Leaf morphological variation in Ribes alpinum L. across elevation gradients in the Dinaric Alps

Mountain ecosystems are shaped by steep environmental gradients that influence plant morphology and adaptation. Ribes alpinum L., a deciduous shrub with a wide European distribution, remains poorly studied in terms of its intraspecific variability. This study aimed to investigate leaf morphological variation across five natural populations from the Dinaric Alps, focusing on differences in leaf size and shape in relation to elevation and habitat conditions. Leaves were sampled from four populations and photographed in situ at a fifth site located within a strict nature reserve. Ten morphometric traits were measured—five related to leaf size (e.g., area, length, petiole length) and five describing leaf shape and lobe configuration. Statistical analyses revealed significant differences among populations in seven traits, with leaf size parameters showing the greatest divergence. Populations from contrasting elevations were consistently identified as morphologically distinct. The low-elevation population showed the greatest degree of within-population morphological diversity, likely reflecting the influence of heterogeneous terrain and fine-scale microhabitat variation. Multivariate analyses (PCA and clustering) confirmed population-level structuring, while Redundancy Analysis (RDA) showed that geographic coordinates had no significant influence on trait variation. Instead, elevation-related environmental gradients emerged as the dominant drivers of morphological differentiation. These findings suggest that leaf traits in R. alpinum are shaped primarily by local ecological pressures, reflecting phenotypic plasticity rather than broad spatial separation. The study highlights the adaptive flexibility of R. alpinum and underscores the ecological importance of the Dinaric Alps as a valuable setting for investigating plant responses to environmental heterogeneity.