Impact of rainfall regime on methane flux from a cool temperate fen depends on vegetation cover

Radu, Danielle D.; Duval, Tim P.

doi:10.1016/j.ecoleng.2017.06.047

Cited by 14 publications

(8 citation statements)

References 72 publications

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“…Under field conditions, CH 4 production in deeper peat layers would contribute to overall emissions, while hydraulic lift could maintain moisture content in the peat surface layer under dry conditions. Interestingly, our findings contrast those from Radu and Duval (2018a). They found that more extreme regimes increased CH 4 emission overall and stipulated that rainfall oscillations stimulated the build-up of labile substrate as result of aerobe respiration, which upon repeated rewetting boost CH 4 production.…”

Section: Methane Emissionscontrasting

confidence: 99%

“…We observed that rewetting during the resilience phase led to a steep increase in CH 4 flux rates compared to the resistance phase which tended to be restricted in the more extreme precipitation treatments. Although these results indicate that more extreme rainfall reduces the CH 4 emissions from peatlands, the contrasting results from Radu and Duval (2018a) and the variable rewetting responses between peatland types (Turetsky et al, 2014) make further investigation of gas flux responses to shifting rainfall across peatland types under field conditions advisable.…”

Section: Methane Emissionsmentioning

confidence: 87%

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Come Rain, Come Shine: Peatland Carbon Dynamics Shift Under Extreme Precipitation

Barel

Moulia

Hamard

et al. 2021

Front. Environ. Sci.

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Precipitation patterns are becoming increasingly extreme, particularly at northern latitudes. Current climate models predict that this trend will continue in the future. While droughts have been repeatedly studied in many ecosystems over the last decades, the consequences of increasingly intense, but less frequent rainfall events, on carbon (C) cycling are not well understood. At northern latitudes, peatlands store one third of the terrestrial carbon and their functioning is highly dependent on water. Shifts in rainfall regimes could disrupt peatland C dynamics and speed-up the rates of C loss. How will these immense stocks of C be able to withstand and recover from extreme rainfall? We tested the resistance and resilience effects of extreme precipitation regimes on peatland carbon dioxide (CO2) and methane (CH4) fluxes, pore water dissolved organic carbon (DOC) and litter decomposition rates by exposing intact peat cores to extreme, spring-time rainfall patterns in a controlled mesocosm experiment. We find that more intense but less frequent rainfall destabilized water table dynamics, with cascading effects on peatland C fluxes. Decomposition and respiration rates increased with a deeper mean water table depth (WTD) and larger WTD fluctuations. We observed similar patterns for CO2 uptake, which were likely mediated by improved vascular plant performance. After a three-week recovery period, CO2 fluxes still displayed responses to the earlier WTD dynamics, suggesting lagged effects of precipitation regime shifts. Furthermore, we found that CH4 emissions decreased with deeper mean WTD, but this showed a high resilience once WTD dynamics stabilised. Not only do our results illustrate that shifting rainfall patterns translate in altered WTD dynamics and, consequentially, influence C fluxes, they also demonstrate that exposure to altered rainfall early in the growing season can have lasting effects on CO2 exchange. Even though the increased CO2 assimilation under extreme precipitation patterns signals peatland resistance under changing climatic conditions, it may instead mark the onset of vascular plant encroachment and the associated C loss.

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Section: Methane Emissionscontrasting

confidence: 99%

Section: Methane Emissionsmentioning

confidence: 87%

Come Rain, Come Shine: Peatland Carbon Dynamics Shift Under Extreme Precipitation

Barel

Moulia

Hamard

et al. 2021

Front. Environ. Sci.

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“…Water table positions were allowed to naturally fluctuate. Further details on core collection and experimental setup can be found in Radu and Duval (2017).…”

Section: Laboratory Experimentsmentioning

confidence: 99%

Precipitation frequency alters peatland ecosystem structure and CO₂ exchange: Contrasting effects on moss, sedge, and shrub communities

Radu

Duval

2018

Global Change Biology

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Climate projections forecast a redistribution of seasonal precipitation for much of the globe into fewer, larger events spaced between longer dry periods, with negligible changes in seasonal rainfall totals. This intensification of the rainfall regime is expected to alter near-surface water availability, which will affect plant performance and carbon uptake. This could be especially important in peatland systems, where large stores of carbon are tightly coupled to water surpluses limiting decomposition. Here, we examined the role of precipitation frequency on vegetation growth and carbon dioxide (CO ) balances for communities dominated by a Sphagnum moss, a sedge, and an ericaceous shrub in a cool temperate poor fen. Field plots and laboratory monoliths received one of three rainfall frequency treatments, ranging from one event every three days to one event every 14 days, while total rain delivered in a two-week cycle and the entire season to each treatment remained the same. Separating incident rain into fewer but larger events increased vascular cover in all peatland communities: vascular plant cover increased 6× in the moss-dominated plots, nearly doubled in the sedge plots, and tripled in the shrub plots in Low-Frequency relative to High-Frequency treatments. Gross ecosystem productivity was lowest in moss communities receiving low-frequency rain, but higher in sedge and shrub communities under the same conditions. Net ecosystem exchange followed this pattern: fewer events with longer dry periods increased CO flux to the atmosphere from the moss while vascular plant-dominated communities became more of a sink for CO . Results of this study suggest that changes to rainfall frequency already occurring and predicted to continue will lead to increased vascular plant cover in peatlands and will impact their carbon-sink function.

