Original article The effects of climatic variability on radial growth of two varieties of sand pine (Pinus clausa)

Abstract – Total ring, earlywood, and latewood master chronologies were derived for six stands (three of each of the two varieties) of sand pine (Pinus clausa) spanning the geographic breadth of the species extant range in Florida, USA. Climate/growth correlations, ana-lysis of extreme growth years, and multiple regression models were developed to relate growing season (current and lagged) monthly temperature and precipitation with interannual variability in sand pine growth increments. Four research hypotheses were evaluated: (1) Sand pine growth is more sensitive to variation in precipitation than variation in temperature. (2) Sand pine growth variation is linked to El Niño-Southern Oscillation warm- vs. cold-phase events. (3) Climate/growth relations are stronger for the peninsular (Ocala; P. c. var. clausa) variety of sand pine than the panhandle (Choctawhatchee; P. c. var. immuginata) variety. (4) Climatic signals are stronger for coastal populations (vs. inland) for both varieties. Precipitation (especially in the winter/spring season of current-year growth) was more strongly linked to sand pine growth than temperature, earlywood growth was significantly greater in warm-phase El Niño-Southern Oscillation years in four of the six stands, and climate/growth relationships were stronger in coastal populations. We found no consistent inter-varietal contrasts in the strength of climatic signals, although climate/growth relationships were distinctive in the two inland pan-handle stands, where canopy/understory interactions may partially obscure expression of climatic influence. We found greater sensitivi-ty to temperature in inland panhandle stands (especially in latewood series), but consistently strong growth response to precipitation in the other four stands (especially in earlywood and total ring series). Our findings extend the evidence for ENSO influence on terrestrial biophysical phenomena in Florida