@phdthesis{Kath2022,
  author    = {Kath, Nadja Jeanette},
  title     = {Functional traits determine biomass dynamics, coexistence and energetics in plankton food webs},
  doi       = {10.25932/publishup-55123},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-551239},
  school      = {Universit{\"a}t Potsdam},
  pages     = {197},
  year      = {2022},
  abstract  = {Plankton food webs are the basis of marine and limnetic ecosystems. Especially aquatic ecosystems of high biodiversity provide important ecosystem services for humankind as providers of food, coastal protection, climate regulation, and tourism. Understanding the dynamics of biomass and coexistence in these food webs is a first step to understanding the ecosystems. It also lays the foundation for the development of management strategies for the maintenance of the marine and freshwater biodiversity despite anthropogenic influences. Natural food webs are highly complex, and thus often equally complex methods are needed to analyse and understand them well. Models can help to do so as they depict simplified parts of reality. In the attempt to get a broader understanding of the complex food webs, diverse methods are used to investigate different questions. In my first project, we compared the energetics of a food chain in two versions of an allometric trophic network model. In particular, we solved the problem of unrealistically high trophic transfer efficiencies (up to 70\%) by accounting for both basal respiration and activity respiration, which decreased the trophic transfer efficiency to realistic values of ≤30\%. Next in my second project I turned to plankton food webs and especially phytoplankton traits. Investigating a long-term data set from Lake Constance we found evidence for a trade-off between defence and growth rate in this natural phytoplankton community. I continued working with this data set in my third project focusing on ciliates, the main grazer of phytoplankton in spring. Boosted regression trees revealed that temperature and predators have the highest influence on net growth rates of ciliates. We finally investigated in my fourth project a food web model inspired by ciliates to explore the coexistence of plastic competitors and to study the new concept of maladaptive switching, which revealed some drawbacks of plasticity: faster adaptation led to higher maladaptive switching towards undefended phenotypes which reduced autotroph biomass and coexistence and increased consumer biomass. It became obvious that even well-established models should be critically questioned as it is important not to forget reality on the way to a simplistic model. The results showed furthermore that long-term data sets are necessary as they can help to disentangle complex natural processes. Last, one should keep in mind that the interplay between models and experiments/ field data can deliver fruitful insights about our complex world.},
  language  = {en}
}
@phdthesis{Fuhrmann2018,
  author    = {Fuhrmann, Saskia},
  title     = {Physiologically-based pharmacokinetic and mechanism-based pharmacodynamic modelling of monoclonal antibodies with a focus on tumour targeting},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-418861},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xvii, 171},
  year      = {2018},
  abstract  = {Monoclonal antibodies (mAbs) are an innovative group of drugs with increasing clinical importance in oncology, combining high specificity with generally low toxicity. There are, however, numerous challenges associated with the development of mAbs as therapeutics. Mechanistic understanding of factors that govern the pharmacokinetics (PK) of mAbs is critical for drug development and the optimisation of effective therapies; in particular, adequate dosing strategies can improve patient quality life and lower drug cost. Physiologically-based PK (PBPK) models offer a physiological and mechanistic framework, which is of advantage in the context of animal to human extrapolation. Unlike for small molecule drugs, however, there is no consensus on how to model mAb disposition in a PBPK context. Current PBPK models for mAb PK hugely vary in their representation of physiology and parameterisation. Their complexity poses a challenge for their applications, e.g., translating knowledge from animal species to humans. In this thesis, we developed and validated a consensus PBPK model for mAb disposition taking into account recent insights into mAb distribution (antibody biodistribution coefficients and interstitial immunoglobulin G (IgG) pharmacokinetics) to predict tissue PK across several pre-clinical species and humans based on plasma data only. The model allows to a priori predict target-independent (unspecific) mAb disposition processes as well as mAb disposition in concentration ranges, for which the unspecific clearance (CL) dominates target-mediated CL processes. This is often the case for mAb therapies at steady state dosing. The consensus PBPK model was then used and refined to address two important problems: 1) Immunodeficient mice are crucial models to evaluate mAb efficacy in cancer therapy. Protection from elimination by binding to the neonatal Fc receptor is known to be a major pathway influencing the unspecific CL of both, endogenous and therapeutic IgG. The concentration of endogenous IgG, however, is reduced in immunodeficient mouse models, and this effect on unspecific mAb CL is unknown, yet of great importance for the extrapolation to human in the context of mAb cancer therapy. 