The joint diversity of plant and springtail communities in Mediterranean urban ecosystems

The extent to which green areas can preserve biodiversity and ecological functioning in urban ecosystems can depend upon factors acting at multiple scales, including their management. The complexity of terrestrial ecosystems, where above- and below-ground communities participate in joint dynamics, further limits our prediction of the effects of these factors, as well as our capability to develop sustainable management approaches. With a view to shed light on the joint variations in the biodiversity of above- and below-ground communities in man- aged urban ecosystems at small spatial scale, we studied the richness, composition and abundance of plants and of springtails in a Mediterranean urban lawn subjected to different land uses (pathways and tree rows), which was regularly irrigated, fertilized and, before the study, mowed. Plants were collected in 24 plots (25x25 cm2), identified at the species level and quantified in terms of cover, number of individuals and dry mass. Springtails were collected through 2 soil cores (78,5 cm3) next to each plant survey plot, extracted using MacFadyen funnels, identified at the species level and quantified in terms of number of individuals. Plant functional traits were obtained from literature, whereas those for springtails were obtained both through the analysis of calibrated photographs of each animal and from literature. Findings highlighted that land use explained a substantial proportion of the spatial variability in the diversity of plants and springtails. Changes in vegetation were observed primarily at the structural level, while the spatial variations in springtail communities were mainly recorded at the functional level. In terms of community interactions, results suggest that management directly controls vegetation diversity and indirectly affects springtail communities by acting on key plant species, which functionally couple above- and below-ground ecological dynamics, likely by affecting soil characteristics such as the pore-size distribution and the availability of resources.