TY - JOUR A1 - Korup, Oliver A1 - Görüm, Tolga A1 - Hayakawa, Yuichi T1 - Without power? - Landslide inventories in the face of climate change JF - Earth surface processes and landforms : the journal of the British Geomorphological Research Group N2 - Projected scenarios of climate change involve general predictions about the likely changes to the magnitude and frequency of landslides, particularly as a consequence of altered precipitation and temperature regimes. Whether such landslide response to contemporary or past climate change may be captured in differing scaling statistics of landslide size distributions and the erosion rates derived thereof remains debated. We test this notion with simple Monte Carlo and bootstrap simulations of statistical models commonly used to characterize empirical landslide size distributions. Our results show that significant changes to total volumes contained in such inventories may be masked by statistically indistinguishable scaling parameters, critically depending on, among others, the size of the largest of landslides recorded. Conversely, comparable model parameter values may obscure significant, i.e. more than twofold, changes to landslide occurrence, and thus inferred rates of hillslope denudation and sediment delivery to drainage networks. A time series of some of Earth's largest mass movements reveals clustering near and partly before the last glacial-interglacial transition and a distinct step-over from white noise to temporal clustering around this period. However, elucidating whether this is a distinct signal of first-order climate-change impact on slope stability or simply coincides with a transition from short-term statistical noise to long-term steady-state conditions remains an important research challenge. KW - landslide KW - climate change KW - magnitude & frequency Y1 - 2012 U6 - https://doi.org/10.1002/esp.2248 SN - 0197-9337 VL - 37 IS - 1 SP - 92 EP - 99 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Huggel, Christian A1 - Clague, John J. A1 - Korup, Oliver T1 - Is climate change responsible for changing landslide activity in high mountains? JF - Earth surface processes and landforms : the journal of the British Geomorphological Research Group N2 - Climate change, manifested by an increase in mean, minimum, and maximum temperatures and by more intense rainstorms, is becoming more evident in many regions. An important consequence of these changes may be an increase in landslides in high mountains. More research, however, is necessary to detect changes in landslide magnitude and frequency related to contemporary climate, particularly in alpine regions hosting glaciers, permafrost, and snow. These regions not only are sensitive to changes in both temperature and precipitation, but are also areas in which landslides are ubiquitous even under a stable climate. We analyze a series of catastrophic slope failures that occurred in the mountains of Europe, the Americas, and the Caucasus since the end of the 1990s. We distinguish between rock and ice avalanches, debris flows from de-glaciated areas, and landslides that involve dynamic interactions with glacial and river processes. Analysis of these events indicates several important controls on slope stability in high mountains, including: the non-linear response of firn and ice to warming; three-dimensional warming of subsurface bedrock and its relation to site geology; de-glaciation accompanied by exposure of new sediment; and combined short-term effects of precipitation and temperature. Based on several case studies, we propose that the following mechanisms can significantly alter landslide magnitude and frequency, and thus hazard, under warming conditions: (1) positive feedbacks acting on mass movement processes that after an initial climatic stimulus may evolve independently of climate change; (2) threshold behavior and tipping points in geomorphic systems; (3) storage of sediment and ice involving important lag-time effects. KW - climate change KW - landslides KW - glaciers KW - permafrost Y1 - 2012 U6 - https://doi.org/10.1002/esp.2223 SN - 0197-9337 VL - 37 IS - 1 SP - 77 EP - 91 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - De Frenne, Pieter A1 - Graae, Bente J. A1 - Brunet, Jörg A1 - Shevtsova, Anna A1 - De Schrijver, An A1 - Chabrerie, Olivier A1 - Cousins, Sara A. O. A1 - Decocq, Guillaume A1 - Diekmann, Martin A1 - Hermy, Martin A1 - Heinken, Thilo A1 - Kolb, Annette A1 - Nilsson, Christer A1 - Stanton, Sharon A1 - Verheyen, Kris T1 - The response of forest plant regeneration to temperature variation along a latitudinal gradient JF - Annals of botany N2 - The response of forest herb regeneration from seed to temperature variations across latitudes was experimentally assessed in order to