Leistungen der ökologischen Landwirtschaft zur Reduzierung des Erosions- und Hochwasserrisikos im Vergleich zu konventioneller Bewirtschaftung – Ergebnisse einer systematischen Vergleichsstudie

Niederschlagsveränderungen durch den Klimawandel führen zu einem erhöhten Risiko für Erosion und Hochwasser in Deutschland. Aufgrund von guter Bodenbedeckung und einer verbesserten Bodenstruktur hat der ökologische Landbau ein hohes Erosions- und Hochwasserschutzpotenzial, allerdings ist die Datenlage unzureichend. Daten aus 43 Studien wurden für 7 Parameter qualitativ ausgewertet. Die Vergleichspaare wurden in die Kategorien „kleiner“, „größer“ bzw. „gleich“ eingeordnet, je nachdem, ob der untersuchte Parameter unter ökologischer Bewirtschaftung besser, schlechter oder ähnlich wie unter konventioneller Bewirtschaftung ausgewiesen wurde. Ergebnisse für bodenstrukturelle Parameter weisen auf eine niedrigere Erodierbarkeit der ökologisch bewirtschafteten Böden hin. Der Bewirtschaftungsfaktor (C-Faktor) aus der ABAG war auch niedriger für die ökologischen Varianten. Dementsprechend war die Infiltration höher und der Oberflächenabfluss und Bodenabtrag niedriger in den ökologischen Systemen. Eine Vergleichbarkeitsanalyse der Studien ist nötig

Biogenic Greenhouse Gas Emissions from Agriculture in Europe - Quantification and Mitigation

Die Dissertation analysiert Klimaschutzmaßnahmen in der europäischen Landwirtschaft im Hinblick auf Potentiale, Umweltwirkungen, Minderungskosten und damit verbundene Unsicherheiten im Hinblick auf die Umsetzung des Kyoto-Protokolls. Dazu werden Literaturstudien durchgeführt, Lebensweganalysen und Treibhausgasinventare methodisch weiterentwickelt und schließlich Treibhausgasemissionen und deren Minderungspotential auf europäischer Ebene berechnet und bewertet. Die europäische Landwirtschaft emittierte im Jahr 1995 0.84 ± 0.29 Tg N2O, 8.1 ± 1.9 Tg Methan (CH4) und 39 Tg ± 25 Kohlendioxid (CO2), insgesamt 470 ± 80 Tg CO2-Äquivalente oder 11 % der gesamten anthropogenen Treibhausgase der EU. Die hier entwickelte Berechnungsmethodik bildet regionale Charakteristika der landwirtschaftlichen Produktion ab und halbiert die methodische Unsicherheit gegenüber den offiziellen nationalen Inventaren. Landwirtschaftliche Böden Europas werden kurzfristig maximal etwa 200 Tg a-1 CO2 aufnehmen können, wobei entsprechende Maßnahmen auch andere positive Umweltwirkungen zeigen. Das biologische Substitutionspotential von Bioenergie in der EU liegt zwischen 400 und 800 Tg a-1 CO2-Äquivalente. Aus Umweltaspekten heraus sollten perenne, holzige Kulturen statt annuelle Intensivkulturen genutzt werden. Das Minderungspotential der technischen Maßnahmen zur direkten Treibhausgasminderung liegt zwischen 100 und 200 Tg a-1 CO2-Äquivalenten, z.B. durch eine Extensivierung der Pflanzenproduktion mit reduziertem Einsatz von Stickstoff bzw. technologische Innovation im Bereich der Tierhaltung, die möglichst von einem Abbau der Tierzahlen flankiert wird, sowie die Wiedervernässung von gedränten Moorböden. Eine Veränderung der sozioökonomischen und politischen Rahmenbedingungen kann das Minderungspotential erhöhen.This dissertation analyses relevant potential mitigation strategies of biogenic greenhouse gases (GHGs) in the agriculture of the European Union (EU) in light of the Kyoto Protocol. It identifies where important sources and mitigation potentials are located and what uncertainty, environmental ancillary effects and costs are associated with them. Literature reviews are performed and methodologies for environmental assessment and GHG accounting are further developed. On this basis, GHG emissions are quantified and reduction potentials are assessed at European level. In 1995, European agriculture emitted 0.84 ± 0.29 Tg N2O, 8.1 ± 1.9 Tg methane (CH4) and 39 Tg ± 25 carbon dioxide (CO2), which adds up to 470 ± 80 Tg CO2-equivalents or 11% of the overall anthropogenic greenhouse gas emissions of the EU. The detailed methodology developed here adequately resolves regional specifics of agricultural conditions and reduces the methodological uncertainty in the estimates to half of the one in the official national inventories. European agricultural soils will at maximum sequester carbon in the order of 100 Tg a-1 CO2 over the coming years, which may also provide other environmental benefits. The biological potential of bioenergy in the EU allows to substitute for 400 to 800 Tg a-1 CO2-equivalents. From an environmental perspective, the use of perennials, especially of residues and woody biomass, is preferable to intensively grown annual crops. The biological potential for technical GHG reduction measures in EU agriculture is between 100 and 200 Tg a-1 CO2-equivalents. Promising measures promote the extensivation of arable cropping by reducing nitrogen inputs, technological innovation in animal husbandry, which is best accompanied by a further decline in animal numbers, as well as rewetting drained organic soils. Most measures will provide ancillary environmental benefits. Changing the socio-economic and political frame conditions may enhance the GHG mitigation potential