2) The distribution of mAbs into solid tumours is of great interest. To comprehensively investigate mAb distribution within tumour tissue and its implications for therapeutic efficacy, we extended the consensus PBPK model by a detailed tumour distribution model incorporating a cell-level model for mAb-target interaction. We studied the impact of variations in tumour microenvironment on therapeutic efficacy and explored the plausibility of different mechanisms of action in mAb cancer therapy. The mathematical findings and observed phenomena shed new light on therapeutic utility and dosing regimens in mAb cancer treatment.},
  language  = {en}
}
@phdthesis{Lischke2015,
  author    = {Lischke, Betty},
  title     = {Food web regulation under different forcing regimes in shallow lakes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-89149},
  school      = {Universit{\"a}t Potsdam},
  pages     = {131},
  year      = {2015},
  abstract  = {The standing stock and production of organismal biomass depends strongly on the organisms' biotic environment, which arises from trophic and non-trophic interactions among them. The trophic interactions between the different groups of organisms form the food web of an ecosystem, with the autotrophic and bacterial production at the basis and potentially several levels of consumers on top of the producers. Feeding interactions can regulate communities either by severe grazing pressure or by shortage of resources or prey production, termed top-down and bottom-up control, respectively. The limitations of all communities conglomerate in the food web regulation, which is subject to abiotic and biotic forcing regimes arising from external and internal constraints. This dissertation presents the effects of alterations in two abiotic, external forcing regimes, terrestrial matter input and long-lasting low temperatures in winter. Diverse methodological approaches, a complex ecosystem model study and the analysis of two whole-lake measurements, were performed to investigate effects for the food web regulation and the resulting consequences at the species, community and ecosystem scale. Thus, all types of organisms, autotrophs and heterotrophs, at all trophic levels were investigated to gain a comprehensive overview of the effects of the two mentioned altered forcing regimes. In addition, an extensive evaluation of the trophic interactions and resulting carbon fluxes along the pelagic and benthic food web was performed to display the efficiencies of the trophic energy transfer within the food webs. All studies were conducted in shallow lakes, which is worldwide the most abundant type of lakes. The specific morphology of shallow lakes allows that the benthic production contributes substantially to the whole-lake production. Further, as shallow lakes are often small they are especially sensitive to both, changes in the input of terrestrial organic matter and the atmospheric temperature. Another characteristic of shallow lakes is their appearance in alternative stable states. They are either in a clear-water or turbid state, where macrophytes and phytoplankton dominate, respectively. Both states can stabilize themselves through various mechanisms. These two alternative states and stabilizing mechanisms are integrated in the complex ecosystem model PCLake, which was used to investigate the effects of the enhanced terrestrial particulate organic matter (t-POM) input to lakes. The food web regulation was altered by three distinct pathways: (1) Zoobenthos received more food, increased in biomass which favored benthivorous fish and those reduced the available light due to bioturbation. (2) Zooplankton substituted autochthonous organic matter in their diet by suspended t-POM, thus the autochthonous organic matter remaining in the water reduced its transparency. (3) T-POM suspended into the water and reduced directly the available light. As macrophytes are more light-sensitive than phytoplankton they suffered the most from the lower transparency. Consequently, the resilience of the clear-water state was reduced by enhanced t-POM inputs, which makes the turbid state more likely at a given nutrient concentration. In two subsequent winters long-lasting low temperatures and a concurrent long duration of ice coverage was observed which resulted in low overall adult fish biomasses in the two study lakes - Schulzensee and Gollinsee, characterized by having and not having submerged macrophytes, respectively. Before the partial winterkill of fish Schulzensee allowed for a higher proportion of piscivorous fish than Gollinsee. However, the