forecast the likely response of understorey community dynamics to climate warming. Seeds of two characteristic forest plants (Anemone nemorosa and Milium effusum) were collected in natural populations along a latitudinal gradient from northern France to northern Sweden and exposed to three temperature regimes in growth chambers (first experiment). To test the importance of local adaptation, reciprocal transplants were also made of adult individuals that originated from the same populations in three common gardens located in southern, central and northern sites along the same gradient, and the resulting seeds were germinated (second experiment). Seedling establishment was quantified by measuring the timing and percentage of seedling emergence, and seedling biomass in both experiments. Spring warming increased emergence rates and seedling growth in the early-flowering forb A. nemorosa. Seedlings of the summer-flowering grass M. effusum originating from northern populations responded more strongly in terms of biomass growth to temperature than southern populations. The above-ground biomass of the seedlings of both species decreased with increasing latitude of origin, irrespective of whether seeds were collected from natural populations or from the common gardens. The emergence percentage decreased with increasing home-away distance in seeds from the transplant experiment, suggesting that the maternal plants were locally adapted. Decreasing seedling emergence and growth were found from the centre to the northern edge of the distribution range for both species. Stronger responses to temperature variation in seedling growth of the grass M. effusum in the north may offer a way to cope with environmental change. The results further suggest that climate warming might differentially affect seedling establishment of understorey plants across their distribution range and thus alter future understorey plant dynamics. KW - Anemone nemorosa KW - climate change KW - common garden KW - growth chambers KW - latitudinal gradient KW - local adaptation KW - Milium effusum KW - plant regeneration KW - range edges KW - recruitment KW - seedling establishment KW - temperature Y1 - 2012 U6 - https://doi.org/10.1093/aob/mcs015 SN - 0305-7364 VL - 109 IS - 5 SP - 1037 EP - 1046 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Schewe, Jacob A1 - Levermann, Anders T1 - A statistically predictive model for future monsoon failure in India JF - Environmental research letters N2 - Indian monsoon rainfall is vital for a large share of the world's population. Both reliably projecting India's future precipitation and unraveling abrupt cessations of monsoon rainfall found in paleorecords require improved understanding of its stability properties. While details of monsoon circulations and the associated rainfall are complex, full-season failure is dominated by large-scale positive feedbacks within the region. Here we find that in a comprehensive climate model, monsoon failure is possible but very rare under pre-industrial conditions, while under future warming it becomes much more frequent. We identify the fundamental intraseasonal feedbacks that are responsible for monsoon failure in the climate model, relate these to observational data, and build a statistically predictive model for such failure. This model provides a simple dynamical explanation for future changes in the frequency distribution of seasonal mean all-Indian rainfall. Forced only by global mean temperature and the strength of the Pacific Walker circulation in spring, it reproduces the trend as well as the multidecadal variability in the mean and skewness of the distribution, as found in the climate model. The approach offers an alternative perspective on large-scale monsoon variability as the result of internal instabilities modulated by pre-seasonal ambient climate conditions. KW - monsoon failure KW - climate change KW - coupled climate model KW - stochastic model KW - non-linear dynamics Y1 - 2012 U6 - https://doi.org/10.1088/1748-9326/7/4/044023 SN - 1748-9326 VL - 7 IS - 4 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Schurr, Frank Martin A1 - Pagel, Jörn A1 - Sarmento, Juliano Sarmento A1 - Groeneveld, Juergen A1 - Bykova, Olga A1 - O'Hara, Robert B. A1 - Hartig, Florian A1 - Kissling, W. Daniel A1 - Linder, H. Peter A1 - Midgley, Guy F. A1 - Schröder-Esselbach, Boris A1 - Singer, Alexander A1 - Zimmermann, Niklaus E. T1 - How to understand species' niches and range dynamics: a demographic research agenda for biogeography JF - Journal of biogeography N2 - Range dynamics causes mismatches between a species geographical distribution and the set of suitable environments in which population growth is positive (the Hutchinsonian niche). This is because sourcesink population