Intensified Precipitation Seasonality Reduces Soil Inorganic N Content in a Subtropical Forest: Greater Contribution of Leaching Loss Than N 2 O Emissions

Soil nitrogen (N) loss has been predicted to intensify with increased global precipitation changes. However, the relative contributions of leaching and gaseous N emissions to intensified N losses are largely unknown. Thus, we simulated intensified precipitation seasonality in a subtropical forest by extending the dry season via rainfall exclusion and increasing the wet-season storms via irrigation without changing the total annual precipitation. Extending the dry season length increased the monthly mean soil NO 3 − content by 25%–64%, net N mineralization rate by 32%–40%, and net nitrification rate by 25%–28%. After adding water in the wet season, the monthly NO 3 − leaching was enhanced by 43% in the relatively dry year (2013, 2,094-mm annual rainfall), but reduced by 51% in the relatively wet year (2014, 1,551 mm). In contrast, the monthly mean N 2 O emissions were reduced by 24% in 2013 but increased by 78% in 2014. Overall, the annual inorganic N content was decreased significantly by the precipitation changes. Decrease of soil inorganic N might be linked to the enhanced NO 3 − leaching in 2013, and be linked to the increased N 2 O emissions in 2014. However, in both years the annual total amount of N lost through leaching was significantly greater than that through N 2 O emissions. The enhanced N 2 O emissions driven by wet-season storms were correlated with an increase in nirS abundance. Our results suggest that increased frequency of droughts and storms will decrease soil inorganic N content in warm and humid subtropical forests mainly through enhanced leaching losses. ©2019. American Geophysical Union. All Rights Reserved.

Chen J.1, 2, 3 , Kuzyakov Y. 4, 5, 6 , Jenerette G.D.7 , Xiao G.1, 3 , Liu W.1 , Wang Z.1 , Shen W.1
Blackwell Publishing Ltd
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  • 1 Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
  • 2 Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou, China
  • 3 University of Chinese Academy of Sciences, Beijing, China
  • 4 Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany
  • 5 Agro-Technology Institute, RUDN University, Moscow, Russian Federation
  • 6 Institute of Environmental Sciences, Kazan Federal University, Kazan, Russian Federation
  • 7 Department of Botany and Plant Sciences, University of California, Riverside, CA, United States
Ключевые слова
field experiment; microbial functional gene; N 2 O; nitrogen transformation; precipitation change; subtropical forest
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