Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments
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Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments. / Rousk, Kathrin; Michelsen, Anders; Rousk, Johannes.
I: Global Change Biology, Bind 22, Nr. 12, 2016, s. 4150-4161.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments
AU - Rousk, Kathrin
AU - Michelsen, Anders
AU - Rousk, Johannes
N1 - CENPERM[2016]
PY - 2016
Y1 - 2016
N2 - Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed ‘priming’. We investigated how warming (+1.1 °C over ambient using open top chambers) and litter addition (90 g m−2 yr−1) treatments in the subarctic influenced the susceptibility of SOM mineralization to priming, and its microbial underpinnings. Labile C appeared to inhibit the mineralization of C from SOM by up to 60% within hours. In contrast, the mineralization of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile C inhibited C mineralization is compatible with previously reported findings termed ‘preferential substrate utilization’ or ‘negative apparent priming’, while the stimulated N mineralization responses echo recent reports of ‘real priming’ of SOM mineralization. However, C and N mineralization responses derived from the same SOM source must be interpreted together: This suggested that the microbial SOM-use decreased in magnitude and shifted to components richer in N. This finding highlights that only considering SOM in terms of C may be simplistic, and will not capture all changes in SOM decomposition. The selective mining for N increased in climate change treatments with higher fungal dominance. In conclusion, labile C appeared to trigger catabolic responses of the resident microbial community that shifted the SOM mining to N-rich components; an effect that increased with higher fungal dominance. Extrapolating from these findings, the predicted shrub expansion in the subarctic could result in an altered microbial use of SOM, selectively mining it for N-rich components, and leading to a reduced total SOM-use.
AB - Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed ‘priming’. We investigated how warming (+1.1 °C over ambient using open top chambers) and litter addition (90 g m−2 yr−1) treatments in the subarctic influenced the susceptibility of SOM mineralization to priming, and its microbial underpinnings. Labile C appeared to inhibit the mineralization of C from SOM by up to 60% within hours. In contrast, the mineralization of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile C inhibited C mineralization is compatible with previously reported findings termed ‘preferential substrate utilization’ or ‘negative apparent priming’, while the stimulated N mineralization responses echo recent reports of ‘real priming’ of SOM mineralization. However, C and N mineralization responses derived from the same SOM source must be interpreted together: This suggested that the microbial SOM-use decreased in magnitude and shifted to components richer in N. This finding highlights that only considering SOM in terms of C may be simplistic, and will not capture all changes in SOM decomposition. The selective mining for N increased in climate change treatments with higher fungal dominance. In conclusion, labile C appeared to trigger catabolic responses of the resident microbial community that shifted the SOM mining to N-rich components; an effect that increased with higher fungal dominance. Extrapolating from these findings, the predicted shrub expansion in the subarctic could result in an altered microbial use of SOM, selectively mining it for N-rich components, and leading to a reduced total SOM-use.
KW - bacterial growth
KW - biogeochemistry
KW - fungal growth
KW - microbial ecology
KW - nitrogen cycling
KW - nitrogen limitation
KW - soil carbon sequestration
KW - the priming effect
U2 - 10.1111/gcb.13296
DO - 10.1111/gcb.13296
M3 - Journal article
C2 - 27010358
AN - SCOPUS:84995704288
VL - 22
SP - 4150
EP - 4161
JO - Global Change Biology
JF - Global Change Biology
SN - 1354-1013
IS - 12
ER -
ID: 169731970