ANALYSIS OF LOBLOLLY PINE (PINUS TAEDA) TREE RING AND CLIMATE RECORDS OF ASSATEAGUE ISLAND AND CHINCOTEAGUE BAY REGION, VIRGINIA

Loblolly pine forests on barrier islands are declining to the point of developing large stands of dead trees. Termed ghost forests, this decline has been studied on the mainland, Wallops, and southern Assateague Islands (AI), Chincoteague Bay, VA, but is still poorly understood. Efforts have focused on identifying geospatial trends in the distribution of ghost forests, their soil/sediment characteristics, and their dendroecologic growth histories. This study documents daily weather records (temp, precipitation) for AI for 50+ years and compares these to tree ring records from this barrier island (BI) and neighboring areas. Instrumental records up to 2018 show trends toward: 1) warmer climate conditions for low and average temperatures, 2) decreasing snowfall rates, and 3) increasing rainfall. With warmer wetter conditions, annual tree growth histories should, hypothetically, show increased growth rates in both new and old wood bands. However tree growth rates are declining suggesting tree health is increasingly impaired in living forests irrespective of more optimum conditions for tree growth. This indicates other direct and indirect variables impact tree health on these BI’s. Saltwater intrusion and higher groundwater tables from increased rainfall and sea level rise contribute to the expansion of fresh and brackish water wetlands at the expense of the low-elevation forests. Previous work shows proximity to the shoreline negatively impacts tree growth as well. Evidence from AI and this study now also points to indirect climate change impacts that also likely impair tree health. On AI pine bark beetle infestation events have been reported since 1962. From 1983-2019 infestations are more widespread, of longer duration, and the hiatus between outbreaks is decreasing. The average hiatus between outbreaks for the 30+ years of monitoring is 3.6 years, but hiatus periods between outbreaks lasted 5 to 7 years from 1983 to early 2000’s but are much shorter since. Warmer weather likely allows more beetles to successfully overwinter. This coupled with already declining tree health may make the trees more susceptible to infestations and other climatic impacts. If existing trends continue, BI’s may lose their forests entirely and this will lead to a substantial change in the ecosystem services they provide to the region.