Dew formation is associated with higher ecosystem productivity across diverse ecosystems.

Dew is a common yet often overlooked water input in terrestrial ecosystems. Current dew research is constrained to a limited number of leaf-level field measurements, leaving a key knowledge gap in how dew affects vegetation productivity at the ecosystem scale. Using eddy covariance data from the National Ecological Observatory Network from 2017 to 2022, we quantify characteristics of dew formation in the U.S. and examine their impacts on vegetation gross primary productivity across two focal ecosystem types (grasslands and forests) and climatic regions (i.e., drylands and non-drylands). We find that dew formation is significantly associated with higher gross primary productivity across grasslands, forests, drylands, and non-drylands, highlighting the ecological contribution of dew to ecosystem productivity. Although its contribution is smaller than that of major climatic predictors, higher gross primary productivity is more pronounced with longer dew duration, particularly in grasslands and drylands. Our findings demonstrate that dew plays a significant role in shaping ecosystem carbon dynamics, particularly in drylands, and is likely to have broad implications for future carbon-water feedback in a changing climate.