TY - JOUR A1 - Gabriel, Marvin A1 - Toader, Camelia A1 - Faul, Franziska A1 - Rosskopf, Niko A1 - Grundling, Piet-Louis A1 - van Huyssteen, Cornelius W. A1 - Grundling, Althea T. A1 - Zeitz, Jutta T1 - Physical and hydrological properties of peat as proxies for degradation of South African peatlands: Implications for conservation and restoration JF - Mires and peat N2 - The physical and hydrological properties of peat from seven peatlands in northern Maputaland (South Africa) were investigated and related to the degradation processes of peatlands in different hydrogeomorphic settings. The selected peatlands are representative of typical hydrogeomorphic settings and different stages of human modification from natural to severely degraded. Nineteen transects (141 soil corings in total) were examined in order to describe peat properties typical of the distinct hydrogeomorphic settings. We studied degree of decomposition, organic matter content, bulk density, water retention, saturated hydraulic conductivity and hydrophobicity of the peats. From these properties we derived pore size distribution, unsaturated hydraulic conductivity and maximum capillary rise. We found that, after drainage, degradation advances faster in peatlands containing wood peat than in peatlands containing radicell peat. Eucalyptus plantations in catchment areas are especially threatening to peatlands in seeps, interdune depressions and unchannelled valley bottoms. All peatlands and their recharge areas require wise management, especially valley-bottom peatlands with swamp forest vegetation. Blocking drainage ditches is indispensable as a first step towards achieving the restoration of drained peatland areas, and further measures may be necessary to enhance the distribution of water. The sensitive swamp forest ecosystems should be given conservation priority. KW - moorsh forming process KW - swamp forest KW - restoration KW - unsaturated hydraulic conductivity Y1 - 2018 U6 - https://doi.org/10.19189/MaP.2018.OMB.336 SN - 1819-754X VL - 21 PB - International Peat Society CY - Dundee ER - TY - JOUR A1 - Walter, Judith A1 - Lück, Erika A1 - Bauriegel, Albrecht A1 - Facklam, Michael A1 - Zeitz, Jutta T1 - Seasonal dynamics of soil salinity in peatlands BT - a geophysical approach JF - Geoderma : an international journal of soil science N2 - Inland salt meadows are particularly valuable ecosystems, because they support a variety of salt-adapted species (halophytes). They can be found throughout Europe; including the peatlands of the glacial lowlands in northeast Germany. These German ecosystems have been seriously damaged through drainage. To assess and ultimately limit the damages, temporal monitoring of soil salinity is essential, which can be conducted by geoelectrical techniques that measure the soil electrical conductivity. However, there is limited knowledge on how to interpret electrical conductivity surveys of peaty salt meadows. In this study, temporal and spatial monitoring of dissolved salts was conducted in saline peatland soils using different geoelectrical techniques at different scales (1D: conductivity probe, 2D: conductivity cross-sections). Cores and soil samples were taken to validate the geoelectrical surveys. Although the influence of peat on bulk conductivity is large, the seasonal dynamics of dissolved salts within the soil profile could be monitored by repeated geoelectrical measurements. A close correlation is observed between conductivity (similar to salinity) at different depths and temperature, precipitation and corresponding groundwater level. The conductivity distribution between top- and subsoil during the growing season reflected the leaching of dissolved salts by precipitation and the capillary rise of dissolved salts by increasing temperature (similar to evaporation). Groundwater levels below 0.38 cm resulted in very low conductivities in the topsoil, which is presumably due to limited soil moisture and thus precipitation of salts. Therefore, to prevent the disappearance of dissolved salts from the rooting zone, which are essential for the halophytes, groundwater levels should be adjusted to maintain depths of between 20 and 35 cm. Lower groundwater levels will lead to the loss of dissolved salts from the rooting zone and higher levels to increasing dilution with fresh rainwater. The easy-to-handle conductivity probe is an appropriate tool for salinity monitoring. Using this probe with regressions adjusted for sandy and organic substrates (peat and organic gyttja) additional influences on bulk conductivity (e.g. cation exchange capacity, water content) can be compensated for and the correlation between salinity and electrical conductivity is high. KW - Peatlands KW - Inland salinization KW - Soil salinity dynamics KW - Electrical conductivity KW - Pore-fluid conductivity Y1 - 2017 U6 - https://doi.org/10.1016/j.geoderma.2017.08.022 SN - 0016-7061 SN - 