TREE-RING ANALYSIS OF BARRIER ISLAND AND MAINLAND MARITIME FORESTS, CHINCOTEAGUE BAY, VIRGINIA, USA

Maritime forests on the East Coast have been subject to many stressors due to human impacts including livestock grazing, invasive species, sea-level, and climate change. These low-lying ecosystems are “ghosting” as Loblolly pines in these forests are dying. Studies have correlated degraded tree health to increasing soil pH and conductivity driven by changes in groundwater systems. With changes in storm intensity, higher sea-levels, and changing land use, freshwater aquifers are being disrupted. In order to investigate the history of tree health, this study builds on prior dendro-studies for the Chincoteague Bay (CB) region. The goal is to evaluate ties between regional climate relative to local, site-specific dynamics linked to changes in management on barrier islands (i.e. on Wallops Island, WI) or other factors relative to mainland settings.

In this study, 30 Loblolly Pines (Pinus taeda) were sampled with increment bores on WI (home to NASA’s flight facility) and on the mainland near Greenbackville, VA. Cores are being analyzed to produce a geospatially-constrained growth record from which we can evaluate changes in tree health and gauge environmental stressors. These cores were dyed using phloroglucinol to highlight annual growth. Once stained, tpsDig2 and CDendro are used to measure growth rings, and these are compared to regional climate data to discriminate regional and local factors.

Preliminary data from an elevated bluff on the mainland uncovered a correlation between impacted tree growth, proximity to shoreline and higher soil pH (Allen & Cornell, 2018). These authors hypothesized that dead trees near the shoreline were the result of saltwater exposure from salt spray, storm surge, and saltwater intrusion into the groundwater as the bluff eroded. Likewise a study by Gildner (2017) showed a strong correlation between soil pH, soil conductivity, and lower tree health for sites on Assateague Island, VA. This study integrates the climate data for the region and evaluates tree rings from WI, which has been influenced by beach nourishment that has improved the freshwater lens and reduced the impact of saltwater intrusion. The results of this combined CB region dendroecology dataset, with the regional climate data record set, and different land use practices on the mainland/barrier islands will be presented.