Climate Sensitivity and Growth Response of Genetically Improved Loblolly Pine: A Case Study from a 20-Year Genetic Trial in the West Gulf Coastal Plain

Identifying genotype-specific climate sensitivities can guide the selection and deployment strategies for improved loblolly pine ( Pinus taeda L. ). We used increment cores from a 20-year-old loblolly pine genetic trial established in 2004 to reconstruct annual basal area increment (BAI) and to evaluate the relationship between growth and temporal climatic parameters among different genetic entries in the West Gulf Coastal Plain (WGCP), a drought-prone region of the southern United States. Genotypes were three open-pollinated (OP 7–56, OP 8–103, and OP LA) and two varietals (V9 and V93) planted at the same site. OP 7–56 exhibited the highest mean BAI (17.3 cm 2 by age 20), with peak growth between ages 6 and 10, whereas V9 and V93 showed more moderate but stable growth trajectories. Response-function analyses indicated that V9 and V93 were most sensitive to current-year climate, particularly spring precipitation, and late-summer to autumn drought indices, while OP 7–56 and OP 8–103 responded more strongly to previous-year early-summer temperatures, and OP LA showing the weakest climatic signal. After controlling for multiple comparisons using a false discovery rate procedure, growth-climate relationships remained detectable for key genotypes, offering preliminary evidence of differential climate sensitivity worth further investigation. Wavelet analysis revealed persistent interannual (2–4-year) and multi-year (3–6-year) growth periodicities and genotype-specific sensitivity to longer-term climate variability. Overall, improved loblolly pine genotypes may differ in both growth performance and temporal climate sensitivity, which needs to be accounted for in improving the resilience of southern pine plantations to climate change, particularly in the West Gulf Coastal Plain.