Ecosystems worldwide are under increasing anthropogenic stress, resulting in widespread declines of many species and ultimately species extinctions. Not neglecting the direct commercial, cultural and/or esthetical value that these species may represent, most species also have roles to play in various ecosystem processes. Thus, a pressing question is how species loss will affect processes responsible for ecosystem functions and services important for human society. One such function of relevance for agriculture and forestry is ‘biological control’ where natural predators may reduce the damage caused by pest organisms on crops.
In most ecosystems there exist a suite of predator species feeding on another suite of prey species (including one or several potential pest species). This suite of predator species are neither completely different nor identical in terms of their contribution to the service of biological control. Some species are more different to each other and thus complement each other in carrying out a function, while other species are more similar and may thus provide ‘back-up’ if any one fails. An important, but yet poorly studied question is how this affects the ecosystem service such sets of species provide collectively. More specifically, how does different degrees of complementarity and redundancy among the species in the predator guild affect the performance (level of) as well as stability (reliability) of the ecosystem service of biological control? This question is difficult to address empirically and I here aim to address it theoretically, using numerical simulations of mathematical models of species interactions.
More specifically, dynamical so called bipartite models of ecological communities (consisting of two trophic levels) will be formulated, varying in species richness and trophic complementarity of the predators. These models will be analysed to increase our understanding of how species richness and trophic complementarity of predators affect the performance and stability of the ecosystem service of biological control.
We anticipate that this project will significantly advance our understanding of ecosystem functioning in multitrophic communities by provide insight into functions such as predation and the service of biological control provided by this function.