Photo of Stacy Clark

Stacy Clark

Research Forester
2431 Joe Johnson Drive, Room 274 EPSB
University of Tennessee, Dept. of Forestry, Wild., and Fish
 Knoxville, TN 37996
Phone: 865-974-0932
Fax: 865-974-4714
stacy.l.clark@usda.gov

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

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

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 and Products

Publications

Research Highlights

American Chestnut Restoration Research (2010)
SRS-2010-008 Hundreds of blight-resistant American chestnut trees planted last winter in three national forests in North Carolina, Tennessee, and Virginia are thriving. SRS is monitoring the growth of the American chestnuts. In 2010, partners will test plant 500 more blight-resistant chestnuts in the three national forests.
Oak woodland restoration improves forest health (2017)
SRS-2017-157 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 National Forest. Trees that remained following the restoration treatment had larger tree-ring growth and were more resilient to a recent drought compared to the trees that were removed.
Partnerships in American Chestnut Research Reach Decade Milestone (2019)
SRS-2019-44 USDA Forest Service scientists at the agency's Southern Research Station have been conducting research for the last ten years on a historic forest icon, the American chestnut. The scientists have built partnerships with state agencies and universities, The American Chestnut Foundation, and within the Forest Service to transfer technology to stakeholders who desire to see this tree restored. More than 4,000 trees have been planted and carefully monitored to reveal that the American chestnut has potential to be restored throughout its native range if certain challenges can be met.
Scientists Embrace Shared Stewardship to Deliver Silviculture Research (2020)
SRS-2020-55 Since 1992, the SRS Upland Hardwood Ecology and Management Research Work Unit has provided workshops and trainings to fulfill continuing education requirements for both federal and non-federal land managers. In 2020, scientists planned to introduce an updated Upland Hardwood Silviculture course to meet training needs of state partners in the southern region. However, the COVID-19 pandemic forced scientists to quickly modify the logistics and structure of this highly anticipated training. With assistance from SRS IT specialists, SRS scientists conducted an all-virtual short course. The course delivered the most up-to-date information about the management of upland hardwood forests to more than 100 foresters and natural resource practitioners.
R&D Affiliations
Research Topics
Priority Areas
SRS Science Area
Experimental Forests and Ranges
External Resources
  • The sites listed below are third-party sites which the Forest Service has provided for reference only.
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