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Soren Christensen - One of the best experts on this subject based on the ideXlab platform.
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natural perturbations drying wetting and freezing thawing cycles and the emission of nitrous oxide carbon dioxide and methane from farmed Organic Soils
Soil Biology & Biochemistry, 2001Co-Authors: Anders Prieme, Soren ChristensenAbstract:Abstract We investigated the effects of drying–wetting and freezing–thawing cycles on the emission of nitrous oxide, carbon dioxide and methane from intact soil cores from farmed Organic Soils at sites in Germany, Sweden and Finland. During the first week following wetting or thawing, cores from the German and Swedish sites produced an up to 1000-fold increase in N 2 O emission rates. The total surplus N 2 O emission due to the first wetting event ranged between 3 and 140 mg N–N 2 O m −2 , and between 13 and 340 mg N–N 2 O m −2 due to the first thawing event but declined following two successive freeze–thaw events. Wetting and thawing produced a greater surplus emission of N 2 O from grassland sites compared to arable sites. Following wetting, denitrification was responsible for the majority of N 2 O emission from the German grassland soil while in the German ploughed soil and the Swedish Soils denitrification was responsible for less than 60% of the N 2 O emission. In contrast, following thawing, denitrification was responsible for 2 O emission from the German grassland soil while in the remaining German and Swedish Soils denitrification was responsible for most of the emission. Wetting or thawing of soil cores from the Finnish sites did not result in any significant increase in N 2 O emission rates perhaps because a prolonged drought at the time of soil core collection had changed soil properties considerably. The CO 2 emission rates increased up to 5-fold following wetting or thawing. The total surplus CO 2 emission ranged from 0.0 to 13 g C–CO 2 m −2 , differed between locations and land use, and decreased during successive cycles of freezing and thawing. The total surplus CO 2 emission from grassland sites following thawing was generally higher than from arable and forest sites probably due to decomposition of carbon sources liberated from stressed grass roots. Methane emission rates were very small and often below our detection limit ( 4 m −2 h −1 ); no effects of wetting or thawing on CH 4 emission rates were observed at any of the sites. A comparison with annual emission rates of N 2 O and CO 2 showed that even a single wetting or thawing event may account for a large proportion of the N 2 O emission from farmed Organic Soils.
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natural perturbations drying wetting and freezing thawing cycles and the emission of nitrous oxide carbon dioxide and methane from farmed Organic Soils
Soil Biology & Biochemistry, 2001Co-Authors: Anders Prieme, Soren ChristensenAbstract:Abstract We investigated the effects of drying–wetting and freezing–thawing cycles on the emission of nitrous oxide, carbon dioxide and methane from intact soil cores from farmed Organic Soils at sites in Germany, Sweden and Finland. During the first week following wetting or thawing, cores from the German and Swedish sites produced an up to 1000-fold increase in N2O emission rates. The total surplus N2O emission due to the first wetting event ranged between 3 and 140 mg N–N2O m−2, and between 13 and 340 mg N–N2O m−2 due to the first thawing event but declined following two successive freeze–thaw events. Wetting and thawing produced a greater surplus emission of N2O from grassland sites compared to arable sites. Following wetting, denitrification was responsible for the majority of N2O emission from the German grassland soil while in the German ploughed soil and the Swedish Soils denitrification was responsible for less than 60% of the N2O emission. In contrast, following thawing, denitrification was responsible for
Anders Prieme - One of the best experts on this subject based on the ideXlab platform.
