Fast mineralization of land-born C in inland waters: first experimental evidences of aquatic priming effect

Guenet, Bertrand; Danger, Michaël; Harrault, Loïc; Allard, Bruno; Jauset-Alcala, Marta; Bardoux, Gérard; Benest, D.; Abbadie, Luc; Lacroix, Gérard

doi:10.1007/s10750-013-1635-1

Cited by 104 publications

(114 citation statements)

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“…Although Jacinthe et al (35) found, in an incubation experiment, that a substantial fraction of SOC (20-50%) degraded into CO 2 after 100 d, other studies [e.g., Wang et al (34) and Van Hemelryck (36)] reported that the additional release was hardly induced by erosion compared with the baseline condition of noneroding soil. Following Guenet et al (37), who measured the enhanced emission when SOC enters the aquatic environment, we assumed that the rate of decomposition is ∼63% higher during transport. As a result, we further derived the erosioninduced flux component during transport F5 to be a CO 2 source of 1 ± 0.5 Mt C·y , which is relatively small compared with F3.…”

Section: Resultsmentioning

confidence: 99%

Lateral transport of soil carbon and land−atmosphere CO ₂ flux induced by water erosion in China

Yao

Ciais

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

134

158

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Soil erosion by water impacts soil organic carbon stocks and alters CO 2 fluxes exchanged with the atmosphere. The role of erosion as a net sink or source of atmospheric CO 2 remains highly debated, and little information is available at scales larger than small catchments or regions. This study attempts to quantify the lateral transport of soil carbon and consequent land−atmosphere CO 2 fluxes at the scale of China, where severe erosion has occurred for several decades. Based on the distribution of soil erosion rates derived from detailed national surveys and soil carbon inventories, here we show that water erosion in China displaced 180 ± 80 Mt C·y −1 of soil organic carbon during the last two decades, and this resulted a net land sink for atmospheric CO 2 of 45 ± 25 Mt C·y , equivalent to 8-37% of the terrestrial carbon sink previously assessed in China. Interestingly, the "hotspots," largely distributed in mountainous regions in the most intensive sink areas (>40 g C·m ), occupy only 1.5% of the total area suffering water erosion, but contribute 19.3% to the national erosion-induced CO 2 sink. The erosion-induced CO 2 sink underwent a remarkable reduction of about 16% from the middle 1990s to the early 2010s, due to diminishing erosion after the implementation of large-scale soil conservation programs. These findings demonstrate the necessity of including erosion-induced CO 2 in the terrestrial budget, hence reducing the level of uncertainty.land−atmosphere CO 2 flux | soil carbon displacement | water erosion | national scale T errestrial ecosystems are a net sink of anthropogenic CO 2 globally (1, 2) but can be net sources or sinks regionally [e.g., Northeast Region of China (3)]. Knowledge of the distribution, magnitude, and variability of land carbon fluxes and underlying processes is important both for improving model-based projections of the carbon cycle and for designing ecosystem management options that effectively preserve carbon stocks and enhance carbon sinks. Despite considerable efforts made by the research community, the mechanisms governing uptake or release of carbon from land ecosystems are still poorly quantified (4).Soil erosion occurs naturally but is accelerated by human cultivation of the landscape, and modifies CO 2 exchange (5) between the soil and atmosphere. Soil erosion destroys the physical protection of carbon in soil aggregates and accelerates decomposition, inducing a net CO 2 source. Continuous erosion over a long period can destabilize carbon in deeper soil horizons and trigger its decomposition e.g., as conditions of temperature and moisture become more favorable (6, 7). Soil erosion also decreases nutrient availability and reduces soil water holding capacity, affecting ecosystem productivity (8) with feedback to the ecosystem carbon balance. However, because only a fraction of eroded carbon is lost to the atmosphere, the rest may be lost to streams and rivers and eventually delivered to marine ecosystems or deposited in the landscape. With the fine and light soil particles p...

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Section: Resultsmentioning

confidence: 99%

Lateral transport of soil carbon and land−atmosphere CO ₂ flux induced by water erosion in China

Yao

Ciais

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

134

158

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“…It appears that as lakes become more productive, bacteria consume increasing proportions of algal C (Figure 4), yet the efficiency of incorporation of terrestrial C also increases along the same productivity gradient (Figure 2), such that the actual proportion of terrestrial C in bacterial biomass remains relatively constant across lakes. It has recently been hypothesized that an increase in the availability of labile compounds of algal origin may enhance the degradation of recalcitrant terrestrial DOC by aquatic bacterial communities (Danger et al, 2013;Guenet et al, 2014;Hotchkiss et al, 2014), although the actual occurrence and significance of this priming mechanism is still debated (Bengtsson et al, 2014;Catalán et al, 2015). Our experimental set up did not allow to directly test this hypothesis in terms of the enhancement of the consumption of terrestrial C, yet our results do suggest a significant interplay between the preferential allocation of algal-derived C to respiration and the incorporation of terrestrial DOC into bacteria biomass.…”

