The Importance of Aquatic Carbon Fluxes in Net Ecosystem Carbon Budgets: A Catchment-Scale Review

Webb, Jackie R.; Santos, Isaac R.; Maher, Damien T.; Finlay, Kerri

doi:10.1007/s10021-018-0284-7

Cited by 79 publications

(90 citation statements)

References 110 publications

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“…The detailed mechanisms differ- Gannon et al (2015) emphasize distal-to-stream connections driven by shallow soils around bedrock and Zimmer and McGlynn (2018) highlight the role of frequent storms driving shallow subsurface connectionswhereas here we emphasize soil-saprolite connections driven by drift-melt pulses. These findings, in addition to our results, demonstrate that, although hydrological controls are critical for estimates of aquatic carbon fluxes (Raymond and Saiers, 2010;Leach et al, 2016;Webb et al, 2018), it is important to understand the spatial and temporal constraints on hydrologic processes that drive streamflow. Our observations also highlight the risk of using DOC itself as a tracer: even if the source of carbon for a given catchment is correctly identified, there is a risk that flowpaths will be oversimplified if all SOC is assumed to become DOC by lateral flow of water through soils to the stream.…”

Section: Is Soil Water a Major Component Of The Hydrograph Or Is Carsupporting

confidence: 74%

Spatiotemporal Heterogeneity of Water Flowpaths Controls Dissolved Organic Carbon Sourcing in a Snow-Dominated, Headwater Catchment

et al. 2019

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Section: Is Soil Water a Major Component Of The Hydrograph Or Is Carsupporting

confidence: 74%

Spatiotemporal Heterogeneity of Water Flowpaths Controls Dissolved Organic Carbon Sourcing in a Snow-Dominated, Headwater Catchment

et al. 2019

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“…The lateral C fluxes, for example, C loss via stream discharge in a boreal forest landscape (or catchment), are also important components of the landscape‐scale C budget (Butman et al, ; Wallin et al, ; Webb, Santos, Maher, & Finlay, ) but are often neglected. The amount of aquatic C exports in the forms of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC; i.e.,

{normalH}_{2} {CO}_{3}

{HCO}_{3}^{-}

, and

{CO}_{3}^{2 -}

), and dissolved CO 2 and CH 4 reflect furthermore the aquatic‐terrestrial links between water bodies and the surrounding soil and plants within the landscape (Cole et al, ).…”

Section: Introductionmentioning

confidence: 99%

The Net Landscape Carbon Balance—Integrating terrestrial and aquatic carbon fluxes in a managed boreal forest landscape in Sweden

Chi

Nilsson

Laudon

et al. 2020

Global Change Biology

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The boreal biome exchanges large amounts of carbon (C) and greenhouse gases (GHGs) with the atmosphere and thus significantly affects the global climate. A managed boreal landscape consists of various sinks and sources of carbon dioxide (CO2), methane (CH4), and dissolved organic and inorganic carbon (DOC and DIC) across forests, mires, lakes, and streams. Due to the spatial heterogeneity, large uncertainties exist regarding the net landscape carbon balance (NLCB). In this study, we compiled terrestrial and aquatic fluxes of CO2, CH4, DOC, DIC, and harvested C obtained from tall‐tower eddy covariance measurements, stream monitoring, and remote sensing of biomass stocks for an entire boreal catchment (~68 km2) in Sweden to estimate the NLCB across the land–water–atmosphere continuum. Our results showed that this managed boreal forest landscape was a net C sink (NLCB = 39 g C m−2 year−1) with the landscape–atmosphere CO2 exchange being the dominant component, followed by the C export via harvest and streams. Accounting for the global warming potential of CH4, the landscape was a GHG sink of 237 g CO2‐eq m−2 year−1, thus providing a climate‐cooling effect. The CH4 flux contribution to the annual GHG budget increased from 0.6% during spring to 3.2% during winter. The aquatic C loss was most significant during spring contributing 8% to the annual NLCB. We further found that abiotic controls (e.g., air temperature and incoming radiation) regulated the temporal variability of the NLCB whereas land cover types (e.g., mire vs. forest) and management practices (e.g., clear‐cutting) determined their spatial variability. Our study advocates the need for integrating terrestrial and aquatic fluxes at the landscape scale based on tall‐tower eddy covariance measurements combined with biomass stock and stream monitoring to develop a holistic understanding of the NLCB of managed boreal forest landscapes and to better evaluate their potential for mitigating climate change.

