This data set comprises two years of data (2016 and 2017) from one trial (Hucking, Kent, UK) and one year (2017) from a second trial (Hartshorne, Derbyshire, UK). Data was collected on tree traits (tree height, shoot length, tree provenance), abundance of foliar insect herbivores (gallers, leaf manipulators and leaf miners) and leaf damage by oak powdery mildew, a foliar fungal pathogen. Data was collected from plots differing in tree diversity (provenance and species diversity). Full details about this dataset can be found at https://doi.org/10.5285/cbccb101-c877-4e43-ac70-e8a852b51f07
