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Differences in SOM decomposition and temperature sensitivity among soil aggregate size classes in a temperate grasslands.


ABSTRACT: The principle of enzyme kinetics suggests that the temperature sensitivity (Q10) of soil organic matter (SOM) decomposition is inversely related to organic carbon (C) quality, i.e., the C quality-temperature (CQT) hypothesis. We tested this hypothesis by performing laboratory incubation experiments with bulk soil, macroaggregates (MA, 250-2000 ?m), microaggregates (MI, 53-250 ?m), and mineral fractions (MF, <53 ?m) collected from an Inner Mongolian temperate grassland. The results showed that temperature and aggregate size significantly affected on SOM decomposition, with notable interactive effects (P<0.0001). For 2 weeks, the decomposition rates of bulk soil and soil aggregates increased with increasing incubation temperature in the following order: MA>MF>bulk soil >MI(P <0.05). The Q10 values were highest for MA, followed (in decreasing order) by bulk soil, MF, and MI. Similarly, the activation energies (Ea) for MA, bulk soil, MF, and MI were 48.47, 33.26, 27.01, and 23.18 KJ mol-1, respectively. The observed significant negative correlations between Q10 and C quality index in bulk soil and soil aggregates (P<0.05) suggested that the CQT hypothesis is applicable to soil aggregates. Cumulative C emission differed significantly among aggregate size classes (P <0.0001), with the largest values occurring in MA (1101 ?g g-1), followed by MF (976 ?g g-1) and MI (879 ?g g-1). These findings suggest that feedback from SOM decomposition in response to changing temperature is closely associated withsoil aggregation and highlights the complex responses of ecosystem C budgets to future warming scenarios.

SUBMITTER: Wang Q 

PROVIDER: S-EPMC4334239 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Differences in SOM decomposition and temperature sensitivity among soil aggregate size classes in a temperate grasslands.

Wang Qing Q   Wang Dan D   Wen Xuefa X   Yu Guirui G   He Nianpeng N   Wang Rongfu R  

PloS one 20150218 2


The principle of enzyme kinetics suggests that the temperature sensitivity (Q10) of soil organic matter (SOM) decomposition is inversely related to organic carbon (C) quality, i.e., the C quality-temperature (CQT) hypothesis. We tested this hypothesis by performing laboratory incubation experiments with bulk soil, macroaggregates (MA, 250-2000 μm), microaggregates (MI, 53-250 μm), and mineral fractions (MF, <53 μm) collected from an Inner Mongolian temperate grassland. The results showed that te  ...[more]

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