Influence of bottom-up, top-down and external forces on compensatory dynamics - a model study related to plankton data of Lake Constance
Final Report Abstract
This small project helped to finalize a Ph.D. on observational data (phytoplankton in Lake Constance), and to study the impact of top-down and bottom-up control on the overall degree of synchronization within modelled predator and prey communities. The later may help to explain potential mechanisms underlying previous unexpected observational findings. Strong top-down control promoted synchrony among population dynamics. In contrast, strong competition favored compensatory dynamics. Reliable quantification of the synchronization of populations at the community level turned out to be more complex than originally anticipated as all established synchronization indices (including e.g. the variance ratio) are sensitive to parameters like species richness, unequal variances of population biomasses and pair-wise covariances between population biomasses. This bias had to be addressed carefully since it had a relevant impact on our overall results. We developed a framework how to cope with these influential factors. We expect that this work will be of broader relevance as synchronization of populations determines key processes in community ecology like the reliability of ecosystem functions and potentially also the maintenance of biodiversity.
Publications
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(2012) Seasonal variations alter the impact of functional traits on plankton dynamics. PLoS ONE 7(12): e51257
Rocha, M. R. D. Vasseur & U. Gaedke
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(2014) Diversity, functional similarity and top-down control drive synchronization and the reliability of ecosystem function. Am. Nat. 183: 394-409
Bauer B., M. Vos, T. Klauschies & U. Gaedke