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“…The stream exports of carbon from peatlands have attracted scientific interest over the last decades (Cole et al, 2007;Gandois et al, 2013;Laudon et al, 2011;Roulet & Moore, 2006;Webb et al, 2018). Due to their high organic carbon content and hydraulic connectivity to streams, peatlands have been identified as major carbon contributors to surface waters, both globally (Aitkenhead & McDowell, 2000;Hope et al, 1994) and locally (Ågren et al, 2014;Billett et al, 2006;Laudon et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Due to their high organic carbon content and hydraulic connectivity to streams, peatlands have been identified as major carbon contributors to surface waters, both globally (Aitkenhead & McDowell, 2000;Hope et al, 1994) and locally (Ågren et al, 2014;Billett et al, 2006;Laudon et al, 2011). Stream carbon exports include dissolved organic carbon (DOC) and particulate organic carbon (POC) as well as dissolved CO 2 and CH 4 (Webb et al, 2018). In vast and peat-dominated watersheds, DOC is the main form, contributing more than 90% of total carbon exports (Dinsmore et al, 2010;Hope et al, 2001;Laudon et al, 2011;Leach et al, 2016;Roulet et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Peatland Contribution to Stream Organic Carbon Exports From a Montane Watershed

et al. 2019

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Mountains contain many small and fragmented peatlands within watersheds. As they are difficult to monitor, their role in the water and carbon cycle is often disregarded. This study aims to assess the stream organic carbon exports from a montane peatland and characterizes its contribution to the water chemistry in a headstream watershed. High frequency in situ monitoring of turbidity and fDOM were used to quantify respectively particulate organic carbon (POC) and dissolved organic carbon (DOC) exports at the inlet and outlet of a peatland over three years in a French Pyrenean watershed (1,343 m.a.s.l.). The DOC and POC signals are both highly dynamic, characterized by numerous short peaks lasting from a few hours to a few days. Forty-six percent of the exports occurred during 9% of the time corresponding to the highest flows monitored at the outlet. Despite its small area (3%) within the watershed, the peatland contributes at least 63% of the DOC export at the outlet. The specific DOC flux ranges from 16.1 ± 0.4 to 34.6 ± 1.5 g m 2 year −1 . POC contributes 17% of the total stream organic carbon exports from the watershed. As the frequency of extreme climatic events is expected to increase in the context of climate change, further studies should be conducted to understand the evolution of underestimated mountainous peatland carbon fluxes and their implication in the carbon cycle of headwaters. Plain Language SummarySince the last glacial period, peatlands have accumulated large stocks of organic carbon. Despite representing only 3% of global continental surfaces, they store about 22% of the continental soil carbon stock. In the context of global change, peatland carbon sequestration capacity needs to be carefully monitored. In addition to greenhouse gas exchanges with the atmosphere, determining this capacity requires the quantification of aquatic organic carbon exports. Aquatic organic carbon exports have rarely been investigated at mountainous peatlands. Moreover, global change is expected to drastically modify mountain hydrology, influencing aquatic carbon exports and carbon balance of mountainous peatlands. Using high frequency in situ instrumentation, this study shows the annual quantity of aquatic organic carbon exported from a montane peatland in the French Pyrenees is in the same range as Northern lowland peatlands. These highly variable exports mainly occur during high discharge events due to snowmelt or rainfalls. Despite its restricted area, this montane peatland is the main contributor of aquatic organic carbon in the watershed. Peatlands influence headwater chemistry and further study must be conducted to monitor the evolution of these mountainous carbon stocks.

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The Importance of Aquatic Carbon Fluxes in Net Ecosystem Carbon Budgets: A Catchment-Scale Review

Cited by 79 publications

References 110 publications

Spatiotemporal Heterogeneity of Water Flowpaths Controls Dissolved Organic Carbon Sourcing in a Snow-Dominated, Headwater Catchment

Spatiotemporal Heterogeneity of Water Flowpaths Controls Dissolved Organic Carbon Sourcing in a Snow-Dominated, Headwater Catchment

The Net Landscape Carbon Balance—Integrating terrestrial and aquatic carbon fluxes in a managed boreal forest landscape in Sweden

Peatland Contribution to Stream Organic Carbon Exports From a Montane Watershed

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