Uncertain role of conservation areas to protect soil biodiversity and functioning

Soil biodiversity and functioning are the foundation of ecosystem sustainability, but we do not know whether current nature conservation areas are efficiently protecting soils. Here, we investigated the contribution of terrestrial nature conservation areas to protect soil biodiversity and functioning across scales. We found no general positive effect on diversity of bacteria, fungi, protists, invertebrates, and nematodes, captured as richness, Shannon diversity and dissimilarity, and 5 soil functions (pathogen control, nutrient provision, soil carbon, soil organic matter decomposition, and soil aggregate stability). Our findings suggest that nature conservation areas show an inconsistent role in protecting soil biodiversity and functioning, as we found mostly non-significant and otherwise mixed effects across scales. Despite few positive and negative effects of protection status, our work highlights the urgent need to directly target soils in nature conservation.