Arboreal arthropod sampling methods for urban trees

Large, isolated trees are a prominent part of town planning, and the nature of the urban environment poses unique challenges in sampling the arthropod assemblages found on them. As part of a larger study on the role of these trees in supporting wider biodiversity, we undertook a trial of arthropod sampling methods to compare the relative impact of sampling method versus the species of tree sampled. Using four species of study trees, three sampling methods were trialed: an inverted cone based bole trap, a compact flight intercept trap, and branch bagging and clipping. Total arthropod abundance, richness, and diversity were modeled using generalised linear mixed models, which showed that in many cases the variation between sampling method was larger than that found between tree species. All three of the sampling methods proved to be practical in the field, and overcame the challenges faced in sampling urban trees, thereby providing the opportunity for more detailed study. Our findings also highlight the case for a multifaceted approach to sampling arthropods if a complete picture of the community assemblage is to be gained.