Moss-driven facilitation promotes species coexistence in Andean páramo peatlands

Andean páramo peatlands are fragile high-altitude ecosystems shaped by frequent fog, intense solar radiation, strong diurnal temperature fluctuations, water saturation stress, and low nutrient availability. These harsh conditions make them ideal systems for studying plant–plant facilitation. We examined a peatland in Chingaza National Park (Colombia) to assess how mosses and species associations influence microclimate, water dynamics, and soil nutrients. At the peatland scale (820 m²), we recorded 65 species and 5,368 individuals; 89% of individuals and 54% of species occurred on moss-dominated hummocks, which covered only 29% of the area. These hummocks, primarily formed by Chusquea tessellata , Sphagnum magellanicum , Kurzia capillaris , Breutelia squarrosa , and S. cuspidatum , showed strong species co-occurrence (χ² = 11091.77, p < 0.001), suggesting facilitative interactions drive community structure. Across 170 hummocks, we found 5,299 species interactions and identified nine non-vascular species as potential facilitators. Generalized linear models showed that non-vascular richness significantly predicted vascular plant diversity, especially when interacting with hummock area (AIC = 654.95). Mosses integrated structural and abiotic influences, regulating water capture, infiltration, and nutrient dynamics. Species differed in their effects: K. capillaris and B. squarrosa enhanced soil nitrogen, phosphorus, and carbon more than S. magellanicum . Upper moss layers promoted water input, while lower layers retained moisture and buffered nutrient availability. Our results show that moss-dominated hummocks act as facilitative microhabitats, enhancing biodiversity through microenvironmental modification. These results underscore the role of moss-driven facilitation in shaping species-rich microsites, offering key insights for biodiversity conservation and the restoration of Andean peatlands.