Climate change effects on the stability and chemistry of soil organic carbon pools in a subalpine grassland

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• 作者：Jérémy Puissant ; Robert T. E. Mills ; Bjorn J. M. Robroek…
• 关键词：Water extractable organic carbon ; Particulate organic matter ; Mineral associated organic matter ; Infrared spectroscopy ; 3D fluorescence spectroscopy
• 刊名：Biogeochemistry
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：132
• 期：1-2
• 页码：123-139
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Biogeosciences; Ecosystems; Environmental Chemistry; Life Sciences, general;
• 出版者：Springer International Publishing
• ISSN：1573-515X
• 卷排序：132

文摘

Mountain soils stock large quantities of carbon as particulate organic matter that may be highly vulnerable to climate change. To explore potential shifts in soil organic matter (SOM) form and stability under climate change (warming and reduced precipitations), we studied the dynamics of SOM pools of a mountain grassland in the Swiss Jura as part of a climate manipulation experiment. The climate manipulation (elevational soil transplantation) was set up in October 2009 and simulated two realistic climate change scenarios. After 4 years of manipulation, we performed SOM physical fractionation to extract SOM fractions corresponding to specific turnover rates, in winter and in summer. Soil organic matter fraction chemistry was studied with ultraviolet, 3D fluorescence, and mid-infrared spectroscopies. The most labile SOM fractions showed high intra-annual dynamics (amounts and chemistry) mediated via the seasonal changes of fresh plant debris inputs and confirming their high contribution to the microbial loop. Our climate change manipulation modified the chemical differences between free and intra-aggregate organic matter, suggesting a modification of soil macro-aggregates dynamics. Interestingly, the 4-year climate manipulation affected directly the SOM dynamics, with a decrease in organic C bulk soil content, resulting from significant C-losses in the mineral-associated SOM fraction (MAOM), the most stable form of SOM. This SOC decrease was associated with a decrease in clay content, above- and belowground plants biomass, soil microbial biomass and activity. The combination of these climate changes effects on the plant–soil system could have led to increase C-losses from the MAOM fraction through clay-SOM washing out and DOC leaching in this subalpine grassland.