A comparison of the climate response of longleaf pine ( Pinus palustris Mill.) trees among standardized measures of earlywood, latewood, adjusted latewood, and totalwood radial growth

Longleaf pine radial growth is primarily driven by late summer moisture availability, latewood and adjusted latewood are more sensitive to climate than either earlywood or totalwood, and there is a high level of agreement spatially in growth/climate responses. Our objective was to examine broadly the climate–growth responses of longleaf pine (Pinus palustris Mill.) on the Coastal Plain province of North and South Carolina to temperature, precipitation, and drought severity. We compared the responses between standardized earlywood, latewood, adjusted latewood, and totalwood radial tree growth. We sampled mature longleaf pine growing in open-canopy savanna environments and developed six tree-ring chronologies using standard dendroecological techniques. We used a combination of Pearson correlation, moving interval correlation, and Fisher r–z tests to determine which monthly and seasonal variables were most closely related to radial growth, the temporal stability of the dominant growth/climate relationship, and whether earlywood and latewood growth provide significantly different climate responses. Our results show that the strongest relationships with climate are with adjusted latewood growth and that rainfall in the later parts of the growing season (i.e., July–September) is the primary control of radial growth. Spatially, we found that growth/climate responses were similar throughout the Coastal Plain region encompassing the six study sites. Temporally, we found that July–September precipitation produced significant (p < 0.05) relationships with radial growth for extended annual intervals, but there were shorter periods when this relationship was non-significant. In general, growth/climate relationships were stronger for latewood compared to earlywood, and these responses were significantly (p < 0.05) different at about half of our study sites. Our findings are congruent with prior research in this region showing that short-duration precipitation events are a critical component for radial growth. Further, these results emphasize the importance of latewood growth—particularly adjusted latewood growth—in capturing interannual climate/growth responses.