Microhabitat-driven acclimation links functional and germination traits in the narrow endemic Saxifraga berica (Bég.) D.A. Webb.

The concept of seed germination niche provides a framework for linking germination data with ecological conditions, helping to reveal how regeneration traits mirror the environments in which species evolve and persist. Understanding these relationships is especially relevant for narrow endemics, whose restricted distributions often reflect fine-scale environmental heterogeneity. We investigated the sub-alpine Saxifraga berica to test whether microhabitat variability influences functional traits and seed germination patterns. Individuals were sampled across contrasting light microenvironments, characterized through field measurements of irradiance, light spectra, temperature, and humidity. Functional traits related to photosynthetic efficiency, photoprotection, pigment composition, and leaf morphology were assessed in the field, while seed germination percentage and timing were evaluated under controlled conditions. Multivariate analyses revealed two distinct environmental clusters associated with consistent differences in photosynthetic performance, pigment composition, and leaf structure, indicating divergent physiological acclimation strategies to light availability. Germination percentage remained generally high across clusters, but germination timing varied markedly, suggesting that microenvironmental conditions experienced by plants influence seed germination rate. Overall, S. berica exhibits two ecologically differentiated germination strategies reflecting the contrasting microhabitats. These findings highlight the importance of integrating functional traits for understanding persistence strategies in narrow-distributed endemics and provide key insights for their conservation.