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The aims of this study were to quantify the key mineralization processes and the resulting nutrient release potentials of different sediment types, their ranges of extent and dependency on varying environmental conditions such as seasonal variations or shifts in oxygen availability. Benthic phosphate fluxes and flux potentials were of particular interest as P is an essential nutrient for algal growth in marine systems and phosphate is often limiting primary production, hence strongly promotes the production of new biomass. A major P source in marine environments are mineralization products of early diagenetic processes.
To gain insight into the pathways of organic matter mineralization and subsequent secondary reactions, key reactants in the solid and the dissolved phase were considered in typical sediments of the Baltic Sea and the Black Sea. Seven study sites in the German Baltic Sea region, representative of the major depositional environments, including coarse and fine grained sediments, both rich or poor in organic carbon, were intensively studied. The investigations were conducted on a seasonal basis during ten ship-based expeditions between July 2013 and March 2016, covering spring- and autumn algal blooms, stagnation periods with bottom water hypoxia and winter dormancy. Hypoxic conditions frequently developed in the bottom waters of the Bay of Mecklenburg, Stoltera and the Arkona Basin sites, shallower stations like the Tromper Wiek, the Oder Bank and the Darss Sill were usually not affected by hypoxia. Increased nutrient concentrations in the bottom waters coincided with oxygen depletion. High salinity dynamics were observed in the bottom waters above the studied sediments, which were due to frequent salt water inflows from the North Sea. Bottom water temperature variability was seasonally conditioned.
The studied sands showed 2-3 orders of magnitude higher permeability values and about one order of magnitude lower organic matter contents compared to the studied muds. Occasionally, strongly increased organic matter contents were observed in the sands, likely induced by downward mixing of plankton bloom derived particles. The organic matter was found to be essentially supplied by marine phytoplankton, indicated by its elemental composition and isotopic signature.
Additionally, an adapted approach of the Keeling plot method was made to characterize the source material of organic matter mineralization. In marine environments, dissolved inorganic carbon concentrations often increase with depth together with an isotopic carbon signature shift to lighter values due to organic matter mineralization. The Keeling plot method was commonly used to determine the isotopic signature of carbon sources for ecosystem respiration. Conventionally, the influence of respiratory depletion of 13CO2 on the isotopic composition of the atmosphere was studied in terrestrial and limnic biogeochemistry. The same approach was applied on organic matter mineralization in sediments and the water column during this study. Mixing of bottom water derived background DIC and DIC released into the environment during organic carbon decomposition was assumed. In a modification of previous approaches, where changes in concentration and δ13C of DIC were followed over time, vertical profiles were analyzed in this study, which represent time-dependent variations superimposed by transport processes . DI13C gradients in the water column of the Black Sea and pore water profiles in the Black Sea and the Baltic Sea were used to estimate the 13C signature of the mineralized organic carbon via Keeling plot analysis. The Black Sea water column revealed a δ13C signature of the organic matter source close to the signature of typical particulate organic matter in the ocean and previously reported values for the Black Sea euphotic zone. In the pore waters of Black Sea sediments (from short and long sediment cores), Keeling plot analysis clearly demonstrates that the released DIC at depth can be derived from different sources. An isotopically very light carbon source (< –60 ‰) was associated with anaerobic oxidation of methane in the Black Sea. Marine organic matter was the principal source for DIC in the deeps of Baltic Sea basins, while the calculated carbon source isotopic signature in sediments of sand flats and bays was shifted to heavier δ13C signatures compared to marine organic matter. These shifts were attributed to potential dissolution of sedimentary carbonates or organic inputs of terrestrial C4 vascular plants like maize and other agricultural plants. The carbon source isotopic composition calculated via Keeling plot analysis correlated well with directly measured δ13C signatures of surface sediments POM.
Organic matter mineralization activity in the southern Baltic Sea sediments was studied via gross sulfate reduction rate analysis and total oxygen uptake measurements in sands and muds. Oxygen penetration depths were less than 4 mm in both, muddy and sandy sediments. Oxygen uptake rates were similar in muds (10.2 mmol m–2 d–1) and sands (10.7 mmol m–2 d–1), while significantly higher rates were measured in the coastal near sites of the Bay of Mecklenburg (about 12 mmol m–2 d–1) than in the deeper Arkona Basin (about 9 mmol m–2 d–1). Substantial sulfate reduction was measured in the muddy (about 4 mmol m–2 d–1) and the sandy (about 1 mmol m–2 d–1) study sites. Highest sulfate reduction rates (4.4 – 5 mmol m–2 d–1) were detected in the muds of the Bay of Mecklenburg during summer, about twice as high as in the Arkona Basin muds. Increased mineralization activity of the coastal near muds of the Bay of Mecklenburg is attributed to enhanced input of fresh organic matter during algal blooms.
About twofold higher oxygen consumption and sulfate reduction rates were measured in summer compared to winter in sandy and muddy sediments.
The studied sites were usually characterized by a typical biogeochemical zonation with oxic, suboxic and sulfidic zones. The concentration profiles in the muds reflected sulfate reduction and secondary redox-reactions, liberating dissolved carbon, nitrogen, phosphorus and hydrogen sulfide into the interstitial waters. Orders of magnitude lower concentrations were detected in the sands, while their top centimeters were mostly irrigated and mineralization products only accumulated below.
A several centimeter thick suboxic zone was sustained by active downward transport of oxidized material in the southern Baltic Sea coastal sediments, presumably mainly through bioturbation. Especially sulfur and iron species were involved in the secondary reactions between the metabolites of early diagenetic processes occurring in the suboxic zone. Partly high temporal variability was observed in the form of vertical migration of the sulfidic zone and a corresponding expansion and shrinking of the suboxic zone. The Arkona Basin site showed the most stable geochemical zonation over time, while the Luebeck Bight site and especially the Mecklenburg Bight site showed striking dynamics. The consequent redox-regime shifts within the surface sediments might promote mineralization of organic matter as higher sulfate reduction rates and higher total oxygen uptake were measured in these more dynamic muds. The vertical shifts of the redox-gradients can largely be explained by temporal and spatial variability of bioturbation activity, but also anthropogenic activities may play a role. Bottom trawling, may be the dominant mixing process at the Mecklenburg Bight site.
