Wood anatomical acclimation in the endemic genus Polylepis in Peruvian Andean forests

Polylepis (Queñua) is a dominant woody plant genus in Andean Puna forests that occurs in a wide range of montane habitats and is ecologically diverse in endemism, which may be particularly threatened by climate change. Wood anatomical traits are essential for understanding how plants adjust their ecophysiological requirements and maximize their resilience, resistance, and recovery to extreme climates. Although the effects of extreme climatic conditions in high altitude ecosystems have been studied extensively, our knowledge is relatively limited to quantitative differences in the main xylem tissues. To address this gap, we assessed the acclimation of wood anatomical traits in six Peruvian Andean Polylepis species with different water availability (semi-dry with high moisture and semiarid with dry winters). We selected hydraulic diameter, vessel density, vessel grouping index, solitary vessel index, vulnerability index, mesomorphy index, vessel element length, fiber length, fiber wall thickness, fiber lumen diameter, and total fiber diameter that can provide relevant eco-wood anatomical acclimation to hydric stress. We performed multivariate analysis to determine the leading dimensions of covariation among Polylepis species and climatic factors. Specific wood anatomical traits (vessel grouping index, vulnerability index, and fiber wall thickness) were dissimilar between xeric- and mesic-Polyelpis species. This study demonstrates that wood anatomical traits in Peruvian Andean Polylepis species provides high-resolution and long-term eco-wood anatomical signals on how climate oscillations drive the acclimation processes of fiber and vessel traits. Our findings underscore the significance of xylem hydraulic adjustment to various hydrological environments in Andean puna forests. By evaluating the effects of drought on wood anatomical characteristics and ecological function, we demonstrate the capacity of tree species to adapt and endure climate-related changes, thereby emphasizing their resilience and adaptability.