The importance of infrequent, high-intensity rainfall events for longleaf pine (Pinus palustris Mill.) radial growth and implications for dendroclimatic research

Abstract

Tree-ring based precipitation reconstructions are beneficial in placing interannual variability in an historical context. However, absent specificity on what is being modeled (e.g., event type or rainfall intensity), similar rainfall totals inferred from reconstructions between different years imply similar conditions. Consequently, variability in specific precipitation event types or intensity can affect radial growth widths despite no changes in overall precipitation amount. Here, we use a longleaf pine latewood chronology to demonstrate how infrequent, intense (i.e., > 2.0 SD above mean) rainfall events (IREs), representing ~ 50% of total summer (July–September) precipitation amounts and 14.1% of rainfall events, principally determine interannual variability (R2 = 40.7%) in latewood while total summer rainfall amounts excluding IREs provide minimal explanatory power (R2 = 10.4%). These results suggest that slight decreases in IRE frequency can promote significant reductions in latewood growth indicating strong sensitivity to minor changes in climate.