In the sands, less reactive iron and manganese contents were available compared to the studied muds, which may be due to frequent irrigation of the top centimeters leading to a loss of pore water reservoirs like dissolved Fe and Mn.
Another mixing process, storm induced sediment resuspension, was suggested to be important for the sediments in the study area. A severe sediment resuspension event at the silty Tromper Wiek site was indicated by steep gradients in pore water concentration and particulate mater content profiles in the top ∼ 5 cm sediments. Carrying out non steady state modeling (Bo Liu, IOW), the successive re-development of the pore water profiles towards a steady-state was simulated and the time span necessary to establish measured pore water profiles after the sediment disturbance event was approximated. In the predicted time span, daily average wind speeds reached an annual high of the category ‘gale’ which was probably sufficient to resuspend and irrigate the surface silt-type sediments.
This study showed that sediment mixing processes have a strong influence on early diagenetic reactions, solute release potentials and actual fluxes from the sediments. Also the sediment mixing via bottom trawl fishing can be regarded as an event-like disturbance. The newly developed approach of non-steady-state modeling of pore water sets (Bo Liu; IOW) can help to answer the question, how long it takes to reach a steady-state after a sediment disturbance event.
The concentration profiles in interstitial waters were used to calculate net transformation rates via the transport-reaction models REC and PROFILE. The calculations revealed net release of H4SiO4 and PO4 within the top 20 cm of the studied muds, while net DIC and NH+4 consumption and sulfate production was clearly evident within the top ∼ 5 cm. Intensive reoxidation of sulfide that was produced via sulfate reduction was also indicated by large deviations between the modeled net sulfate transformation rates and experimentally derived gross sulfate reduction rates. These surface near transformations were probably associated with microbial chemosynthesis.
The studied sands of the southern Baltic Sea were usually characterized by very low pore water gradients, probably due to their frequent irrigation. Accordingly, calculated transformation rates were one to two orders of magnitude lower in the studied sands compared to the muds of the southern Baltic Sea. However, during a situation with a stratified water column, substantial pore water reservoirs with the typical concentration trends were present in the sandy Darss Sill sediments. Integrated production rates of PO4, Mn2+ and H4SiO4 derived from these concentration profiles were in the same order of magnitude as in the muddy Arkona Basin.
Intensive pore water irrigation is also capable to transport fresh organic matter into the sediment as was occasionally indicated by strongly increased surface near TOC in the sands. Considerable gross sulfate reduction rates and total oxygen uptake rates were measured in the sandy Oder Bank sediments, where pore water concentration profiles rather suggested absence of diagenetic processes. The studied sands were, hence, not unreactive substrates but usually rather unable to preserve the mineralization products.
This reflects the often limited significance of pore water evaluations in irrigated sandy sites but also the high mineralization potentials of coastal sands. Early diagenetic processes and the impact of intense benthic-pelagic exchange in such shallow marine environments is still poorly understood, as they were rarely investigated in the past and are methodologically more difficult to investigate.
The Baltic Sea deeps Gotland Deep and Landsort Deep were mainly controlled by sulfate reduction and shallow anaerobic oxidation of methane. Calculated rates of net sulfate reduction and net sulfide production were equivalent, indicating a lack of sulfide re-oxidation reactions. Phosphate liberation rates were low in the surface sediments, but strong linear concentration gradients indicated liberation at depth.
The euxinic Black Sea sediments were purely controlled by sulfate reduction via anaerobic oxidation of methane at the sulfate-methane transition zone in sediment depths of up to several meters. Subsequent diffusive concentration gradients clearly dominated pore water profiles in the surface sediments.
Benthic solute reservoirs of the top 10 cm pore waters were generally higher in the muds than in the sands of the southern Baltic Sea. The smaller reservoirs in the sands were cause by intensive exchange between pore water and bottom water in these permeable sediments. The three studied muddy sites of the southern Baltic Sea showed great dissimilarities with respect to their pore water compositions. Large observed pools of dissolved Fe2+ and PO4 clearly point to reduction of reactive Fe and release of adsorbed P pools. Multi-dimensional scaling analysis showed that seasonal variability played only a minor role for the observed variability of the benthic solute reservoirs. Principal component analysis revealed that the studied sediments can be characterized by essentially two factors based on their pore water reservoirs of the top 10 cm: 1) their mineralization and accumulation efficiency and 2) their secondary reactions in the suboxic zone, reflecting fundamental differences in their sedimentation conditions and mixing processes. While the sands were similar to each other due to their overall low reservoirs, sands, silts and muds mainly differed in their mineralization and accumulation efficiency. Large variability was also observed within the studied muds regarding their predominating redox metabolites. Highest dissimilarities were evident between the neighboring sites Mecklenburg Bight (mostly suboxic) and Luebeck Bight (mostly sulfidic). Therefore, the biogeochemical state in the studied sediments were shown to be mainly controlled by their sediment type and the transport of reactive iron into the sediments. The supply of organic matter to the sea floor controlled the overall mineralization activity, while the sediment permeability determined the accumulation efficiency of the sediment. Mixing of surface sediments together with the complex relation of oxygen, sulfur, iron and phosphorus in the solid and aqueous phase is controlling benthic nutrient fixation/liberation reactions. Salinity variability showed no noticeable effects on early diagenetic processes. During four sampling occasions in the Arkona Basin, bottom water salinity showed strong variability which was also effecting pore water concentration profiles in more than 15 cm depth. However, concentration profiles of typical organic matter mineralization products remained remarkably stable. Also gross sulfate reduction rates seemed to be unaffected by the variable pore water sulfate concentrations.
