Influences of Root Hydraulic Redistribution on N₂O Emissions at AmeriFlux Sites

It has long been suspected that root hydraulic redistribution (HR) affects the carbon and nitrogen cycles. Nitrous oxide (N₂O) is an important greenhouse gas and is the primary stratospheric ozone-depleting substance. To our knowledge, the influences of HR on N₂O emissions have not been investigated. Here we use the HR schemes of Ryel et al. and Amenu and Kumar incorporated into CLM4.5 to examine N₂O emissions at five AmeriFlux sites. The results show that HR reduced N₂O emissions by 28–92% in the four natural ecosystems experiencing a dry season, whereas it had a very limited effect on the Corn Belt site that has strong emissions but with no distinct dry season. We hypothesize that N₂O emissions in ecosystems with a distinct dry season are likely overestimated by CENTURY-based Earth system models.