Structural variation of secondary xylem and acclimation responses of two Atlantic Forest tree species in heterogeneous environments

Abstract

Biodiversity loss exacerbated by climate change compromises habitat conservation and restoration strategies. Analyzing the functional traits of secondary xylem is a valuable tool for understanding how species respond to environmental conditions. This study aimed to characterize the anatomical structures of the secondary xylem in Miconia prasina (Sw.) DC. (Melastomataceae) and Nectandra membranacea (Sw.) Griseb. (Lauraceae) and investigate how wood anatomical variations contribute to understanding intraspecific variation in these species across the ombrophilous forest and restinga areas. To achieve this, we collected branches from five individuals of each species in both study areas, totaling 20 samples. The secondary xylem samples were subjected to plant anatomy techniques, including transverse, tangential, radial sectioning, staining, and microscopic analysis. We observed low intraspecific variability in the anatomical traits of the secondary xylem of M. prasina and N. membranacea across different phytophysiognomies. In M. prasina, the tangential vessel diameter, wall thickness, and vessel element length were greater in the ombrophilous forest than in the restinga. In contrast, N. membranacea exhibited functional stability, with conservative traits such as sparse axial parenchyma in both phytophysiognomies, reflecting a strategy focused on safety and water storage. Understanding these variations is essential for predicting species acclimation in heterogeneous environments and contributing to conservation strategies in the face of anthropogenic impacts and extreme climatic events.