Influence of bottom-up, top-down and external forces on compensatory dynamics - a model study related to plankton data of Lake Constance

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Our overall goal is to understand how planktonic trait diversity influences the stability of lake ecosystem functions. The latter is influenced by the degree of covariation among component populations which may be related to functional similarity of ecological traits between plankton populations. In particular, we aim to understand how competition, abiotic forcing and grazing impact the relationship between species covariation and their functional similarity. After having analyzed observational phytoplankton data in this respect we want to extend our conceptual understanding using a suitable dynamic model comprising the interactions between diverse predator and prey communities. We will employ a factorial manipulation of the model parameters which govern the relative strength of competition, abiotic environmental forcing and grazing to generate insights and new hypotheses about relationships between the functional similarity and the covariation among phytoplankton morphotypes and among various groups of zooplankton (ciliates, rotifers, cladocerans, copepods). The latter differ with respect to factors likely influencing the relationship between functional and dynamic similarity such as grazing selectivity, metabolic rates, and susceptibility to abiotic forcing. In a later step these conceptual insights will be related to long-term lake data sets.