partial winterkill of fish aligned both communities as piscivorous fish are more sensitive to low oxygen concentrations. Young of the year fish benefitted extremely from the absence of adult fish due to lower predation pressure. Therefore, they could exert a strong top-down control on crustaceans, which restructured the entire zooplankton community leading to low crustacean biomasses and a community composition characterized by copepodites and nauplii. As a result, ciliates were released from top-down control, increased to high biomasses compared to lakes of various trophic states and depths and dominated the zooplankton community. While being very abundant in the study lakes and having the highest weight specific grazing rates among the zooplankton, ciliates exerted potentially a strong top-down control on small phytoplankton and particle-attached bacteria. This resulted in a higher proportion of large phytoplankton compared to other lakes. Additionally, the phytoplankton community was evenly distributed presumably due to the numerous fast growing and highly specific ciliate grazers. Although, the pelagic food web was completely restructured after the subsequent partial winterkills of fish, both lakes were resistant to effects of this forcing regime at the ecosystem scale. The consistently high predation pressure on phytoplankton prevented that Schulzensee switched from the clear-water to the turbid state. Further mechanisms, which potentially stabilized the clear-water state, were allelopathic effects by macrophytes and nutrient limitation in summer. The pelagic autotrophic and bacterial production was an order of magnitude more efficient transferred to animal consumers than the respective benthic production, despite the alterations of the food web structure after the partial winterkill of fish. Thus, the compiled mass-balanced whole-lake food webs suggested that the benthic bacterial and autotrophic production, which exceeded those of the pelagic habitat, was not used by animal consumers. This holds even true if the food quality, additional consumers such as ciliates, benthic protozoa and meiobenthos, the pelagic-benthic link and the potential oxygen limitation of macrobenthos were considered. Therefore, low benthic efficiencies suggest that lakes are primarily pelagic systems at least at the animal consumer level. Overall, this dissertation gives insights into the regulation of organism groups in the pelagic and benthic habitat at each trophic level under two different forcing regimes and displays the efficiency of the carbon transfer in both habitats. The results underline that the alterations of external forcing regimes affect all hierarchical level including the ecosystem.},
  language  = {en}
}
@phdthesis{Schuette2011,
  author    = {Sch{\"u}tte, Moritz},
  title     = {Evolutionary fingerprints in genome-scale networks},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57483},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Mathematical modeling of biological phenomena has experienced increasing interest since new high-throughput technologies give access to growing amounts of molecular data. These modeling approaches are especially able to test hypotheses which are not yet experimentally accessible or guide an experimental setup. One particular attempt investigates the evolutionary dynamics responsible for today's composition of organisms. Computer simulations either propose an evolutionary mechanism and thus reproduce a recent finding or rebuild an evolutionary process in order to learn about its mechanism. The quest for evolutionary fingerprints in metabolic and gene-coexpression networks is the central topic of this cumulative thesis based on four published articles. An understanding of the actual origin of life will probably remain an insoluble problem. However, one can argue that after a first simple metabolism has evolved, the further evolution of metabolism occurred in parallel with the evolution of the sequences of the catalyzing enzymes. Indications of such a coevolution can be found when correlating the change in sequence between two enzymes with their distance on the metabolic network which is obtained from the KEGG database. We observe that there exists a small but significant correlation primarily on nearest neighbors. This indicates that enzymes catalyzing subsequent reactions tend to be descended from the same precursor. Since this correlation is relatively small one can at least assume that, if new enzymes are no "genetic children" of the previous enzymes, they certainly be descended from any of the already existing ones. Following this hypothesis, we introduce a model of enzyme-pathway coevolution. By iteratively adding enzymes, this model explores the metabolic network in a manner similar to diffusion. With implementation of an Gillespie-like algorithm we are able to introduce a tunable parameter that controls the weight of sequence similarity when choosing a new enzyme. Furthermore, this method also defines a time difference between successive evolutionary innovations