Nitrogen mineralization and gaseous nitrogen losses from waterlogged and drained organic soils in a black alder (<i>Alnus glutinosa</i> (L.) Gaertn.) forest

Black alder (<i>Alnus glutinosa</i> (L.) Gaertn.) forests on peat soils have been reported to be hotspots for high nitrous oxide (N₂O) losses. High emissions may be attributed to alternating water tables of peatlands and to the incorporation of high amounts of easily decomposable nitrogen (N) into the ecosystem by symbiotic dinitrogen (N₂)-fixation of alder trees. Our study addressed the question to what extent drainage enhances the emissions of N₂O from black alder forests and how N turnover processes and physical factors influence the production of N₂O and total denitrification. The study was conducted in a drained black alder forest with variable groundwater tables at a southern German fen peatland. Fluxes of N₂O were measured using the closed chamber method at two drained sites (D-1 and D-2) and one undrained site (U). Inorganic N contents and net N mineralization rates (NNM) were determined. Additionally a laboratory incubation experiment was carried out to investigate greenhouse gas and N₂ fluxes at different temperature and soil moisture conditions. Significantly different inorganic N contents and NNM rates were observed, which however did not result in significantly different N₂O fluxes in the field but did in the laboratory experiment. N₂O fluxes measured were low for all sites, with total annual emissions of 0.51 ± 0.07 (U), 0.97 ± 0.13 (D-1) and 0.93 ± 0.08 kg N₂O–N ha⁻¹ yr^&minus;1 (D-2). Only 37% of the spatiotemporal variation in field N₂O fluxes could be explained by peat temperature and groundwater level, demonstrating the complex interlinking of the controlling factors for N₂O emissions. However, temperature was one of the key variables of N₂O fluxes in the incubation experiment conducted. Increasing soil moisture content was found to enhance total denitrification losses during the incubation experiment, whereas N₂O fluxes remained constant. At the undrained site, permanently high groundwater level was found to prevent net nitrification, resulting in a limitation of available nitrate (NO₃^&minus;) and negligible gaseous N losses. N₂O flux rates that were up to four times higher were measured in the incubation experiment. They reveal the potential of high N₂O losses under changing soil physical conditions at the drained alder sites. The high net nitrification rates observed and high NO₃^&minus; contents bear the risk of considerable NO₃^&minus; leaching at the drained sites

Elements for the Expected Mechanisms on Reduced Emissions from Deforestation and Degradation, REDD under UNFCCC

Carbon emissions from deforestation and degradation account for 20% of the global anthropogenic emissions (IPCC WG I, 2007). Since the eleventh session of the Conference of the Parties to the United Nations Convention on Climate Change (UNFCCC) in December 2005, strategies and incentives for Reduced Emissions from Deforestation and Degradation (REDD) have emerged as one of the most attended negotiation items. It is not easy to build an international agreement on the role of REDD in a future climate change regime, but now we are close to an achievable historical decision on the future of forests: the Bali mandate on REDD. In this paper we suggest some elements for an effective long-term implementation of a REDD mechanism under the UNFCCC and for closing gaps in the forestry accounting system. These elements are related both to ecological and political processes, reflecting some of the most critical and debated negotiation points. The proposed elements are: a) carbon (C) losses from forests; b) incentives for all stages of reducing emissions, stabilizing and maintaining forest C stocks; c) national approach; d) data availability at national scale; e) conservativeness approach for carbon accounting.JRC.H.2-Climate chang

Elements for the expected mechanisms on 'reduced emissions from deforestation and degradation, REDD' under UNFCCC

