The ratio of methanogens to methanotrophs and water-level dynamics drive methane exchange velocity in a temperate kettle-hole peat bog

Abstract. Peatlands are a large source of methane (CH4) to the atmosphere, yet the uncertainty around the estimates of CH4 flux from peatlands is large. To better understand the spatial heterogeneity in temperate peatland CH4 emissions and their response to physical and biological drivers, we studied CH4 dynamics throughout the growing seasons of 2017 and 2018 in Flatiron Lake Bog, a kettle-hole peat bog in Ohio. The site is composed of six different hydro-biological zones: an open water zone, four concentric vegetation zones surrounding the open water, and a restored zone connected to the main bog by a narrow channel. At each of these locations, we monitored water level (WL), CH4 pore-water concentration at different peat depths, CH4 fluxes from the ground and from representative plant species using chambers, and microbial community composition with a focus here on known methanogens and methanotrophs. Integrated CH4 emissions for the growing season were estimated as 315.4±166 mgCH4m-2d-1 in 2017 and 362.3±687 mgCH4m-2d-1 in 2018. Median CH4 emission was highest in the open water, then it decreased and became more variable through the concentric vegetation zones as the WL dropped, with extreme emission hotspots observed in the tamarack mixed woodlands (Tamarack) and low emissions in the restored zone (18.8–30.3 mgCH4m-2d-1). Generally, CH4 flux from above-ground vegetation was negligible compared to ground flux (<0.4 %), although blueberry plants were a small CH4 sink. Pore-water CH4 concentrations varied significantly among zones, with the highest values in the Tamarack zone, close to saturation, and the lowest values in the restored zone. While the CH4 fluxes and pore-water concentrations were not correlated with methanogen relative abundance, the ratio of methanogens to methanotrophs in the upper portion of the peat was significantly correlated to CH4 transfer velocity (the CH4 flux divided by the difference in CH4 pore-water concentration between the top of the peat profile and the concentration in equilibrium with the atmosphere). Since ebullition and plant-mediated transport were not important sources of CH4 and the peat structure and porosity were similar across the different zones in the bog, we conclude that the differences in CH4 transfer velocities, and thus the flux, are driven by the ratio of methanogen to methanotroph relative abundance close to the surface. This study illustrates the importance of the interactions between water-level and microbial composition to better understand CH4 fluxes from bogs and wetlands in general.

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Review of The ratio of methanogens to methanotrophs and water-level dynamics drive methane exchange velocity in a temperate kettle-hole peat bog

10.5194/bg-2019-116-rc2 ◽

2019 ◽

Author(s):

Anonymous

Keyword(s):

Water Level ◽

Peat Bog ◽

Kettle Hole

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Regulation of Vegetation and Evapotranspiration by Water Level Fluctuation in Shallow Lakes

Water ◽

10.3390/w13192651 ◽

2021 ◽

Vol 13 (19) ◽

pp. 2651

Author(s):

Qiang Liu ◽

Liqiao Liang ◽

Xiaomin Yuan ◽

Sirui Yan ◽

Miao Li ◽

...

Keyword(s):

Water Level ◽

Open Water ◽

Water Area ◽

Water Level Fluctuation ◽

Water Levels ◽

Water Level Fluctuations ◽

Water Evaporation ◽

Level Fluctuation ◽

Open Water Area ◽

Annual Scale

Water level fluctuations play a critical role in regulating vegetation distribution, composition, cover and richness, which ultimately affect evapotranspiration. In this study, we first explore water level fluctuations and associated impacts on vegetation, after which we assess evapotranspiration (ET) under different water levels. The normalized difference vegetation index (NDVI) was used to estimate the fractional vegetation cover (Fv), while topography- and vegetation-based surface-energy partitioning algorithms (TVET model) and potential evaporation (Ev) were used to calculate ET and water evaporation (Ep). Results show that: (1) water levels were dramatically affected by the combined effect of ecological water transfer and climate change and exhibited significant decreasing trends with a slope of −0.011 m a−2; and (2) as predicted, there was a correlation between water level fluctuation at an annual scale with Phragmites australis (P. australis) cover and open-water area. Water levels also had a controlling effect on Fv values, an increase in annual water levels first increasing and then decreasing Fv. However, a negative correlation was found between Fv values and water levels during initial plant growth stages. (iii) ET, which varied under different water levels at an annual scale, showed different partition into transpiration from P. australis and evaporation from open-water area and soil with alterations between vegetation and open water. All findings indicated that water level fluctuations controlled biological and ecological processes, and their structural and functional characteristics. This study consequently recommends that specifically-focused ecological water regulations (e.g., duration, timing, frequency) should be enacted to maintain the integrity of wetland ecosystems for wetland restoration.

