Opposite priming responses to labile carbon versus oxygen pulses in anoxic peat

IF 9.8 1区 农林科学 Q1 SOIL SCIENCE
Namid Krüger, Klaus-Holger Knorr, Peter Mueller
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引用次数: 0

Abstract

Vegetation shifts in peatlands might change the stability of soil organic carbon (SOC) stocks via rhizosphere priming effects. However, mechanisms and magnitude of priming effects in peat soils are poorly understood. Beyond supplying C-rich root exudates - a central driver of priming in upland soils - wetland vascular plants supply oxygen to reducing soil systems.We evaluated priming effects in anoxic peat soils driven by labile C-exudate inputs (glucose), oxygen inputs and their interaction. Using incubation experiments, we mimicked oxygen loss and exudation rates of wetland plants and separated peat SOC- and glucose-derived respiration rates using a C stable isotope approach.Oxygen pulses and oxygen + glucose pulses stimulated SOC mineralization through positive priming of > + 350% and > + 200%, respectively. By contrast, glucose pulses alone caused negative priming, with the most negative effect (< - 70%) at maximum glucose input. However, even glucose-C inputs smaller than the estimated microbial biomass C led to negative or no priming. Both positive and negative priming effects continued for several weeks after inputs stopped and increased in magnitude.We demonstrate that labile C inputs into an anoxic soil can strongly suppress SOC mineralization, in contrast to positive priming effects often observed in oxic upland soils. We hypothesize that negative priming driven by preferential substrate usage is amplified in anoxic soils due to electron-acceptor exhaustion through exudate-fueled respiration. Our results imply that expansion of vascular plants into peatlands could stimulate SOC mineralization through root oxygen loss, while labile C-inputs might stabilize SOC.

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来源期刊
Soil Biology & Biochemistry
Soil Biology & Biochemistry 农林科学-土壤科学
CiteScore
16.90
自引率
9.30%
发文量
312
审稿时长
49 days
期刊介绍: Soil Biology & Biochemistry publishes original research articles of international significance focusing on biological processes in soil and their applications to soil and environmental quality. Major topics include the ecology and biochemical processes of soil organisms, their effects on the environment, and interactions with plants. The journal also welcomes state-of-the-art reviews and discussions on contemporary research in soil biology and biochemistry.
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