Evidence That Anthropogenic Disturbances Are Associated with Growth Changes in Earlywood and Latewood of a Forested Peatland Conifer

Chamaecyparis thyoides forested peatlands in the mid-Atlantic USA store carbon and enhance biodiversity but have declined through altered hydrology. Ditched sites shifted to temporarily flooded hydrologic regimes and were replaced by other forest types. Sites exposed to sea level rise (SLR) have persisted with a seasonally flooded, saturated hydrologic regime, but are transitioning to ghost forests. The purpose of this study is to aid conservation efforts by analyzing climate variable correlations with seasonal growth. Chamaecyparis thyoides tree rings from a ditched site exhibited overall faster growth rates, and earlywood was more sensitive to climate variables (temperature and Palmer Drought Severity Index, PDSI) than latewood. At a site exposed to SLR, division of early- and latewood chronologies was performed at the age midpoint, and growth responses in prior (1939–1970) and recent periods (1970–2003) diverged. Temperature and PDSI correlations with growth occurred in both early- and latewood, and patterns shifted between prior and recent periods. Stressors may include the timing of soil anoxia and shifts in availability of nonstructural carbon at both sites, and salinity at the SLR-impacted site. Climate and growth correlations at the SLR site may represent a form of reference for hydrologic restoration of seasonally flooded, saturated hydrologic regimes.