Patterned fens of western Labrador and adjacent Quebec: phytosociology, water chemistry, landform features, and dynamics of surface patterns

The landforms, vegetation, water chemistry, and stratigraphy of four patterned fens (aapamires) in western Labrador and adjacent Quebec are described in a study investigating the origin and characteristics of surface patterns on northern peatlands. Phytosociological analysis by the relevé approach, in conjunction with analysis by TWINSPAN, is used to describe 11 floristic noda. The vegetational patterns are largely controlled by depth to the water table. Mire landforms discussed in detail include ice-push ridges, flarks and pools, peat ridges, and mire-margin hummocks. Water chemistry is typical of minerotrophic conditions, with pH ranging from 4.4 to 6.7 and calcium concentrations from 20 to 430 μiequiv. L−1. The water chemistry, vegetation, and landforms on the mires are compared with other studies from Labrador and circumboreal regions. Stratigraphic results and field observations support the theory that surface patterns on the mire develop slowly through the interplay of biological and hydrological processes, specifically differential rate of peat accumulation controlled by vegetation type and depth to water table. Pool formation apparently involves four steps: (i) gradual differentiation of shallow flarks on previously undifferentiated mire surface; (ii) expansion and deepening of flarks and development of ridges due to differential peat accumulation; (iii) degradation of flark vegetation into mud bottoms and open-water pools; and (iv) coalescence, continued expansion, and deepening of open-water areas. Hydrological controls over the rate and extent of pool formation are discussed as a probable explanation of the geographical distribution of patterned mires.

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The influence of water-table depth and pH on the spatial distribution of diatom species in peatlands of the Boreal Shield and Hudson Plains, Canada

Botany ◽

10.1139/cjb-2014-0138 ◽

2015 ◽

Vol 93 (2) ◽

pp. 57-74 ◽

Cited By ~ 15

Author(s):

Kathryn E. Hargan ◽

Kathleen M. Rühland ◽

Andrew M. Paterson ◽

Sarah A. Finkelstein ◽

James R. Holmquist ◽

...

Keyword(s):

Environmental Change ◽

Water Table ◽

Vegetation Type ◽

Diatom Assemblage ◽

Diatom Species ◽

Diatom Assemblages ◽

Poor Fen ◽

Influence Of Water ◽

Boreal Shield ◽

Northern Peatlands

Diatoms collected from 113 surface peat samples from the Boreal Shield and Hudson Plains show taxonomic distributions that are associated with macro-vegetation type, pH, and position relative to the water table, the main environmental variables measured in this study. The overall goal of our research was to determine the ecological distribution and response of diatoms to microhabitat conditions, and to assess the potential for diatoms to be applied as indicators of long-term environmental change in northern peatlands. Our results indicate that diatom assemblage composition was determined by both the broader peatland type (i.e., bog, rich and poor fens) and microhabitats within peatland formations (e.g., hummock, hollow). The diatom assemblages were primarily influenced by pH with the sites divided at a critical pH of 5.5, and secondarily by the depth to the water table. Acidic bog hollow and hummock microhabitats were species-poor and dominated almost exclusively by Eunotia paludosa A.Grunow and (or) Eunotia mucophila (H.Lange-Bertalot, M.Nörpel-Schempp & E.Alles) H.Lange-Bertalot. These acidophilic and aerophilic diatom species were associated with the narrow pH optima of the dominant Sphagnum L. species (e.g., Sphagnum fuscum (Schimp.) Klinggr., Sphagnum angustifolium (C.E.O.Jensen ex Russow) C.E.O.Jensen) found in these bog habitats. Rich and poor fen samples, which were less acidic, supported a more diverse diatom assemblage (>30 species) with greater variability in both diatom and bryophyte pH tolerances. The diatom assemblages recorded in the bogs and fens of our study are similar to those found in peatlands around the world, demonstrating that diatom species are very specialized to exist in these often harsh semi-aquatic environments. Diatoms from peatlands have great potential as biomonitors of environmental change in these important ecosystems.

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Improving a plot-scale methane emission model and its performance at a Northeastern Siberian tundra site

Biogeosciences Discussions ◽

10.5194/bgd-10-20005-2013 ◽

2013 ◽

Vol 10 (12) ◽

pp. 20005-20046 ◽

Cited By ~ 2

Author(s):

Y. Mi ◽

J. van Huissteden ◽

F. J. W. Parmentier ◽

A. Gallagher ◽

A. Budishchev ◽

...