Carbon emissions from deforestation and degradation account for about 20% of global anthropogenic emissions. Strategies and incentives for reduced emissions from deforestation and degradation (REDD) have emerged as one of the most active areas in the international climate change negotiations under the United Nations Framework Convention on Climate Change (UNFCCC). While the current negotiations focus on a REDD mechanism in developing countries, it should be recognized that risks of carbon losses from forests occur in all climate zones and also in industrialized countries. A future climate change agreement would be more effective if it included all carbon losses and gains from land use in all countries and climate zones. The REDD mechanism will be an important step towards reducing emissions from land use change in developing countries, but needs to be followed by steps in other land use systems and regions. A national approach to REDD and significant coverage globally are needed to deal with the risk that deforestation and degradation activities are displaced rather than avoided. Favourable institutional and governance conditions need to be established that guarantee in the long-term a stable incentive and control system for maintaining forest carbon stocks. Ambitious emission reductions from deforestation and forest degradation need sustained financial incentives, which go beyond positive incentives for reduced emissions but also give incentives for sustainable forest management. Current data limitations need-and can be-overcome in the coming years to allow accurate accounting of reduced emissions from deforestation and degradation. A proper application of the conservativeness approach in the REDD context could allow a simplified reporting of emissions from deforestation in a first phase, consistent with the already agreed UNFCCC reporting principles. [References: 19

EU Peatlands: Current Carbon Stocks and Trace Gas Fluxes

Peatlands in Europe has formed a significant sink for atmospheric CO2 since the last glacial maximum. Currently they are estimated to hold ca. 42 Gt carbon in the form of peat and are therefore a considerable component in the European carbon budget. Due to the generally wet soil conditions in peatlands they are also significant emitters of the strong greenhouse gas (GHG) methane (CH4) and in some cases also of nitrous oxide (N2O). The EU funded CarboEurope-GHG Concerted Action attempts to develop a reliable and complete greenhouse gas budget for Europe and this report aims to provide a review and synthesis of the available information about GHG exchanges in European peatlands and their underlying processes. A best estimate for all the European countries shows that some are currently sinks for atmospheric CO2 while others are sources. In contrast, for CH4 and N2O, only the sources are relevant. Whilst some countries are CO2 sinks, all countries are net GHG emitters from peatlands. The results presented, however, carry large uncertainties, which cannot be adequately quantified yet. One outstanding uncertainty is the distribution of land use types, particular in Russia, the largest European peat nation. The synthesis of GHG exchange, nevertheless, indicates some interesting features. Russia hosts an estimated 41% of European peatlands and contributes most to all GHG exchanges (CO2: 25%, CH4: 52%, N2O: 26%, Total: 37%). Germany is the second-largest emitter (12% of European total) although it contains only 3.2% of European peatlands. The reason is the use of most of the peatland area for intensive cropland and grassland. The largest CO2 emitters are countries with large agricultural peatland areas (Russia, Germany, Belarus, Poland), the largest N2O emitters are those with large agricultural fen areas (Russia, Germany, Finland). In contrast, the largest CH4 emitters are concentrated in regions with large areas of intact mires, namely Russia and Scandinavia. High average emission densities above 3.5 t C-equiv. ha-1 are found in the Southeast Mediterranean, Germany and the Netherlands where agricultural use of peatlands is intense. Low average emission densities below 0.3 t C-equiv. ha-1 occur where mires and peatland forests dominate, e.g. Finland and the UK. This report concludes by pointing at key gaps in our knowledge about peatland carbon stocks and GHG exchanges which include insufficient basic information on areal distribution of peatlands, measurements of peat depth and also a lack of flux datasets providing full annual budgets of GHG exchanges

The relevance of particulate organic carbon (POC) for carbon composition in the pore water of drained and rewetted fens of the "Donauried" (South-Germany)

International audienceNumerous studies have dealt with carbon (C) concentrations in Histosols, but there are no studies quantifying the relative importance of all individual C components in pore waters. For this study, measurements were made of all the carbon components (i.e., particulate organic carbon, POC; dissolved organic carbon, DOC; dissolved inorganic carbon, DIC; dissolved methane, CH4) in the soil pore water of a calcareous fen under three different water management regimes (re-wetted, deeply and moderately drained). Pore water was collected weekly or biweekly (April 2004 to April 2006) at depths between 10 and 150 cm. The main results obtained were: (1) DIC (94?280 mg C l?1) was the main C-component. (2) POC and DOC concentrations in the pore water (14?125 mg C l?1 vs. 41?95 mg C l?1) were pari passu. (3) Dissolved CH4 was the smallest C component (0.005?0.9 mg C l?1). Interestingly, about 30% of the POM particles were colonized by microbes indicating that they are active in the internal C transfer in the soil profile ("C-Shuttles"). Consequently, it was concluded that POC is at least as important as DOC for internal soil C turnover. There is no reason to assume significant biochemical differences between POC and DOC as they only differ in size. Therefore, both POC and DOC fractions are essential components of C budgets of peatlands. Furthermore dissolved CO2 in all forms of DIC apparently is an important part of peatland C-balances

