Here, recent changes in the Finnish landscape are treated as a large-scale experiment. With a net loss of over 80% of cattle farms over the last 50 years, dung beetles have suffered from both habitat loss and fragmentation. Currently, more than half of an original 47 species are considered regionally extinct, endangered or near threatened.
In 2011, we embarked on a four-year research project that explored the relationship between decreased dung beetle diversity and ecosystem functioning. What is more important to the ecosystem services that dung beetles provide, species or functional group diversity? Is the answer the same across different habitats and for different ecosystem services? Are some species more important to specific habitats? And are the most vulnerable species also the most functionally important?
First, in the summer of 2011, we continued our previously successful partnership with volunteers from the Finnish 4H Federation. Volunteers conducted nationwide field experiments. They placed experimental cowpats into the field, with treatments that excluded various groups of dung beetles and other decomposers. We found dor beetles to be key decomposers: they removed dung twice as fast as smaller dung beetles and earthworms. We also found a powerful effect of climate, thanks to the large scale of the experiment.
After our large-scale experiment, we moved on to more carefully controlled, smaller-scale experiments for 2012-2014. These mesocosm experiments further teased out the effects of species and functional group diversity, as well as factors such as climate, on ecosystem functioning. We found that beetle community composition also influences dung pat microbial communities and greenhouse gas emissions. Overall, we have found that community composition and species identity can be vital to ecosystem services, independently of diversity. The connection between biodiversity and ecosystem services is best understood by looking at community composition and multiple functions at once. We also examined the effects of antibiotics on the dung system and in the summer of 2017, we are continuing this work in both Finland in Sweden.
Since much of our sampling of dung beetles builds on the involvement of laymen, we have invested much work in public outreach. To stimulate interest in dung beetles, and to make species identification as easy as possible, we (Roslin & Heliövaara) published a book on the dung beetles of Finland. The first edition of the book was written in Finnish, to reach a relevant target audience. To make the same information available to a Scandinavian audience we created a Swedish version, at the same time expanding the contents to cover all Nordic species of dung beetles. This initiative is co-authored by Nordic entomologists Mattias Forshage (SLU, Sweden) and Frode Ødegaard (NINA, Norway). More info in Norwegian here.
For our main dung beetle site (in Finnish), click here