Biodiversity is a multidimensional concept and several dimensions of biodiversity such as taxonomic, functional and phylogenetic diversity have been shown to affect ecosystem functioning. However, previous experiments were established to manipulate species richness and therefore separating the effects of these different dimensions is challenging due to correlations between them. Factorial manipulations of different dimensions are needed to disentangle their effects.

Specialist pests and pathogens may be strong drivers of positive effects of biodiversity on functioning. This is because low diversity communities suffer high pest and pathogen attack, which reduces their functioning. However, it is unknown whether pests and pathogens also drive relationships between functional or phylogenetic diversity and ecosystem functioning. We might expect more generalist insect herbivores to drive effects of functional diversity, whereas specialist fungal pathogens could drive phylogenetic diversity effects.

To test these ideas, we set up the PhyloFun mesocosm experiment in summer 2016. It consists of 48 mesocosms containing native plant communities of varying functional and phylogenetic diversity that are each factorially treated with insecticide and fungicide. We measure several functions such as biomass production, soil fertility (with a novel crop phytometer approach) and soil enzymatic activities. Additionally, we measure attack by insect herbivores and foliar fungal pathogens.

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