Keyword(s):

Water Table ◽

Vegetation Type ◽

Spatial Scales ◽

Open Water ◽

Soil Freezing ◽

Subsurface Water ◽

Water Evaporation ◽

Model Parameters ◽

Emission Model ◽

Ch4 Emissions

Abstract. In order to better address the feedbacks between climate and wetland methane (CH4) emissions, we tested several mechanistic improvements to the wetland CH4 emission model Peatland-VU with a longer Arctic dataset than any other model: (1) inclusion of an improved hydrological module; (2) incorporation of a gross primary productivity (GPP) module; (3) a more realistic soil-freezing scheme. A long time series of field measurements (2003–2010) from a tundra site in Northeastern Siberia is used to validate the model, and the Generalized Likelihood Uncertainty Estimation (GLUE) methodology is used to test the sensitivity of model parameters. Peatland-VU is able to capture both the annual magnitude and seasonal variations of the CH4 flux, water table position and soil thermal properties. However, detailed daily variations are difficult to evaluate due to data limitation. Improvements due to the inclusion of a GPP module are less than anticipated, although this component is likely to become more important at larger spatial scales because the module can accommodate the variations in vegetation traits better than at plot-scale. Sensitivity experiments suggest that the methane production rate factor, the methane plant oxidation parameter, the reference temperature for temperature dependent decomposition, and the methane plant transport rate factor are the most important parameters affecting the data fit, regardless of vegetation type. Both wet and dry vegetation cover are sensitive to the minimum water table level, in addition to the runoff threshold and open water correction factor and the subsurface water evaporation and evapotranspiration correction factors, respectively. These results shed light on model parameterization and future improvement of CH4 modelling. However, high spatial variability of CH4 emissions within similar vegetation/soil units and data quality prove to impose severe limits on model testing and improvement.

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Methane flux from drained northern peatlands: Effect of a persistent water table lowering on flux

Global Biogeochemical Cycles ◽

10.1029/93gb01931 ◽

1993 ◽

Vol 7 (4) ◽

pp. 749-769 ◽

Cited By ~ 112

Author(s):

Nigel T. Roulet ◽

R. Ash ◽

W. Quinton ◽

Tim Moore

Keyword(s):

Water Table ◽

Methane Flux ◽

Northern Peatlands

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Monitoring of water table dynamics in peatlands with OPTRAM: Towards globally applicable algorithms in Google Earth Engine using Landsat and Sentinel-2

10.5194/egusphere-egu21-4698 ◽

2021 ◽

Author(s):

Iuliia Burdun ◽

Michel Bechtold ◽

Viacheslav Komisarenko ◽

Annalea Lohila ◽

Elyn Humphreys ◽

...

Keyword(s):

Time Series ◽

Water Table ◽

Input Data ◽

Short Wave ◽

Google Earth ◽

Google Earth Engine ◽

Short Wave Infrared ◽

Northern Peatlands ◽

Sentinel 2

<p>Fluctuations of water table depth (WTD) affect many processes in peatlands, such as vegetation development and emissions of greenhouse gases. Here, we present the OPtical TRApezoid Model (OPTRAM) as a new method for satellite-based monitoring of the temporal variation of WTD in peatlands. OPTRAM is based on the response of short-wave infrared reflectance to the vegetation water status. For five northern peatlands with long-term in-situ WTD records, and with diverse vegetation cover and hydrological regimes, we generate a suite of OPTRAM index time series using (a) different procedures to parametrise OPTRAM (peatland-specific manual vs. globally applicable automatic parametrisation in Google Earth Engine), and (b) different satellite input data (Landsat vs. Sentinel-2). The results based on the manual parametrisation of OPTRAM indicate a high correlation with in-situ WTD time-series for pixels with most suitable vegetation for OPTRAM application (mean Pearson correlation of 0.7 across sites), and we will present the performance differences when moving from a manual to an automatic procedure. Furthermore, for the overlap period of Landsat and Sentinel-2, which have different ranges and widths of short-wave infrared bands used for OPTRAM calculation, the impact of the satellite input data to OPTRAM will be analysed. Eventually, the challenge of merging different satellite missions in the derivation of OPTRAM time series will be explored as an important step towards a global application of OPTRAM for the monitoring of WTD dynamics in northern peatlands.</p>

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Evaporation characteristics of wetlands: experience from a wetgrassland and a reedbed using eddy correlation measurements

Hydrology and Earth System Sciences ◽

10.5194/hess-7-11-2003 ◽

2003 ◽

Vol 7 (1) ◽

pp. 11-21 ◽

Cited By ~ 45

Author(s):

M. C. Acreman ◽

R. J. Harding ◽

C. R. Lloyd ◽

D. D. McNeil

Keyword(s):

Water Table ◽

Surface Resistance ◽

Correlation Method ◽

Open Water ◽

Eddy Correlation ◽

Evaporative Water ◽

Water Table Level ◽

Wet Grassland ◽

The Difference ◽

Reed Bed

Abstract. Measurements of evaporation were made from July to November 1999 using the eddy correlation method on two wetland types – wet grassland and reedbeds – in south west England. The evaporative water use of a reed bed exceeded that of the grassland wetland by 15% (or 50 mm over the 5 months). The evaporation rates at both sites exceed of the Penman Potential Evaporation estimates calculated for this area. The difference between sites results from the higher roughness length of the reed bed and the lower effective surface resistance of the reed/open water assemblage. At the grassland site, a significant relationship between the surface resistance and water table level has been demonstrated. The water table at this site is managed to maintain the plant diversity and allow some agricultural access. This regime specifies a water table below the surface during the summer period, which results in higher surface resistances and lower evaporation. The results have important implications for local water resources management, especially where wetlands are maintained by pumping from rivers or groundwater. Keywords: wetlands, evaporation, eddy correlation, wet grassland, reedbed, vapour pressure, water table level

