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 l..., We 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. ,