Nutrient fluxes across the sediment-water interface were obtained by the interpretation of vertical pore water concentration profiles via different models (diffusive fluxes) and via incubation of intact sediment cores (total fluxes). Benthic diffusive fluxes represent potential release of solutes into the water column. They were often strongly associated with the benthic reservoirs, thus fluxes were highest in the muds, considerably lower in the organic-poorer silts, and generally close to zero in the sands. The dissimilarities between diffusive fluxes in the different sediments were mainly controlled by the sediment type. Highest variability was observed within the muds, controlled by their different diagenetic pathways due to different sediment mixing intensities.
In the muddy sediments, diffusive PO4 fluxes were much higher than mineralization of organic matter with the common element ratios of marine organic matter can provide, indicating active recycling of phosphorus within the muds due to recurring adsorption and re-release on reactive iron oxyhydroxide phases. Especially in the strongly mixed Mecklenburg Bight sediments, pore water dissolved PO4 was primarily controlled by the release of adsorbed P. Actual PO4 release into the bottom waters (determined via core incubation experiments) was only measured under extended bottom water oxygen deficiency conditions. The same applied to the redox-sensitive solutes Fe2+, Mn2+ and sulfide.
For the less redox-sensitive solutes, diffusion usually accounted only for a fraction of the total interfacial flux. The proportion of advective to diffusive transport was estimated with different methods. Bioturbation induced sediment mixing was quantified by comparing the diffusive H4SiO4 fluxes derived from pore water modeling with the total fluxes derived from the core incubations. The studied muds showed infauna induced advection proportions of about 35 – 100 %. Only when infauna was absent, diffusion became the dominant transport process across the sediment-water interface. In the studied sands, advection was the dominating transport process, since their generally low surface near reservoirs lead to diffusive fluxes close to zero. However, it remains unclear whether bioturbation or hydrodynamic irrigation are responsible for that. An attempt was made to estimate the effect of hydrodynamic irrigation for a range of reasonable bottom water velocities from the sediment bedform geometry after Neumann et al. (2017). However, resulting potential hydrodynamic irrigation was found to be rather low compared to reported values from the literature and may significantly underestimate actual irrigation of the sandy sediments.
In a new non steady-state multi-element diagenetic modeling approach (Bo Liu, IOW), vertical δ13C pore water profiles were used to estimate the significance of advective transport processes. Mixing processes at the sediment-water interface were expressed as multiple of pure diffusion (ε). By adjusting this mixing coefficient as boundary condition for best fits of predicted to measured pore water profiles, the degree of these mixing processes was estimated. In the Arkona Basin surface sediments, this approach revealed best fits assuming a mixing depth of 3.5 cm with a tenfold higher total mixing degree based on diffusional transport. The calculated mixing depths and intensities were similar to bioturbation depths and rates obtained via traditional methods (Morys, 2016). The novel modeling approach is a promising method to evaluate surface sediment mixing processes.
Increased mineralization activity during productive seasons lead to increased oxygen consumption and therefore frequent bottom water hypoxia. The effects of hypoxic bottom water conditions on the early diagenetic processes in the sediments were studied via prolonged core incubation experiments. Shifts to bottom water oxygen deficiency had various consequences for benthic reservoirs and fluxes. The oxygen consumption decreased during hypoxic incubation phases. Decreased bioturbation activity diminished advective transport so that total fluxes of redox-insensitive solutes (e.g. H4SiO4) were decreased. Reactive iron and manganese oxides act as barrier (“iron curtain”) in the suboxic zone, preventing redox-sensitive solutes from their release into the water column. After a shift to bottom water hypoxia, these reactive oxides are re-dissolved and liberated into the water column. Prolonged incubation experiments suggested that the Mn-oxide reservoirs were depleted first before the Fe-oxides with the adsorptively bound phosphate were liberated.
The release of nutrients (especially phosphorus), dissolved inorganic carbon, and redox- sensitive compounds (e.g. hydrogen sulfide) strongly varied in the different studied environments, covering coastal-near oxic, temporary hypoxic and euxinic conditions.
In environments, where advection through hydrodynamic irrigation or bioturbation do not occur, like in anoxic or euxinic systems, surface-near pore water gradients reflect total solute interfacial fluxes. They depend on the supply of organic matter to the sea floor, the mineralization rates in the sediments and the composition of the overlying bottom water. In the Black Sea, much of the organic matter mineralization was performed already in the water column and not in the sediments, leading to a decreasing export of organic matter to the sediment and increasing concentrations of mineralization products in the bottom water with increasing water depth. Accordingly, benthic fluxes across the sediment-water interface of the deep Black Sea sites were the lowest of the entire study, essentially reflecting the low mineralization rates of AOM in deeper layers. Highest fluxes in the Black Sea were observed at the continental slope at intermediate water depths, but were still lower than in the Baltic Sea deeps.
In contrast, highest DIC fluxes were detected in the oxygen depleted Baltic Sea deeps Gotland Deep and Landsort Deep. These basins are shallow enough that reactive organic matter reaches the sea floor, where it is mineralized via sulfate reduction close to the sediment surface. Strong concentration gradients and therefore high diffusive interfacial fluxes across the sediment-water interface were evident. As bioturbation was absent, these diffusive fluxes were representative for total interfacial fluxes unlike in sediments with additional advective flux components.
In more complex environments, like coastal oxic sediments, inhabited by macrofauna, overflowed by currents and affected by resuspension events, the sediment surface represents an interface between turbulent and calm conditions, high and low concentrations and/or different redox-states. Such gradients are the basis for intensive exchange processes. The surface sediments in the coastal sites of the southern Baltic Sea were characterized by active organic matter mineralization via sulfate reduction and mixing induced secondary reactions taking place in the suboxic zone. This included the removal of dissolved sulfide due to iron oxide reduction with simultaneous liberation of PO4 into the interstitial waters. High surface near P reservoirs existed due to internal P cycling within the sediments, which was in turn driven by continuous re-oxidation of the reduced iron by downwards transported oxygen. These reservoirs were only actually released into the water column during bottom water oxygen deficiency situations, when the iron re-oxidation was inhibited.
