The earlywood, latewood and xylem vessel chronologies of Teak tree (Tectona grandis) provide important insight into xylem hydraulic adjustment to past climate variability

Abstract

Intra-annual growth (earlywood and latewood) and xylem vessel formation dynamics may provide high resolution climate signals and understanding of xylem hydraulic adjustment to climatic stress since xylem vessel formation of angiosperm trees are highly sensitive to climate. We evaluate the potential of Tectona grandis L.f. tree rings to archive high resolution climate signals in intra-annual growth zones and in xylem anatomical features and aim at understanding the hydraulic adjustment mechanism in a Bangladeshi tropical moist mixed deciduous forest. Standard dendrochronological technique was applied to develop chronologies of ring width (RW), Earlywood (EW), Latewood (LW), and xylem vessel features that spanned over 54-year period (1966–2020). Pearson correlation analysis revealed that tree growth, particularly earlywood growth, was negatively influenced by maximum temperature (Tmax) in pre-monsoon and at the beginning of monsoon season. Pre-monsoon nighttime temperature (Tmin) favored xylem cell enlargement allowing higher water transport but decreased vessel density leaving the tree at the higher risk of hydraulic failure. On the other hand, the main monsoon precipitation was positively correlated to whole ring vessel density and latewood growth thus precipitation helped achieve overall safety of trees against hydraulic failure. On a spatial scale, a significant correlation of intra-annual growth and xylem vessel features with regional climate variables indicate that the tree ring features of T. grandis are a good natural archive of local and regional climate information. Our analyses suggest that studying long term wood anatomical features along with growth dynamics offers important insight into long-term xylem hydraulic adjustment of tropical ring porous species to climate variability and changes.