Patterns and drivers of tufa moss diversity across alpine petrifying springs landscape gradient on the Tibetan Plateau

Petrifying springs characterized by active tufa deposition represent priority habitats due to their ecological and geomorphological importance. These fragile ecosystems harbor specialized bryophyte assemblages that maintain essential ecosystem functions and actively mediate calcium carbonate precipitation, thereby shaping landscape-scale habitat heterogeneity. However, the mechanisms linking environmental variation, moss functional traits, and community-level diversity across tufa landscapes remain poorly understood. Here, we investigated moss communities within the Yalonggou Tufa Terrace (YTT) on the southeastern Tibetan Plateau to disentangle patterns of alpha and beta diversity and identify their potential drivers. A total of 41 moss species (23 genera, 10 families) were recorded, dominated by Cratoneuron filicinum , Drepanocladus vernicosus , and Bryum pseudotriquetrum . The flora was mainly composed of North Temperate and Cosmopolitan elements, with predominantly dioecious reproduction and life forms characterized by weft, short-turf, and tall-turf growth forms. Moss alpha diversity exhibited a unimodal pattern along the tufa landscape gradient, peaking in waterfall zones characterized by intermediate disturbance and hydrochemical conditions. Although environmental variables strongly influenced ecophysiological traits, these traits showed limited direct explanatory power for diversity patterns, indicating a scale-dependent decoupling between physiological responses and community assembly. In contrast, beta diversity increased consistently along geographic, environmental, and trait distance gradients, driven primarily by species turnover. Our findings suggest that environmental heterogeneity generated by biologically mediated calcification promotes species replacement across the tufa landscape, while physiological plasticity buffers local persistence without directly determining diversity outcomes. These results advance understanding of biodiversity maintenance in alpine petrifying spring ecosystems and provide a scientific basis for conservation prioritization under ongoing climate change. This graphical abstract illustrates the multiscale mechanisms underlying moss diversity patterns in alpine petrifying spring ecosystems. Along the tufa landscape gradient, alpha diversity followed a unimodal pattern, whereas beta diversity increased primarily through species turnover, reflecting pronounced spatial heterogeneity. Geospatial gradients and hydro-environmental variability influenced community composition indirectly by shaping moss physiological responses. Although physiological traits responded strongly to environmental variation, they did not exert significant direct effects on diversity, indicating that community assembly arises from scale-dependent interactions among spatial structure, environmental filtering, and species replacement. Consequently, moss communities in tufa systems persist through physiological buffering at local scales while undergoing compositional turnover across landscapes. • Alpha diversity shows a unimodal pattern along tufa gradients. • Beta diversity increases with landscape distance via turnover. • Environmental filtering shapes moss diversity through traits. • Petrifying springs support mosses of high conservation value.