The Ecological Role of Mosses in Green Roof Systems : A Systematic Review

Sammanfattning

Green roofs are widely used on urban infrastructure, valued for their roles in stormwater management, temperature regulation, and habitat provision. While most research has focused on vascular plants, particularly Sedum species, mosses (bryophytes) remain comparatively understudied despite their frequent presence and ecological potential on extensive green roofs. This systematic literature review synthesizes findings from 37 peer-reviewed studies to assess the functional role of mosses in green roof ecosystems. It addresses five research questions concerning moss establishment, interactions with substrate properties, hydrological performance, growth form differences (acrocarpous vs. pleurocarpous), and interactions with vascular vegetation. Results reveal that mosses are not only frequent colonizers but also modify substrate conditions by enhancing moisture retention, reducing erosion, and buffering temperature extremes. Their poikilohydric physiology enables high water-holding capacity and rapid rehydration, contributing significantly to stormwater management. Growth form emerged as a critical functional trait, with acrocarpous species dominating in dry, exposed environments, while pleurocarpous species perform better under stable moisture conditions. Moss-vascular plant interactions were found to be highly context-dependent, shaped by substrate, microclimate, and species traits. Despite growing interest in bryophytes on green roofs, gaps remain in trait-based species selection, long-term performance data, and experimental studies of plant-plant interactions. This review provides a foundation for more intentional integration of mosses into green roof design and calls for expanded research to optimize their ecological function and practical application.