dynamics cause species to occupy unsuitable environments, and because environmental change creates non-equilibrium situations in which species may be absent from suitable environments (due to migration limitation) or present in unsuitable environments that were previously suitable (due to time-delayed extinction). Because correlative species distribution models do not account for these processes, they are likely to produce biased niche estimates and biased forecasts of future range dynamics. Recently developed dynamic range models (DRMs) overcome this problem: they statistically estimate both range dynamics and the underlying environmental response of demographic rates from species distribution data. This process-based statistical approach qualitatively advances biogeographical analyses. Yet, the application of DRMs to a broad range of species and study systems requires substantial research efforts in statistical modelling, empirical data collection and ecological theory. Here we review current and potential contributions of these fields to a demographic understanding of niches and range dynamics. Our review serves to formulate a demographic research agenda that entails: (1) advances in incorporating process-based models of demographic responses and range dynamics into a statistical framework, (2) systematic collection of data on temporal changes in distribution and abundance and on the response of demographic rates to environmental variation, and (3) improved theoretical understanding of the scaling of demographic rates and the dynamics of spatially coupled populations. This demographic research agenda is challenging but necessary for improved comprehension and quantification of niches and range dynamics. It also forms the basis for understanding how niches and range dynamics are shaped by evolutionary dynamics and biotic interactions. Ultimately, the demographic research agenda should lead to deeper integration of biogeography with empirical and theoretical ecology. KW - Biodiversity monitoring KW - climate change KW - ecological forecasts KW - ecological niche modelling KW - ecological theory KW - geographical range shifts KW - global environmental change KW - mechanistic models KW - migration KW - process-based statistics Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-2699.2012.02737.x SN - 0305-0270 VL - 39 IS - 12 SP - 2146 EP - 2162 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Tekken, Vera A1 - Kropp, Jürgen T1 - Climate-Driven or Human-Induced indicating severe water scarcity in the Moulouya River Basin (Morocco) JF - Water N2 - Many agriculture-based economies are increasingly under stress from climate change and socio-economic pressures. The excessive exploitation of natural resources still represents the standard procedure to achieve socio-economic development. In the area of the Moulouya river basin, Morocco, natural water availability represents a key resource for all economic activities. Agriculture represents the most important sector, and frequently occurring water deficits are aggravated by climate change. On the basis of historical trends taken from CRU TS 2.1, this paper analyses the impact of climate change on the per capita water availability under inclusion of population trends. The Climatic Water Balance (CWB) shows a significant decrease for the winter period, causing adverse effects for the main agricultural season. Further, moisture losses due to increasing evapotranspiration rates indicate problems for the annual water budget and groundwater recharge. The per capita blue water availability falls below a minimum threshold of 500 m(3) per year, denoting a high regional vulnerability to increasing water scarcity assuming a no-response scenario. Regional development focusing on the water-intense sectors of agriculture and tourism appears to be at risk. Institutional capacities and policies need to address the problem, and the prompt implementation of innovative water production and efficiency measures is recommended. KW - North Africa KW - Moulouya river basin KW - climate change KW - population growth KW - regional development KW - water availability KW - water management KW - water scarcity Y1 - 2012 U6 - https://doi.org/10.3390/w4040959 SN - 2073-4441 VL - 4 IS - 4 SP - 959 EP - 982 PB - MDPI CY - Basel ER - TY - THES A1 - Lohmann, Dirk T1 - Sustainable management of semi-arid African savannas under environmental and political change T1 - Nachhaltige Nutzung semiarider Savannen in Afrika unter dem Einfluss von klimatischem und politischem Wandel N2 - Drylands cover about 40% of the earth’s land surface and provide the basis for the livelihoods of 38% of the global human population. Worldwide, these ecosystems are prone to heavy degradation. Increasing levels of dryland