in terms of a new enzyme. Overall, these simulations generate putative time-courses of the evolutionary walk on the metabolic network. By a time-series analysis, we find that the acquisition of new enzymes appears in bursts which are pronounced when the influence of the sequence similarity is higher. This behavior strongly resembles punctuated equilibrium which denotes the observation that new species tend to appear in bursts as well rather than in a gradual manner. Thus, our model helps to establish a better understanding of punctuated equilibrium giving a potential description at molecular level. From the time-courses we also extract a tentative order of new enzymes, metabolites, and even organisms. The consistence of this order with previous findings provides evidence for the validity of our approach. While the sequence of a gene is actually subject to mutations, its expression profile might also indirectly change through the evolutionary events in the cellular interplay. Gene coexpression data is simply accessible by microarray experiments and commonly illustrated using coexpression networks where genes are nodes and get linked once they show a significant coexpression. Since the large number of genes makes an illustration of the entire coexpression network difficult, clustering helps to show the network on a metalevel. Various clustering techniques already exist. However, we introduce a novel one which maintains control of the cluster sizes and thus assures proper visual inspection. An application of the method on Arabidopsis thaliana reveals that genes causing a severe phenotype often show a functional uniqueness in their network vicinity. This leads to 20 genes of so far unknown phenotype which are however suggested to be essential for plant growth. Of these, six indeed provoke such a severe phenotype, shown by mutant analysis. By an inspection of the degree distribution of the A.thaliana coexpression network, we identified two characteristics. The distribution deviates from the frequently observed power-law by a sharp truncation which follows after an over-representation of highly connected nodes. For a better understanding, we developed an evolutionary model which mimics the growth of a coexpression network by gene duplication which underlies a strong selection criterion, and slight mutational changes in the expression profile. Despite the simplicity of our assumption, we can reproduce the observed properties in A.thaliana as well as in E.coli and S.cerevisiae. The over-representation of high-degree nodes could be identified with mutually well connected genes of similar functional families: zinc fingers (PF00096), flagella, and ribosomes respectively. In conclusion, these four manuscripts demonstrate the usefulness of mathematical models and statistical tools as a source of new biological insight. While the clustering approach of gene coexpression data leads to the phenotypic characterization of so far unknown genes and thus supports genome annotation, our model approaches offer explanations for observed properties of the coexpression network and furthermore substantiate punctuated equilibrium as an evolutionary process by a deeper understanding of an underlying molecular mechanism.},
  language  = {en}
}
@phdthesis{Huber2010,
  author    = {Huber, Veronika Emilie Charlotte},
  title     = {Climate impact on phytoplankton blooms in shallow lakes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-42346},
  school      = {Universit{\"a}t Potsdam},
  year      = {2010},
  abstract  = {Lake ecosystems across the globe have responded to climate warming of recent decades. However, correctly attributing observed changes to altered climatic conditions is complicated by multiple anthropogenic influences on lakes. This thesis contributes to a better understanding of climate impacts on freshwater phytoplankton, which forms the basis of the food chain and decisively influences water quality. The analyses were, for the most part, based on a long-term data set of physical, chemical and biological variables of a shallow, polymictic lake in north-eastern Germany (M{\"u}ggelsee), which was subject to a simultaneous change in climate and trophic state during the past three decades. Data analysis included constructing a dynamic simulation model, implementing a genetic algorithm to parameterize models, and applying statistical techniques of classification tree and time-series analysis. Model results indicated that climatic factors and trophic state interactively determine the timing of the phytoplankton spring bloom (phenology) in shallow lakes. Under equally mild spring conditions, the phytoplankton spring bloom collapsed earlier under high than under low nutrient availability, due to a switch from a bottom-up driven to a top-down driven collapse. A novel approach to model phenology proved useful to assess the timings of population peaks in an artificially forced zooplankton-phytoplankton system. Mimicking climate warming by lengthening the growing period advanced algal blooms and consequently also peaks in