Chin J Plant Ecol ›› 2021, Vol. 45 ›› Issue (9): 1006-1023.DOI: 10.17521/cjpe.2021.0040

• Research Articles • Previous Articles     Next Articles

Influencing factors of soil nitrous oxide emission during freeze-thaw cycles

GAO De-Cai, BAI E()   

  1. Key Laboratory of Geographical Processes and Ecological Security of Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China
  • Received:2021-01-29 Accepted:2021-05-09 Online:2021-09-20 Published:2021-11-18
  • Contact: BAI E
  • Supported by:
    National Key R&D Program of China(2019YFA0607301);National Natural Science Foundation of China(31901157);National Natural Science Foundation of China(41971058);China Postdoctoral Science Foundation(2020T130088);Natural Science Foundation of Jilin Province, China(YDZJ202101ZYTS104);Natural Science Foundation of Jilin Province, China(20180520087JH)


Aims Enhanced duration, intensity, and frequency of freeze-thaw cycles owing to global climate change may significantly affect soil nitrous oxide (N2O) emission. N2O is an important greenhouse gas, but our current understanding of soil N2O emission and its influencing factors during freeze-thaw cycles is still limited.

Methods Here, we adopted the meta-analysis method and collected 30 articles on the effects of freeze-thaw cycles on soil N2O flux and cumulative emission from peer-reviewed journal articles. Our objectives were to explore the effects of freeze-thaw cycles on N2O emissions in different ecosystems and to comprehensively explore the influencing factors from the perspectives of experimental settings, soil physical and chemical properties, and the patterns of freeze-thaw cycles.

Important findings Results showed that freeze-thaw cycles significantly increased N2O instantaneous emission, cumulative emission, and nitrification by 72.34%, 143.25%, and 124.63%, respectively. Freeze-thaw cycles also increased denitrification by 162.56%. Conversely, freeze-thaw cycles significantly decreased microbial biomass nitrogen by 6.39%. The effect of freeze-thaw cycles on N2O emission was significantly affected by the variations in soil microclimate and soil physical and chemical properties in different ecosystems. When the mean annual temperature (MAT) of a site exceeded 5 °C, freeze-thaw cycles could significantly enhance the N2O flux by 104.13%, which was significantly higher than that the effect at sites with MAT between 0-5 °C (25.56%) or less than 0 °C (55.29%). When soil moisture was greater than 70%, the increase of soil N2O flux caused by freeze-thaw cycles was 109.17%, which was significantly higher than that when soil moisture was between 50%-70% (65.67%) or less than 50% (20.37%). The higher soil clay and nutrient contents were, the greater the increase in N2O emission caused by freeze-thaw cycles became. Freeze-thaw cycles could significantly increase soil N2O flux by 91.21% in the presence of plants, which was higher than the effect in the absence of plants (54.43%). The impact of freeze-thaw cycles on N2O emission could be enhanced by soil sieving. In addition, soils sampled during the freeze-thaw cycling period showed more responses to freeze-thaw cycles than soils sampled during other times. The response of cumulative N2O emissions to freeze-thaw cycles was significantly improved by longer duration of thawing, higher intensity of freezing, and higher frequency of freeze-thaw cycles. When the freezing temperature was lower than -10 °C, freeze-thaw cycles could enhance soil N2O flux by 100.73%, which was significantly higher than the effect when the freezing temperature was between -10- -5 °C (47.74%) or more than -5 °C (70.25%). The main reason was that higher intensity of freezing could promote the release of more nutrients from soil microorganisms and soil structure, thereby increasing the production and emission of N2O. Overall, these results can help better understand the response of soil N2O to freeze-thaw cycles and its influencing factors, and provide scientific data for accurately predicting the impact of global climate change on N2O emission in the future.

Key words: freeze-thaw, nitrous oxide (N2O), microbial biomass, global climate change, denitrification