Functionally rich dung beetle assemblages are required to provide multiple ecosystem services

Abstract

Dung beetles mediate a variety of important ecosystem services in both natural and human-modified habitats. These services are associated with the exploitation of dung by beetles for breeding and feeding, with different functional groups using dung in different ways. While many studies have considered how individual ecosystem functions and services (primarily dung removal and seed dispersal) are affected by changes in dung beetle diversity, fewer studies have considered the consequences for multiple functions and services. We used manipulative experiments to evaluate the functional efficiency of three species of dung beetles, each representing one of the three functional groups present in temperate Europe. Standardising beetle biomass, we compared single-species treatments to a three-species mixture containing each of the species in equal biomass. We then measured three ecosystem services relevant in supporting pasture-based livestock production systems: dung removal, soil fauna activity, and soil aeration. The presence of dung beetles significantly elevated all three ecosystem services. However, delivery of each service peaked under different treatments, indicating that no single-species assemblage can provide maximum functioning across multiple services. For all three services, the three-species polyculture provided a level of functioning indistinguishable from the most efficient single-species treatment. Our results highlight the importance of considering multiple functions and services when assessing the relationship between biodiversity and ecosystem functioning, and suggest that the conservation of functional richness within dung beetle communities could play an important role in securing the delivery of multiple ecosystem services.