Mosses play a crucial role in forest ecosystems by regulating hydrological processes, particularly in semi-arid regions where water retention is vital for ecological stability. Despite their significance, limited research has quantified their water-holding capacity at a landscape scale. This study evaluates the water retention potential of moss species in Eldivan Mountain, T & uuml;rkiye, a region subject to reforestation efforts following a catastrophic flood in 1952. The analysis revealed a total net water-holding capacity of approximately 46 150 631 liters across the 4200-hectare study area. The epiphytic moss Lewinskya affinis (Brid.) F. Lara, Garilleti & Goffinet could hold the most water, up to 3 502 893 liters. The forest floor species Abietinella abietina (Hedw.) M. Fleisch., on the other hand, could hold the most water, 18 349 333 liters. It's worth mentioning that mosses could hold about 13.5 times their dry weight in water, which is much higher than the normal 8-10x range for mosses. Some species were even able to hold up to 200-300 times their dry weight. These results show how important mosses are for storing water in forests and suggest that they might be able to help protect against soil erosion and flooding in semi-arid areas. Future research should explore the impact of environmental stressors, such as air pollution and climate change, on moss water retention dynamics.