Plastic Responses of Magnolia schiedeana Schltdl., a Relict-Endangered Mexican Cloud Forest Tree, to Climatic Events: Evidences from Leaf Venation and Wood Vessel Anatomy

Abstract

The Mexican tropical montane cloud forest trees occur under special and limited climatic conditions; many of these species are particularly more sensitive to drought stress. Hydric transport in leaf veins and wood features are influenced by climatic variations and individual intrinsic factors, which are essential processes influencing xylogenesis. We assessed the plastic response to climatic oscillation in two relict-endangered Magnolia schiedeana Schltdl. populations and associated the architecture of leaf vein traits with microenvironmental factors and wood anatomy features with climatic variables. The microenvironmental factors differed significantly between the two Magnolia populations and significantly influenced variation in M. schiedeana leaf venation traits. The independent chronologies developed for the two study forests were dated back 171–190 years. The climate-growth analysis showed that M. schiedeana growth is strongly related to summer conditions and growth responses to Tmax, Tmin, and precipitation. Our study highlights the use of dendroecological tools to detect drought effects. This association also describes modifications in vessel traits recorded before, during, and after drought events. In conclusion, our results advance our understanding of the leaf vein traits and wood anatomy plasticity in response to microenvironmental fluctuations and climate in the tropical montane cloud forest.