Fungal diversity and network complexity sustain soil multifunctionality across Europe

Abstract

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 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 and network complexity, mean annual temperature (MAT), mean annual precipitation (MAP), and soil pH and C/N ratio were key contributors to SMF, while prokaryotic alpha-diversity had little effect. Both prokaryotic and fungal communities were predominantly structured by dispersal limitation, climate, land cover, and soil properties, with fungal communities more strongly limited by spatial dispersion. Our study highlights the significant role of fungal alpha-diversity in sustaining SMF across diverse biomes and demonstrates the importance of both large-scale climatic and biogeographical factors and local edaphic and land cover variables in shaping microbial diversity.