TY  - JOUR
A1  - Milcu, Alexandru
A1  - Heim, Angela
A1  - Ellis, Richard J.
A1  - Scheu, Stefan
A1  - Manning, Pete
T1  - Identification of general patterns of nutrient and labile carbon control on soil carbon dynamics across a successional gradient
T2  - Ecosystems
N2  - Carbon (C) inputs and nutrient availability are known to affect soil organic carbon (SOC) stocks. However, general rules regarding the operation of these factors across a range of soil nutrient availabilities and substrate qualities are unidentified. "Priming" (stimulated decomposition by labile C inputs) and 'preferential substrate utilization' (retarded decomposition due to shifts in community composition towards microbes that do not mineralize SOC) are two hypotheses to explain effects of labile C additions on SOC dynamics. For effects of nutrient additions (nitrogen and phosphorus) on SOC dynamics, the stoichiometric (faster decomposition of materials of low carbon-to-nutrient ratios) and 'microbial mining' (that is, reduced breakdown of recalcitrant C forms for nutrients under fertile conditions) hypotheses have been proposed. Using the natural gradient of soil nutrient availability and substrate quality of a chronosequence, combined with labile C and nutrient amendments, we explored the support for these contrasting hypotheses. Additions of labile C, nitrogen (N), phosphorus (P), and combinations of C and N and C and P were applied to three sites: 2-year fallow grassland, mature grassland and forest, and the effects of site and nutrient additions on litter decomposition and soil C dynamics were assessed. The response to C addition supported the preferential substrate hypothesis for easily degradable litter C and the priming hypothesis for SOC, but only in nitrogen-enriched soils of the forest site. Responses to N addition supported the microbial mining hypothesis irrespective of C substrate (litter or SOC), but only in the forest site. Further, P addition effects on SOC support the stoichiometric hypothesis; P availability appeared key to soil C release (priming) in the forest site if labile C and N is available. These results clearly link previously contrasting hypotheses of the factors controlling SOC with the natural gradient in litter quality and nutrient availability that exists in ecosystems at different successional stages. A holistic theory that incorporates this variability of responses, due to different mechanisms, depending on nutrient availability and substrate quality is essential for devising management strategies to safeguard soil C stocks.
KW  - carbon sequestration
KW  - priming effect
KW  - microbial mining
KW  - succession
KW  - microorganisms
KW  - litter decomposition
Y1  - 2011
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/36723
SN  - 1432-9840
VL  - 14
IS  - 5
SP  - 710
EP  - 719
PB  - Springer
CY  - New York
ER  -