1872-6259 VL - 310 SP - 1 EP - 11 PB - Elsevier Science CY - Amsterdam ER - TY - JOUR A1 - Walter, J. A1 - Lück, Erika A1 - Heller, C. A1 - Bauriegel, Albrecht A1 - Zeitz, Jutta T1 - Relationship between electrical conductivity and water content of peat and gyttja BT - implications for electrical surveys of drained peatlands JF - Near surface geophysics N2 - The application of electrical resistivity tomography to peatlands supports conventional coring by providing data on the current condition of peatlands, including data on stratigraphy, peat properties and thickness of organic deposits. Data on the current condition of drained peatlands are particularly required to improve estimates of carbon storage as well as losses and emissions from agriculturally used peatlands. However, most of the studies focusing on electrical resistivity tomography surveys have been conducted on natural peatlands with higher groundwater levels. Peatlands drained for agriculture have not often been studied using geophysical techniques. Drained sites are characterized by low groundwater levels and high groundwater fluctuations during the year, which lead to varying levels of water saturation. To validate better electrical resistivity tomography surveys of drained peatlands, the aim of this laboratory study is to investigate the influence of varying water saturation levels on electrical conductivity (reciprocal of resistivity) for a variety of peat and gyttja types, as well as for different degrees of peat decomposition. Results show that different levels of water saturation strongly influence bulk electrical conductivity. Distinct differences in this relationship exist between peat and gyttja substrates and between different degrees of peat decomposition. Peat shows an exponential relationship for all degrees of decomposition, whereas gyttja, in particular organic-rich gyttja, is characterized by a rather unimodal relationship. The slopes for the relationship between electrical conductivity and water content are steeper at high degrees of decomposition than for peat of low degrees of decomposition. These results have direct implications for field electrical resistivity tomography surveys. In drained peatlands that are strongly susceptible to drying, electrical resistivity tomography surveys have a high potential to monitor the actual field water content. In addition, at comparable water saturations, high or low degrees of decomposition can be inferred from electrical conductivity. KW - Electrical conductivity KW - Peat KW - Gyttja Y1 - 2019 U6 - https://doi.org/10.1002/nsg.12030 SN - 1569-4445 SN - 1873-0604 VL - 17 IS - 2 SP - 169 EP - 179 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Mueller, R. A1 - Heinicke, T. A1 - Juschus, O. A1 - Zeitz, Jutta T1 - Genesis and abiotic characteristics of three high-altitude peatlands in the Tien Shan Mountains (Kyrgyzstan), with focus on silty peatland substrates JF - Mires and peat N2 - Peatlands are scarce and threatened ecosystems in the semiarid region of Kyrgyzstan. Knowledge about the Kyrgyz peatlands is still poor and, especially, their genesis has hardly been investigated so far. Typically, the peatland substrates are characterised by the admixture of silt-sized particles in various quantities. In this work we report the abiotic properties and genesis of three peatlands within different altitudinal zones in southern Kyrgyzstan. We surveyed the stratification of the peatlands and their water chemistry. In addition, we investigated whether the silt found in the peatland substrates was deposited by wind, rivers or springs. The mineral constituents of the peatland substrates were analysed for particle size distribution and their elemental composition was compared with that of nearby loess, river and spring sediments using the immobile trace element titanium. One peatland shows a high abundance of different peatland substrates, indicating a frequent change of ecological conditions in the past. All three peatlands are fed by groundwater. Overgrazing and trampling by cattle has led to recent degradation of the upper peat layer. The resulting compaction of the peats prevents water from seeping into the substrates of the peatlands and subsequently changes their hydrology. Our results indicate that both wind and rivers have deposited silt in the peatlands, depending on their positions in the relief. Silts may also have been relocated by springs within the peatlands. KW - aeolian KW - fluvial KW - mire KW - particle size KW - X-ray fluorescence Y1 - 2016 U6 - https://doi.org/10.19189/MaP.2015.OMB.217 SN - 1819-754X VL - 18 PB - International Peat Society CY - Dundee ER - TY - JOUR A1 - Walter, J. A1 - Hamann, Göran A1 - Lück, Erika A1 - Klingenfuss, C. A1 - Zeitz, Jutta T1 - Stratigraphy and soil properties of fens: Geophysical case studies from northeastern Germany JF - Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution N2 - The determination of the total carbon storage of peatlands is of high relevance in the context of climate-change mitigation efforts. This determination relies on data about stratigraphy and peat properties, which are conventionally collected by coring. Ground-penetrating radar (GPR) and electrical resistivity imaging (ERI) can support these point data by providing subsoil information in two-dimensional cross-sections. In this study, GPR and ERI were conducted at two groundwater-fed fen sites located in the temperate zone in north-east Germany. The fens of this region are embedded in low conductive glacial sand and are characterised by thick layers of gyttja, which can be either mineral or organic. The two study sites are representative of this region with respect to stratigraphy (total thickness, peat and gyttja types) and ecological conditions (pH-value, trophic condition). The aim of this study is to assess the suitability of GPR and ERI to detect stratigraphy and peat properties under these characteristic site conditions. Results show that GPR clearly detects the interfaces between (i) Carex and brown-moss peat, (ii) brown-moss peat and organic gyttja, (iii) organic- and mineral gyttja, and (iv) mineral gyttja and the parent material (glacial sand). These layers differ in bulk density and the related organic matter content. ERI, however, does not delineate these layers; rather it delineates regions of varying properties. At our base-rich site, pore fluid conductivity and cation.exchange capacity are the main factors that determine peat electrical conductivity (reverse of resistivity), whereas organic matter and water content are most influential at the more acidic site. Thus the correlation between peat properties and electrical conductivity are driven by site-specific conditions, which are mainly determined by the solute load in the groundwater at fens. When the total organic deposits exceed a thickness of 5 m, the depth of investigation by GPR is limited due to increasing attenuation. This is not a limiting factor for ERI, where the transition from organic deposits to glacial sand is visible at both sites. Due to these specific sensitivities, a combined application of GPR and ERI meets the demand for up-to-date information on carbon storage of peatlands, which is, moreover, very site-specific because of the inherent variety of ecological conditions and stratigraphy between peatlands in general and between fens and bogs in particular. (C) 2016 Elsevier B.V. All rights reserved. KW - Fen stratigraphy KW - Peat properties KW - Gyttja KW - Ground penetrating radar KW - Electrical conductivity KW - Electrical resistivity imaging Y1 - 2016 U6 - https://doi.org/10.1016/j.catena.2016.02.028 SN - 0341-8162 SN - 1872-6887 VL - 142 SP - 112 EP - 125 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Walter, Judith A1 - Lueck, Erika A1 - Bauriegel, Albrecht A1 - Richter, C. A1 - Zeitz, Jutta T1 - Multi-scale analysis of electrical conductivity of peatlands for the assessment of peat properties JF - European journal of soil science N2 - Peatlands store large amounts of carbon. This storage function has been reduced through intensive drainage, which leads to the decomposition of peat, resulting in a loss of carbon. Measurements of the real (sigma) and imaginary part (sigma) of electrical conductivity can deliver information on peat properties, such as the pore fluid conductivity (sigma(w)), cation exchange capacity (CEC), bulk density ((b)), water content (WC) and soil organic matter (SOM) content. These properties change with the peat's degree of decomposition (DD). To explore the relationships between the peat properties, sigma, sigma and DD, we focused on three different types of survey and scales. First, point measurements were made with a conductivity probe at various locations over a large area of northeast Germany to determine the degree of correlation between sigma and DD. Second, nine of these locations were selected for sampling to determine which of the properties sigma(w), CEC, (b), WC and SOM predominantly influence sigma and sigma. This multisite dataset includes the entire range of DD and was analysed in the laboratory. Third, one site was selected for a survey of sigma including sampling, to identify which properties mainly control sigma in a single-site approach. Statistical analysis revealed that for the multisite laboratory dataset, sigma(w) has the strongest effect on sigma, followed by CEC, whereas sigma is mainly determined by CEC. In a single-site approach, WC followed by CEC had a dominant effect on sigma. No clear correlation could be observed between (i) DD and peat properties and (ii) DD and sigma or sigma. This is because of the complex changes in properties with increasing DD. Y1 - 2015 U6 - https://doi.org/10.1111/ejss.12251 SN - 1351-0754 SN - 1365-2389 VL - 66 IS - 4 SP - 639 EP - 650 PB - Wiley-Blackwell CY - Hoboken ER -