Fungal diversity as a key driver of soil multifunctionality along a European latitudinal gradient

• Soil multifunctionality (SMF) showed a hump-shape with latitude across Europe. • SMF peaked at mid-latitude temperate forests. • Fungal diversity decreased but prokaryotic diversity increased with latitude. • Fungal diversity but not prokaryotic diversity sustained SMF. • MAP, MAT, and soil pH and C/N ratio also contributed to SMF. Soils harbor a vast diversity of microorganisms and play a crucial role in global carbon and nutrients cycles. Yet, the extent and drivers of variations in soil microbial diversity and functioning across environmental gradients at continental scales remain poorly understood. Here, we investigated the diversity and network complexity of prokaryotic and fungal communities and their relationships with soil multifunctionality (SMF) – an integrative index for C-, N- and P-cycling functions – along a 3,000-km latitudinal transect across Europe (37° to 62°N), spanning biomes from Mediterranean drylands, temperate to boreal forests. We found that SMF followed a hump-shaped latitudinal pattern, peaking at mid-latitude temperate forests and declining toward the southern Mediterranean drylands and northern boreal forests. Fungal alpha-diversity, together with mean annual precipitation (MAP), mean annual temperature (MAT), and soil pH and C/N ratio, were key contributors to SMF across latitudes, while prokaryotic alpha-diversity had little effect. Both prokaryotic and fungal communities were predominantly structured by dispersal limitation, land cover, climate and soil properties, with fungal communities more strongly limited by spatial dispersion. Our study highlights the significant role of fungal diversity in sustaining SMF along the European latitudinal gradient and demonstrates the importance of both large-scale climatic and biogeographical factors and local edaphic and land cover variables in shaping microbial diversity. Our findings offer valuable insights for the conservation of ecosystem functions.