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  • 1
    UID:
    gbv_860335224
    Format: 131 Seiten , Diagramme, Illustrationen
    Content: 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, …
    Note: Enthält 4 Publikationen , kumulative Dissertation , Dissertation University of Potsdam 2016
    Additional Edition: Erscheint auch als Online-Ausgabe Lischke, Betty Food web regulation under different forcing regimes in shallow lakes - synthesis and modelling Potsdam, 2016
    Language: English
    Keywords: Hochschulschrift
    Author information: Gaedke, Ursula
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  • 2
    UID:
    gbv_175552272X
    Format: 192 Seiten , Illustrationen, Diagramme
    Content: Predation drives coexistence, evolution and population dynamics of species in food webs, and has strong impacts on related ecosystem functions (e.g. primary production). The effect of predation on these processes largely depends on the trade-offs between functional traits in the predator and prey community. Trade-offs between defence against predation and competitive ability, for example, allow for prey speciation and predator-mediated coexistence of prey species with different strategies (defended or competitive), which may stabilize the overall food web dynamics. While the importance of such trade-offs for coexistence is widely known, we lack an understanding and the empirical evidence of how the variety of differently shaped trade-offs at multiple trophic levels affect biodiversity, trait adaptation and biomass dynamics in food webs. Such mechanistic understanding is crucial for predictions and management decisions that aim to maintain biodiversity and the capability of communities to adapt to environmental change ensuring their ...
    Note: kumulative Dissertation , Dissertation Universität Potsdam 2019
    Additional Edition: Erscheint auch als Online-Ausgabe Ehrlich, Elias On the role of trade-offs in predator-prey interactions Potsdam, 2019
    Language: English
    Keywords: Ökosystemforschung ; Wechselwirkung ; Hochschulschrift
    Author information: Gaedke, Ursula
    Author information: Becks, Lutz 1978-
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  • 3
    UID:
    gbv_1758253584
    Format: vii, 166 Seiten , Illustrationen, Diagramme
    Content: There is a general consensus that diverse ecological communities are better equipped to adapt to changes in their environment, but our understanding of the mechanisms by which they do so remains incomplete. Accurately predicting how the global biodiversity crisis affects the functioning of ecosystems, and the services they provide, requires extensive knowledge about these mechanisms. Mathematical models of food webs have been successful in uncovering many aspects of the link between diversity and ecosystem functioning in small food web modules, containing at most two adaptive trophic levels. Meaningful extrapolation of this understanding to the functioning of natural food webs remains difficult, due to the presence of complex interactions that are not always accurately captured by bitrophic descriptions of food webs. In this dissertation, we expand this approach to tritrophic food web models by including the third trophic level. Using a functional trait approach, coexistence of all species is ensured using fitness-balancing ...
    Note: kumulative Dissertation , Dissertation Universität Potsdam 2021
    Additional Edition: Erscheint auch als Online-Ausgabe Ceulemans, Ruben Diversity effects on ecosystem functions of tritrophic food webs Potsdam, 2020
    Language: English
    Keywords: Ökosystemforschung ; Hochschulschrift
    Author information: Gaedke, Ursula
    Author information: Becks, Lutz 1978-
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  • 4
    UID:
    gbv_1740777530
    Format: 1 Online-Ressource (161 Seiten, 4860 KB) , Illustrationen, Diagramme
    Content: Phytoplankton growth depends not only on the mean intensity but also on the dynamics of the light supply. The nonlinear light-dependency of growth is characterized by a small number of basic parameters: the compensation light intensity PARcompμ, where production and losses are balanced, the growth efficiency at sub-saturating light αµ, and the maximum growth rate at saturating light µmax. In surface mixed layers, phytoplankton may rapidly move between high light intensities and almost darkness. Because of the different frequency distribution of light and/or acclimation processes, the light-dependency of growth may differ between constant and fluctuating light. Very few studies measured growth under fluctuating light at a sufficient number of mean light intensities to estimate the parameters of the growth-irradiance relationship. Hence, the influence of light dynamics on µmax, αµ and PARcompμ are still largely unknown. By extension, accurate modelling predictions of phytoplankton development under fluctuating light exposure remain ...
    Note: kumulative Dissertation , Dissertation Universität Potsdam 2020
    Additional Edition: Erscheint auch als Druck-Ausgabe Guislain, Alexis Eco-physiological consequences of fluctuating light on phytoplankton Potsdam, 2019
    Language: English
    Keywords: Phytoplankton ; Pflanzenwachstum ; Lichtmenge ; Hochschulschrift
    Author information: Köhler, Jan 1961-
    Author information: Gaedke, Ursula
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  • 5
    UID:
    gbv_1809386330
    Format: 1 Online-Ressource (197 Seiten, 8079 KB) , Illustrationen, Diagramme
    Content: 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. [...]
    Note: Kumulative Dissertation , Dissertation Universität Potsdam 2022
    Additional Edition: Erscheint auch als Druck-Ausgabe Kath, Nadja Jeanette Functional traits determine biomass dynamics, coexistence and energetics in plankton food webs Potsdam, 2022
    Language: English
    Keywords: Hochschulschrift ; Hochschulschrift
    Author information: Tollrian, Ralph 1960-
    Author information: Matthiessen, Birte 1975-
    Author information: Gaedke, Ursula
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  • 6
    UID:
    gbv_1819276597
    Format: 1 Online-Ressource (250 Seiten, 18249 KB) , Illustrationen, Diagramme
    Content: In this thesis, a collection of studies is presented that advance research on complex food webs in several directions. Food webs, as the networks of predator-prey interactions in ecosystems, are responsible for distributing the resources every organism needs to stay alive. They are thus central to our understanding of the mechanisms that support biodiversity, which in the face of increasing severity of anthropogenic global change and accelerated species loss is of highest importance, not least for our own well-being. The studies in the first part of the thesis are concerned with general mechanisms that determine the structure and stability of food webs. It is shown how the allometric scaling of metabolic rates with the species' body masses supports their persistence in size-structured food webs (where predators are larger than their prey), and how this interacts with the adaptive adjustment of foraging efforts by consumer species to create stable food webs with a large number of coexisting species. The importance of the master ...