This also applies for sediments of the Gulf of Finland and the deeper Baltic Sea basins Bornholm Basin and Gdanks basin, where temporary hypoxic conditions are responsible for recurrent benthic phosphate release.
The widespread occurring phosphate adsorption on sedimentary solid iron phases is a much debated ecosystem service of marine sediments. As discussed in this work, the sedimentary P liberation rates and pools of readily bio-available dissolved phosphate can be substantial in Baltic Sea muddy sediments. Actual phosphate fluxes across the sediment-water interface, though, are relatively small because phosphate is scavenged by adsorption on iron oxyhydroxides that are usually an integral part of coastal marine sediments if overlain by oxic bottom waters. Although muddy sediments often show only an oxic layer of only few millimeters thickness, adsorption capacities of iron oxyhydroxides are large enough to substantially retain P from being liberated into the water column. Falling under reducing conditions, iron oxyhydroxides are re-dissolved, liberating high amounts of PO4 into the surrounding waters. While permanently oxic sediments will preserve adsorbed P, permanently anoxic sediments steadily release mineralized P into the water column. However, sedimentary environments of oscillating redox conditions are predestined for high, burst-like benthic P fluxes. Especially in a quasi isolated environment like the Baltic Sea, with high nutrient inputs but only few sinks, these internal recycling processes promote eutrophication in the long-term. Further expanding hypoxia and anoxia in the Baltic Sea with a subsequent loss of benthic fauna and altered nutrient dynamics in the surface sediments may be the consequence.
In M.-V. werden wesentliche politische Entscheidungen regelmäßig von Hinweisen auf Bevölkerungsprognosen begleitet. Dabei sind es Bevölkerungsvorausberechnungen, deren Ergebnisse maßgeblich von den getroffenen Annahmen, den zugrundeliegenden Bevölkerungsdaten und der Methodik abhängen. In Kombination mit deren weiteren Prinzipien handelt es sich eher um Modelle, deren Aussagekraft bezüglich eines langen Prognosezeitraumes stark limitiert ist. Da alternative Instrumente demgegenüber deutlich zurückstehen, können Infrastrukturentscheidungen nicht in ausreichendem Maße abgesichert werden.
Vor dem Hintergrund, dass M.-V. bspw. durch eine geringe Bevölkerungsdichte oder eine Vielzahl kleiner Gemeinden gekennzeichnet ist, sollte es die oberste Prämisse sein, langfristig weithin akzeptierte Strukturen zu schaffen, die den Gemeinden eine Perspektive gibt. In diesem Sinne ist der bisherige Ansatz der Stärkung der Zentren und der infrastrukturellen Marginalisierung der übrigen Gemeinden nicht erstrebenswert. Diesem Ansatz wird eine Flexibilisierung von Infrastruktur entgegengestellt, mit der alles erfasst wird, was im politisch gesetzten Auftrag bestehende Funktionsdefizite ausgleicht oder abdeckt. Gleichzeitig wird dem Begriff der Daseinsvorsorge eine Absage erteilt, da von Grunddaseinsfunktionen bei einem staatlichen Rückzug aus der Fläche nicht mehr gesprochen werden kann. Andernfalls würden bspw. die über 65-Jährigen nicht in die Zentren „flüchten‟. Zudem muss festgehalten werden, dass mit der Flexibilisierung des Begriffes Infrastruktur auch eine Neuinterpretation der Begriffe Mobilität und Verkehr einhergeht. Mobilität zeichnet bisher durch eine technische Überbetonung aus und zielt auch auf Ortsveränderungen ab. Damit überschneidet sich Mobilität definitorisch mit Verkehr. Zugleich ist die Rolle der Infrastruktur von nachrangiger Bedeutung. Die Integration des flexiblen Infrastrukturbegriffes führt zu einer Mobilität, die einfach die Fähigkeit zur Interaktion beschreibt und Verkehr wird zu konkreten Handlungen von Subjekten oder sozialen Gruppen. Beide sind dann nur noch von den individuellen Präferenzen und der Infrastruktur abhängig, wobei die Unplanbarkeit der individuellen Präferenzen festgehalten werden muss. Die infrastrukturelle Abhängigkeit zeigt sich auch bei Vulnerabilität und Resilienz. Während Vulnerabilität für Prozesse und deren Wirkungen auf Systeme sowie Organisationen in Abhängigkeit von Infrastruktur steht, bezeichnet Resilienz den Umgang mit vulnerablen Prozessen in Abhängigkeit von der Infrastruktur und der Zielsetzung. Aufgrund der nur unzureichend vorhandenen Informationen über die Gemeinden in M.-V. stand die Verbesserung der empirischen Basis gegenüber de-taillierten Maßnahmen im Fokus.
