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Research Project: Understanding Water-Driven Ecohydrologic and Erosion Processes in the Semiarid Southwest to Improve Watershed Management

Location: Southwest Watershed Research Center

Title: Joint control by soil moisture, functional genes and substrates on response of N2O flux to climate extremes in a semiarid grassland

Author
item LI, L.F. - Chinese Academy Of Sciences
item HAO, Y.B. - Chinese Academy Of Sciences
item WANG, W.J. - Griffiths University
item Biederman, Joel
item WANG, Y.F. - University Of Chinese Academy Of Sciences
item ZHENG, Z.Z. - University Of Chinese Academy Of Sciences
item WEN, F. - University Of Chinese Academy Of Sciences
item QIAN, R - University Of Chinese Academy Of Sciences
item ZHANG, B. - Griffiths University
item SONG, X.N. - Griffiths University
item CUI, X.Y. - University Of Chinese Academy Of Sciences
item XU, Z.H. - Griffiths University

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2022
Publication Date: 2/4/2022
Publication URL: https://handle.nal.usda.gov/10113/7663249
Citation: Li, L., Hao, Y., Wang, W., Biederman, J.A., Wang, Y., Zheng, Z., Wen, F., Qian, R., Zhang, B., Song, X., Cui, X., Xu, Z. 2022. Joint control by soil moisture, functional genes and substrates on response of N2O flux to climate extremes in a semiarid grassland. Agricultural and Forest Meteorology. 316. Article 108854. https://doi.org/10.1016/j.agrformet.2022.108854.
DOI: https://doi.org/10.1016/j.agrformet.2022.108854

Interpretive Summary: Nitrous oxide (N2O) is a key greenhouse gas which is more than 250 times as potent as the more well-studied carbon dioxide (CO2). Agroecosystem emission of N2O to the atmosphere by soil microbes is likely to be impacted increasingly by frequent and severe climate extremes including drought and heat waves. Here we experimentally imposed drought, heat wave, and their combination (hot drought) over semiarid grassland plots. We found that N2O emissions were rapidly curtailed by drought due to decreased soil moisture and nutrient availability for soil microbes. However, emissions returned quickly to normal after drought ended, indicating resilience. Heat waves alone or in combination with drought had relatively little impact, suggesting that soil water availability is the primary control on N2O emissions.

Technical Abstract: Nitrous oxide (N2O), the third most important greenhouse gas, contributes to the increasing frequency and severity of climate extremes. Disentangling feedbacks of climate extremes on terrestrial N2O emission is important for forecasting future climate changes. Here, we experimentally imposed extreme drought and heat wave events during three years in a semiarid grassland to investigate the resistance and resilience of N2O flux to individual and combined climate extremes and elicit the underlying mechanisms. N2O emission was suppressed during the droughts. Meanwhile, drought reduced soil water content (SWC), microbial biomass carbon (MBC), soil inorganic nitrogen (SIN) and dissolved organic carbon (DOC) contents, and the abundance of archaeal amoA, nirK, and narG. Upon rewetting following drought, the SIN, DOC, soil functional genes, and resultant N2O emission completely recovered to the magnitude of the ambient control. In contrast, heat waves alone or in combination with drought had little impact on N2O fluxes or the underlying physical, chemical and microbial states. Our results suggest that N2O fluxes therefore had low resistance but high resilience to droughts while N2O fluxes were resistant to heat wave alone or in combination with drought. Additionally, soil water content induced changes in C and N substrates and the community size of soil functional microorganisms jointly influenced N2O responses to climate extremes.