degradation result a strong decline of ecosystem services. In addition, in highly variable semi-arid environments changing future environmental conditions will potentially have severe consequences for productivity and ecosystem dynamics. Hence, global efforts have to be made to understand the particular causes and consequences of dryland degradation and to promote sustainable management options for semi-arid and arid ecosystems in a changing world. Here I particularly address the problem of semi-arid savanna degradation, which mostly occurs in form of woody plant encroachment. At this, I aim at finding viable sustainable management strategies and improving the general understanding of semi-arid savanna vegetation dynamics under conditions of extensive livestock production. Moreover, the influence of external forces, i.e. environmental change and land reform, on the use of savanna vegetation and on the ecosystem response to this land use is assessed. Based on this I identify conditions and strategies that facilitate a sustainable use of semi-arid savanna rangelands in a changing world. I extended an eco-hydrological model to simulate rangeland vegetation dynamics for a typical semi-arid savanna in eastern Namibia. In particular, I identified the response of semi-arid savanna vegetation to different land use strategies (including fire management) also with regard to different predicted precipitation, temperature and CO2 regimes. Not only environmental but also economic and political constraints like e.g. land reform programmes are shaping rangeland management strategies. Hence, I aimed at understanding the effects of the ongoing process of land reform in southern Africa on land use and the semi-arid savanna vegetation. Therefore, I developed and implemented an agent-based ecological-economic modelling tool for interactive role plays with land users. This tool was applied in an interdisciplinary empirical study to identify general patterns of management decisions and the between-farm cooperation of land reform beneficiaries in eastern Namibia. The eco-hydrological simulations revealed that the future dynamics of semi-arid savanna vegetation strongly depend on the respective climate change scenario. In particular, I found that the capacity of the system to sustain domestic livestock production will strongly depend on changes in the amount and temporal distribution of precipitation. In addition, my simulations revealed that shrub encroachment will become less likely under future climatic conditions although positive effects of CO2 on woody plant growth and transpiration have been considered. While earlier studies predicted a further increase in shrub encroachment due to increased levels of atmospheric CO2, my contrary finding is based on the negative impacts of temperature increase on the drought sensitive seedling germination and establishment of woody plant species. Further simulation experiments revealed that prescribed fires are an efficient tool for semi-arid rangeland management, since they suppress woody plant seedling establishment. The strategies tested have increased the long term productivity of the savanna in terms of livestock production and decreased the risk for shrub encroachment (i.e. savanna degradation). This finding refutes the views promoted by existing studies, which state that fires are of minor importance for the vegetation dynamics of semi-arid and arid savannas. Again, the difference in predictions is related to the bottleneck at the seedling establishment stage of woody plants, which has not been sufficiently considered in earlier studies. The ecological-economic role plays with Namibian land reform beneficiaries showed that the farmers made their decisions with regard to herd size adjustments according to economic but not according to environmental variables. Hence, they do not manage opportunistically by tracking grass biomass availability but rather apply conservative management strategies with low stocking rates. This implies that under the given circumstances the management of these farmers will not per se cause (or further worsen) the problem of savanna degradation and shrub encroachment due to overgrazing. However, as my results indicate that this management strategy is rather based on high financial pressure, it is not an indicator for successful rangeland management. Rather, farmers struggle hard to make any positive revenue from their farming business and the success of the Namibian land reform is currently disputable. The role-plays also revealed that cooperation between farmers is difficult even though obligatory due to the often small farm sizes. I thus propose that cooperation needs to be facilitated to improve the success of land reform beneficiaries. N2 - Semiaride (halbtrockene) Savannen