Raised Bog

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Marija Tamkeviciūtė - One of the best experts on this subject based on the ideXlab platform.

  • climate change and water table fluctuation implications for Raised Bog surface variability
    Geomorphology, 2018
    Co-Authors: Julius Taminskas, Rita Linkevicienė, Rasa Simanauskienė, Laurynas Jukna, Gintautas Kibirkstis, Marija Tamkeviciūtė
    Abstract:

    Abstract Cyclic peatland surface variability is influenced by hydrological conditions that highly depend on climate and/or anthropogenic activities. A low water level leads to a decrease of peatland surface and an increase of C emissions into the atmosphere, whereas a high water level leads to an increase of peatland surface and carbon sequestration in peatlands. The main aim of this article is to evaluate the influence of hydrometeorological conditions toward the peatland surface and its feedback toward the water regime. A regional survey of the Raised Bog water table fluctuation and surface variability was made in one of the largest peatlands in Lithuania. Two appropriate indicators for different peatland surface variability periods (increase and decrease) were detected. The first one is an ~ 200 mm y− 1 average net rainfall over a three-year range. The second one is an average annual water depth of 25–30 cm. The application of these indicators enabled the reconstruction of Cepkeliai peatland surface variability during a 100 year period. Processes of peatland surface variability differ in time and in separate parts of peatland. Therefore, internal subbasins in peatland are formed. Subbasins involve autogenic processes that can later affect their internal hydrology, nutrient status, and vegetation succession. Internal hydrological conditions, surface fluctuation, and vegetation succession in peatland subbasins should be taken into account during evaluation of their state, nature management projects, and other peatland research works.

Julius Taminskas - One of the best experts on this subject based on the ideXlab platform.

  • climate change and water table fluctuation implications for Raised Bog surface variability
    Geomorphology, 2018
    Co-Authors: Julius Taminskas, Rita Linkevicienė, Rasa Simanauskienė, Laurynas Jukna, Gintautas Kibirkstis, Marija Tamkeviciūtė
    Abstract:

    Abstract Cyclic peatland surface variability is influenced by hydrological conditions that highly depend on climate and/or anthropogenic activities. A low water level leads to a decrease of peatland surface and an increase of C emissions into the atmosphere, whereas a high water level leads to an increase of peatland surface and carbon sequestration in peatlands. The main aim of this article is to evaluate the influence of hydrometeorological conditions toward the peatland surface and its feedback toward the water regime. A regional survey of the Raised Bog water table fluctuation and surface variability was made in one of the largest peatlands in Lithuania. Two appropriate indicators for different peatland surface variability periods (increase and decrease) were detected. The first one is an ~ 200 mm y− 1 average net rainfall over a three-year range. The second one is an average annual water depth of 25–30 cm. The application of these indicators enabled the reconstruction of Cepkeliai peatland surface variability during a 100 year period. Processes of peatland surface variability differ in time and in separate parts of peatland. Therefore, internal subbasins in peatland are formed. Subbasins involve autogenic processes that can later affect their internal hydrology, nutrient status, and vegetation succession. Internal hydrological conditions, surface fluctuation, and vegetation succession in peatland subbasins should be taken into account during evaluation of their state, nature management projects, and other peatland research works.

Simon H Bottrell - One of the best experts on this subject based on the ideXlab platform.

  • sulphur isotopic investigation of a polluted Raised Bog and the uptake of pollutant sulphur by sphagnum
    Environmental Pollution, 1998
    Co-Authors: A Thompson, Simon H Bottrell
    Abstract:

    The sulphur content and sulphur isotopic composition of Sphagnum as well as anionic compositions and sulphur isotope ratios of rainwater inputs and Bog waters have been measured at Thorne Moors, a Raised Bog in eastern England. Rainwater sulphate isotopic composition shows the sulphur input at this site to be dominated by anthropogenic pollution from fossil fuel burning. Strong depletion of sulphate (low SO2−4Cl−) and enrichment in 34S in sulphate occurs at depth in the Bog porewaters due to bacterial sulphate reduction. Some surface waters have low SO2−4Cl− and are 34S enriched due to removal of sulphate by downward diffusion into a sulphate-reducing zone. Other sites have high SO2−4Cl− which appears to result from oxidation of organically bound sulphur in the peat. Sulphur is present in Sphagnum at around 0.2% by weight and is depleted by 0 to -9‰ in the heavier 34S isotope compared to sulphate. Comparison with similar data from pristine coastal sites shows that sulphur incorporation into Sphagnum is enhanced in the polluted site (as Sphagnum sulphur concentrations are higher at lower total sulphur inputs) and that sulphur incorporation is accompanied by a smaller isotopic shift than in the pristine sites. The data support a model of preferential incorporation of partially reduced sulphur species (probably HSO−3) into Sphagnum. In pristine sites these are only available as oxidation products of sulphide formed by sulphate reduction and are 32S depleted. In polluted sites this source is augmented by sulphur(IV) species in atmospheric inputs and the resultant mixture is less depleted in 32S. Thus, in the polluted sites more HSO−3 is available for uptake and the isotopic shift between Sphagnum and aqueous sulphur species is smaller.