Section: Discussionmentioning

confidence: 99%

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria

2015

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Here we explore strategies of resource utilization and allocation of algal versus terrestrially derived carbon (C) by lake bacterioplankton. We quantified the consumption of terrestrial and algal dissolved organic carbon, and the subsequent allocation of these pools to bacterial growth and respiration, based on the δ 13 C isotopic signatures of bacterial biomass and respiratory carbon dioxide (CO 2 ). Our results confirm that bacterial communities preferentially remove algal C from the terrestrially dominated organic C pool of lakes, but contrary to current assumptions, selectively allocate this autochthonous substrate to respiration, whereas terrestrial C was preferentially allocated to biosynthesis. The results provide further evidence of a mechanism whereby inputs of labile, algal-derived organic C may stimulate the incorporation of a more recalcitrant, terrestrial C pool. This mechanism resulted in a counterintuitive pattern of high and relatively constant levels of allochthony (~76%) in bacterial biomass across lakes that otherwise differ greatly in productivity and external inputs.

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“…So far, our approach does not distinguish between heterotrophic respiration of DOC and photo-oxidation, which would make the simulation of the DOC fate more complex. For heterotrophic respiration, inclusion of the priming effects of more labile organic carbon on the decomposition of more refractory fractions could also be implemented (Guenet et al, 2014;Ward et al, 2016). Here, in particular, the labile pools produced by autotrophic processes could be of importance.…”

Section: Simplification Of Biogeochemical Processes In the River Networkmentioning

confidence: 99%

ORCHILEAK (revision 3875): a new model branch to simulate carbon transfers along the terrestrial–aquatic continuum of the Amazon basin

et al. 2017

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Abstract. Lateral transfer of carbon (C) from terrestrial ecosystems into the inland water network is an important component of the global C cycle, which sustains a large aquatic CO 2 evasion flux fuelled by the decomposition of allochthonous C inputs. Globally, estimates of the total C exports through the terrestrial-aquatic interface range from 1.5 to 2.7 Pg C yr −1 (Cole et al., 2007;Battin et al., 2009;Tranvik et al., 2009), i.e. of the order of 2-5 % of the terrestrial NPP. Earth system models (ESMs) of the climate system ignore these lateral transfers of C, and thus likely overestimate the terrestrial C sink.In this study, we present the implementation of fluvial transport of dissolved organic carbon (DOC) and CO 2 into ORCHIDEE (Organising Carbon and Hydrology in Dynamic Ecosystems), the land surface scheme of the Institut PierreSimon Laplace ESM. This new model branch, called OR-CHILEAK, represents DOC production from canopy and soils, DOC and CO 2 leaching from soils to streams, DOC decomposition, and CO 2 evasion to the atmosphere during its lateral transport in rivers, as well as exchange with the soil carbon and litter stocks on floodplains and in swamps. We parameterized and validated ORCHILEAK for the Amazon basin, the world's largest river system with regard to discharge and one of the most productive ecosystems in the world.With ORCHILEAK, we are able to reproduce observed terrestrial and aquatic fluxes of DOC and CO 2 in the Amazon basin, both in terms of mean values and seasonality. In addition, we are able to resolve the spatio-temporal variability in C fluxes along the canopy-soil-water continuum at high resolution (1 • , daily) and to quantify the different terrestrial contributions to the aquatic C fluxes. We simulate that more than two-thirds of the Amazon's fluvial DOC export are contributed by the decomposition of submerged litter. Throughfall DOC fluxes from canopy to ground are about as high as the total DOC inputs to inland waters. The latter, however, are mainly sustained by litter decomposition. Decomposition of DOC and submerged plant litter contributes slightly more than half of the CO 2 evasion from the water surface, while the remainder is contributed by soil respiration. Total CO 2 evasion from the water surface equals about 5 % of the terrestrial NPP. Our results highlight that ORCHILEAK is well suited to simulate carbon transfers along the terrestrialaquatic continuum of tropical forests. It also opens the perspective that provided parameterization, calibration and validation is performed for other biomes, the new model branch could improve the quantification of the global terrestrial C sink and help better constrain carbon cycle-climate feedbacks in future projections.

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Fast mineralization of land-born C in inland waters: first experimental evidences of aquatic priming effect

Cited by 104 publications

References 45 publications

Lateral transport of soil carbon and land−atmosphere CO ₂ flux induced by water erosion in China

Lateral transport of soil carbon and land−atmosphere CO ₂ flux induced by water erosion in China

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria

ORCHILEAK (revision 3875): a new model branch to simulate carbon transfers along the terrestrial–aquatic continuum of the Amazon basin

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Fast mineralization of land-born C in inland waters: first experimental evidences of aquatic priming effect

Cited by 104 publications

References 45 publications

Lateral transport of soil carbon and land−atmosphere CO 2 flux induced by water erosion in China

Lateral transport of soil carbon and land−atmosphere CO 2 flux induced by water erosion in China

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria

ORCHILEAK (revision 3875): a new model branch to simulate carbon transfers along the terrestrial–aquatic continuum of the Amazon basin

Contact Info

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Lateral transport of soil carbon and land−atmosphere CO ₂ flux induced by water erosion in China

Lateral transport of soil carbon and land−atmosphere CO ₂ flux induced by water erosion in China