Ganz allgemein vollzog sich auf der Gemeindeebene zwischen 1990 und 2012 eine sehr vielschichtige Entwicklung. Das betrifft neben der Einwohnerzahl auch die altersgruppenspezifische Betrachtung, die der Beschäftigung sowie die Gemeindefinanzen. In Bezug zu den Einwohnerzahlen führte der Zensus zu eine deutlichen Bereinigung der Statistik. Jedoch wurde eine Rückrechnung für frühere Jahre per Gerichtsentscheid für unzulässig erklärt. Daher behalten die Werte vor 2011 ihre Gültigkeit. Während in den Jahren vor 2000 eine deutliche Suburbanisierung erkennbar war und sich in den Stadt-Umland-Bereichen entsprechende arbeitsräumliche Verflechtungen etablierten, hat sich die Suburbanisierung in der Folgezeit stark abgeschwächt und teilweise ins Gegenteil verkehrt. Getragen wird diese Entwicklung insbesondere durch die 20 - 25 sowie die über 65-Jährigen. Während bei den 20 - 25 Jährigen die ökonomischen Motive überwiegen, welche eine selektive Reurbanisierung stützt, hat die Wanderung der über 65-Jährigen eher infrastrukturelle Gründe. Die infrastrukturelle Marginalisierung der kleinen Gemeinden trifft auf eine Altersgruppe, die in zunehmenden Maße zu keiner Kompensation mehr fähig ist und so in Richtung der zentralen Orte abwandert. Alternativ zieht es diese Altersgruppe auch in touristisch bedeutsame Gemeinden. Damit tritt eine planerisch opportune Wanderungsbewegung ein, welche die Prämisse der Stärkung der Zen-tren unterstützt. Diese Segregation vollzieht sich vor einer dispersen Siedlungsstruktur, welche durch die politische Rahmensetzung und gezielte Vermarktungsstrategien in der Vergangenheit verfestigt wurde, die den individuellen Präferenzen viel Freiraum ermöglichte. Die Infrastrukturkonzentration destabilisiert die Strukturen und fördert wiederum die Arbeitsplatzkonzentration in den Zentren. Allein die Ober- und Mittelzentren vereinten 2012 60 % der SV Beschäftigungsverhältnisse. Die Arbeitsplätze sind damit weit stärker konzentriert als die Bevölkerung und hohe Auspendlerquoten die Folge. Dabei obliegt der Ausgleich infrastruktureller Defizite den Gemeinden, die wiederum eine hohe fremdbestimmte Ausgabenlast zu bewältigen haben. Demgegenüber steht ein KFA, der sich nicht an den realen Aufwendungen orientiert, so dass infolgedessen die Investitionen reduziert wurden. Des Weiteren sind finanzielle Spielräume kaum vorhanden. Im Ergebnis markiert bspw. die selektive Bevölkerungsentwicklung oder die Handlungsunfähigkeit der Gemeinden, die aus der Entwicklung der Gemeindefinanzen resultiert, jeweils einen vulnerablen Prozess, die bisher nicht adäquat bewältigt werden. Die Stärkung der Zentren kann nur im Hinblick auf die politische Zielsetzung als eine positive Resilienzstrategie für eine Handvoll Gemeinden bezeichnet werden.
Um eine zukünftige Alternativendiskussion anzuregen, wurden die Gemeinden im Anschluss einer multivariaten Analyse unterzogen. Zur Absicherung der Ergebnisse wurde eine Prüfung auf Normalverteilung sowie eine Untersuchung auf stochastische Unabhängigkeit vorgeschaltet. Die Prüfung auf Normalverteilung hat ergeben, dass diese für keine der 165 Variablen vorlag. Die maßgebliche Ursache hierfür liegt in der Betrachtungsebene der administrativen Einheiten und dem hohen Anteil der Gemeinden bis 2.000 Einwohner. Allerdings sind die Gemeinde gerade Untersuchungsgegenstand dieser Arbeit, so dass sich eine Änderung der Betrachtungsebene ausschloss. Folglich führte die Gliederung der administrativen Einheiten in M.-V. in Abhängigkeit von den Einwohnerzahlen zu Autokorrelationen zwischen den einzelnen Variablen. Diese Zusammenhänge bestanden auch bei Variablen mit einem zeitlichen Trend, so dass als Folge der Prüfung auf stochastische Unabhängigkeit die Clusteranalyse in zwei Analysen mit jeweils einem Variablenblock geteilt wurde. Die Anzahl der betrachteten Variablen reduzierte sich hierbei auf insgesamt 88. Das Resultat der ersten Clusteranalyse waren 5 Klassen, wobei Rostock eine eigene Klasse bildete. Die anderen Städte wie Greifswald, Stralsund, Neubrandenburg, Wismar sowie Schwerin formten ihrerseits einen Cluster und die übrigen Gemeinden verteilten sich auf die anderen drei Klassen. Insbesondere zahlreiche Tourismusgemeinden und zentrale Orte traten in einem eigenen Cluster deutlich hervor. Die Dominanz der großen Gebietskörperschaften zeigte sich auch in der zweiten Clusteranalyse, wobei sich die Struktur mit 6 Klassen als sehr stabil erwies. Die Ergebnisse wurden nach-folgend in einer Typisierung zusammengefasst, wobei sich 14 Regionaltypen erga-ben, deren Interpretation 7 Haupttypen offenbarte. Neben Rostock als Regiopole treten u. a. Regionalzentren, Kleinstgemeinden oder Gemeinden mit eingeschränkter Leistungsfähigkeit auf. Durchaus bemerkenswert ist der Umstand, dass einige Gemeinden von Usedom und Rügen eher Stadt-Umland-Gemeinden entsprechen und solche mit einer eingeschränkten Leistungsfähigkeit eher im Osten des Landes anzutreffen sind. Daneben sind Tourismusgemeinden ähnlich strukturiert wie Mittelzentren und zahlreiche Grundzentren grenzen sich lediglich über ihren Status von anderen Landgemeinden ab. Darüber hinaus grenzt sich diese Gliederung deutlich von der des Landes mit den ländlichen Gestaltungsräumen ab. Zur Identifizierung dieser wurden Kriterien herangezogen, die stochastisch nicht unabhängig sind, welche zur Basis für ein politisch motiviertes Ranking wurden. Die damit aufgeworfene These von der fragwürdigen Zukunftsfähigkeit, ist in erster Linie politisch determiniert.