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natural perturbations drying wetting and freezing thawing cycles and the emission of nitrous oxide carbon dioxide and methane from farmed Organic Soils
Soil Biology & Biochemistry, 2001Co-Authors: Anders Prieme, Soren ChristensenAbstract:Abstract We investigated the effects of drying–wetting and freezing–thawing cycles on the emission of nitrous oxide, carbon dioxide and methane from intact soil cores from farmed Organic Soils at sites in Germany, Sweden and Finland. During the first week following wetting or thawing, cores from the German and Swedish sites produced an up to 1000-fold increase in N 2 O emission rates. The total surplus N 2 O emission due to the first wetting event ranged between 3 and 140 mg N–N 2 O m −2 , and between 13 and 340 mg N–N 2 O m −2 due to the first thawing event but declined following two successive freeze–thaw events. Wetting and thawing produced a greater surplus emission of N 2 O from grassland sites compared to arable sites. Following wetting, denitrification was responsible for the majority of N 2 O emission from the German grassland soil while in the German ploughed soil and the Swedish Soils denitrification was responsible for less than 60% of the N 2 O emission. In contrast, following thawing, denitrification was responsible for 2 O emission from the German grassland soil while in the remaining German and Swedish Soils denitrification was responsible for most of the emission. Wetting or thawing of soil cores from the Finnish sites did not result in any significant increase in N 2 O emission rates perhaps because a prolonged drought at the time of soil core collection had changed soil properties considerably. The CO 2 emission rates increased up to 5-fold following wetting or thawing. The total surplus CO 2 emission ranged from 0.0 to 13 g C–CO 2 m −2 , differed between locations and land use, and decreased during successive cycles of freezing and thawing. The total surplus CO 2 emission from grassland sites following thawing was generally higher than from arable and forest sites probably due to decomposition of carbon sources liberated from stressed grass roots. Methane emission rates were very small and often below our detection limit ( 4 m −2 h −1 ); no effects of wetting or thawing on CH 4 emission rates were observed at any of the sites. A comparison with annual emission rates of N 2 O and CO 2 showed that even a single wetting or thawing event may account for a large proportion of the N 2 O emission from farmed Organic Soils.
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natural perturbations drying wetting and freezing thawing cycles and the emission of nitrous oxide carbon dioxide and methane from farmed Organic Soils
Soil Biology & Biochemistry, 2001Co-Authors: Anders Prieme, Soren ChristensenAbstract:Abstract We investigated the effects of drying–wetting and freezing–thawing cycles on the emission of nitrous oxide, carbon dioxide and methane from intact soil cores from farmed Organic Soils at sites in Germany, Sweden and Finland. During the first week following wetting or thawing, cores from the German and Swedish sites produced an up to 1000-fold increase in N2O emission rates. The total surplus N2O emission due to the first wetting event ranged between 3 and 140 mg N–N2O m−2, and between 13 and 340 mg N–N2O m−2 due to the first thawing event but declined following two successive freeze–thaw events. Wetting and thawing produced a greater surplus emission of N2O from grassland sites compared to arable sites. Following wetting, denitrification was responsible for the majority of N2O emission from the German grassland soil while in the German ploughed soil and the Swedish Soils denitrification was responsible for less than 60% of the N2O emission. In contrast, following thawing, denitrification was responsible for
C D Evans - One of the best experts on this subject based on the ideXlab platform.
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greenhouse gas emission factors associated with rewetting of Organic Soils
Mires and Peat, 2016Co-Authors: D Wilson, D. Blain, Daniel Murdiyarso, John Couwenberg, Andrey Sirin, C D Evans, Susan E Page, Florence Renouwilson, J O Rieley, Maria StrackAbstract:Drained Organic Soils are a significant source of greenhouse gas (GHG) emissions to the atmosphere. Rewetting these Soils may reduce GHG emissions and could also create suitable conditions for return of the carbon (C) sink function characteristic of undrained Organic Soils. In this article we expand on the work relating to rewetted Organic Soils that was carried out for the 2014 Intergovernmental Panel on Climate Change (IPCC) Wetlands Supplement. We describe the methods and scientific approach used to derive the Tier 1 emission factors (the rate of emission per unit of activity) for the full suite of GHG and waterborne C fluxes associated with rewetting of Organic Soils. We recorded a total of 352 GHG and waterborne annual flux data points from an extensive literature search and these were disaggregated by flux type (i.e. CO2, CH4, N2O and DOC), climate zone and nutrient status. Our results showed fundamental differences between the GHG dynamics of drained and rewetted Organic Soils and, based on the 100 year global warming potential of each gas, indicated that rewetting of drained Organic Soils leads to: net annual removals of CO2 in the majority of Organic soil classes; an increase in annual CH4 emissions; a decrease in N2O and DOC losses; and a lowering of net GHG emissions. Data published since the Wetlands Supplement (n = 58) generally support our derivations. Significant data gaps exist, particularly with regard to tropical Organic Soils, DOC and N2O. We propose that the uncertainty associated with our derivations could be significantly reduced by the development of country specific emission factors that could in turn be disaggregated by factors such as vegetation composition, water table level, time since rewetting and previous land use history.
