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Universal temperature sensitivity of denitrification nitrogen losses in forest soils

Citation

Yu, Haoming et al. (2022), Universal temperature sensitivity of denitrification nitrogen losses in forest soils, Dryad, Dataset, https://doi.org/10.5061/dryad.hqbzkh1jg

Abstract

Soil nitrous oxide (N2O) and nitrogen gas (N2) produced from denitrification are crucial components of the global nitrogen cycle and contribute to nitrogen limitation in terrestrial ecosystems. However, the temperature sensitivity of these gaseous N losses and their underlying processes in forest soils are poorly constrained, limiting our ability to predict nitrogen cycling responses to global warming. Here, we quantify temperature sensitivities (expressed as Q10) of denitrification N2O and N2 production in 18 forest soils across China and explore their major driving factors in an incubation experiment, using the 15N labelling technique (applying Na15NO3). Soils span a wide climate gradient ranging from -5.4 to 21.5°C mean annual temperature. N2O and N2 production rates showed a positive exponential relationship with incubation temperature, with a large variation in absolute rates between soils. By contrast, Q10 values for N2O and N2 production were surprisingly similar among soils, in most cases ranging from 1.7 to 3.0 (2.1 ± 0.1, mean ± one standard error) for N2O production, 2 to 3.6 (2.6 ± 0.1) for N2 production and 1.7 to 3.0 (2.3 ± 0.1) for denitrification (N2O +N2 production). The Q10values were not related to any of the studied soil microbial and chemical variables, nor to climate and latitude of the forest sites. The Q10 values for denitrification were similar to those reported for aquatic sediments. Collectively, these results indicate a universal temperature sensitivity of gaseous nitrogen losses from denitrification. The presented data will facilitate modelling nitrogen losses in response to global warming at the global scale. 

Methods

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. 

Funding

National Natural Science Foundation of China, Award: 41773094

National Natural Science Foundation of China, Award: 31800412

National Natural Science Foundation of China, Award: 31770498