Insgesamt zeigt sich mit der Handlungsmaxime „Stärkung der Zentren‟ ein vulnerabler Prozess, der sich in der Gemeindeentwicklung deutlich niederschlägt. Zur Vermeidung einer weiteren Vertiefung ist zunächst eine theoretische Neuausrichtung, wie sie in Grundzügen vorgestellt wurde, notwendig. Dabei ist die Forderung, dass Infrastruktur flexibilisiert werden muss, nicht neu. Sie wurde bspw. schon in Zusammenhang neuer interkommunaler Kooperationsformen postuliert. Die bisherige normative Fixierung der langfristigen Infrastrukturentwicklung über ROG und LPlG manifestiert die Reduzierung des ländlichen Raumes auf seinen existentiellen Kern und ignoriert gewachsenen Strukturen und individuelle Präferenzen der lokalen Bevölkerung. Im nächsten Schritt sollten die Bevölkerungsprognosen um andere Instrumente ergänzt werden, um frühzeitig bestimmte Entwicklungen aufzudecken und zu gestalten. Hierbei sollten die Akteure vor Ort, insbesondere die Gemeinden, auch in der Lage sein, die Gestaltungskompetenz wahrzunehmen. Das setzt voraus, dass zur Erfüllung der Pflichtaufgaben keine Liquiditätskredite erforderlich sind. Sollte eine aufgabengerechte Finanzausstattung nicht möglich sein, muss die derzeitige Aufgabenverteilung zwischen den Kommunen, dem Land sowie dem Bund neu geregelt werden. Eine fremdbestimmte Aufgabenträgerschaft und starre Richtwerte hinsichtlich der infrastrukturellen Ausgestaltung sind Mittel der Vergangenheit, die eine Flexibilisierung und mehr gemeindliche Selbstverantwortung nicht zulassen. Danach kann man beginnen über eine Gemeindegebietsreform Organisationsschwächen zu beseitigen und eine Resilienzstrategie zu verfolgen, die sich nicht allein in einer weiteren Infrastrukturkonzentration erschöpft.
Coastal and marginal seas – like the Baltic Sea – serve as natural reaction sites for the turnover and accumulation of land-derived inputs. The main location for the modification and deposition of the introduced material is, in most cases, not the water mass, but the sediment. Its key function as central reactor in the interaction between land and sea has so far been insufficiently studied and assessed. This study was part of the interdisciplinary SECOS project that aimed to identify and evaluate the service functions of sediments in German coastal seas in the context of human use with a focus on the Baltic Sea. One of its goals was to assess sediment functions related to the intermediate storage or final sink of imported material like nutrients and contaminants, and quantify their inventory as well as their mass accumulation rates on multi-decadal to multi-centennial time scales. For that, a detailed examination of the natural and anthropogenic processes that interfere with sediment accumulation in the south-western Baltic Sea basins is essential.
Certain basal Teleostei from the Early Jurassic of Mecklenburg-Western Pomerania (Germany) and the Late Jurassic of the Franconian Alb (Bavaria, Germany), the Swabian Alb (Baden-Württemberg, Germany) and the western Jura-Mountains (Ain, France) are described. The present doctoral dissertation includes four studies, dealing with representatives of “Pholidophoriformes”, Leptolepidae and Orthogonikleithridae. These studies include anatomical descriptions of new taxa and reviews of poorly known fishes. Furthermore, the stratigraphic and palaeobiogeographical distributions of the examined taxa are discussed.
Quang Xuong is considered as one of the most developed districts in Thanh Hoa Province in terms of agricultural. The major purpose of this research is to find good places to suggest for annual crops production in the case study. Therefore, the assessment of land potential productivity, land suitability, and land cover/land use change in different periods is essential for making strategies of sustainable agricultural development as this will help land-users and land managers to discover the potential and limitations of the current existing land conditions to make appropriate policies and plans for future land use. Its results will provide basic information to make reasonable decisions for investments and rational reclamations of cultivated land before and after each crop season in order to meet the objectives of sustainable development in terms of economic efficiency, social acceptability, and environmental protection. The research site is located at latitudes 19 degree 34 minute N - 19 degree 47 minuteN and at longitudes 105 degree 46 minute E - 105 degree 53 minute E. The total area is about 227km2; in which 128km2 is in use for agricultural activities. Based on soil classification methods by FAO-UNESCO (1988), the agricultural land is classified into six main soil groups, including Arenosols, Salic Fluvisols, Fluvisols, Gleysols, Acrisols, and Leptosols, 12 soil units and 18 sub-units. The largest area belongs to the Fluvisols group with 9358.29ha and the smallest area is identified as the Leptosol group with 219.33ha. Most of the soil in this district has low to moderate nutrition, but in general, they are still suitable for agricultural production. There are 42 land units defined in the land mapping, which can be different from each other by one or more land characteristics. The land mapping unit is created from the overlay of all thematic maps of soil chemicals, soil physical characteristics, and relative topography together by application of GIS techniques. It presents land characteristics and properties in this case study and will be used in comparasion with a particular crop requirement for growth in land suitability evaluation process. A certain land unit may be suitable for one or more types of different land use. It is also classified as highly suitable for a specific land utilization type, but less suitable or unsuitable for other crops. For example, in this study, land unit 26 is determined as highly suitable (S1) for growing paddy rice and maize, but it falls into moderately suitability (S2) for groundnut crop by using parametric (square root) method used in this thesis. Depending on the kind of crops need to be evaluated and its requirement for development compared with each land unit characteristics, land-users will determine the best suitable place for crop production. Identification of land use change in different periods of time has become a central key to monitoring of land resources. It is relatively important for effective land management to protect the land resources, especially the land used for agricultural production from overuse and environmental changes. The sprawl of inhabitant areas, development of rural infrastructures, and industrialization are responsible for serious losses of agricultural land. In this study, remote sensing techniques were applied to studying the trends of land cover change in the abovementioned district in a period of about 24 years from 1989 to 2013. ArcGIS software was adopted to develop the land cover and the change of land use maps from 1989 to 2013. Two satellite images with moderate resolution were collected from USGS Earth Explorer website, Landsat5 TM for 1989 and Landsat8 OLI & TIRS for 2013. After image geo-processing, the images were classified into six land cover categories by applying supervised classification method (Maximum Likelihood). The six main obtained land cover types were built-up