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“…In addition to the direct effects of climate and hydrology on peatland C cycling and autogenic hydrological feedbacks that occur within peatlands (Waddington et al, 2015), changes in temperature and water table also indirectly influence C cycling through changes in the relative abundance and productivity of dominant plant functional types (PFTs; bryophyte, graminoid and ericoid) (Gavazov et al, 2018; Laine et al, 2011; Riutta, Korrensalo, Laine, Laine, & Tuittila, 2020). Warmer and drier conditions are predicted to favour a shift from bryophyte to vascular plant dominance (Buttler et al, 2015; Dieleman, Branfireun, McLaughlin, & Lindo, 2015; Walker, Ward, Ostle, & Bardgett, 2015), with implications for microclimates and GHG emissions (Gavazov et al, 2018; Radu & Duval, 2018; Robroek et al, 2015; Ward et al, 2013). However, a mechanistic explanation of PFT effects on the sensitivity of the peatland C balance to environmental change remains elusive (Robroek et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Plant functional type indirectly affects peatland carbon fluxes and their sensitivity to environmental change

Whitaker

Richardson

Ostle

et al. 2020

European J Soil Science

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The sensitivity of peatland carbon (C) fluxes to changes in climate and hydrology are uncertain due to the complex interactions between plants and peat properties. In this study we examine how peat cores taken from under three plant functional types (PFT) (bryophyte, graminoid and ericoid) differ in their biotic and abiotic properties and how this indirectly modulates the response of C fluxes to environmental change. Peat cores taken from under three PFTs had their aboveground vegetation removed to exclude direct plant‐mediated effects, and were incubated in a temperature × water table factorial experiment at 12, 14 and 16°C (air temperature) with the water table level −25, −15 or −5 cm below the peat surface. Carbon dioxide (CO2) and methane (CH4) fluxes were measured over 11 months. Emissions of CO2 and CH4 increased with temperature, with strong positive (CH4) and negative (CO2) interactions with increasing water table level. There were significant effects of removed PFT on the environmental sensitivity of CH4, but not CO2 fluxes. CH4 emissions were greatest in peat with graminoid PFT removed at the warmest temperature but these indirect effects were not explained by peat abiotic or biotic properties, which did not differ between PFTs. These results show that climate change‐induced expansion of graminoids in northern peatlands will have direct and indirect effects on C fluxes and the stability of peatland C stores. These responses will be determined by the interactive effects of vegetation composition, hydrology and warming on methane‐cycling microbial communities.Highlights Peatland carbon flux strength under a changing climate is influenced by PFT. Peat from under graminoid PFT emits more methane than peat from under bryophyte or ericoid PFT. Prior PFT cover influenced methane emissions, but did not affect peat abiotic or biotic properties. Increases in graminoid cover with climate change could indirectly increase peatland methane fluxes.

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Impact of rainfall regime on methane flux from a cool temperate fen depends on vegetation cover

Cited by 14 publications

References 72 publications

Come Rain, Come Shine: Peatland Carbon Dynamics Shift Under Extreme Precipitation

Come Rain, Come Shine: Peatland Carbon Dynamics Shift Under Extreme Precipitation

Precipitation frequency alters peatland ecosystem structure and CO₂ exchange: Contrasting effects on moss, sedge, and shrub communities

Plant functional type indirectly affects peatland carbon fluxes and their sensitivity to environmental change

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Impact of rainfall regime on methane flux from a cool temperate fen depends on vegetation cover

Cited by 14 publications

References 72 publications

Come Rain, Come Shine: Peatland Carbon Dynamics Shift Under Extreme Precipitation

Come Rain, Come Shine: Peatland Carbon Dynamics Shift Under Extreme Precipitation

Precipitation frequency alters peatland ecosystem structure and CO2 exchange: Contrasting effects on moss, sedge, and shrub communities

Plant functional type indirectly affects peatland carbon fluxes and their sensitivity to environmental change

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Precipitation frequency alters peatland ecosystem structure and CO₂ exchange: Contrasting effects on moss, sedge, and shrub communities