CR 78:249-259 (2019)  -  DOI: https://doi.org/10.3354/cr01573

ABSTRACT: We present a new method for identifying historic tropical cyclone activity utilizing frequencies of intra-annual density fluctuations in longleaf pine in western Florida. In addition, in this work we provide information about the causal factors that determine the formation of intra-annual density fluctuations (IADFs) in longleaf pine latewood. Specifically, we test the viability of using late latewood (L+) IADFs in longleaf pine as a proxy for historic tropical cyclone frequency and precipitation for the period 1950-2017. The stabilized frequency of L+ IADF occurrence is significantly (p < 0.01) associated with the Palmer drought severity index (PDSI) for the months June through October, indicating that high amounts of late growing-season moisture promote the formation of IADFs in latewood. We find the strongest relationships between PDSI and IADF occurrence during September and October, indicating the influence of tropical cyclone (TC)-sourced precipitation on IADF formation. High IADF stabilized frequencies (i.e. >0.50) nearly always (88%) coincide with a TC tracking into the study area, and we find a significant (p < 0.01) relationship between TC-sourced precipitation and the stabilized frequency of L+ IADFs. Via this relationship, reconstruction of historic tropical cyclone frequency and precipitation is probable, which would allow for increased understanding of historic tropical cyclone activity prior to the historic climate record.

KEY WORDS: Tropical cyclone · Intra-annual density fluctuation · Dendroclimatology · Florida · Longleaf pine