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acidity controls on dissolved Organic carbon mobility in Organic Soils
Global Change Biology, 2012Co-Authors: C D Evans, Nick Ostle, Joanna M Clark, Timothy G Jones, Annette Burden, Piotr Zielinski, Mark D A Cooper, Mike Peacock, Filip OulehleAbstract:Dissolved Organic carbon (DOC) concentrations in surface waters have increased across much of Europe and North America, with implications for the terrestrial carbon balance, aquatic ecosystem functioning, water treatment costs and human health. Over the past decade, many hypotheses have been put forward to explain this phenomenon, from changing climate and land management to eutrophication and acid deposition. Resolution of this debate has been hindered by a reliance on correlative analyses of time series data, and a lack of robust experimental testing of proposed mechanisms. In a 4 year, four-site replicated field experiment involving both acidifying and deacidifying treatments, we tested the hypothesis that DOC leaching was previously suppressed by high levels of soil acidity in peat and organo-mineral Soils, and therefore that observed DOC increases a consequence of decreasing soil acidity. We observed a consistent, positive relationship between DOC and acidity change at all sites. Responses were described by similar hyperbolic relationships between standardized changes in DOC and hydrogen ion concentrations at all sites, suggesting potentially general applicability. These relationships explained a substantial proportion of observed changes in peak DOC concentrations in nearby monitoring streams, and application to a UK-wide upland soil pH dataset suggests that recovery from acidification alone could have led to soil solution DOC increases in the range 46–126% by habitat type since 1978. Our findings raise the possibility that changing soil acidity may have wider impacts on ecosystem carbon balances. Decreasing sulphur deposition may be accelerating terrestrial carbon loss, and returning surface waters to a natural, high-DOC condition.
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rapid immobilisation and leaching of wet deposited nitrate in upland Organic Soils
Environmental Pollution, 2008Co-Authors: C D Evans, Nick Ostle, D A Norris, Helen Grant, Ed Rowe, C J Curtis, B ReynoldsAbstract:Nitrate (NO3-) is often observed in surface waters draining terrestrial ecosystems that remain strongly nitrogen (N) limited. It has been suggested that this occurs due to hydrological bypassing of soil or vegetation N retention, particularly during high flows. To test this hypothesis, artificial rain events were applied to 12 replicate soil blocks on a Welsh podzolic acid grassland hillslope, labelled with 15N-enriched NO3- and a conservative bromide (Br-) tracer. On average, 31% of tracer-labelled water was recovered within 4 h, mostly as mineral horizon lateral flow, indicating rapid vertical water transfer through the Organic horizon via preferential flowpaths. However, on average only 6% of 15N-labelled NO3- was recovered. Around 80% of added NO3- was thus rapidly immobilised, probably by microbial communities present on the surfaces of preferential flowpaths. Transitory exceedance of microbial N-uptake capacity during periods of high water and N flux may therefore provide a mechanism for NO3- leaching.