zooplankton abundance. Investigating the reasons for the contrasting development of cyanobacteria during two recent summer heat wave events revealed that anomalously hot weather did not always, as often hypothesized, promote cyanobacteria in the nutrient-rich lake studied. The seasonal timing and duration of heat waves determined whether critical thresholds of thermal stratification, decisive for cyanobacterial bloom formation, were crossed. In addition, the temporal patterns of heat wave events influenced the summer abundance of some zooplankton species, which as predators may serve as a buffer by suppressing phytoplankton bloom formation. This thesis adds to the growing body of evidence that lake ecosystems have strongly responded to climatic changes of recent decades. It reaches beyond many previous studies of climate impacts on lakes by focusing on underlying mechanisms and explicitly considering multiple environmental changes. Key findings show that climate impacts are more severe in nutrient-rich than in nutrient-poor lakes. Hence, to develop lake management plans for the future, limnologists need to seek a comprehensive, mechanistic understanding of overlapping effects of the multi-faceted human footprint on aquatic ecosystems.},
  language  = {en}
}
@phdthesis{Grimbs2009,
  author    = {Grimbs, Sergio},
  title     = {Towards structure and dynamics of metabolic networks},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32397},
  school      = {Universit{\"a}t Potsdam},
  year      = {2009},
  abstract  = {This work presents mathematical and computational approaches to cover various aspects of metabolic network modelling, especially regarding the limited availability of detailed kinetic knowledge on reaction rates. It is shown that precise mathematical formulations of problems are needed i) to find appropriate and, if possible, efficient algorithms to solve them, and ii) to determine the quality of the found approximate solutions. Furthermore, some means are introduced to gain insights on dynamic properties of metabolic networks either directly from the network structure or by additionally incorporating steady-state information. Finally, an approach to identify key reactions in a metabolic networks is introduced, which helps to develop simple yet useful kinetic models. The rise of novel techniques renders genome sequencing increasingly fast and cheap. In the near future, this will allow to analyze biological networks not only for species but also for individuals. Hence, automatic reconstruction of metabolic networks provides itself as a means for evaluating this huge amount of experimental data. A mathematical formulation as an optimization problem is presented, taking into account existing knowledge and experimental data as well as the probabilistic predictions of various bioinformatical methods. The reconstructed networks are optimized for having large connected components of high accuracy, hence avoiding fragmentation into small isolated subnetworks. The usefulness of this formalism is exemplified on the reconstruction of the sucrose biosynthesis pathway in Chlamydomonas reinhardtii. The problem is shown to be computationally demanding and therefore necessitates efficient approximation algorithms. The problem of minimal nutrient requirements for genome-scale metabolic networks is analyzed. Given a metabolic network and a set of target metabolites, the inverse scope problem has as it objective determining a minimal set of metabolites that have to be provided in order to produce the target metabolites. These target metabolites might stem from experimental measurements and therefore are known to be produced by the metabolic network under study, or are given as the desired end-products of a biotechological application. The inverse scope problem is shown to be computationally hard to solve. However, I assume that the complexity strongly depends on the number of directed cycles within the metabolic network. This might guide the development of efficient approximation algorithms. Assuming mass-action kinetics, chemical reaction network theory (CRNT) allows for eliciting conclusions about multistability directly from the structure of metabolic networks. Although CRNT is based on mass-action kinetics originally, it is shown how to incorporate further reaction schemes by emulating molecular enzyme mechanisms. CRNT is used to compare several models of the Calvin cycle, which differ in size and level of abstraction. Definite results are obtained for small models, but the available set of theorems and algorithms provided by CRNT can not be applied to larger models due to the computational limitations of the currently available implementations of the provided algorithms. Given the stoichiometry of a metabolic network together with steady-state fluxes and concentrations, structural kinetic modelling allows to analyze the dynamic behavior of the metabolic network, even if the explicit rate equations are not known. In particular, this sampling approach is used to study the stabilizing effects of allosteric