Moss-driven facilitation promotes species coexistence in Andean páramo peatlands

Andean páramo peatlands are fragile high-altitude ecosystems characterized by frequent fog, intense seasonal solar radiation, strong daily temperature fluctuations, water saturation, and nutrient scarcity. These extreme conditions make them ideal systems for examining facilitative plant interactions and their influence on microclimate, soil nutrient dynamics, and biodiversity. We recorded 65 plant species and 5,368 individuals; 54% of the species and 89% of the individuals occurred on moss-dominated hummocks that covered only 29% of the surface. These structures, supported by the bamboo Chusquea tessellata , host extensive mats of Sphagnum magellanicum , Kurzia capillaris , Breutelia squarrosa , and S. cuspidatum . Strong species co-occurrence within these microhabitats suggests that there are positive interactions among mosses, liverworts, and vascular plants. At the hummock scale, we identified 5,299 species associations and nine non-vascular species acting as potential facilitators. Generalized linear models showed that non-vascular richness significantly predicted vascular diversity, particularly in combination with hummock area. By forming the basal substrate, mosses and liverworts regulate key ecological processes, such as water capture, infiltration, and nutrient cycling. Vertically structured assemblages played complementary roles: basal and middle layers dominated by K. capillaris , S. cuspidatum , and B. squarrosa enriched soils with nitrogen, phosphorus, and carbon; S. magellanicum , typically found in intermediate layers, buffered temperature; and upper Frullania convoluta cushions increased relative humidity during dry periods, while basal strata retained moisture. These findings demonstrate that moss-mediated interactions shape species-rich microsites, providing insights into biodiversity conservation and the restoration of Andean peatlands.