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Warming promotes loss of subsoil carbon through accelerated degradation of plant-derived organic matter

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Ofiti Nicholas O.E., Zosso Cyrill U., Soong Jennifer L., Solly Emily F., Torn Margaret S., Wiesenberg Guido L.B., Schmidt Michael W.I.,
Project When trees die: Understanding how plants and microbes interact and influence soil biogeochemical processes
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Original article (peer-reviewed)

Journal Soil Biology and Biochemistry
Volume (Issue) 156
Page(s) 108185 - 108185
Title of proceedings Soil Biology and Biochemistry
DOI 10.1016/j.soilbio.2021.108185

Open Access

URL http://doi.org/10.1016/j.soilbio.2021.108185
Type of Open Access Publisher (Gold Open Access)

Abstract

Increasing global temperatures have the potential to stimulate decomposition and alter the composition of soil organic matter (SOM). However, questions remain about the extent to which SOM quality and quantity along the soil profile may change under future warming. In this study we assessed how +4 °C whole-soil warming affected the quantity and quality of SOM down to 90 cm depth in a mixed-coniferous temperate forest using biomarker analyses. Our findings indicate that 4.5 years of soil warming led to divergent responses in subsoils (>20 cm) as compared to surface soils. Warming enhanced the accumulation of plant-derived n-alkanes over the whole soil profile. In the subsoil, this was at the expense of plant- and microorganism-derived fatty acids, and the relative abundance of SOM molecular components shifted from less microbially transformed to more transformed organic matter. Fine root mass declined by 24.0 ± 7.5% with warming over the whole soil profile, accompanied by reduced plant-derived inputs and accelerated decomposition of aromatic compounds and plant-derived fatty acids in the subsoils. Our study suggests that warming accelerated microbial decomposition of plant-derived inputs, leaving behind more degraded organic matter. The non-uniform, and depth dependent SOM composition and warming response implies that subsoil carbon cycling is as sensitive and complex as in surface soils.
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