regulation in a model of human erythrocytes. Furthermore, the reactions of that model can be ranked according to their impact on stability of the steady state. The most important reactions in that respect are identified as hexokinase, phosphofructokinase and pyruvate kinase, which are known to be highly regulated and almost irreversible. Kinetic modelling approaches using standard rate equations are compared and evaluated against reference models for erythrocytes and hepatocytes. The results from this simplified kinetic models can simulate acceptably the temporal behavior for small changes around a given steady state, but fail to capture important characteristics for larger changes. The aforementioned approach to rank reactions according to their influence on stability is used to identify a small number of key reactions. These reactions are modelled in detail, including knowledge about allosteric regulation, while all other reactions were still described by simplified reaction rates. These so-called hybrid models can capture the characteristics of the reference models significantly better than the simplified models alone. The resulting hybrid models might serve as a good starting point for kinetic modelling of genome-scale metabolic networks, as they provide reasonable results in the absence of experimental data, regarding, for instance, allosteric regulations, for a vast majority of enzymatic reactions.},
  language  = {en}
}
@phdthesis{Rossmanith2005,
  author    = {Rossmanith, Eva},
  title     = {Breeding biology, mating system and population dynamics of the Lesser Spotted Woodepcker (Picoides minor) : combining empirical and model investigations},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-5328},
  school      = {Universit{\"a}t Potsdam},
  year      = {2005},
  abstract  = {The protection of species is one major focus in conservation biology. The basis for any management concept is the knowledge of the species autecology. In my thesis, I studied the life-history traits and population dynamics of the endangered Lesser Spotted Woodpecker (Picoides minor) in Central Europe. Here, I combine a range of approaches, from empirical investigations of a Lesser Spotted Woodpecker population in the Taunus low mountain range in Germany, the analysis of empirical data and the development of an individual-based stochastic model simulating the population dynamics. In the field studies I collected basic demographic data of reproductive success and mortality. Moreover, breeding biology and behaviour were investigated in detail. My results showed a significant decrease of the reproductive success with later timing of breeding, caused by deterioration in food supply. Moreover, mate fidelity was of benefit, since pairs composed of individuals that bred together the previous year started earlier with egg laying and obtained a higher reproductive success. Both sexes were involved in parental care, but the care was only shared equally during incubation and the early nestling stage. In the late nestling stage, parental care strategies differed between sexes: Females considerably decreased feeding rate with number of nestlings and even completely deserted small broods. Males fed their nestlings irrespective of brood size and compensated for the females absence. The organisation of parental care in the Lesser Spotted Woodpecker is discussed to provide the possibility for females to mate with two males with separate nests and indeed, polyandry was confirmed. To investigate the influence of the observed flexibility in the social mating system on the population persistence, a stochastic individual-based model simulating the population dynamics of the Lesser Spotted Woodpecker was developed, based on empirical results. However, pre-breeding survival rates could not be obtained empirically and I present in this thesis a pattern-oriented modelling approach to estimate pre-breeding survival rates by comparing simulation results with empirical pattern of population structure and reproductive success on population level. Here, I estimated the pre-breeding survival for two Lesser Spotted Woodpecker populations on different latitudes to test the reliability of the results. Finally, I used the same simulation model to investigate the effect of flexibility in the mating system on the persistence of the population. With increasing rate of polyandry in the population, the persistence increased and even low rates of polyandry had a strong influence. Even when presuming only a low polyandry rate and costs of polyandry in terms of higher mortality and lower reproductive success for the secondary male, the positive effect of polyandry on the persistence of the population was still strong. This thesis greatly helped to increase the knowledge of the autecology of an endangered woodpecker species. Beyond the relevance for the species, I could demonstrate here that in general flexibility in mating systems are buffer mechanisms and reduce the impact of environmental and demographic noise.},
  subject      = {Modellierung},
  language  = {en}