bedecken große Teile der Erdoberfläche und sichern die Lebensgrundlage von vielen Millionen Menschen. Die häufigste Form der Landnutzung in diesen Trockengebieten ist die Produktion von Vieh in extensiver Weidelandbewirtschaftung. In Folge klimatischer Veränderungen und als Konsequenz aus der teils intensiven Beweidung dieser Trockengebiete kommt es häufig zur Degradierung derselben in Form einer Zunahme von ‚unerwünschter‘ holziger Vegetation auf Kosten von futterverwertbaren Gräsern. Dieser als Verbuschung bezeichnete Prozess hat schwere negative Auswirkungen auf die betroffenen Ökosysteme und ist die Ursache für einen zunehmenden Rückgang der ökonomischen Leistungsfähigkeit der betroffenen Betriebe. In meiner Dissertation befasse ich mich mit den Auswirkungen von Klimawandel und politischen Veränderungen auf die Savannenvegetation im südlichen Afrika und auf die Möglichkeiten für die Nutzung dieser Ökosysteme in Form von Viehwirtschaft. Hierbei möchte ich sowohl das allgemeine Verständnis der ökologischen Zusammenhänge verbessern, als auch Strategien für die nachhaltige Nutzung der Savannen identifizieren und bewerten. Da nicht nur ökologische, sondern auch ökonomische und politische Einflussfaktoren, wie zum Beispiel die umfangreichen Landumverteilungen im Rahmen der Bodenreform im südlichen Afrika auf die tatsächliche Landnutzung wirken, habe ich im Rahmen der Dissertation zudem untersucht, nach welchen Umwelt und Kapitalvariablen sich die Farmer, welche Ihr Land im Rahmen der Bodenreform zugeteilt bekommen haben, bei Ihren Entscheidungen richten. Methodisch verwende ich verschiedene Simulationsmodelle, welche zur Untersuchung der langfristigen Veränderungen von verschiedensten Szenarien (Klimawandel, Landnutzung) geeignet sind. Hierbei habe ich teilweise bestehende Modelle angepasst, aber auch ein neues Modell, welches zur Befragung von Farmern in Namibia verwendet wurde, entwickelt. Meine Dissertation führt im Wesentlichen zu vier Erkenntnissen: Erstens, zeigen meine Ergebnisse, welche große Bedeutung die spezifischen ökologischen Eigenschaften der Bäume und Sträucher in semiariden Savannen für die Vorhersage der Entwicklung dieser Systeme unter Klimawandel hat. Hierbei zeigte sich, dass insbesondere die Sensitivität der Keimlinge gegenüber Trockenheit und Feuer eine entscheidende Rolle spielt. Daraus folgt die zweite wesentliche Erkenntnis: Feuer eignet sich in herausragender Weise, um halbtrockene Savannen vor der Verbuschung zu bewahren. Drittens haben die Rollenspiele mit Farmern in Namibia gezeigt, dass deren Entscheidungen im Wesentlichen von finanziellen Schwierigkeiten und nicht von Umwelteinflüssen getrieben werden. Dennoch zeigten meine Ergebnisse, dass diese Farmer mit Ihrem derzeitigen Verhalten wahrscheinlich nicht zur weiteren Degradierung der Savannenvegetation beitragen. Die vierte, und mit am bedeutendste Erkenntnis aus meiner Arbeit ist, dass konservative Beweidungsstrategien mit geringen und konstanten Viehdichten notwendig sind um semiaride Savannen dauerhaft in ökologisch und ökonomisch nachhaltiger Weise zu Nutzen. KW - Savanne KW - nachhaltige Landnutzung KW - ökohydrologische Modellierung KW - Land Reform KW - Klimawandel KW - Savanna KW - sustainable land use KW - eco-hydrological modelling KW - land reform KW - climate change Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-65069 ER - TY - THES A1 - Waha, Katharina T1 - Climate change impacts on agricultural vegetation in sub-Saharan Africa T1 - Auswirkungen von Klimaänderungen auf die landwirtschaftliche Vegetation in Afrika südlich der Sahara N2 - Agriculture is one of the most important human activities providing food and more agricultural goods for seven billion people around the world and is of special importance in sub-Saharan Africa. The majority of people depends on the agricultural sector for their livelihoods and will suffer from negative climate change impacts on agriculture until the middle and end of the 21st century, even more if weak governments, economic crises or violent conflicts endanger the countries’ food security. The impact of temperature increases and changing precipitation patterns on agricultural vegetation motivated this thesis in the first place. Analyzing the potentials of reducing negative climate change impacts by adapting crop management to changing climate is a second objective of the thesis. As a precondition for simulating climate change impacts on agricultural crops with a global crop model first the timing of sowing in the tropics was improved and validated as this is an important factor determining the length and timing of the crops´ development phases, the occurrence of water stress and final crop yield. Crop yields are projected to decline in most regions which is evident from