Effects of extra-extreme precipitation variability on multi-year cumulative nitrous oxide emission in a semiarid grassland

Authors: LI, L.F. - Chinese Academy Of Sciences; HAO, Y.B. - Chinese Academy Of Sciences; WANG, W.J. - Griffiths University; Biederman, Joel; ZHENG, Z.Z. - Chinese Academy Of Sciences; WANG, Y.F. - Chinese Academy Of Sciences; TUDI, M. - Queensland Department Of Environmental Science; QIAN, R.Y. - Chinese Academy Of Sciences; ZHANG, B. - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A; CHE, R.X. - Yunnan University; SONG, X.N. - Yunnan University; CUI, X.Y. - Yunnan University; XU, Z.H. - Griffiths University

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2023
Publication Date: 10/23/2023
Citation: Li, L., Hao, Y., Wang, W., Biederman, J.A., Zheng, Z., Wang, Y., Tudi, M., Qian, R., Zhang, B., Che, R., Song, X., Cui, X., Xu, Z. 2023. Effects of extra-extreme precipitation variability on multi-year cumulative nitrous oxide emission in a semiarid grassland. Agricultural and Forest Meteorology. 343. Article 109761. https://doi.org/10.1016/j.agrformet.2023.109761.
DOI: https://doi.org/10.1016/j.agrformet.2023.109761

Interpretive Summary: In many rangeland areas of the world, a widely observed change in the climate is that rainstorms are becoming less frequent, with longer dry periods between. This temporal repackaging of precipitation into fewer, sometimes larger events has unknown impacts on the release from soils of some key greenhouse gases, including nitrous oxide (N2O). Here we conducted a three-year manipulative field experiment in which a constant precipitation amount per year was repackaged into 6, 12, 18 or 24 rainstorms, representing a gradient from few/large to many/small. We detected few differences on soil N2O release during the first two summer growing seasons, but in the third year, which was the hottest, the few/large rainfall regime released much less N2O to the atmosphere. These results suggest that the combined effects of ongoing warming and a move towards fewer, larger storms may decreased the release of an important greenhouse gas.

Technical Abstract: High temporal precipitation variability, characterized by less frequent but larger-magnitude precipitation events, is increasing. However, how precipitation variability affects N2O emissions and the underlying mechanisms remain unclear, especially at multiple-year scales. We conducted a 3-year manipulative experiment in which the same long-term mean growing season precipitation total was repackaged into events of inversely varying magnitude and frequency to simulate four levels of precipitation variability (extra-extreme, extreme, medium, and normal) in a semiarid grassland. Cumulative N2O emissions was the smallest under the extra-extreme precipitation variability scenario (6 very large rainfall events), 26% less than emission under the other three treatments (10, 16, and 24 rainfall events) over the three growing seasons. However, this difference was almost entirely due to three sampling events in the third year. Plant community (biomass and biodiversity), soil abiotic properties (water, dissolved organic carbon and pH), soil microbial biomass (carbon, nitrogen and the ratio), and soil functional genes (archaeal and bacterial amoA, nirS, nirK, narG, and nosZ) explained 61% of the variation in N2O emissions in response to the precipitation variability. Structural equation modelling indicated that the precipitation variability had direct positive effects, and indirect negative effects via soil abiotic properties, on soil functional genes that ultimately had positive effects on N2O emissions. The reduction in N2O emission in the extra-extreme precipitation variability scenario in the third year was due to low levels of soil water content, soil pH, aboveground biomass, and microbial biomass carbon simultaneously. Our results suggest that at the multiyear timescale, semiarid grasslands may have negative feedbacks to future precipitation regimes with higher variability.