Nitrogen Availability and Changes in Precipitation Alter Microbially Mediated NO and NO Emissions From a Pinyon-Juniper Dryland.
Sharon Zhao, Alexander H Krichels, Elizah Z Stephens, Anthony D Calma, Emma L Aronson, G Darrel Jenerette, Marko J Spasojevic, Joshua P Schimel, Erin J Hanan, Peter M Homyak
Author Information
Sharon Zhao: Department of Environmental Sciences, University of California, Riverside, California, USA. ORCID
Alexander H Krichels: Department of Environmental Sciences, University of California, Riverside, California, USA. ORCID
Elizah Z Stephens: Department of Environmental Sciences, University of California, Riverside, California, USA. ORCID
Anthony D Calma: Department of Environmental Sciences, University of California, Riverside, California, USA.
Emma L Aronson: Department of Microbiology and Plant Pathology, University of California, Riverside, California, USA. ORCID
G Darrel Jenerette: Department of Botany and Plant Sciences, University of California, Riverside, California, USA. ORCID
Marko J Spasojevic: Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA. ORCID
Joshua P Schimel: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California, USA. ORCID
Erin J Hanan: Department of Natural Resources & Environmental Science, University of Nevada, Reno, Nevada, USA. ORCID
Peter M Homyak: Department of Environmental Sciences, University of California, Riverside, California, USA. ORCID
Climate change is altering precipitation regimes that control nitrogen (N) cycling in terrestrial ecosystems. In ecosystems exposed to frequent drought, N can accumulate in soils as they dry, stimulating the emission of both nitric oxide (NO; an air pollutant at high concentrations) and nitrous oxide (NO; a powerful greenhouse gas) when the dry soils wet up. Because changes in both N availability and soil moisture can alter the capacity of nitrifying organisms such as ammonia-oxidizing bacteria (AOB) and archaea (AOA) to process N and emit N gases, predicting whether shifts in precipitation may alter NO and NO emissions requires understanding how both AOA and AOB may respond. Thus, we ask: How does altering summer and winter precipitation affect nitrifier-derived N trace gas emissions in a dryland ecosystem? To answer this question, we manipulated summer and winter precipitation and measured AOA- and AOB-derived N trace gas emissions, AOA and AOB abundance, and soil N concentrations. We found that excluding summer precipitation increased AOB-derived NO emissions, consistent with the increase in soil N availability, and that increasing summer precipitation amount promoted AOB activity. Excluding precipitation in the winter (the most extreme water limitation we imposed) did not alter nitrifier-derived NO emissions despite N accumulating in soils. Instead, nitrate that accumulated under drought correlated with high NO emission via denitrification upon wetting dry soils. Increases in the timing and intensity of precipitation that are forecasted under climate change may, therefore, influence the emission of N gases according to the magnitude and season during which the changes occur.