Ecosystem services assessment at Steart Peninsula, Somerset, UK

© 2014 Elsevier B.V. A systemic valuation was undertaken of marginal changes in ecosystem services assessed as likely to result from the Steart Coastal Management project, some in monetary terms and others semi-quantified. The Steart Coastal Management project entails allowing seawater once again to inundate formerly defended farmland, including modifications to the landform of to assist the re-creation of a range of wetland habitats on the Steart Peninsula. Primary drivers for this project include habitat creation and management of coastal flooding, although implications for a range of other connected services need also to be taken into account. Ecosystem services for which a market exists (typically traded goods with associated use values) were valued using market prices. For non-traded services, this study relied substantially on the economic valuation technique of 'value transfer'. Despite having to rely on some wide but transparently stated assumptions and uncertainties, a conservative, yet considerable, net annual benefit range of £491,155 to £913,752 was deduced. Research gaps that limited our ability to quantify and/or value several ecosystem services were identified

High soil solution carbon and nitrogen concentrations in a drained Atlantic bog are reduced to natural levels by 10 years of rewetting

Anthropogenic drainage of peatlands releases additional greenhouse gases to the atmosphere, and dissolved carbon (C) and nutrients to downstream ecosystems. Rewetting drained peatlands offers a possibility to reduce nitrogen (N) and C losses. In this study, we investigate the impact of drainage and rewetting on the cycling of dissolved C and N as well as on dissolved gases, over a period of 1 year and a period of 4 months. We chose four sites within one Atlantic bog complex: a near-natural site, two drained grasslands with different mean groundwater levels and a former peat cutting area rewetted 10 years ago. Our results clearly indicate that long-term drainage has increased the concentrations of dissolved organic carbon (DOC), ammonium, nitrate and dissolved organic nitrogen (DON) compared to the near-natural site. DON and ammonium contributed the most to the total dissolved nitrogen. Nitrate concentrations below the mean groundwater table were negligible. The concentrations of DOC and N species increased with drainage depth. In the deeply-drained grassland, with a mean annual water table of 45 cm below surface, DOC concentrations were twice as high as in the partially rewetted grassland with a mean annual water table of 28 cm below surface. The deeply drained grassland had some of the highest-ever observed DOC concentrations of 195.8 ± 77.3 mg L−1 with maximum values of >400 mg L−1. In general, dissolved organic matter (DOM) at the drained sites was enriched in aromatic moieties and showed a higher degradation status (lower DOC to DON ratio) compared to the near-natural site. At the drained sites, the C to N ratios of the uppermost peat layer were the same as of DOM in the peat profile. This suggests that the uppermost degraded peat layer is the main source of DOM. Nearly constant DOM quality through the profile furthermore indicated that DOM moving downwards through the drained sites remained largely biogeochemically unchanged. Unlike DOM concentration, DOM quality and dissolved N species distribution were similar in the two grasslands and thus unaffected by the drainage depth. Methane production during the winter months at the drained sites was limited to the subsoil, which was quasi-permanently water saturated. The recovery of the water table in the winter months led to the production of nitrous oxide around mean water table depth at the drained sites. The rewetted and the near-natural site had comparable DOM quantity and quality (DOC to DON ratio and aromaticity). 10 years after rewetting quasi-pristine biogeochemical conditions have been re-established under continuously water logged conditions in the former peat cut area. Only the elevated dissolved methane and ammonium concentrations reflected the former disturbance by drainage and peat extraction. Rewetting via polder technique seems to be an appropriate way to revitalize peatlands on longer timescales and to improve the water quality of downstream water bodies

Einfluss des ökologischen Landbaus auf Erosion- und Hochwasserrisiko – Eine qualitative Literaturanalyse

Niederschlagsveränderungen durch den Klimawandel führen zu einem erhöhten Risiko für Erosion und Hochwasser in Deutschland. Aufgrund von guter Bodenbedeckung und einer verbesserten Bodenstruktur hat der ökologische Landbau ein hohes Erosions- und Hochwasserschutzpotenzial, allerdings war die Datenlage bisher unzureichend. Deshalb wurden Daten aus 43 Vergleichsstudien für 7 Parameter qualitativ ausgewertet, und die relativen Unterschiede in Prozent zwischen ökologischen und konventionellen Systemen berechnet. Ergebnisse für bodenstrukturelle Parameter weisen auf eine geringere Erodierbarkeit der ökologisch bewirtschafteten Böden hin. Der Bewirtschaftungsfaktor (C-Faktor) aus der ABAG fiel für die ökologischen Varianten ebenfalls kleiner aus. Dementsprechend war die Infiltration in den ökologischen Systemen höher und der Oberflächenabfluss und Bodenabtrag geringer. Eine Vergleichbarkeitsanalyse der Studien ist nötig