Mosses & Liverworts - Rocky Mountain National Park (U.S. National Park Service) Colony of Mosses growing on soil. NPS photo by A. Schanlou. Moss on hillside by a river NPS photo by J. Marino. Small, fleshy, green mats lie on the forest floor, cover the sides of rocks and cling to tree trunks collecting water to sustain life. Mosses and liverworts may be small in size but play a keen role in landscape evolution in the mountainous Rockies. They retain water and stabilize slopes, helping prevent erosion. Other plants living nearby benefit from water and nutrients that they collect. Because they can live in poor soil and even on rocks, they colonize disturbed and barren areas. Mosses and liverworts also provide a humid shelter to a diverse group of invertebrates.