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alternative explanations for rising dissolved Organic carbon export from Organic Soils
Global Change Biology, 2006Co-Authors: C D Evans, P J Chapman, Joanna M Clark, D T Monteith, M S CresserAbstract:Since 1988, there has been, on average, a 91% increase in dissolved Organic carbon (DOC) concentrations of UK lakes and streams in the Acid Waters Monitoring Network (AWMN). Similar DOC increases have been observed in surface waters across much of Europe and North America. Much of the debate about the causes of rising DOC has, as in other studies relating to the carbon cycle, focused on factors related to climate change. Data from our peat-core experiments support an influence of climate on DOC, notably an increase in production with temperature under aerobic, and to a lesser extent anaerobic, conditions. However, we argue that climatic factors may not be the dominant drivers of DOC change. DOC solubility is suppressed by high soil water acidity and ionic strength, both of which have decreased as a result of declining sulphur deposition since the 1980s, augmented during the 1990s in the United Kingdom by a cyclical decline in sea-salt deposition. Our observational and experimental data demonstrate a clear, inverse and quantitatively important link between DOC and sulphate concentrations in soil solution. Statistical analysis of 11 AWMN lakes suggests that rising temperature, declining sulphur deposition and changing sea-salt loading can account for the majority of the observed DOC trend. This combination of evidence points to the changing chemical composition of atmospheric deposition, particularly the substantial reduction in anthropogenic sulphur emissions during the last 20 years, as a key cause of rising DOC. The implications of rising DOC export for the carbon cycle will be very different if linked primarily to decreasing acid deposition, rather than to changes in climate, suggesting that these systems may be recovering rather than destabilising.
Bärbel Tiemeyer - One of the best experts on this subject based on the ideXlab platform.
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Peat and other Organic Soils under agricultural use in Germany: Properties and challenges for classification
International Mire Conservation Group and International Peat Society, 2021Co-Authors: Mareille Wittnebel, Bärbel Tiemeyer, Ullrich DettmannAbstract:Under natural conditions, peatlands store large amounts of soil Organic carbon (SOC). However, they are under threat due to drainage which leads to mineralisation of soil Organic matter to carbon dioxide (CO2). This situation is especially severe in Germany, where more than 70 % of peat and other Organic Soils are used for agriculture. This study assessed the properties of these Soils within the framework of the first German Agricultural Soil Inventory. In a nationwide 8 × 8 km grid, Soils from a total of 3104 sites were sampled to depths of up to one metre or down to the peat base. Of these sites, 146 were on peat and other Organic Soils; and 31 % of the 146 sites were being affected not only by drainage but also by changes in horizonation (e.g. mineral covers, deep ploughing). The classification of heavily disturbed sites is limited within the German Manual of Soil Mapping, which has led to the development of an adapted classification scheme for peat and other Organic Soils under agricultural use in Germany. The respective peat classes showed distinct patterns of SOC and total nitrogen (Nt) contents and stocks, bulk density (BD) and C:N ratios. Overall, a SOC stock of 529 ± 201 t ha-1 and a Nt stock of 29.3 ± 13.9 t ha-1 were found within a depth of 0–100 cm. However, in deeper profiles, 48 % of the total SOC was stored below 100 cm depth down to the peat base. High SOC stocks were also found in peat-derived, mineral-covered and deep-ploughed Organic Soils, which might be classified as mineral Soils depending on the classification system used but are still prone to mineralisation and need to be considered in terms of emissions reporting and mitigation. Logarithmic and quadratic pedotransfer functions were developed to estimate BD and SOC density, respectively, from SOC contents. This is necessary for the calculation of SOC stocks when analyses of BD are absent. The quadratic relationship between SOC content and SOC density clearly showed that heavily degraded Organic Soils store as much SOC in a defined volume as more natural ones, and that any estimates of differences in potential CO2 emissions should not be based on SOC content, but on SOC density instead