Benjamin William James Surridge - One of the best experts on this subject based on the ideXlab platform.

  • controls on near surface hydraulic conductivity in a Raised Bog
    Water Resources Research, 2019
    Co-Authors: Paul J Morris, Andrew Baird, Phil A Eades, Benjamin William James Surridge
    Abstract:

    Shallow water tables protect northern peatlands and their important carbon stocks from aerobic decomposition. Hydraulic conductivity, K, is a key control on water tables. The controls on K, particularly in degraded and restored peatlands, remain a subject of ongoing research. We took 29 shallow (~50 cm) peat cores from an estuarine Raised Bog in Wales, UK. Parts of the Bog are in close-to-natural condition, while other areas have undergone shallow peat cutting for fuel and drainage, followed by restoration through ditch blocking. In the laboratory we measured horizontal (Kh) and vertical (Kv) hydraulic conductivity. We fitted linear multiple regression models to describe log10-transformed Kh and Kv on the basis of simple, easy-to-measure predictors. Dry bulk density and degree of decomposition were the strongest predictors of Kh and Kv. Perhaps surprisingly, the independent effect of hummocks was to produce higher-Kv peat than in lawns; while the independent effect of restored diggings was to produce higher-K peat than in uncut locations. Our models offer high explanatory power for Kh (adjusted r2 = 0.740) and K (adjusted r2 = 0.787). Our findings indicate that generalizable predictive models of peat K, similar to pedotransfer functions for mineral soils, may be attainable. Kh and Kv possess subtly different controls that are consistent with the contrasting roles of these two properties in peatland water budgets. Our near-surface samples show no evidence for the low-K marginal peat previously observed in deeper layers at the same site, indicating that such structures may be less important than previously believed.

  • The hydraulic structure of a Raised Bog and its implications for ecohydrological modelling of Bog development
    Ecohydrology, 2008
    Co-Authors: Andrew Baird, Phil A Eades, Benjamin William James Surridge
    Abstract:

    Raised Bogs are important ecohydrological systems in which there are strong two-way links between plant succession, litter and peat decay, and hydrological functioning. Using recently established protocols, we measured the hydraulic structure of a Raised Bog in West Wales. We tested two hypotheses: (i) that the hydraulic conductivity (K) of the peat shows depth dependency such that lower layers of peat are effectively impermeable, and (ii) that the K of the marginal peat of the Bog dome is lower than that in central areas. From 107 piezometer measurements we found there was depth dependency of K but that lower peat layers were not poorly permeable or impermeable. We also found that the K of the peat on the margin of the Bog dome was generally significantly lower than that in central areas. Our results suggest that, for some Bogs at least, it is important to simulate water flow through deeper peats when simulating peatland development or growth. They also raise the intriguing possibility that the low K of marginal peat is important in maintaining wet conditions in central Bog areas, allowing Bogs to reach greater thicknesses than they would do in the absence of the low-K margin; an idea first proposed for blanket Bogs by Lapen et al. (2005).

Brian Johnson - One of the best experts on this subject based on the ideXlab platform.

  • a paleoecological perspective of vegetation succession on Raised Bog microforms
    Ecological Monographs, 2004
    Co-Authors: Andy J Mcmullen, K E Barber, Brian Johnson
    Abstract:

    Peat cores were taken from eight primary and one secondary Raised Bog sites throughout the United Kingdom in order to determine the pathways of succession between the microform (hummock, ridge, lawn, hollow, and pool) plant communities of the mid to late Holocene. All of these sites have undergone drainage and/or cutting in the recent past, at least. The plant communities were reconstructed by using plant macrofossil analysis, and they are defined primarily by the dominant species of Sphagnum. While plant macrofossils may be used to infer hydrological conditions, an alternative proxy, using testate amoebae, was utilized. This group of organisms was used to avoid circular arguments when relating the vegetation changes to hydrological events. Consequently, a conceptual model of late Holocene succession on British Raised mires is constructed that elucidates succession between the microform plant communities according to changes in the water table depth, its stability, quality, and physical disturbance of the vegetation cover. The general sequence of ombrogenous communities was elucidated to be, with increasing height above the water tables, S. cuspidatum and S. auriculatum > Sphagnum sect. Cymbifolia taxa > Sphagnum sect. Acutifolia taxa > a return of Sphagnum sect. Cymbifolia taxa > non-Sphagnum mosses. A major pathway toward degradation of the mire is apparent in modern times, and recovery is typically via a phase of dominance by S. tenellum prior to the establishment of either S. magellanicum or S. papillosum. Although this disturbance is of a large magnitude, it was found that equable or more severe perturbations to the water table had occurred in the past, especially at coastal sites where marine regression led to the establishment of Sphagnum-poor communities dominated by Calluna and Eriophorum vaginatum. The long- term persistence of hummock–hollow vegetation communities is demonstrated, but the appearance of persistent, more homogeneous phases suggests that this surface topography is not always well developed.