Concatenating latewood blue intensity and wood anatomical sensitivity in Neotropical montane podocarps: How does sex-related climate trigger tracheid plasticity?

Abstract

Increased hydric stress may result in a reshaping of tree species distribution in moist environments. Dioecious tree species may be more vulnerable to climate warming if sex-related sensitivity to drought occurs since lower performance of one sex may drive differential stress tolerance and sex-related mortality rates. We assessed sex-related differences in Neotropical montane podocarps (Podocarpus matudae subsp. matudae) Latewood Blue Intensity (LWBI) and tracheid anatomical plasticity, including lumen radial diameter, wall tangential thickness, cell radial diameter, Mork's index, and hydraulic efficiency and safety. We hypothesized that podocarp latewood growth shows increasing sensitivity to extreme climatic events (i.e. the wettest and driest years), and that the anatomical adaptation (phenotypic plasticity) of the latewood tracheids is influenced identically by limiting climatic factors in both sexes. In addition, this study aimed to 1) test podocarp sex-related differences in LWBI chronology and regional climate sensitivity, as well as spatial signatures of these relationships; 2) assess the influence of climate on tracheid anatomical features between female and male podocarps; and 3) evaluate wood anatomical adaptation between female and male podocarps in the historically wettest and driest years. The responses of the LWBI to the local mean maximum temperature, minimum temperature, and monthly precipitation showed sex-related differences. Specifically, sex differences in LWBI chronology demonstrated dissimilar spatial precipitation signals across Tropical Montane Cloud Forests. Female and male latewood tracheid traits show high anatomical plasticity associated with hydraulic efficiency, which is essential for understanding the resilience of tropical dioecious conifers in moist slope environments. Our results provide insights into how sex differences in LWBI chronologies and sex tracheid anatomical traits may be differentially adapted to wetter and drier climates.