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Landform-Soil-Vegetation-Water Chemistry Relationships, Wrigley Area, N.W.T.: II. Chemical, Physical, and Mineralogical Determinations and Relationships1

Soil Science Society of America Journal ◽

10.2136/sssaj1975.03615995003900010025x ◽

1975 ◽

Vol 39 (1) ◽

pp. 89 ◽

Cited By ~ 3

Author(s):

M. E. Walmsley ◽

L. M. Lavkulich

Keyword(s):

Water Chemistry ◽

Vegetation Water

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Water Table Fluctuation in Peatlands Facilitates Fungal Proliferation, Impedes Sphagnum Growth and Accelerates Decomposition

Frontiers in Earth Science ◽

10.3389/feart.2020.579329 ◽

2021 ◽

Vol 8 ◽

Author(s):

Jinhyun Kim ◽

Line Rochefort ◽

Sandrine Hogue-Hugron ◽

Zuhair Alqulaiti ◽

Christian Dunn ◽

...

Keyword(s):

Organic Matter ◽

Microbial Community ◽

Water Table ◽

High Frequency ◽

Organic Matter Decomposition ◽

Anaerobic Conditions ◽

Water Table Fluctuation ◽

Decomposition Of Organic Matter ◽

Northern Peatlands ◽

Low Rate

Northern peatlands are substantial carbon sinks because organic matter in peat is highly stable due to the low rate of decomposition. Waterlogged anaerobic conditions induce accumulation of Sphagnum-derived phenolic compounds that inhibit peat organic matter decomposition, a mechanism referred to as the “enzymic latch”. Recent studies have predicted that the water table in northern peatlands may become unstable. We observed that such unstable water table levels can impede the development of Sphagnum mosses. In this study, we determined the effects of low and high frequency water table fluctuation regimes on Sphagnum growth and peat organic matter decomposition, by conducting a year-long mesocosm experiment. In addition, we conducted a molecular analysis to examine changes in abundance of fungal community which may play a key role in the decomposition of organic matter in peatlands. We found that rapid water table fluctuation inhibited the growth of Sphagnum due to fungal infection but stimulated decomposition of organic matter that may dramatically destabilize peatland carbon storage. Increased pH, induced by the fluctuation, may contribute to the enhanced activity of hydrolases in peat. We demonstrated that the water table fluctuation in peatlands impeded Sphagnum growth and accelerates decomposition due to fungal proliferation. Thus, we suggested that understanding the microbial community in the northern peatlands is essential for elucidating the possible changes in carbon cycle of peatland under the changing world.

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Northern peatland carbon stocks and dynamics: a review

Biogeosciences Discussions ◽

10.5194/bgd-9-5073-2012 ◽

2012 ◽

Vol 9 (4) ◽

pp. 5073-5107 ◽

Cited By ~ 9

Author(s):

Z. Yu

Keyword(s):

Current Knowledge ◽

Carbon Stocks ◽

Carbon Accumulation ◽

Peat Moss ◽

Peat Accumulation ◽

The Holocene ◽

Sphagnum Peat Moss ◽

Process Understanding ◽

Net Ecosystem Carbon Balance ◽

Northern Peatlands

Abstract. Here I review different approaches and associated uncertainties of estimates in the literature of carbon stocks and found that there is most likely 500 (± 100 range) gigatons of carbon (Gt C) in northern peatlands. The greatest uncertainty for all the approaches is the lack or insufficient representation of data, including depth, bulk density and carbon accumulation data, especially from the world's large peatlands. Several ways to improve estimates of peat carbon stocks were also discussed in this paper. Changes in peatland carbon stocks over time, estimated using Sphagnum (peat moss) spore data and down-core peat accumulation records, show different patterns during the Holocene. Considering long-term peat decomposition using peat accumulation data allows estimates of net carbon sequestration rates by peatlands, or net ecosystem carbon balance (NECB), which indicates more than half of peat carbon (> 270 Gt C) was sequestrated before 7000 yr ago during the Holocene. Contemporary carbon flux studies at 5 peatland sites show much larger NECB during the last decade (32 ± 7.8 (S.E.) g C m−2 yr−1) than during the last 7000 yr (~ 11 g C m−2 yr−1) as modeled from peat records across northern peatlands. This discrepancy highlights the urgent need for carbon accumulation data and process understanding, especially at decadal and centennial timescales, that would bridge current knowledge gaps and facilitate comparisons of NECB across all timescales.

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