Studying bryophyte diversity in the high Arctic, like Svalbard, is vital due to their resilience in extreme conditions. Mosses are pioneers in colonizing newly exposed areas, offering insight into ecosystem health. They act as carbon sinks and regulate the hydrological cycle, which is crucial for ecosystem processes. They also host a large number of species, creating a microecosystem often called the bryosphere. Understanding how these plants adapt to climate change is essential for predicting broader ecosystem changes. However, limited knowledge exists due to their small size and lack of taxonomical knowledge. Shifts in vegetation cover and changes in ecological traits, as well as in the bryosphere food web can serve as early indicators of environmental shifts, making mosses valuable for monitoring Arctic ecosystem health. Ongoing fieldwork at the ITEX site in Endalen, which includes experimental warming, will help unravel their ecological significance. This project is connected to the RiS project "International Tundra Experiment in Svalbard – Endalen" aiming to understand climate change's impact on bryophyte diversity and tundra ecosystems.