the results of this thesis, but the uncertainties that exist in climate projections and in the efficiency of adaptation options because of political, economical or institutional obstacles have to be considered. The effect of temperature increases and changing precipitation patterns on crop yields can be analyzed separately and varies in space across the continent. Southern Africa is clearly the region most susceptible to climate change, especially to precipitation changes. The Sahel north of 13° N and parts of Eastern Africa with short growing seasons below 120 days and limited wet season precipitation of less than 500 mm are also vulnerable to precipitation changes while in most other part of East and Central Africa, in contrast, the effect of temperature increase on crops overbalances the precipitation effect and is most pronounced in a band stretching from Angola to Ethiopia in the 2060s. The results of this thesis confirm the findings from previous studies on the magnitude of climate change impact on crops in sub-Saharan Africa but beyond that helps to understand the drivers of these changes and the potential of certain management strategies for adaptation in more detail. Crop yield changes depend on the initial growing conditions, on the magnitude of climate change, and on the crop, cropping system and adaptive capacity of African farmers which is only now evident from this comprehensive study for sub-Saharan Africa. Furthermore this study improves the representation of tropical cropping systems in a global crop model and considers the major food crops cultivated in sub-Saharan Africa and climate change impacts throughout the continent. N2 - Landwirtschaft ist eine der wichtigsten menschlichen Aktivitäten, sie stellt Nahrungsmittel und andere landwirtschaftliche Produkte für weltweit 7 Milliarden Menschen zur Verfügung und ist in den Ländern Afrikas südlich der Sahara von besonderer Bedeutung. Die Mehrheit der afrikanischen Bevölkerung bestreitet ihren Lebensunterhalt in der Landwirtschaft und wird von Klimaänderungen stark betroffen sein. Die Doktorarbeit ist durch die Frage motiviert, wie sich von Klimamodellen vorhergesagte Temperaturerhöhungen und sich verändernde Niederschlagsverteilungen auf die landwirtschaftliche Vegetation auswirken werden. Die Forschungsfragen in diesem Kontext beschäftigen sich mit regionalen Unterschieden von Klimaänderungen und ihren Auswirkungen auf die Landwirtschaft und mit möglichen Anpassungsstrategien die mit geringem technischem Aufwand genutzt werden können. In diesem Zusammenhang wird schnell deutlich, dass Daten über die komplexen landwirtschaftlichen Systeme in Afrika südlich der Sahara häufig nur selten vorhanden sind, aus fragwürdigen Quellen stammen oder von schlechter Qualität sind. Die Methoden und Modelle zur Untersuchung der Auswirkungen von Klimaänderungen auf die Landwirtschaft werden zudem ausschließlich in Europa oder Nordamerika entwickelt and häufig in den temperierten Breiten aber seltener in tropischen Gebieten angewendet. Vor allem werden globale, dynamische Vegetationsmodelle in Kombination mit Klimamodellen eingesetzt um Änderungen in der landwirtschaftlichen Produktion auf Grund von Klimaänderungen in der zweiten Hälfte des 21.Jahrhunderts abzuschätzen. Die Ergebnisse der Arbeit zeigen einen mittleren Ertragsrückgang für die wichtigsten landwirtschaftlichen Pflanzen um 6% bis 24% bis 2090 je nach Region, Klimamodell und Anpassungsstrategie. Dieses Ergebnis macht deutlich, dass Landwirte die negativen Folgen von Klimaänderungen abschwächen können, wenn sie die Wahl der Feldfrucht, die Wahl des Anbausystems und den Aussaattermin an geänderte Klimabedingungen anpassen. Die Arbeit stellt methodische Ansätze zur Berechung des Aussaattermins in temperierten und tropischen Gebieten (Kapitel 2) sowie zur Simulation von Mehrfachanbausystemen in den Tropen vor (Kapitel 3). Dabei werden wichtige Parameter für das globale, dynamische Vegetationsmodell LPJmL überprüft und neu berechnet. Es zeigt sich, dass das südliche Afrika und die Sahelregion die am stärksten betroffenen Regionen sind, vor allem aufgrund von Niederschlagsänderungen, weniger aufgrund von Temperaturerhöhungen. In den meisten anderen Teilen, vor allem Zentral- und Ostafrikas bedingen Temperaturerhöhungen Rückgänge der Erträge (Kapitel 4). Diese Arbeit leistet einen wichtigen und umfassenden Beitrag zum Verständnis der Auswirkung von Klimaänderung auf die landwirtschaftliche Vegetation und damit zu einem großen Teil auf die Lebensgrundlage von afrikanischen Landwirten. KW - Klimawandel KW - Anpassung KW - Afrika KW - Pflanzenwachstum KW - Landwirtschaft KW - climate change KW - Africa KW - crop modeling KW - adapation KW - agriculture Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-64717 ER -