Biodiversity-function relationships in ecosystems are known to be driven by environmental conditions, including climate change. Plant functional groups (PFGs), specifically their evolutionary history, nitrogen-fixation capacity or photosynthetic-pathway likely play a critical role in shaping microbial communities and their impact on ecosystem functions, but experimental evidence is limited. Here, we simultaneously manipulated plant and microbial diversity in a microcosm study to investigate their interactions and impact on soil functions during drought. Our results highlight the dominant role of PFGs in explaining the effects of biodiversity loss on soil functions. Microbial diversity loss significantly influenced microbially-driven soil N and P pools and processes, with PFGs moderating these effects, especially under drought. Our findings offer crucial mechanistic insights for ecosystem management in the face of climate change, emphasizing the significance of PFGs in shaping soil functions and their resilience. This study underscores the importance of considering above- and belowground biodiversity, for preserving belowground functions in changing environments.

Use of synthetic microbial communities (SynComs) is a promising approach that harness nature-based solutions to support soil fertility and food security, mitigate climate change impacts and restore terrestrial ecosystems. Several microbial products are in the market and, many others are at different stages of development and commercialization. Yet, we are still far from being able to fully harness the potential and successful applications of such biotechnological tools. The limited field efficiency and efficacy of SynComs and other microbial tools have significantly constrained commercial opportunities, resulting in market growth falling below expectations. To overcome these challenges and manage expectations, it is critical to address current limitations, failures, and potential environmental consequences of SynComs. Here, we discuss the current status of SynComs and identify the next steps needed to develop and deploy the next generation tools to boost their ability to support multiple ecosystem services, including food security and environmental sustainability.

The rhizosphere influence on the soil microbiome and function of crop wild progenitors remains virtually unknown, despite its relevance to develop microbiome-oriented tools in sustainable agriculture. Here, we quantified the rhizosphere influence -- a comparison between rhizosphere and bulk soil samples -- on bacterial, fungal, protists and invertebrates communities and on soil multifunctionality across nine crop wild progenitors in their sites of origin. Overall, rhizosphere influence was higher on abundant taxa across the four microbial groups, and had a positive influence on increased rhizosphere carbon storage and nutrient contents compared to bulk soils. The rhizosphere influence on abundant soil microbiomes were more important for soil multifunctionaility than rare taxa and envirommental conditions. Our results are a starting point to uncover the roles of both abundant and rare soil taxa in enhancing multifunctionality in agroecosystems.

Soil carbon is a critical ecosystem function in drylands. In these ecosystems, positive relationships between plant species richness (SR) and soil carbon storage (SOC) that have been found in biodiversity experiments and observational studies may be reduced by grazing and aridity. However, studies about the extent to which SR, grazing intensity, and aridity are interactively and directly or indirectly related with SOC so far provided mixed results. Using a network of 199 grassland sites across a large aridity gradient in western China, selected to represent low, medium, and high grazing intensity, we found that SOC at the depth of 0–30 cm was positively related with SR and, to a lesser degree, with grazing intensity. Aridity had no direct relationship with SOC but affected it indirectly and negatively via its negative relationships with both SR and grazing intensity and via its positive relationship with soil pH. There were no indications that grazing intensity could modify the positive SR–SOC relationship, possibly because very high grazing intensities did not occur in the study region. We conclude that current levels of SR and grazing intensity should be maintained to avoid SOC-loss and CO2 release form grassland under predicted aridity increases in the study region.