James Palus' Graduate Defense Seminar
A Graduate Defense Seminar will be presented by James Palus, MS Candidate in Ecological Restoration. His presentation is Influence of Landscape Position on Succession in Forests Undergoing Mesophication and will be in 333 Kottman Hall.
Fire suppression in oak–hickory forests of the eastern U.S. has driven the recruitment of shade-tolerant mesophytic species into the understory. This transition in vegetation community composition results in a loss of ecosystem services provided by these forests, affecting timber production, wildlife habitat, and water availability, among others. Further, differences in the physical and chemical properties of oak and maple leaf litter lead to fundamental changes in the behavior of fires when they do occur, so restoration of these forests is not straightforward. To examine if there are environmental factors that may confer resilience to mesophication, we studied 20 years of succession in forests by resampling a network of permanent plots across the Wayne National Forest in southeastern Ohio. NMDS ordination analyses show clear separation of overstory communities across different landscape positions, primarily driven by moisture availability. Variability in the rate and direction of movement in ordination space suggests that xeric ridges consistently move toward a similar mesophytic state. Sites along slopes, however, are more variable in their change, and intermediate disturbances (e.g., windfall) on very xeric sites (e.g., southerly upper slopes) may successfully shift these forests back to an oak–hickory state. These forests are increasingly susceptible to novel disturbances (e.g., insects, drought), and their current successional trajectory may exhibit low resilience to conditions predicted under future climate scenarios. This study serves to identify linkages between environmental parameters and community resilience, allowing restoration practitioners to better tailor efforts to particular forest ecosystem types.