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The spatial variation of oxygen condition in carp pond located in nature reserve „Stawy Milickie” / Przestrzenne zróżnicowanie warunków tlenowych w stawie karpiowym położonym w rezerwacie przyrody „Stawy Milickie”

Journal of Water and Land Development ◽

10.2478/jwld-2013-0015 ◽

2013 ◽

Vol 19 (1) ◽

pp. 47-52 ◽

Cited By ~ 1

Author(s):

Bartosz Jawecki ◽

Tomasz Jaroszewicz-Smyk ◽

Andrzej Drabiński

Keyword(s):

Dissolved Oxygen ◽

Spatial Variation ◽

Oxygen Concentration ◽

Water Concentration ◽

Open Water ◽

Average Concentration ◽

Optimum Level ◽

Emergent Plants ◽

Oxygen Conditions ◽

Oxygen Condition

Abstract The paper presents the results of research on the spatial variation of oxygen condition in a carp pond. The analysis of dissolved oxygen was carried out in the summer in 29 measuring points. In the analysed months the differences were determined between dissolved oxygen concentration in the strip of rushes and the part of the pond free from macrophytes. In the strip of rushes, the average concentration of dissolved oxygen was between 4.69-6.49 mg O2·dm-3. In the part of pond located near the strip of rushes the oxygen concentration was between 6.23-7.91 mg O2·dm-3 and in open water concentration of dissolved oxygen was in range 7.60-9.09 mg O2·dm-3. It was found that the biggest differences in oxygen concentration occur between the strip of rushes and the open water column: 40% in June, 26% in July, 28% in August, 38% in September, respectively. In the south-western part of the pond, covered with macrophytes and shaded by trees, the worst oxygen conditions were observed - below the optimum level for carps, sometimes reaching lethal values. The best oxygen conditions, noted in July and August, were in the central and northern part of the pond including the fishery and feeding point. In order to improve the oxygen conditions in macrophytes zone it is recommended to remove the rushes periodically and to remember to leave the part of emergent plants that are necessary for breeding and living avifauna. The scope and timing of the removal of plants has to be consulted and co-ordinated with the Regional Conservator of Nature.

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High net CO<sub>2</sub> and CH<sub>4</sub> release at a eutrophic shallow lake on a formerly drained fen

Biogeosciences ◽

10.5194/bg-13-3051-2016 ◽

2016 ◽

Vol 13 (10) ◽

pp. 3051-3070 ◽

Cited By ~ 28

Author(s):

Daniela Franz ◽

Franziska Koebsch ◽

Eric Larmanou ◽

Jürgen Augustin ◽

Torsten Sachs

Keyword(s):

Global Warming ◽

Shallow Lake ◽

Typha Latifolia ◽

Open Water ◽

Emergent Vegetation ◽

Lake Ecosystem ◽

Co2 Uptake ◽

Mild Winter ◽

Ch4 Emissions ◽

Northeastern Germany

Abstract. Drained peatlands often act as carbon dioxide (CO2) hotspots. Raising the groundwater table is expected to reduce their CO2 contribution to the atmosphere and revitalise their function as carbon (C) sink in the long term. Without strict water management rewetting often results in partial flooding and the formation of spatially heterogeneous, nutrient-rich shallow lakes. Uncertainties remain as to when the intended effect of rewetting is achieved, as this specific ecosystem type has hardly been investigated in terms of greenhouse gas (GHG) exchange. In most cases of rewetting, methane (CH4) emissions increase under anoxic conditions due to a higher water table and in terms of global warming potential (GWP) outperform the shift towards CO2 uptake, at least in the short term.Based on eddy covariance measurements we studied the ecosystem–atmosphere exchange of CH4 and CO2 at a shallow lake situated on a former fen grassland in northeastern Germany. The lake evolved shortly after flooding, 9 years previous to our investigation period. The ecosystem consists of two main surface types: open water (inhabited by submerged and floating vegetation) and emergent vegetation (particularly including the eulittoral zone of the lake, dominated by Typha latifolia). To determine the individual contribution of the two main surface types to the net CO2 and CH4 exchange of the whole lake ecosystem, we combined footprint analysis with CH4 modelling and net ecosystem exchange partitioning.The CH4 and CO2 dynamics were strikingly different between open water and emergent vegetation. Net CH4 emissions from the open water area were around 4-fold higher than from emergent vegetation stands, accounting for 53 and 13 g CH4 m−2 a−1 respectively. In addition, both surface types were net CO2 sources with 158 and 750 g CO2 m−2 a−1 respectively. Unusual meteorological conditions in terms of a warm and dry summer and a mild winter might have facilitated high respiration rates. In sum, even after 9 years of rewetting the lake ecosystem exhibited a considerable C loss and global warming impact, the latter mainly driven by high CH4 emissions. We assume the eutrophic conditions in combination with permanent high inundation as major reasons for the unfavourable GHG balance.

