Plant-bacteria-soil response to frequency of simulated nitrogen deposition has implications for global ecosystem change

Atmospheric nitrogen (N) deposition, generally, has been simulated through a single or relatively few N applications per year for its ecological effect study. Despite the importance of timing in ecosystem processes, ecological experiments with more realistic N addition frequencies are rare.
We employed a novel design with typical twice (2X) vs. atypical monthly (12X) N applications per year to explore effects of N addition frequency on above- and below-ground biodiversity and function.
Each year, several response variables from either belowground or aboveground growth, N status and cycling, or plant and bacterial diversity differed as a result of N addition frequency. BNPP showed a large frequency effect in the relatively moist year but not in the dry year. Nitrogen addition decreased root growth in the monthly relative to the biannual applications, which could be highly consequential for predicting changes in global carbon and nitrogen cycling. Simulated N deposition tended to ...