Drs. G. A. K. (George) van Voorn
Bifurcation analysis of community models
One item in ecology is how it is possible that ecosystems, large food webs, can persist. Previous studies have always focused on small food chains (Rosenzweig) or small food webs (May). Results from these studies have led to the believe that larger and more complex food webs or food chains are, in general, instable.
In this project larger food webs will be studied through bifurcation analysis
applied to ODE-systems used to describe the dynamical behaviour of these food
webs. Contrary to the more popular models these systems explicitly describe the
nutrients the producers feed on, while also taking into account mass conservation. The aim of this project is to gain an overview of the most important local bifurcations in ecosystem models. Also, there is a focus on global bifurcations, such as homoclinic orbits and the Shil'nikov bifurcation.
In the models, based on Dynamic
Energy Budget theory, it is assumed that populations live in
an open environment, a chemostat. The programs AUTO, Content and
LOCBIF are used to apply bifurcation analysis to analyze numerically
the dynamical behaviour of these models. Case studies involving
different kinds of interactions or trophic levels (omnivory,
symbiosis, multiple resources, pathogens) will be made in this
projects to gain insight into the behaviour of large scale ecosystems.
This is the symposium that concludes my project. George
defended his thesis in Oldenburg at 2009/07/17, and acquired the
distinction magna cum laude, and will defend his thesis again in
Amsterdam at 2009/09/30.