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Emergent plant communities of oxbow lakes in northeastern Alberta: salinity, water-level fluctuation, and succession

Canadian Journal of Botany ◽

10.1139/b84-049 ◽

1984 ◽

Vol 62 (2) ◽

pp. 310-316 ◽

Cited By ~ 16

Author(s):

V. J. Lieffers

Keyword(s):

Water Level ◽

Detrended Correspondence Analysis ◽

Open Water ◽

Water Levels ◽

Water Level Fluctuations ◽

Individual Species ◽

Acorus Calamus ◽

Oxbow Lakes ◽

Salinity Water ◽

Northeastern Alberta

Emergent vegetation was sampled in 15 oxbow lakes in a 50-km segment of the Athabasca River in northeastern Alberta. Cover of individual species was visually assessed in plots at the outer, middle, and (or) inner edge of the emergent zone of each lake (n, 37 sample units). Detrended correspondence analysis showed two main axes of variation. The first axis related to salinity. Water conductivity ranged from 170 to 12200 μS cm−1 and community types ranged from freshwater fens to saline wetland communities dominated by Scolochloa festucacea, Scirpus maritimus, and Triglochin maritima. The second axis of variation related to water-level fluctuations. Half of the lakes had an increase in water level in the recent past (ca. 6–30 years). In these lakes, Typha latifolia was dominant in both grounded and floating substrates subjected to increased water levels. Sedge communities dominated by Carex rostrata, C. aquatilis, and Acorus calamus were common in sites with stable water levels. In freshwater lakes, floating substrates were established over open water by the lateral growth of floating stems of Calla palustris and Potentilla palustris. Floating substrates were not in the saline sites probably because these open-water colonizers were not present under saline regimes.

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Habitat selection by booming bitterns Botaurus stellaris in French Mediterranean reed-beds

Oryx ◽

10.1017/s0030605305000864 ◽

2005 ◽

Vol 39 (3) ◽

pp. 265-274 ◽

Cited By ~ 17

Author(s):

Brigitte Poulin ◽

Gaëtan Lefebvre ◽

Raphaël Mathevet

Keyword(s):

Habitat Selection ◽

Water Level ◽

Environmental Changes ◽

Open Water ◽

Site Management ◽

Clear Water ◽

Percentage Cover ◽

Multivariate Statistical ◽

Reed Beds ◽

Ecological Requirements

Data on habitat requirements of the threatened Eurasian bittern Botaurus stellaris are largely qualitative and limited to countries holding small populations. We assessed the habitat spectrum exploited by male bitterns during the breeding season, based on the analysis of 40 booming sites and 33 non-booming sites in 2,500 ha of heterogeneous reed-beds in the Camargue, France. Environmental variables contributing to booming site selection were, in decreasing order of importance, determined by their contribution to multivariate statistical models: water level in April, proportion of open water, density of dry and green reeds, percentage cover of non-reed species, salinity and turbidity of surface water, and reed height and diameter. Overall, booming sites were characterized by a homogeneous cover of relatively sparse green and dry reeds growing with other plant species in shallow (10–15 cm), clear water. Because these findings are contrary to the traditional perception of bittern habitat in Europe, a reassessment of the species' ecological requirements throughout its distributional range is warranted. In the Camargue the main factors involved in habitat selection (water level and dry reed density) are directly associated with site management, and bitterns respond rapidly to slight environmental changes.