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a new methodology for Organic Soils in national greenhouse gas inventories data synthesis derivation and application
Ecological Indicators, 2020Co-Authors: Bärbel Tiemeyer, Annette Freibauer, Michel Bechtold, Tim Eickenscheidt, Elisa Albiac Borraz, Jurgen Augustin, Sascha Beetz, Colja Beyer, Martin Ebli, Sabine FiedlerAbstract:Abstract Drained Organic Soils are large sources of anthropogenic greenhouse gases (GHG) in many European and Asian countries. Therefore, these Soils urgently need to be considered and adequately accounted for when attempting to decrease emissions from the Agriculture and Land Use, Land Use Change and Forestry (LULUCF) sectors. Here, we describe the methodology, data and results of the German approach for measurement, reporting and verification (MRV) of anthropogenic GHG emissions from drained Organic Soils and outline ways forward towards tracking drainage and rewetting. The methodology was developed for and is currently applied in the German GHG inventory under the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol. Spatial activity data comprise high resolution maps of land-use, type of Organic soil and mean annual water table (WT). The WT map was derived by a boosted regression trees model from data of more than 1000 dipwells. Emissions of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) were synthesized from a unique national data set comprising more than 250 annual GHG balances from 118 sites in most land-use categories and types of Organic Soils. Measurements were performed with harmonized protocols using manual chambers. Non-linear response functions describe the dependency of CO2 and CH4 fluxes on mean annual WT, stratified by land-use where appropriate. Modelling results were aggregated into “implied emission factors” for each land-use category, taking into account the uncertainty of the response functions, the frequency distribution of the WT within each land-use category and further GHG sources such as dissolved Organic carbon or CH4 emissions from ditches. IPCC default emission factors were used for these minor GHG sources. In future, response functions could be applied directly when appropriate WT data is available. As no functional relationship was found for N2O emissions, emission factors were calculated as the mean observed flux per land-use category. In Germany, drained Organic Soils emit more than 55 million tons of GHGs per year, of which 91% are CO2. This is equivalent to around 6.6% of the national GHG emissions in 2014. Thus, they are the largest GHG source from agriculture and LULUCF. The described methodology is applicable on the project scale as well as in other countries where similar data are collected.
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on the potential of sentinel 1 for high resolution monitoring of water table dynamics in grasslands on Organic Soils
Remote Sensing, 2019Co-Authors: Tina Asmus, Michel Bechtold, Bärbel TiemeyerAbstract:For Soils with shallow groundwater and high Organic carbon content, water table depth (WTD) is a key parameter to describe their hydrologic state and to estimate greenhouse gas emissions (GHG). Since the microwave backscatter coefficient (σ0) is sensitive to soil moisture, the application of Sentinel-1 satellite data might support the monitoring of these climate-relevant Soils at high spatial resolution (~100 m) by detecting spatial and temporal changes in local field and water management. Despite the low penetration depth of the C-band, σ0 is influenced by shallow WTD fluctuations via the soil hydraulic connection between the water table and surface soil. Here, we analyzed σ0 at 60 monitoring wells in a drained temperate peatland with degraded Organic Soils used as extensive grassland. We evaluated temporal Spearman correlation coefficients between σ0 and WTD considering the soil and vegetation information. To account for the effects of seasonal vegetation changes, we used the cross-over (incidence) angle method. Climatologies of the slope of the incidence angle dependency derived from two years of Sentinel-1 data and their application to the cross-over angle method did improve correlations, though the effect was minor. Overall, averaged over all sites, a temporal Spearman correlation coefficient of 0.45 (±0.17) was obtained. The loss of correlation during summer (higher vegetation, deeper WTD) and the effects of cuts and grazing are discussed. The site-specific general wetness level, described by the mean WTD of each site was shown to be a major factor controlling the strength of the correlation. Mean WTD deeper than about −0.60 m lowered the correlations across sites, which might indicate an important limit of the application.
