Bryophytes (mosses and their relatives) are important contributors to carbon cycling and storage in land ecosystems, but they are poorly represented in global climate models (Earth System Models, or ESMs). The BryoFITE project addresses this by combining new experiments with a curated trait database to better understand bryophyte physiology. A key focus is how water content influences photosynthesis across varying light, temperature, and CO₂ conditions. Unlike vascular plants, bryophytes can absorb water up to four times their dry mass, and their photosynthesis is tightly linked to their hydration level. By testing how well standard photosynthesis models (like the Farquhar model) capture these dynamics, the project reveals unique thresholds and nonlinear responses in bryophyte function. These insights will support the creation of bryophyte-specific plant functional types (PFTs) for use in ESMs, improving predictions of carbon cycling under global change.