The effect of a freeze–thaw cycle on dissolved nitrogen dynamics and its relation to dissolved organic matter and soil microbial biomass in the soil of a northern hardwood forest
Autor: | Tsunehiro Watanabe, Takuo Hishi, Ryunosuke Tateno, Hiroto Toda, Tomoki Oda, Shogo Imada, Rieko Urakawa, Kazuo Isobe, Nanae Hosokawa, Yoshiyuki Inagaki, Karibu Fukuzawa, Hideaki Shibata, Takahiro Sasai |
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Rok vydání: | 2019 |
Předmět: |
Biogeochemical cycle
010504 meteorology & atmospheric sciences 04 agricultural and veterinary sciences Mineralization (soil science) complex mixtures 01 natural sciences Environmental chemistry Soil water Dissolved organic carbon 040103 agronomy & agriculture 0401 agriculture forestry and fisheries Environmental Chemistry Environmental science Nitrification Ecosystem Leaching (agriculture) Water content 0105 earth and related environmental sciences Earth-Surface Processes Water Science and Technology |
Zdroj: | Biogeochemistry. 142:319-338 |
ISSN: | 1573-515X 0168-2563 |
Popis: | Recent global warming models project a significant change in winter climate over the next few decades. The decrease in snowpack in the winter will decrease the heat insulation function of the snowpack, resulting in increased soil freeze–thaw cycles. Here, we examined the impact of winter freeze–thaw cycles on year-round dissolved nitrogen (N) and carbon (C) dynamics and their relationship with dissolved organic matter and microbial biomass in soil by conducting an in situ experimental reduction in snowpack. We investigated dissolved inorganic N (NH4+ and NO3−), dissolved organic N (DON), dissolved organic carbon (DOC), inorganic N leaching, soil microbial biomass, and microbial activities (mineralization and nitrification) in the surface soil of a northern hardwood forest located in Japan. Experimental snowpack reduction significantly increased the number of soil freeze–thaw cycles and soil frost depth. The NH4+ content of the surface soil was significantly increased by the amplified soil freeze–thaw cycles due to decreased snowpack, while the soil NO3– content was unchanged or decreased slightly. The gravimetric soil moisture, DON and DOC contents in soil and soil microbial biomass significantly increased by the snowpack removal in winter. Our results suggest that the amplified freeze–thaw cycles in soil increase the availability of DON and DOC for soil microbes due to an increase in soil freezing. The increases in both DON and DOC in winter contributed to the enhanced growth of soil microbes, resulting in the increased availability of NH4+ in winter from net mineralization following an increase in soil freeze–thaw cycles. Our study clearly indicated that snow reduction significantly increased the availability of dissolved nitrogen and carbon during winter, caused by increased soil water content due to freeze–thaw cycles in winter. |
Databáze: | OpenAIRE |
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