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Vulnerability of soil Organic matter of anthropogenically disturbed Organic Soils
2017Co-Authors: Annelie Säurich, Bärbel Tiemeyer, Axel Don, Michel Bechtold, Wulf Amelung, Annette FreibauerAbstract:Abstract. Drained peatlands are hotspots of carbon dioxide (CO2) emissions from agriculture. As a consequence of both drainage-induced mineralisation and anthropogenic mixing with mineral Soils, large areas of former peatlands under agricultural use now contain soil Organic carbon (SOC) at the boundary between mineral and Organic Soils and/or underwent a secondary transformation of the peat (e.g. formation of aggregates). However, low carbon Organic Soils have rarely been studied since previous research has mainly focused on either mineral Soils or true peat Soils. The aim of the present study was to evaluate the soil Organic matter (SOM) vulnerability of the whole range of Organic Soils including very carbon rich mineral Soils (73 g kg−1
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fine grained detection of land use and water table changes on Organic Soils over the period 19922012 using multiple data sources in the dromling nature park germany
Land Use Policy, 2016Co-Authors: Johanna Untenecker, Annette Freibauer, Bärbel Tiemeyer, Andreas Laggner, Fred Braumann, Juerg LuterbacherAbstract:Abstract The construction of consistent time series of land use presents a key challenge when accounting for elective land use-based activities under the Kyoto Protocol (wetland drainage and rewetting (WDR), cropland management (CM) and grazing land management (GM)), in which current land use-driven greenhouse gas emissions are compared to a reference situation in 1990. This case study is the first to demonstrate the feasibility of using high-resolution land-use proxies from different datasets for Kyoto accounting in a data-rich case study region in Germany. The study region is characterised by Organic Soils and has been subject to significant nature conservation measures, including land-use changes, reductions in land-use intensity and changes in groundwater table depth. A consistent time series of 20 years of land use with a spatial resolution of 0.01 ha was created from various fine-grained spatial datasets for Organic Soils in the Dromling nature park by applying a newly developed ⿿translation key⿿. The translation key accounted for systematic differences in legends and thematic resolution. We also tested whether the land-use datasets served as trustworthy proxies for groundwater table depth. Land use in the Dromling nature park became less intensive during the study period of 1992⿿2012. The greatest land-use change (142 ha year ⿿1 , 1.14% year ⿿1 ) occurred between 2000 and 2008. This was in line with management measures undertaken in the nature park. The centre of the nature park became wetter and there was an increase in the share of grassland and more natural vegetation types. The groundwater table correlated with land use and land-use intensity on Organic Soils in the study area throughout the entire period. Land-use changes were accompanied by altered groundwater tables, except for the conversion from cropland to grassland. Our study indicates that detailed land-use time series can serve as a semi-quantitative proxy for groundwater depth, but that any robust quantitative assessment of water table changes requires in situ data, e.g. from a network of dipwells. Therefore, the combination of land-use and dipwell data provided an accurate basis for estimating GHG emission reductions from drained Organic Soils since 1990, which is the centre of the Kyoto activity WDR, but also part of afforestation/reforestation (AR) and deforestation (D), forest management (FM), CM and GM. Even the detailed land-use time series on its own would fulfil the requirements for WDR accounting, although with considerable uncertainty about the drainage status of the Organic Soils. We present the study area of Organic Soils as a showcase for combining the difficult issues of monitoring changes in land-use intensity as well as in soil wetness, the latter being most relevant for Organic Soils. The methodology is equally applicable to and relevant for mineral Soils.
Annette Freibauer - One of the best experts on this subject based on the ideXlab platform.