areas, agricultural land, forest land, water surface area, salty land, and unused land. The overall accuracies of land cover maps for 1989 and 2013 were 94.08% and 92.91%, respectively. The results of change detection analysis indicate that the cultivated, water surface and unused lands decreased by 22%, 17%, and 91%, respectively. In other side, the built-up and salty land increased by 78%, 58%, respectively and forest land increased from 52.69ha in 1989 to 395.76ha in 2013. The assessment of land potential productivity for agricultural production and land suitability for selected annual crops was based on FAO guidelines for land evaluation (FAO, 1976, 1985, and 1993) which were adopted and slightly modified for compatibility with Vietnamese conditions. All related data were stored, analyzed, mapped and presented in ArcGIS software. Weighted Linear Combination Method developed by Hopkins (1977) and GIS techniques were used to analyze and determine the land potential for agricultural use in the study area. The results show that 5.26%, 83.10%, 10.06%, and 1.57% of the investigated areas were assessed as high potential, moderate potential, low potential and very low potential for growing crops. Regarding land suitability evaluation, the simple limitation, parametric (square root), and AHP methods were used to evaluate the suitability levels for selected crops, including paddy rice, sweet potato, groundnut, maize, potato, sesame, soybean, and green pepper. The obtained results indicate that each applied method provides different results of land suitability level for a specific crop in certain land units compared to the other two methods, and OM, soil pH, soil texture, and relative topography were found out as the main limitation factors which affected land suitability level. The study also suggests that three different methods as abovementioned can be expanded and applied in other places with the appropriate factors used for land suitability evaluation according to particular area conditions.
A large portion of the earth's surface is covered with various vegetation classes (i.e. grassland, wetland and agricultural area, forest) of many diverse species and canopy configurations. The ability to assess and to monitor canopy parameters, such as biomass, leaf area index, and vegetation water content, is of vital importance to the study of different agronomic processes. Remote sensing techniques provide a unique capability towards probing different vegetation types and canopy by operating at different bands, observation angle etc. Over the past decades, significant progress has been made in remote sensing techniques of land processes specially vegetation characteristics through development of advanced ground-based, airborne and space-borne microwave sensors, methods and approaches such as theoretical, semi-empirical and empirical models, needed for analyzing the data. These activities have sharply increased in recent years since the launch of different active and passive satellites and sensors. Remote Sensing (RS) science and techniques combined with ground truth data can provide new tools for advanced agricultural crop applications. It has been demonstrated that RS has the ability to estimate biophysical parameters of agricultural crops over time at local, regional, and global scales. In this study, RS images in visible/near infrared (VIS/NIR) domain as well as microwave domain combined with ground truth data were used to assess biophysical parameters of agricultural crop during their whole growing season at Durable Environmental Multidisciplinary Monitoring Information Network (DEMMIN) test site in North East Germany. Ground truth studies were carried out for 31 weeks during 17th April – 13th November 2013 over three crop lands including winter wheat, barley and canola. Landsat 8 OLI, Landsat 7 ETM+ were used for the VIS/NIR studies and TerraSAR-X synthetic aperture radar (SAR) images were used to study biophysical parameters of agricultural crops in microwave part of electromagnetic spectrum. The analysis was conducted by calculating different vegetation indices (VIs) to estimate the biomass (fresh and dry), LAI, and vegetation water content (VWC) of three crops using Landsat 8 OLI and Landsat 7 ETM+ combined with ground truth data. A new concept of Soil Line retrieval from Landsat 8 image was also developed to estimate plant biophysical parameters using soil line related vegetation indices in optical domain of electromagnetic spectrum. Different approaches including univariate, multivariate stepwise regression and semi-empirical water cloud model was also used to estimate the biophysical parameters of agricultural crop using TerraSAR-X data in microwave domain of electromagnetic spectrum. Perhaps the most important conclusion of this study is that the RS approach can provide useful information about estimating agricultural crop parameters over time and local scale, which can therefore provide valuable information to aid the agronomy community.
Tourism is a multifaceted economy and based on existing nature, as well as on culture in a geographical space to become a successful destination for tourism. The topic of this survey is how tourism in the transitioning country of Vietnam influences culture and nature or vice versa. A special focus will be on the transitioning aspect. This study gives insights about how in the transitioning country of Vietnam, tourism can act as an additional driver of change in terms of nature and culture or if tourism is only adapting to these changes. Therefore in the beginning the subject of ‘social-ecological transformation’ is described and furthermore the situation in Vietnam will be introduced. The key aspects here will be within the range of geography and sociology. It becomes evident, that scientific views on this topic are rather diverse, but nevertheless many theoretical aspects can be observed also in the investigation area Vietnam. Within the country several aspects of economic transition already became reality, while others, like social, ecological or political reforms, are still at the beginning. The empirical part of this study deals with existing thoughts, according to the topic of transition, in relation to tourism development and respectively to environmental understanding, by analyzing and comparing positions of 21 international and Vietnamese experts, 569 international tourists and 710 Vietnamese students. By doing so, similarities within opinions about tourism development and the environmental situation in the country became observable. While tourism is rated as a mostly positive development, the current environmental situation has mostly been criticized by all survey participants. Apart from that, connections between both aspects (tourism economy and nature) are often of no importance or the relationship is identified to be just a rudimentary one. In case of these opinions, involvement within one social group and personal experience is of larger importance than cultural conditioning (European or Asian), e.g. own travels, own jobs and own education. This fact becomes visible by very similar ratings of environmental problems on the one hand and the beauty of natural landscapes on the other hand, done by both survey groups; namely international tourists and Vietnamese students.
