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In the challenging environmental conditions of high elevation ecosystems, cushion plants create micro-climatic and fertile shelters which host a vast diversity of organisms. Yet, the taxonomic diversity of these hosts remains poorly described, and to what extent cushion plants structure these communities remains unclear. We sampled soils beneath six different species of cushion plants, along with bare-ground controls, across two different elevation gradients in the French Alps. We used environmental DNA metabarcoding to investigate the effect of different species of cushion plants on the α and β diversity of fungi, bacteria, eukaryotes, and for the first time in these ecosystems, unicellular eukaryotes and soil worms. Cushion plants hosted a surprisingly large diversity of organisms, from bacteria to mites and collembolans, forming rich and complex ecosystems. α-diversity between cushion plant and bare soil samples differed only for fungi, with communities partly structured by the cushion plant species’ identity. The effect of cushion plant species on composition and β-diversity of eukaryotic and fungal communities surpassed the environmental effect, while it equaled the site effect for bacterial communities. These results highlight the key role of biotic interactions in shaping the composition of high elevation communities, and clarify the role of cushion plants as engineer and foundation species in these harsh environments. By sheltering highly diverse communities at such high elevation, cushion plants may play a prominent role in the ecological assembly of these diverse, yet poorly known, ecosystems.

Understanding global biodiversity change, its drivers, and the ecosystem consequences requires a better appreciation of both the factors that shape soil macrofauna communities and the ecosystem effects of these organisms. The project “sOilFauna” was funded by the synthesis center sDiv (Germany) to address this major gap by forming a community of soil ecologists, identifying the most pressing research questions and hypotheses, as well as conducting a series of workshops to foster the global synthesis and hypothesis testing of soil macrofauna. The overarching goal is to analyze the most comprehensive soil macrofauna database - the MACROFAUNA database - which collates abundance data of 17 soil invertebrate groups assessed with a standardized method at 7180 sites around the world, and seeks to foster the collection of future data. In a recent kick-off workshop in May 2022, the first research priorities and collaboration guidelines were determined. Here, we summarize the main outcomes of this workshop and highlight the benefits of creating an open global community of soil ecologists providing standardized soil macrofauna data for future research, evaluation of ecosystem health, and nature protection.

Abstract Global change is affecting soil biodiversity and functioning across all terrestrial ecosystems. Still, much is unknown about how soil biodiversity and function will change in the future in response to simultaneous alterations in climate and land use, as well as other environmental drivers. It is crucial to understand the direct, indirect and interactive effects of global change drivers on soil communities and ecosystems across environmental contexts, not only today but also in the near future. This is particularly relevant for international efforts to tackle climate change like the Paris Agreement, and considering the failure to achieve the 2020 biodiversity targets, especially the target of halting soil degradation. Here, we outline the main frontiers related to soil ecology that were presented and discussed at the thematic sessions of the World Biodiversity Forum 2022 in Davos, Switzerland. We highlight multiple frontiers of knowledge associated with data integration, causal inference, soil biodiversity and function scenarios, critical soil biodiversity facets, underrepresented drivers, global collaboration, knowledge application and transdisciplinarity, as well as policy and public communication. These identified research priorities are not only of immediate interest to the scientific community but may also be considered in research priority programmes and calls for funding.

Abstract The increasing severity and frequency of natural disturbances requires a better understanding of their effects on all compartments of biodiversity. In Northern Fennoscandia, recent large-scale moth outbreaks have led to an abrupt change in plant communities from birch forests dominated by dwarf shrubs to grass-dominated systems. However, the indirect effects on the belowground compartment remained unclear. Here, we combined eDNA surveys of multiple trophic groups with network analyses to demonstrate that moth defoliation has far-reaching consequences on soil food webs. Following this disturbance, diversity and relative abundance of certain trophic groups declined (e.g., ectomycorrhizal fungi), while many others expanded (e.g., bacterivores and omnivores) making soil food webs more diverse and structurally different. Overall, the direct and indirect consequences of moth outbreaks increased belowground diversity at different trophic levels. Our results highlight that a holistic view of ecosystems improves our understanding of cascading effects of major disturbances on soil food webs.