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a new methodology for Organic Soils in national greenhouse gas inventories data synthesis derivation and application
Ecological Indicators, 2020Co-Authors: Bärbel Tiemeyer, Annette Freibauer, Michel Bechtold, Tim Eickenscheidt, Elisa Albiac Borraz, Jurgen Augustin, Sascha Beetz, Colja Beyer, Martin Ebli, Sabine FiedlerAbstract:Abstract Drained Organic Soils are large sources of anthropogenic greenhouse gases (GHG) in many European and Asian countries. Therefore, these Soils urgently need to be considered and adequately accounted for when attempting to decrease emissions from the Agriculture and Land Use, Land Use Change and Forestry (LULUCF) sectors. Here, we describe the methodology, data and results of the German approach for measurement, reporting and verification (MRV) of anthropogenic GHG emissions from drained Organic Soils and outline ways forward towards tracking drainage and rewetting. The methodology was developed for and is currently applied in the German GHG inventory under the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol. Spatial activity data comprise high resolution maps of land-use, type of Organic soil and mean annual water table (WT). The WT map was derived by a boosted regression trees model from data of more than 1000 dipwells. Emissions of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) were synthesized from a unique national data set comprising more than 250 annual GHG balances from 118 sites in most land-use categories and types of Organic Soils. Measurements were performed with harmonized protocols using manual chambers. Non-linear response functions describe the dependency of CO2 and CH4 fluxes on mean annual WT, stratified by land-use where appropriate. Modelling results were aggregated into “implied emission factors” for each land-use category, taking into account the uncertainty of the response functions, the frequency distribution of the WT within each land-use category and further GHG sources such as dissolved Organic carbon or CH4 emissions from ditches. IPCC default emission factors were used for these minor GHG sources. In future, response functions could be applied directly when appropriate WT data is available. As no functional relationship was found for N2O emissions, emission factors were calculated as the mean observed flux per land-use category. In Germany, drained Organic Soils emit more than 55 million tons of GHGs per year, of which 91% are CO2. This is equivalent to around 6.6% of the national GHG emissions in 2014. Thus, they are the largest GHG source from agriculture and LULUCF. The described methodology is applicable on the project scale as well as in other countries where similar data are collected.
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Vulnerability of soil Organic matter of anthropogenically disturbed Organic Soils
2017Co-Authors: Annelie Säurich, Bärbel Tiemeyer, Axel Don, Michel Bechtold, Wulf Amelung, Annette FreibauerAbstract:Abstract. Drained peatlands are hotspots of carbon dioxide (CO2) emissions from agriculture. As a consequence of both drainage-induced mineralisation and anthropogenic mixing with mineral Soils, large areas of former peatlands under agricultural use now contain soil Organic carbon (SOC) at the boundary between mineral and Organic Soils and/or underwent a secondary transformation of the peat (e.g. formation of aggregates). However, low carbon Organic Soils have rarely been studied since previous research has mainly focused on either mineral Soils or true peat Soils. The aim of the present study was to evaluate the soil Organic matter (SOM) vulnerability of the whole range of Organic Soils including very carbon rich mineral Soils (73 g kg−1
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fine grained detection of land use and water table changes on Organic Soils over the period 19922012 using multiple data sources in the dromling nature park germany
Land Use Policy, 2016Co-Authors: Johanna Untenecker, Annette Freibauer, Bärbel Tiemeyer, Andreas Laggner, Fred Braumann, Juerg LuterbacherAbstract:Abstract The construction of consistent time series of land use presents a key challenge when accounting for elective land use-based activities under the Kyoto Protocol (wetland drainage and rewetting (WDR), cropland management (CM) and grazing land management (GM)), in which current land use-driven greenhouse gas emissions are compared to a reference situation in 1990. This case study is the first to demonstrate the feasibility of using high-resolution land-use proxies from different datasets for Kyoto accounting in a data-rich case study region in Germany. The study region is characterised by Organic Soils and has been subject to significant nature conservation