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Methane emissions associated with the conversion of marshland to cropland and climate change on the Sanjiang Plain of northeast China from 1950 to 2100

Biogeosciences ◽

10.5194/bg-9-5199-2012 ◽

2012 ◽

Vol 9 (12) ◽

pp. 5199-5215 ◽

Cited By ~ 20

Author(s):

T. Li ◽

Y. Huang ◽

W. Zhang ◽

Y.-Q. Yu

Keyword(s):

Climate Change ◽

Northeast China ◽

Model Simulation ◽

Linear Trend ◽

Sanjiang Plain ◽

Lower Amount ◽

The Sanjiang Plain ◽

Ch4 Flux ◽

Ch4 Emissions ◽

The 1950S

Abstract. Wetland loss and climate change are known to alter regional and global methane (CH4) budgets. Over the last six decades, an extensive area of marshland has been converted to cropland on the Sanjiang Plain in northeast China, and a significant increase in air temperature has also been observed there, while the impacts on regional CH4 budgets remain uncertain. Through model simulation, we estimated the changes in CH4 emissions associated with the conversion of marshland to cropland and climate change in this area. Model simulations indicated a significant reduction of 1.1 Tg yr−1 (0.7–1.8 Tg yr−1) from the 1950s to the 2000s in regional CH4 emissions. The cumulative reduction of CH4 from 1960 to 2009 was estimated to be ~36 Tg (24–57 Tg) relative to the 1950s, and marshland conversion and the climate contributed 86% and 14% of this change, respectively. Interannual variation in precipitation (linear trend with P > 0.2) contributed to yearly fluctuations in CH4 emissions, but the relatively lower amount of precipitation over the period 1960–2009 (47 mm yr−1 lower on average than in the 1950s) contributed ~91% of the reduction in the area-weighted CH4 flux. Global warming at a rate of 0.3 ° per decade (P < 0.001) has increased CH4 emissions significantly since the 1990s. Relative to the mean of the 1950s, the warming-induced increase in the CH4 flux has averaged 19 kg ha−1 yr−1 over the last two decades. In the RCP (Representative Concentration Pathway) 2.6, RCP 4.5, RCP 6.0 and RCP 8.5 scenarios of the fifth IPCC assessment report (AR5), the CH4 fluxes are predicted to increase by 36%, 52%, 78% and 95%, respectively, by the 2080s compared to 1961–1990 in response to climate warming and wetting.

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Characterisation of short-term extreme methane fluxes related to non-turbulent mixing above an Arctic permafrost ecosystem

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-4041-2019 ◽

2019 ◽

Vol 19 (6) ◽

pp. 4041-4059 ◽

Cited By ~ 7

Author(s):

Carsten Schaller ◽

Fanny Kittler ◽

Thomas Foken ◽

Mathias Göckede

Keyword(s):

Steady State ◽

Wavelet Analysis ◽

Strongly Correlated ◽

Atmospheric Conditions ◽

Ch4 Flux ◽

Ch4 Emissions ◽

Stationary Signals ◽

Methane Fluxes ◽

Variable Flux ◽

Mesoscale Processes

Abstract. Methane (CH4) emissions from biogenic sources, such as Arctic permafrost wetlands, are associated with large uncertainties because of the high variability of fluxes in both space and time. This variability poses a challenge to monitoring CH4 fluxes with the eddy covariance (EC) technique, because this approach requires stationary signals from spatially homogeneous sources. Episodic outbursts of CH4 emissions, i.e. triggered by spontaneous outgassing of bubbles or venting of methane-rich air from lower levels due to shifts in atmospheric conditions, are particularly challenging to quantify. Such events typically last for only a few minutes, which is much shorter than the common averaging interval for EC (30 min). The steady-state assumption is jeopardised, which potentially leads to a non-negligible bias in the CH4 flux. Based on data from Chersky, NE Siberia, we tested and evaluated a flux calculation method based on wavelet analysis, which, in contrast to regular EC data processing, does not require steady-state conditions and is allowed to obtain fluxes over averaging periods as short as 1 min. Statistics on meteorological conditions before, during, and after the detected events revealed that it is atmospheric mixing that triggered such events rather than CH4 emission from the soil. By investigating individual events in more detail, we identified a potential influence of various mesoscale processes like gravity waves, low-level jets, weather fronts passing the site, and cold-air advection from a nearby mountain ridge as the dominating processes. The occurrence of extreme CH4 flux events over the summer season followed a seasonal course with a maximum in early August, which is strongly correlated with the maximum soil temperature. Overall, our findings demonstrate that wavelet analysis is a powerful method for resolving highly variable flux events on the order of minutes, and can therefore support the evaluation of EC flux data quality under non-steady-state conditions.

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