Dendroecology and the restoration of Atlantic white cedar forests

Keywords: hydrologic regimes, tree rings, restoration, wetlands
Abstract Type: Poster Abstract

Abstract

Atlantic White Cedar (AWC) swamps perform valuable ecosystem services that are dependent on hydrologic conditions. These globally-threatened ecosystems have a history of being drained by ditching, making the swamps vulnerable to peat-burning fires and shifts in species composition. While land managers are working to restore these threatened ecosystems, restoration efforts have been hampered by a lack of historic hydrologic data. The purpose of this study is to examine radial growth patterns in AWC in order to characterize drainage history and guide hydrologic restoration. Basal area increment (BAI) data were obtained from AWC in 13 stands in the Great Dismal Swamp (GDS). Hydrologic regimes for all stands were initially classified as temporarily flooded based on growth rates, but further hydrologic differences were detected among stands. BAI growth rates were positively affected by increased ditching in the 1950s and 1960s. Water control structures installed in the 1980s resulted in a temporary decline in BAI growth rates, but growth quickly rebounded, suggesting a need for higher water levels. Polar Ordination (PO) showed that distance from a primary ditch separated stands on the first axis (trees in stands close to ditches grew faster), while the second axis elucidated the effects of distance to secondary ditches on stand hydroperiod. The PO was supported by partial Mantel tests, which accounted for differences in stand age and location. Results from this study demonstrate that dendroecology can be useful for describing the history of hydrologic conditions and for providing insights needed for restoration of AWC in the GDS.