measures, including land-use changes, reductions in land-use intensity and changes in groundwater table depth. A consistent time series of 20 years of land use with a spatial resolution of 0.01 ha was created from various fine-grained spatial datasets for Organic Soils in the Dromling nature park by applying a newly developed ⿿translation key⿿. The translation key accounted for systematic differences in legends and thematic resolution. We also tested whether the land-use datasets served as trustworthy proxies for groundwater table depth. Land use in the Dromling nature park became less intensive during the study period of 1992⿿2012. The greatest land-use change (142 ha year ⿿1 , 1.14% year ⿿1 ) occurred between 2000 and 2008. This was in line with management measures undertaken in the nature park. The centre of the nature park became wetter and there was an increase in the share of grassland and more natural vegetation types. The groundwater table correlated with land use and land-use intensity on Organic Soils in the study area throughout the entire period. Land-use changes were accompanied by altered groundwater tables, except for the conversion from cropland to grassland. Our study indicates that detailed land-use time series can serve as a semi-quantitative proxy for groundwater depth, but that any robust quantitative assessment of water table changes requires in situ data, e.g. from a network of dipwells. Therefore, the combination of land-use and dipwell data provided an accurate basis for estimating GHG emission reductions from drained Organic Soils since 1990, which is the centre of the Kyoto activity WDR, but also part of afforestation/reforestation (AR) and deforestation (D), forest management (FM), CM and GM. Even the detailed land-use time series on its own would fulfil the requirements for WDR accounting, although with considerable uncertainty about the drainage status of the Organic Soils. We present the study area of Organic Soils as a showcase for combining the difficult issues of monitoring changes in land-use intensity as well as in soil wetness, the latter being most relevant for Organic Soils. The methodology is equally applicable to and relevant for mineral Soils.
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High CO 2 fluxes from grassland on histic Gleysol along soil carbon and drainage gradients
Biogeosciences, 2014Co-Authors: K. Leiber-sauheitl, Roland Fuß, Carolina Voigt, Annette FreibauerAbstract:Drained Organic Soils are anthropogenic emission hotspots of greenhouse gases (GHGs). Most studies have fo- cused on deep peat Soils and on peats with high Organic car- bon content. In contrast, histic Gleysols are characterized by shallow peat layers, which are left over from peat cutting ac- tivities or by peat mixed with mineral soil. It is unknown whether they emit less GHGs than deep Histosols when drained. We present the annual carbon and GHG balance of grasslands for six sites on nutrient-poor histic Gleysols with a shallow (30 cm) histic horizon or mixed with mineral soil in Northern Germany (soil Organic carbon concentration (Corg) from 9 to 52 %). The net GHG balance, corrected for carbon export by har- vest, was around 4 t CO2-C-eq ha 1 yr 1 on Soils with peat layer and little drainage (mean annual water table < 20 cm below surface). The net GHG balance reached 7-9 t CO2-C- eq ha 1 yr 1 on Soils with sand mixed into the peat layer and water tables between 14 cm and 39 cm below surface. GHG emissions from drained histic Gleysols (i) were as high as those from deep Histosols, (ii) increase linearly from shallow to deeper drainage, (iii) but are not affected by C org content of the histic horizon. Ecosystem respiration (Reco) was lin- early correlated with water table level even if it was below the histic horizon. The Reco/GPP ratio was 1.5 at all sites, so that we ruled out a major influence of the inter-site variability in vegetation composition on annual net ecosystem exchange (NEE). The IPCC definition of Organic Soils includes shallow his- tic topsoil, unlike most national and international definitions of Histosols. Our study confirms that this broader definition is appropriate considering anthropogenic GHG emissions from drained Organic Soils. Countries currently apply soil maps in national GHG inventories which are likely not to include histic Gleysols. The land area with GHG emission hotspots due to drainage is likely to be much higher than an- ticipated. Deeply drained histic Gleysols are GHG hotspots that have so far been neglected or underestimated. Peat mixing with sand does not mitigate GHG emissions. Our study implies that rewetting Organic Soils, including histic Gleysols, has a much higher relevance for GHG mitigation strategies than currently recognized.