There are few observational studies measuring the ecosystem‐scale productivity effects of changes in incident diffuse photosynthetically active radiation (PARdiffuse), especially related to wildfire smoke. Climate change‐induced increases to the duration and intensity of fire conditions have made smoke a common occurrence across western North America, with largely unquantified ecosystem feedbacks. Under equivalent amounts of radiation, increased atmospheric particulate matter could lead to a boost in productivity as scattering redistributes photons throughout multi‐layer canopies. In this work, we leverage a meso‐network of eddy covariance measurement sites across a unique array of managed and restored C3 and C4 canopy types to understand how recent wildfire smoke affected ecosystem productivity during the summer of 2018, an especially smoky year in the agriculturally productive Central Valley.
We find that PARdiffuse increased by more than a third compared to the previous growing season, while total PAR (PARtotal) was only slightly diminished. These conditions caused nearly a doubling of light use efficiency over the range of diffuse fraction observed, with the highest sensitivity to diffuse fraction exhibited by corn and alfalfa crops. We utilized an empirical model to assess the tradeoff between enhanced diffuse fraction and reduced PARtotal. Under mean radiation conditions, daily integrated gross ecosystem productivity increased by 1.2‐4.1% compared to the previous growing season. Finally, we explore the potential negative effect of heightened ozone, a co‐pollutant often associated with wildfire. In addition to the effects of wildfire smoke, the results of this natural experiment can help validate future predictions of aerosol‐productivity feedbacks.