Sean Reynolds Successfully Defends Thesis Research on Physiological Responses of Turkey Oak in Transition Treatments

Submitted by Courtney Peterson on

At the Jones Center at Ichauway, a site dominated by longleaf pine (Pinus palustris Mill.) in southwestern Georgia, one of the main climate change effects being considered under the ASCC project is increased temperature and drought stress. In the transition plots at the Jones Center, where management is aimed at actively changing the ecosystem to encourage adaptive responses to these stressors, one approach is a shift in the hardwood component of the forest towards more xeric species, including turkey oak (Quercus laevis Walt.).

Turkey oak seedling planted in the transition treatment at the Jones Center
Photo credit: Sean Reynolds, The Jones Center at Ichauway 

Sean Reynolds, a recent graduate from Auburn University with an M.S. degree in Forestry, successfully defended his thesis research, addressing the feasibility of regenerating turkey oak seedlings in a longleaf ecosystem by investigating the relationships between overstory metrics, environmental conditions, and seedling leaf gas exchange. Gas exchange and environmental measurements were taken eight times over the 2019 growing season, and then analyzed in relation to canopy openness, as calculated from hemispherical photographs. Seedling physiological performance was negatively correlated with increased overstory levels in mesic soils on site. This effect of the overstory was lessened when environmental conditions were stressful, and was not observed in more xeric soils. Sean concluded that turkey oak seedlings in mesic soils experienced competition from the overstory, with no evidence of facilitation in either mesic or xeric soils. Efforts to transition a longleaf pine ecosystem towards greater drought tolerance may therefore be most effective when planting of turkey oak seedlings is concentrated in canopy openings.

You can watch Sean’s exit seminar on his thesis research here:

Sean IDs trees at the Jones Center
Photo credit: Sean Reynolds, The Jones Center at Ichauway

Sean Reynolds is a recent graduate from Auburn University, with an M.S. degree in Forestry. Sean’s thesis research, under the guidance of Dr. Lisa Samuelson from Auburn University and Dr. Seth Bigelow from the Jones Center at Ichauway, focused on the effects of overstory trees on turkey oak seedlings at a longleaf pine site. Sean is from Westminster, Maryland and graduated from Stevenson University in 2014 with a B.S. in Biology. After graduating, he spent half a year working in the rainforest of Puerto Rico on a tree census crew before moving on to a two year stint working in Washington, D.C. as an urban forestry technician. Before starting his graduate studies, Sean spent a summer in Georgia as an ecohydrology technician. Sean was awarded a Westervelt Fellowship and the Robert Lewis Adams graduate award in 2019. His research has been accepted for presentation at the 2020 annual meeting of the Association of Southeastern Biologists, the 2020 biennial meeting of the Longleaf Alliance, and the 2020 annual meeting of the Ecological Society of America. Sean hopes to enter a career in environmental outreach and education.