Boone National Forest, Kentucky.
• Clark, Stacy L.; Schlarbaum, Scott E.; Saxton, Arnold M.; Hebard, Frederick V. 2016. Establishment of American chestnuts (Castanea dentata) bred for blight (Cryphonectria parasitica ) resistance: influence of breeding and nursery grading.
• Clark, Stacy L.; Schweitzer, Callie J. 2016. Stand dynamics of an oak woodland forest and effects of a restoration treatment on forest health.
• Clark, Stacy L.; Schlarbaum, Scott E.; Pinchot, Cornelia C.; Anagnostakis, Sandra L.; Saunders, Michael R.; Thomas-Van Gundy, Melissa; Schaberg, Paul; McKenna, James; Bard, Jane F.; Berrang, Paul C.; Casey, David M.; Casey, Chris E.; Crane, Barbara; Jackson, Brian D.; Kochenderfer, Jeff D.; MacFarlane, Russ; Makowske, Robert; Miller, Mark D.; Rodrigue, Jason A.; Stelick, Jim; Thornton, Christopher D.; Williamson, Tyler S. 2014. Reintroduction of American Chestnut in the National Forest System.

Publications

• Schweitzer, Callie J.; Calvert, Jared ; Clark, Stacy . 2020. Managers and scientists unit to adapt a shelterwood prescription to shift stand dynamics for competitive oak reproduction.
• Reazin, Christopher ; Baird, Richard ; Clark, Stacy ; Jumpponen, Ari . 2019. Chestnuts bred for blight resistance depart nursery with distinct fungal rhizobiomes.
• Clark, Stacy; Schweitzer, Callie; Todd, David. 2019. Emerging needs for oak management and research..
• Pinchot, Cornelia C.; Schlarbaum, Scott E.; Clark, Stacy L.; Saxton, Arnold M.; Sharp, Ami M.; Schweitzer, Callie J.; Hebard, Frederick V. 2017. Growth, survival, and competitive ability of chestnut (Castanea Mill.) seedlings planted across a gradient of light levels.
• Case, Ashley E.; Mayfield, Albert (Bud); Clark, Stacy L.; Schlarbaum, Scott E.; Reynolds, Barbara C. 2016. Abundance and frequency of the Asiatic oak weevil (Coleoptera: Curculionidae) and defoliation on American, Chinese, and hybrid chestnut ( Castanea ).
• Varner, Julian (Morgan); Arthur, Mary; Clark, Stacy; Dey, Daniel C.; Hart, Justin; Schweitzer, Callie. 2016. Fire in Eastern North American Oak Ecosystems: Filling the Gaps.
• Sung, Shi-Jean Susana; Clark, Stacy L.; Schlarbaum, Scott; Dey, Daniel C.; Leduc, Daniel J. 2016. Performance of container-grown seedlings of American chestnut backcross hybrids BC3 F3 generation in central Louisiana.
• Clark, Stacy L.; Schlarbaum, Scott E.; Keyser, Tara L.; Schweitzer, Callie J.; Spetich, Marty; Simon, Dean; Warburton, Gordon S. 2016. Response of planted northern red oak seedlings to regeneration harvesting, Midstory removal, and prescribed burning.
• Pinchot, Cornelia; Clark, Stacy; Schlarbaum, Scott; Saxton, Arnold; Sung, Shi-Jean; Hebard, Frederick. 2015. Effects of temporal dynamics, nut weight and nut size on growth of American chestnut, Chinese chestnut and backcross generations in a commercial nursery.
• Clark, Stacy; Schlarbaum, Scott; Schweitzer, Callie. 2015. Effects of visual grading on northern red oak (Quercus rubra L.) seedlings planted in two shelterwood stands on the Cumberland Plateau of Tennessee, USA.
• McNab, W. Henry; Spetich, Martin A.; Perry, Roger W.; Haywood, James D.; Laird, Shelby Gull; Clark, Stacy L.; Hart, Justin L.; Torreano, Scott J.; Buchanan, Megan L. 2014. Climate-induced migration of native tree populations and consequences for forest composition.
