Fungal and arthropod consumers constitute the vast majority of global terrestrial biodiversity. Yet, the link from richness and composition of producer (plant) communities to the richness of consumer communities is poorly understood. Fungal and arthropod species richness could be a simple function of producer species richness at a site. Alternatively, it could be a complex function of chemical and structural properties of the producer species making up communities. We used databases on plant-fungus and plant-arthropod trophic links to derive the richness of consumer biota per associated plant species (coined link score). We assessed how well link scores could be predicted by simple attributes of plant species. Next, we used a multi-taxon inventory of 130 sites, representing all major habitat types in a country (Denmark), to investigate whether link scores summed over plant species in communities (coined link sum) could outperform simple plant species richness as predictor of fungal and arthropod richness at the sites. We found plant species’ link scores for both fungi and arthropods to be positively related to plant size, regional occupancy, nativeness and ectomycorrhizal status. Link-based indices generally improved the prediction of richness of fungal and arthropod communities. For fungal communities, both observed link sum (from databases) and predicted link sum (from plant attributes) had high predictive power, while plant richness alone had none. For arthropod communities, predictive performance varied between functional groups. For both fungi and arthropods, richness predictions were further improved by considering abiotic habitat conditions. Our results underline the importance of plants as niche space for the megadiverse groups of arthropods and fungi. The plant-attribute approach holds promise for predicting local and regional consumer richness in areas of the world lacking detailed plant-consumer databases.

Data on plant-fungus and plant-arthropod interaction links for the 549 plant species found across the 130 BioWide sites in Denmark. Detailed descriptions of field data collection protocols are found in Brunbjerg AK, Bruun HH, Brøndum L, Classen AT, Dalby L, Fog K, et al. (2019) A systematic survey of regional multi-taxon biodiversity: evaluating strategies and coverage. BMC Ecology 19(1):43. doi: 10.1186/s12898-019-0260-x. Raw data on known interaction links between all relevant plant taxa (1349 taxa on the species or genus levels) and associated arthropod species were retrieved from the BRC database (https://www.brc.ac.uk/dbif/) and similar data regarding associated fungal species from the Danish Fungal Database (https://svampe.databasen.org/). The raw data were processed to obtain an observed arthropod link score and an observed fungal link score per plant species. The calculus of link scores from raw data is detailed in the associated manuscript. Attributes of the 549 plant species used to model their predicted link score (ectomycorrhizal status, native area, occupancy in Denmark, phylogenetic grouping, lifespan, life form and size) were compiled from sources detailed in the associated manuscript.

This archive includes the R code and formatted data used in the associated manuscript. It may be used to reproduce the figures and tables.