Spatial hotspots and bundles of soil functions across Europe

A challenge in soil research is determining how multifunctional soils respond to a change in management and the environment. This is because soil functions are not independent of each other: complex interactions occur between functions across spatial scales. While a growing body of literature has attempted to quantify soil functions, few studies identified sites of multiple functions occurrence for large geographical areas. In this study, we investigate the spatial overlap between multiple soil functions in European croplands and grasslands. We generated maps of five soil functions using existing multi-attribute models developed for the large-scale assessment of soil functions. Out of these maps, we identified spatial hotspots, i.e. locations that concomitantly have a high supply of several soil functions and spatial coldspots, i.e. areas providing a low supply of functions. A cluster analysis combined with a hierarchical agglomerative clustering further revealed spatial bundles of functions, i.e. a set of soil functions that repeatedly appear together in space. Our analysis shows that hotspots of soil functions, where all five soil functions are supply at a high level, occur only in a few geographically isolated locations in Europe, covering just 0.03% of croplands and grasslands. However, broader zones were identified where three to four soil functions were achieved at an optimal level, together accounting for about 8% of the area. Similarly, only 7% of the area had at least four functions at low supply (i.e. coldspots). The cluster analysis resulted in five bundles that provided a differentiated view on multifunctional soils in Europe, with most soils providing a low to moderate levels of all five functions. Two main bundles, covering about 60% of European croplands and grasslands, were identified: one with high biodiversity and climate regulation but low other functions, and another with high nutrient cycling and biodiversity but low remaining functions. The analysis of spatial hotspots, coldspots and bundles of functions supply may be a tool for the regional-scale management of multifunctional soil so that all regions secure a sustainable supply of soil functions. It is also a first step to avoid potential conflicts between users, by allowing collective decisions on which bundles of functions to prioritize. • Soil multifunctionality hotspots are rare and scattered across European croplands and grasslands. • Grasslands do not consistently outperform croplands in soil function supply across Europe. • Five distinct soil function bundles reflect regional trade-offs and synergies. • Pedological constraints seem to limit multifunctionality despite favourable land management. • Linking soil function supply to stakeholder demand will require negotiation on targeted bundles.