Comprehensive increase in CO<sub>2</sub> release by drying–rewetting cycles among Japanese forests and pastureland soils and exploring predictors of increasing magnitude
<p>It is still difficult to precisely quantify and predict the effects of drying–rewetting cycles (DWCs) on soil carbon dioxide (<span class="inline-formula">CO<sub>2</sub></span>) release due to the paucity of studies using constant moisture conditions equiva...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-01-01
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| Series: | SOIL |
| Online Access: | https://soil.copernicus.org/articles/11/35/2025/soil-11-35-2025.pdf |
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| Summary: | <p>It is still difficult to precisely quantify and predict the effects of drying–rewetting cycles (DWCs) on soil carbon dioxide (<span class="inline-formula">CO<sub>2</sub></span>) release due to the paucity of studies using constant moisture conditions equivalent to the mean water content during DWC incubation. The present study was performed to evaluate overall trends in the effects of DWCs on <span class="inline-formula">CO<sub>2</sub></span> release and to explore environmental and soil predictors for variations in the effect size in 10 Japanese forests and pastureland soils variously affected by volcanic ash during their pedogenesis. Over an 84 d incubation period including three DWCs, <span class="inline-formula">CO<sub>2</sub></span> release was 1.3- to 3.7-fold greater than under continuous constant moisture conditions (<span class="inline-formula"><i>p</i><0.05</span>) with the same mean water content as in the DWC incubations. Analysis of the relations between this increasing magnitude of <span class="inline-formula">CO<sub>2</sub></span> release by DWCs (IF<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="35d0ef4c1024065a846229745b188a25"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-11-35-2025-ie00001.svg" width="18pt" height="10pt" src="soil-11-35-2025-ie00001.png"/></svg:svg></span></span>) and various environmental and soil properties revealed significant positive correlations between IF<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="63e67ec2b1b20349090e8dc0af598eb8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-11-35-2025-ie00002.svg" width="18pt" height="10pt" src="soil-11-35-2025-ie00002.png"/></svg:svg></span></span> and soil organo-metal complex contents (<span class="inline-formula"><i>p</i><0.05</span>), especially pyrophosphate-extractable aluminum (Alp) content (<span class="inline-formula"><i>r</i>=0.74</span>). Molar ratios of soil total carbon (C) and pyrophosphate-extractable C (Cp) to Alp contents and soil-carbon-content-specific <span class="inline-formula">CO<sub>2</sub></span> release rate under continuous constant moisture conditions (q<span class="inline-formula">CO<sub>2</sub></span>_soc) were also correlated with IF<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="63135e49ad21d2214c8c451dfba1e14b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-11-35-2025-ie00003.svg" width="18pt" height="10pt" src="soil-11-35-2025-ie00003.png"/></svg:svg></span></span> (<span class="inline-formula"><i>p</i><0.05</span>). The covariations among Alp, total Cp<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M16" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c6f00d13d95b9183e3e2526db4298e27"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-11-35-2025-ie00004.svg" width="8pt" height="14pt" src="soil-11-35-2025-ie00004.png"/></svg:svg></span></span>Alp, and Cp<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M17" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="a3a809672b156f3719eee3cbaf593ee5"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-11-35-2025-ie00005.svg" width="8pt" height="14pt" src="soil-11-35-2025-ie00005.png"/></svg:svg></span></span>Alp molar ratios and q<span class="inline-formula">CO<sub>2</sub></span>_soc suggested Alp to be the primary predictor of IF<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="99efa2ded52cb90a031e056655c2d973"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-11-35-2025-ie00006.svg" width="18pt" height="10pt" src="soil-11-35-2025-ie00006.png"/></svg:svg></span></span>. Additionally, soil microbial biomass C and nitrogen (N) levels were significantly lower in DWCs than under continuous constant moisture conditions, whereas there was no significant relation between the microbial biomass decrease and IF<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M20" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="7ac8ca304302b1757f1753dcdfec3031"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="soil-11-35-2025-ie00007.svg" width="18pt" height="10pt" src="soil-11-35-2025-ie00007.png"/></svg:svg></span></span>. The present study showed a comprehensive increase in soil <span class="inline-formula">CO<sub>2</sub></span> release by DWC in Japanese forests and pastureland soils, suggesting that Alp is a predictor of the effect size, likely due to vulnerability of organo-Al complexes to DWC.</p> |
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| ISSN: | 2199-3971 2199-398X |