This thesis aims to develop a palaeogeographic and chronostratigraphic model of the southwestern Baltic Sea area, to improve our understanding of the depositional history of the Late Pleistocene on both a local and a transregional scale. New sedimentological, palaeontological and numerical age data will be presented from three reference sites located at the coast of NE Germany. So far, the chronostratigraphic assignment of Saalian and Weichselian sediments of NE Germany has been based mainly on lithostratigraphic methods and on sparse numerical age data, resulting in a fragmentary age database. Modern sedimentological approaches, such as facies analyses, have been applied only at a few isolated profiles. Thus, a reliable reconstruction of the depositional environments and their stratigraphic positions is still missing for the study area, which makes the correlation between Pleistocene successions from NE Germany and other circum-Baltic regions problematic. To address these lithostratigraphic and geochronologic issues, three crucial profiles were re-investigated using a multiproxy approach, including sedimentological, geochronological, and palaeontological techniques. The Glowe and Kluckow sites are located on the peninsula of Jasmund (Rügen Island), whereas the Klein Klütz Höved (KKH) section is situated between Wismar and Travemünde at the coast of the Mecklenburg Bay. The age-constraining of critical horizons was conducted by luminescence dating of feldspar and quartz grain minerals. Together, these successions represent the Late Saalian to Late Weichselian period and give rise to the following picture. The Glowe and Kluckow sections reveal that ice-free conditions dominated the study site between 47 and 42 ka. Deposition occurred in a steppe-like environment with moderate summers and cool winters. Meandering and braided river systems inhabited by various freshwater species, such as Anodonta cygnea, Pisidium amnicum and Perca fluviatilis, shaped the landscape. A subsequent cooling phase resulted in the establishment of a periglacial landscape and the formation of ice-wedges. This phase is shown in this thesis to be connected to the Klintholm advance documented at 34±4 ka in Denmark. Furthermore, the data indicate the formation of a lacustrine basin during the transition of MIS 3 to MIS 2 under sub-arctic climate conditions. A potential link to the Kattegat ice advance (29 – 26 ka) will be proposed. At 23±2 ka, the study area was characterised by proglacial and ice-contact lakes related to the Last Glacial Maximum ice advance of the Scandinavian Ice Sheet (SIS). This is the first documented SIS advance of Weichselian age, which reached Jasmund at 22±2 ka. The KKH sedimentary succession comprises deposits of Late Saalian to Late Weichselian age: after a period of deglaciation between ~139-134 ka (Termination II; MIS 6), which is preserved in a glaciofluvial sequence deposited in a braided river system, a lacustrine environment was established in an arctic to subarctic climate. During this time, the landscape was vegetated by typical Late Saalian flora communities. The Eemian interglacial is represented by lacustrine to brackish deposits covering the reference pollen zones 1 to 3. During this initial part of the Eemian, thermophile forest elements spread (Quercus, Ulmus), indicating a deciduous forest. The presence of brackish ostracods represents the influence of a marine transgression between 300 and 750 years after the beginning of the Eemian period. A hiatus of more than 90,000 years separates the Eemian from the overlying Late Weichselian sediments. During the Late Weichselian period, the deposition at KKH was dominated by glaciolacustrine and subglacial facies, where the first Weichselian ice advance occurred at 20±2 ka. The sedimentological and geochronological findings in this thesis provide valuable information for the reconstruction of the palaeoenvironmental history from the Late Saalian to Late Weichselian period. The Late Saalian palaeoenvironmental setting is reconstructed, including Termination II and the initial phase of the Eemian interglacial. Furthermore, the Eemian marine transgression is shown to have occurred 300 to 750 years after the beginning of this interglacial. The first proven Weichselian advance of the SIS approached NE Germany between ~23 and ~20 ka. In contrast, there is no evidence to support a pre-LGM advance of Weichselian age to the study area, as proposed by several authors, neither at Glowe and Kluckow, nor at the KKH site. Based on the presented results, and contra what was previously assumed, the MIS 3 Ristinge and Klintholm advance of the SIS, documented in Denmark, did not reach NE Germany.
The establishment and management of protected areas has become a universally accepted way to conserve biodiversity and the wide range of goods and services they offer. Sustainable management of forest resources requires good decision-making from a range of different stakeholders. This dissertation develops a model based on spatial data and expert judgments to assess the vulnerability of the most threatened species of fauna and flora in a selected protected area. Based on the study objectives, the availability of data and technology, the study concludes vulnerability as composed of multidimensional losses, which can be measured as a function of the three components: exposure, sensitivity and adaptive capacity. In order to measure vulnerability, the research applies the Analytic Hierarchy Process (AHP), a well-known multi-criteria decision making approach, using the open access Super Decisions software in a spatial database context with the help of Geographic Information Systems (GIS).
Durch die Entstehung neuer Pilgerwege erhoffen sich die Initiatoren eine touristische Erschließung peripherer Räume. Ähnlich beim Projekt des Pommerschen Jakobsweges, welches das Küstenhinterland des südlichen Ostseeraumes im Zuge der Revitalisierung einer kulturhistorischen Pilgerroute touristisch aufwerten soll. Ziel dieser tourismusgeographischen Studie ist es, das Potential des Pommerschen Jakobsweges im Hinblick auf die Nachfrageseite zu untersuchen und Handlungsmöglichkeiten aufzuzeigen. Die Arbeit dient zudem als Konzeption und Leitlinie für zukünftige Projekte und setzt sich kritisch mit gegenwärtigen Forschungsergebnissen auseinander. Der Fokus der Untersuchung wird dabei auf die reisespezifischen Aspekte des Pilgerns sowie die Funktion des Pilgerweges als touristisches Produkt gelegt. Als Ergebnis wurden fünf Reiseformen herausgearbeitet, die inmitten des alternativen Pilgertourismus eine besondere Rolle übernehmen und die nachgewiesene, starke Nachfrage an peripheren Pilgerwegen mitgestalten.