• Belair, Ethan P.; Saunders, Mike R.; Clark, Stacy L. 2014. Effects of simulated prescribed fire on American chestnut and northern red oak regeneration.
• Knapp, Benjamin O.; Wang, G. Geoff; Clark, Stacy L; Pile, Lauren S.; Schlarbaum, Scott E. 2014. Leaf physiology and morphology of Castanea dentata (Marsh) Borkh., Castanea mollissima Blume, and three backcross breeding generations planted in the southern Appalachians, USA.
• Clark, Stacy L.; Schweitzer, Callie J.; Saunders, Mike R.; Belair, Ethan P.; Torreano, Scott J.; Schlarbaum, Scott E. 2014. The American chestnut and fire: 6-year research results.
• Clark, Stacy; Schlarbaum, S.E.; Saxton, F,V. 2014. The first research plantings of third-generation, third-backcross American chestnut (Castanea dentata) in the southeastern United States.
• Clark, Stacy L.; Schweitzer, Callie Jo. 2013. Red maple (Acer rubrum) response to prescribed burning on the William B. Bankhead National Forest, Alabama.
• Wang, G. Geoff; Knapp, Benjamin O.; Clark, Stacy L.; Mudder, Bryan T. 2013. The Silvics of Castanea dentata (Marsh.) Borkh., American chestnut, Fagaceae (Beech Family).
• Clark, Stacy L. 2013. The reintroduction of the American Chestnut.
• Dey, Daniel C.; Stambaugh, Michael C.; Clark, Stacy L.; Schweitzer, Callie J., eds. 2012. Abstracts of the proceedings of the 4th fire in eastern oak forests conference.
• Clark, Stacy L.; Mcnab, Henry; Loftis, David; Zarnoch, Stanley. 2012. American Chestnut Growth and Survival Five Years after Planting in Two Silvicultural Treatments in the Southern Appalachians, USA.
• Pinchot, Cornelia C.; Schlarbaum, Scott E.; Franklin, Jennifer A.; Buckley, David S.; Clark, Stacy L.; Schweitzer, Callie J.; Saxton, Arnold M.; Hebard, Frederick V. 2012. Early results of a chestnut planting in eastern Kentucky illustrate reintroduction challenges.
• Dey, Daniel C.; Stambaugh, Michael C.; Clark, Stacy L.; Schweitzer, Callie J., eds. 2012. Extended abstracts of the proceedings of the 4th fire in eastern oak forests conference.
• Clark, Stacy; Schlarbaum, Scott; Saxton, John; Hebard, Fred; Blanton, John; Casey, David ; Crane, Barbara; MacFarlane, Russ; Rodrigue, Jason; Jim, Stelick. 2012. Lessons from the field: The first tests of restoration American chestnut (Castanea dentata) seedlings planted in the Southern Region.
• Pederson, Neil; Tackett, Kacie; McEwan, Ryan W.; Clark, Stacy; Cooper, Adrienne; Brosi, Glade; Eaton, Ray; Stockwell, R. Drew. 2012. Long-term drought sensitivity of trees in second-growth forests in a humid region.
• Clark, Stacy L.; Schlarbaum, Scott E.; Saxton, Arnold M.; Hebard, Fred V. 2012. Nursery performance of American and Chinese chestnuts and backcross generations in commercial tree nurseries.
• Dey, Daniel C.; Stambaugh, Michael C.; Clark, Stacy L.; Schweitzer, Callie J., eds. 2012. Proceedings of the 4th fire in eastern oak forests conference.
• Clark, Stacy L.; Franzreb, Kathleen E.; Greenberg, Cathryn H.; Keyser, Tara; Loeb, Susan C.; Loftis, David L.; McNab, W. Henry; O'Keefe, Joy M.; Schweitzer, Callie Jo; Spetich, Martin. 2012. Researching effects of prescribed fire in hardwood forests.
• Hart, Justin L.; Clark, Stacy L.; Torreano, Scott J.; Buchanan, Megan L. 2011. Composition, structure, and dendroecology of an old-growth Quercus forest on the tablelands of the Cumberland Plateau, USA..