}
@phdthesis{Baufeld2005,
  author    = {Baufeld, Ralf},
  title     = {GIS-gest{\"u}tzte Prognose der Biotopentwicklung auf Grundlage von Biotoptypen- und Vegetationserhebungen auf geplanten R{\"u}ckdeichungsfl{\"a}chen an der Mittleren Elbe in Sachsen-Anhalt},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-2523},
  school      = {Universit{\"a}t Potsdam},
  year      = {2005},
  abstract  = {Durch die anthropogene Nutzung sind viele Auen in Mitteleuropa ver{\"a}ndert worden, wobei insbesondere die Retentionsfl{\"a}chen stark verringert wurden. W{\"a}hrend Auen seit l{\"a}ngerem im Fokus der wissenschaftlichen Bearbeitung stehen, gibt es bisher große Wissensdefizite in der Frage der Auenreaktivierungen. Zum einen sind derartige Projekte bisher kaum verwirklicht und zum anderen ist ein langfristiges Monitoring notwendig, um die Anpassung von Bioz{\"o}nosen an die ver{\"a}nderten Standortbedingungen beobachten zu k{\"o}nnen. Um die Folgen derartiger Eingriffe zu analysieren, bieten sich computergest{\"u}tzte Modellierungen der Landschaftsentwicklung an, wie sie in der vorliegenden Arbeit verwirklicht wurden. Ziel der Arbeit war, mit Hilfe eines Geografischen Informationssystems (GIS) das Entwicklungspotenzial der Landschaft bei verschiedenen R{\"u}ckdeichungsvarianten auf der Ebene der Biotoptypen darzustellen. Dabei ging es nicht um die Erstellung eines allgemein g{\"u}ltigen Auenmodells sondern um die Erarbeitung eines Modells f{\"u}r einen konkreten Anwendungsfall. Der erarbeitete Ansatz sollte zudem f{\"u}r die landschaftsplanerische Praxis geeignet sein. Als Beispielgebiete wurden Fl{\"a}chen an der Mittleren Elbe bei Rog{\"a}tz und Sandau, beide im n{\"o}rdlichen Teil von Sachsen-Anhalt, ausgew{\"a}hlt. Die vorliegende Arbeit gliedert sich in zwei Teile. Im ersten Teil werden Erhebungen und Auswertungen als Grundlage der Modellentwicklung dargestellt. Dazu wurden die Biotoptypen der Beispielgebiete fl{\"a}chendeckend erhoben und mit punktuellen Vegetationserhebungen erg{\"a}nzt. Aus dem Forschungsprojekt "R{\"u}ckgewinnung von Retentionsfl{\"a}chen und Altauenreaktivierung an der Mittleren Elbe in Sachsen-Anhalt" des Bundesministeriums f{\"u}r Bildung und Forschung (BMBF) standen standort{\"o}kologische Daten der Hydrologie und Bodenkunde zur Verf{\"u}gung. Ziel der Auswertung war, Schl{\"u}sselfaktoren f{\"u}r Hydrologie und Bodenbedingungen innerhalb der rezenten Aue zu identifizieren, die zur Auspr{\"a}gung bestimmter Biotoptypen f{\"u}hren. Im zweiten Teil der Arbeit wurde ein Modell f{\"u}r Biotoptypenpotenziale auf den geplanten R{\"u}ck\–deichungsfl{\"a}chen entwickelt. Das Modell bearbeitet die Datenbank der verwendeten GIS-Dateien, die auf Daten zum Bestand beruht und um solche der Prognose der Standort{\"o}kologie (Hydrologie und Boden) im R{\"u}ckdeichungsfalle aus dem BMBF-Projekt erweitert wurde. Weitere Voraussetzung f{\"u}r die Modellierung war die Erarbeitung von Leitbildern, in denen unterschiedliche Nutzungsszenarios f{\"u}r die Landschaft nach Deichr{\"u}ckverlegung hypothetisch festgelegt wurden. Insbesondere die Nutzungsintensit{\"a}t wurde variiert, von einer Variante intensiver land- und forstwirtschaftlicher Nutzung {\"u}ber sogenannte integrierte Entwicklungsziele aus dem BMBF-Projekt bis hin zu einer Variante der Naturschutznutzung. Zus{\"a}tzlich wurde eine zuk{\"u}nftige Potentielle Nat{\"u}rliche Vegetation modelliert. Eine {\"U}berpr{\"u}fung des Modell fand f{\"u}r den Raum der rezenten Aue in der intensiven Nutzungsvariante statt, die der gegenw{\"a}rtigen Nutzung am n{\"a}chsten kommt. Werden Informationen des Bestandsbiotoptyps als Korrekturgr{\"o}ße in das Modell einbezogen, konnte f{\"u}r viele Biotoptypen eine Trefferquote von {\"u}ber 90 \% erreicht werden. Bei fl{\"a}chenm{\"a}ßig weniger bedeutenden Bio\–toptypen lag dieser Wert aufgrund der schmaleren Datenbasis zwischen 20 und 40 \%. Als Ergebnis liegt f{\"u}r unterschiedliche Deichvarianten und Leitbilder in den Beispielgebieten die Landschaftsentwicklung als Biotoppotenzial vor. Als eine vereinfachte Regionalisierung der punktuellen Vegetationsdaten wurde im Modell gepr{\"u}ft, inwieweit die modellierten Biotopfl{\"a}chen der Charakteristik der pflanzensoziologischen Aufnahmen aus der rezenten Aue entsprechen. In dem Falle wurde die Pflanzengesellschaft der jeweiligen {\"o}kologisch im Rahmen der Untersuchung einheitlichen Fl{\"a}cheneinheit zugeordnet. Anteilig l{\"a}sst sich damit die Biotopprognosefl{\"a}che pflanzensoziologisch konkretisieren. Die vorliegende Arbeit geh{\"o}rt zu den bisher wenigen Arbeiten, die sich mit den Folgen von Auenreaktivierung auf die Entwicklung der Landschaft auseinandersetzen. Sie zeigt eine M{\"o}glichkeit auf, Prognosemodelle f{\"u}r Biotoptypen und Vegetation anhand begrenzter Felduntersuchungen zu entwerfen. Derartige Modelle k{\"o}nnen zum Verst{\"a}ndnis von Eingriffen in den Naturhaushalt, wie sie die Deichr{\"u}ckverlegungen darstellen, beitragen und eine Folgenabsch{\"a}tzung unterst{\"u}tzen.},
  subject      = {Modellierung},
  language  = {de}
}