Experimental throughfall reduction has little effect on shoot and needle developmental patterns or leaf area dynamics in a young longleaf pine (Pinus palustris Mill.) plantation

Reduced precipitation and, consequently, low soil moisture are known to limit tree growth and function by affecting shoot foliage development, as well canopy-scale leaf area dynamics litterfall. Longleaf pine (Pinus palustris Mill.) is considered one of the most drought-resistant forest species in southeastern U.S. could serve a pathway increase drought resistance forests region. Still, reduced impacts on longleaf canopy phenology not understood. Over three years (2017–2019), we determined effects 40% throughfall reduction (TR40) (relative ambient treatment, TR0) young (12–14 yr. old) plantation. Each year, repeatedly measured needle lengths primary secondary branch axes multiple trees each treatment plot. We fit curves for axis estimate rate, start cessation dates, duration (growth - cessation), final lengths. At plot level, documented temporal patterns index (LAI) litterfall determine whether branch-scale phenological responses water availability corresponded with changes LAI observed significant consistent differences elongation between branches. Timing development varied among was generally later successive year. However, were relatively across years. Although lower under reduction, affected. also affected reduction. Our results indicate that reductions rainfall amount (without frequency or timing) may have little impact phenology, litter production established plantations.