    Note: kumulative Habilitationsschrift , Habilitationsschrift Universität Potsdam 2022
    Additional Edition: Erscheint auch als Druck-Ausgabe Guill, Christian Pierre, 1983 - Structure, stability and functioning of food webs Potsdam, 2021
    Language: English
    Keywords: Hochschulschrift
    Author information: Gaedke, Ursula
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  • 7
    UID:
    gbv_1740786165
    Format: 161 Seiten , Illustrationen, Diagramme
    Content: Phytoplankton growth depends not only on the mean intensity but also on the dynamics of the light supply. The nonlinear light-dependency of growth is characterized by a small number of basic parameters: the compensation light intensity PARcompμ, where production and losses are balanced, the growth efficiency at sub-saturating light αµ, and the maximum growth rate at saturating light µmax. In surface mixed layers, phytoplankton may rapidly move between high light intensities and almost darkness. Because of the different frequency distribution of light and/or acclimation processes, the light-dependency of growth may differ between constant and fluctuating light. Very few studies measured growth under fluctuating light at a sufficient number of mean light intensities to estimate the parameters of the growth-irradiance relationship. Hence, the influence of light dynamics on µmax, αµ and PARcompμ are still largely unknown. By extension, accurate modelling predictions of phytoplankton development under fluctuating light exposure remain ...
    Note: kumulative Dissertation , Dissertation Universität Potsdam 2020
    Additional Edition: Erscheint auch als Online-Ausgabe Guislain, Alexis Eco-physiological consequences of fluctuating light on phytoplankton Potsdam, 2019
    Language: English
    Keywords: Phytoplankton ; Pflanzenwachstum ; Lichtmenge ; Hochschulschrift
    Author information: Köhler, Jan 1961-
    Author information: Gaedke, Ursula
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  • 8
    UID:
    gbv_1785192582
    Format: x, 167 Seiten , Illustrationen, Diagramme
    Content: Anthropogenic activities such as continuous landscape changes threaten biodiversity at both local and regional scales. Metacommunity models attempt to combine these two scales and continuously contribute to a better mechanistic understanding of how spatial processes and constraints, such as fragmentation, affect biodiversity. There is a strong consensus that such structural changes of the landscape tend to negatively effect the stability of metacommunities. However, in particular the interplay of complex trophic communities and landscape structure is not yet fully understood. In this present dissertation, a metacommunity approach is used based on a dynamic and spatially explicit model that integrates population dynamics at the local scale and dispersal dynamics at the regional scale. This approach allows the assessment of complex spatial landscape components such as habitat clustering on complex species communities, as well as the analysis of population dynamics of a single species. In addition to the impact of a fixed landscape ...
    Note: kumulative Dissertation , Dissertation Universität Potsdam 2021
    Additional Edition: Erscheint auch als Online-Ausgabe Stark, Markus Implications of local and regional processes on the stability of metacommunities in diverse ecosystems Potsdam, 2021
    Language: English
    Keywords: Hochschulschrift
    Author information: Grimm, Volker 1958-
    Author information: Gaedke, Ursula
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  • 9
    UID:
    gbv_1756638071
    Format: 175 Seiten , Illustrationen, Diagramme
    Content: Predator-prey interactions provide central links in food webs. These interaction are directly or indirectly impacted by a number of factors. These factors range from physiological characteristics of individual organisms, over specifics of their interaction to impacts of the environment. They may generate the potential for the application of different strategies by predators and prey. Within this thesis, I modelled predator-prey interactions and investigated a broad range of different factors driving the application of certain strategies, that affect the individuals or their populations. In doing so, I focused on phytoplankton-zooplankton systems as established model systems of predator-prey interactions. At the level of predator physiology I proposed, and partly confirmed, adaptations to fluctuating availability of co-limiting nutrients as beneficial strategies. These may allow to store ingested nutrients or to regulate the effort put into nutrient assimilation. We found that these two strategies are beneficial at different ...
    Note: Dissertation Universität Potsdam 2019
    Additional Edition: Erscheint auch als Online-Ausgabe Raatz, Michael Strategies within predator-prey interactions – from individuals to ecosystems Potsdam, 2018
    Language: English
    Keywords: Ökosystemforschung ; Wechselwirkung ; Hochschulschrift
    Author information: Gaedke, Ursula
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  • 10
    UID:
    gbv_1809450268
    Format: 197 Seiten , Illustrationen, Diagramme
    Content: 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. [...]
    Note: Kumulative Dissertation , Dissertation Universität Potsdam 2022
    Additional Edition: Erscheint auch als Online-Ausgabe Kath, Nadja Jeanette Functional traits determine biomass dynamics, coexistence and energetics in plankton food webs Potsdam, 2022
    Language: English
    Keywords: Hochschulschrift ; Hochschulschrift
    Author information: Tollrian, Ralph 1960-
    Author information: Matthiessen, Birte 1975-
    Author information: Gaedke, Ursula
    Library Location Call Number Volume/Issue/Year Availability
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