ABSTRACT This study was carried out with bryophyte populations in order to study the presence of populations and how they change over altitudinal gradients. Mosses were chosen as a model to do this study because they have a high sensitivity to climatic conditions and wide distribution. The western region of the Sierra Nevada del Cocuy, Boyacá, Colombia has a wide range of climate and ecosystems due to its complex topography. Plots were sampled every 200 m from the peak of Mount Mahoma at 4,200 m a.s.l. south to the Chicamocha River canyon at 1,200 m a.s.l. Diversity and cover are analyzed in each plot from soil, rock and bark substrates. We found 80 species distributed in 29 families, with Pottiaceae and Brachytheciaceae the most diverse families. Ours results show a tendency of the diversity and the coverage to increase with altitude, and we observed five altitudinal belts with three populations defined by mosses species. The Páramo and Superpáramo belts are the richest ones.