The underappreciated roles of fog and dew on vegetation and biocrusts

Fog and dew represent minor components of ecosystem water budgets in most ecosystems. However, fog and dew can play an essential role in ecosystem dynamics and are particularly important for water-limited systems. In addition to serving as direct water inputs, fog and dew can influence microclimate and water redistribution, thereby promoting the retention of fog and dew water near the canopy/soil surface and benefiting plants and soil microbes. In this review, we highlight recent advances in fog and dew research, emphasizing measurement approaches and the quantitative impacts of fog and dew on plant-soil functions, particularly at large scales. We focus on multiple plant functional types and biogeological soil crusts, as well as multiple spatiotemporal scales (i.e. from individual plants to the regional scale) of fog and dew research. We further highlight key knowledge gaps, including the scarcity of fog and dew-monitoring data, the quantitative role of fog and dew in mediating ecosystem water stress, the mechanisms by which they affect plant-soil processes, and their responses to a changing climate. A better understanding and quantification of the contributions of fog and dew to ecosystem functions are crucial for predicting ecosystem responses and feedback to changing climates, especially in global drylands.