Universal temperature sensitivity of denitrification nitrogen losses in forest soils

Soil nitrous oxide (N2O) and dinitrogen (N2) emissions from denitrification are crucial to the global nitrogen (N) cycle. However, the temperature sensitivities of gaseous N losses in forest soils are poorly understood, limiting our ability to predict N cycling responses to global warming. We quantified temperature sensitivities (Q10) of denitrification-derived potential N2O and N2 production ex-situ for 18 forest soils across China. N2O and N2 production rates increased exponentially with temperature, showing large variation among soils. By contrast, the Q10 values for N2O (2.1±0.5) and N2 (2.6±0.6) were surprisingly similar across soils. N2 was more sensitive to temperature than N2O, suggesting warming could promote complete denitrification. The Q10 values for denitrification (2.3±0.5) were similar to those reported for aquatic sediments. Collectively, our results indicate a universal temperature sensitivity of gaseous N losses from denitrification, which will facilitate modelling N losses in response to warming on the global scale.Funding provided by: National Natural Science Foundation of ChinaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001809Award Number: 41773094, 31600358Funding provided by: K. C. Wong Education FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100012692Award Number: GJTD-2018-07Funding provided by: National Key Research and Development Program of ChinaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100012166Award Number: 2016YFA0600802Funding provided by: Research and Development Project of Scientific Instruments and Equipment of Chinese Academy of Sciences*Crossref Funder Registry ID: Award Number: YJKYYQ20190054Funding provided by: Liaoning Vitalization Talents Program*Crossref Funder Registry ID: Award Number: XLYC1902016Funding provided by: Youth Innovation Promotion Association CASCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100004739Award Number: 2021195We conducted laboratory incubation experiments with soils from 18 forest sites across China along a 4000 km south-north transect spanning a 33° latitudinal range. The soils were anaerobically incubated between 5 and 35°C for 12 h after amending them with Na15NO3 (99.26 atom%). Next, the production of N2O and N2 as well as the consumption of nitrate (NO3-) were measured. In addition, we also measured several chemical and biological soil variables of potential importance for denitrification, such as pH, C/N ratio, water extractable organic carbon (WEOC), and functional genes (nirK, nirS, nosZ) abundance associated with gaseous N production