• Spetich, Martin A.; Perry, Roger W.; Harper, Craig A.; Clark, Stacy L. 2011. Fire in Eastern Hardwood Forests through 14,000 Years.
• Pinchot, Cornelia C.; Schlarbaum, Scott E.; Saxton, Arnold M.; Clark, Stacy L.; Schweitzer, Callie J.; Smith, David R.; Mangini, Alex; Hebard, Frederick V. 2011. Incidence of Craesus castaneae (Hymenoptera: Tenthredinidae) on Chestnut Seedlings Planted in the Daniel Boone National Forest, Kentucky.
• Grayson, Stephen F.; Buckley, David S.; Henning, Jason G.; Schweitzer, Callie J.; Clark, Stacy L. 2011. Influence of alternative silvicultural treatments on spatial variability in light in central hardwood stands on the Cumberland Plateau.
• Clark, Stacy L.; Schlarbaum, Scott E.; Saxton, A.M.; Hebard, Fred V. 2011. Making history: Field testing of blight-resistant American chestnut (Castanea dentata) in the Southern Region.
• Schweitzer, Callie Jo; Gottschalk, Kurt W.; Stringer, Jeff W.; Clark, Stacy L.; Loftis, David L. 2011. Using silviculture to sustain upland oak forests under stress on the Daniel Boone National Forest, Kentucky.
• Clark, Stacy L.; Schweitzer, Callie J.; Schlarbaum, Scott E.; Dimov, Luben D.; Hebard, Frederick V. 2010. Nursery quality and first-year response of american chestnut (Castanea dentata) seedlings planted in the southeastern United States.
• Zak, Joel C.; Dimov, Luben D.; Schweitzer, Callie Jo; Clark, Stacy L. 2010. Relationship between herbaceous layer, stand, and site variables in the Bankhead National Forest, Alabama.
• Anagnostakis, S; Clark, Stacy; Mcnab, Henry. 2009. Preliminary report on the segregation of resistance in chestnuts to infestation by oriental chestnut gall wasp.
• Clark, Stacy; Brosi, Sunshine; Schlarbaum, Scott; Grissino-Mayer, Henri. 2008. Dendrochronology of two butternut (Juglans cinerea) populations in the southeastern United States.
• Clark, Stacy; Spetich, Martin; Evans, Zander. 2008. Drought in the southeast.
• Clark, Stacy L.; Torreano, Scott J.; Loftis, David L.; Dimov, Luben D. 2007. Twenty-two year changes in regeneration potential in an old-growth Quercus forest in the Mid-Cumberland plateau, Tennessee.

Citations of non US Forest Service Publications

• Video on American chestnut restoration in the Southern Appalachians.
  https://srs.fs.usda.gov/uplandhardwood/videos/chestnut-trees/
• Video on American chestnut restoration using containerized and bare-root seedlings
  https://srs.fs.usda.gov/video/american-chestnut-study/
• Inside the Forest Service Newsletter, February 2019. American chestnuts tested on three National Forests. https://www.fs.fed.us/inside-fs/american-chestnuts-tested-three-national-forests

Research Highlights

Highlight	Title	Year
SRS-2010-008	American Chestnut Restoration Research Hundreds of blight-resistant American chestnut trees planted last winter in three national forests in North Carolina, Tennessee, and Virginia ar ...	2010
SRS-2017-157	Oak woodland restoration improves forest health Conversion of a closed canopy oak forest to an oak woodland improved forest health, according to a long-term study initiated on the Daniel Boone ...	2017
SRS-2019-44	Partnerships in American Chestnut Research Reach Decade Milestone USDA Forest Service scientists at the agency's Southern Research Station have been conducting research for the last ten years on a historic fore ...	2019