Effect of topographic and spatial factors on bryophyte communities in riparian forests of the Brazilian Cerrado

Riparian forests are heterogeneous and dynamic ecosystems that serve as biodiversity refuges in the Cerrado, where environmental gradients act as environmental filters that shape bryophyte communities. We aimed to evaluate the influence of topographic and spatial variables on the richness, abundance, and composition of bryophytes communities in the riparian forests of the Brazilian Cerrado. The study was conducted in two riparian forests in the Nascentes do Rio Parnaíba National Park, Brazil. We sampled a total of 30 plots (10 × 10 m). To assess the influence of topographic and spatial predictors on species richness and abundance, we fitted Generalized Linear Mixed Models (GLMMs). Variation in species composition was analyzed with Permutational Multivariate Analysis of Variance (PERMANOVA) and Redundancy Analysis (RDA). We applied Threshold Indicator Taxa Analysis (TITAN) to detect community shifts along environmental gradients. We recorded 1,189 bryophyte specimens, representing 57 species, one subspecies, 35 genera, and 19 families. Although subtle, the altitudinal gradient significantly affected species richness, abundance, and composition. Altitude and slope had a negative effect on species richness and abundance, while species composition was influenced by altitude, distance from the waterfall, and slope. Significant community thresholds were identified between 413 and 458 meters in elevation and at a linear distance of 557.7 meters from the waterfall, with nine and three species responding, respectively. Although slope influenced species composition, it did not exhibit clear threshold patterns. Topographic factors strongly influenced bryophyte communities more than spatial factors, challenging the expectation that moisture availability gradients would shape diversity patterns. Our findings underscore the need to incorporate topographic and spatial gradients into management strategies for conserving the Brazilian Cerrado and offer critical insights into preserving its riparian forests.