Functional diversity mapping for bumblebees to predict regional pollination service potential

To assess the extent and coverage of ecosystem services, we need to know their geographic distributions. These are typically estimated using environmental data such as land cover. But as biodiversity is closely linked with ecosystem functions, variables describing different dimensions of biodiversity should provide essential information to predict and map services produced by these functions. One persistent problem is that most of the organisms primarily responsible for services are invertebrates that suffer from data shortfalls. For example, we still lack estimates of ranges and aggregate biodiversity patterns for most described insect species. But perhaps more importantly, we are missing information on insect functional diversity, or the variation in species’ functional traits, which is most closely linked with the provision of services. The proliferation of open biodiversity data and development of robust modeling methods now make it possible to predict and map species’ distributions even for those with limited data, but the mapping of insect biodiversity patterns is just getting underway. Here, we mapped taxonomic and functional diversity for bumblebees at the country scale for Japan to assess pollination service potential. Specifically, we used citizen science data on bumblebee occurrences and species distribution models to predict bumblebee richness patterns for Japan, then used multivariate trait data to model the functional hypervolumes of bumblebee communities, and finally mapped these values to compare them with richness. We also ran extinction simulations to map functional resilience, or the ability of communities to retain functional diversity after the loss of resident species. Results showed congruences between taxonomic and functional diversity in the central Japanese Alps, also the most resilient region, but mismatch for Hokkaido in Japan’s far north with high richness yet low functional diversity. Such maps can show how dimensions of insect biodiversity differ over space and can lead to different conservation actions depending on whether species or functions are prioritized. An important next step is to integrate these results with ecosystem service models that link functional diversity estimates with actual service provision.