Soils harbor a substantial fraction of the world's biodiversity, contributing to many crucial ecosystem functions. It is thus essential to identify general macroecological patterns related to the distribution and functioning of soil organisms to support their conservation and consideration by governance. These macroecological analyses need to represent the diversity of environmental conditions that can be found worldwide. Here we identify and characterize existing environmental gaps in soil taxa and ecosystem functioning data across soil macroecological studies and 17,186 sampling sites across the globe. These data gaps include important spatial, environmental, taxonomic, and functional gaps, and an almost complete absence of temporally explicit data. We also identify the limitations of soil macroecological studies to explore general patterns in soil biodiversity-ecosystem functioning relationships, with only 0.3% of all sampling sites having both information about biodiversity and function, although with different taxonomic groups and functions at each site. Based on this information, we provide clear priorities to support and expand soil macroecological research.

International audienceMany studies have focused on the impact of intense drought and rain events on soil functioning and diversity, but little attention has been paid to the response of microbial communities to non-extreme soil moisture variations. However, small fluctuations of soil water content represent a common situation that ought to be examined before understanding and deciphering the impact of extreme events. Here, we tested the impact of a decrease in average soil water content and small water content fluctuations in non-extreme conditions on microbial community composition and C mineralisation rate of a temperate meadow soil. Two soil microcosm sets were incubated at high and low constant moisture and a third set was subjected to 4 short dry–wet cycles between these two soil moistures. No robust change in bacterial community composition, molecular microbial biomass, and fungal:bacterial ratio were associated with soil water content change. On the contrary, the fungal community composition rapidly alternated between states corresponding to the high and low levels of soil moisture content. In addition, gross C mineralisation was correlated with soil moisture, with a noteworthy absence of a Birch effect (C over-mineralisation) during the wetting. This study suggests that some fungal populations could coexist by occupying different moisture niches, and high fungal community plasticity would classify them as more sensitive indicators of soil moisture than bacteria. Moreover, under non-stressed conditions, the community composition did not affect metabolic performance so a future decrease in average soil moisture content should not result in a supplemental loss in soil carbon stocks by a Birch effect

Concern about human modification of Earth's ecosystems has recently motivated ecologists to address how global change drivers will impact the simultaneous provisioning of multiple functions, termed ecosystem multifunctionality (EMF). However, metrics of EMF have often been applied in global change studies with little consideration of the information they provide beyond single functions, or how and why EMF may respond to global change drivers. Here, we critically review the current state of this rapidly expanding field and provide a conceptual framework to guide the effective incorporation of EMF in global change research. In particular, we emphasize the need for a priori identification and explicit testing of the biotic and abiotic mechanisms through which global change drivers impact EMF, as well as assessing correlations among multiple single functions because these patterns underlie shifts in EMF. While the role of biodiversity in mediating global change effects on EMF has justifiably received much attention, empirical support for effects via other biotic and physicochemical mechanisms are also needed. Studies also frequently stated the importance of measuring EMF responses to global change drivers to understand the potential consequences for multiple ecosystem services, but explicit links between measured functions and ecosystem services were missing from many such studies. While there is clear potential for EMF to provide novel insights to global change research, predictive understanding will be greatly improved by insuring future research is strongly hypothesis‐driven, is designed to explicitly test multiple abiotic and biotic mechanisms, and assesses how single functions and their covariation drive emergent EMF responses to global change drivers.

Soils harbor a substantial fraction of the world's biodiversity, contributing to many crucial ecosystem functions. It is thus essential to identify general macroecological patterns related to the distribution and functioning of soil organisms to support their conservation and governance. Here we identify and characterize the existing gaps in soil biodiversity and ecosystem function data across soil macroecological studies and >11,000 sampling sites. These include significant spatial, environmental, taxonomic, and functional gaps, and an almost complete absence of temporally explicit data. We also identify the limitations of soil macroecological studies to explore general patterns in soil biodiversity-ecosystem functioning relationships, with only 0.6% of all sampling sites having a non-systematic coverage of both biodiversity and function datasets. Based on this information, we provide clear priorities to support and expand soil macroecological research.

Understanding the consequences of ongoing biodiversity changes for ecosystems is a pressing challenge. Controlled biodiversity-ecosystem function experiments with random biodiversity loss scenarios have demonstrated that more diverse communities usually provide higher levels of ecosystem functioning. However, it is not clear if these results predict the ecosystem consequences of environmental changes that cause non-random alterations in biodiversity and community composition. We synthesized 69 independent studies reporting 660 observations of the impacts of two pervasive drivers of global change (chemical stressors and nutrient enrichment) on animal and microbial decomposer diversity and litter decomposition. Using meta-analysis and structural equation modelling, we show that declines in decomposer diversity and abundance explain reduced litter decomposition in response to stressors but not to nutrients. While chemical stressors generally reduced biodiversity and ecosystem functioning, detrimental effects of nutrients occurred only at high levels of nutrient inputs. Thus, more intense environmental change does not always result in stronger responses, illustrating the complexity of ecosystem consequences of biodiversity change. Overall, these findings provide strong evidence that the consequences of observed biodiversity change for ecosystems depend on the kind of environmental change, and are especially significant when human activities decrease biodiversity.

Soils harbour highly-diverse invertebrate communities that play important roles for ecosystem services, including the mitigation of environmental pollution. Chemical stressors, such as pesticides, pharmaceuticals and metals, are being increasingly spread into ecosystems due to human activities. While it is crucial to predict the consequences of chemical stressors for soil biodiversity, chemical toxicity is often assessed using individuals or populations in laboratory cultures. There has been no systematic evaluation of the evidence documenting the impacts of chemical stressors on diverse, natural soil communities. Here, we use a comprehensive literature review of 274 studies to evaluate the current state of knowledge about the effects of chemicals on soil fauna communities. Most research has had limited spatial scope, with noteworthy gaps in the regions that are potentially the most threatened by soil pollution (Southern Hemisphere). Furthermore, reports generally were constrained to a few emblematic soil fauna groups (nematodes, collembola and earthworms) and chemical stressors (metals). Future research should address biases in spatial distribution of studies, as well as the taxonomic groups and chemical compounds considered. Specifically, emphasis on indirect effects mediated by species interactions, ecosystem functioning and interactive effects of stressors and climate change, currently lacking in the literature, is needed to improve soil-biodiversity conservation and restoration efforts, as well as predictions of global diversity change.

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1. Increasing plant diversity in agricultural systems is a promising way to balance food production and biodiversity conservation. Biological pest control, a crucial ecosystem service delivered by natural enemies, could particularly benefit from increased plant diversity at the local scale. Such positive effects however often depend on the landscape context that shapes the pool of natural enemy species available and their ability to colonize newly created habitats. However, how the landscape context modulates the local effect of plant diversity on natural enemies and pest control services remains unclear.2. Here, we manipulated the diversity of cover crops (2 versus 20 plant species) in nine pairs of vineyards located along a landscape gradient ranging from 20 to 60% of semi-natural habitats. We sampled natural enemy communities in the soil and foliage and measured the predation rate of an important moth pest in European vineyards (Lobesia botrana).3. Diverse cover crops enhanced the abundance of natural enemies by 140% across the experiment, but without changing their taxonomic richness and composition.We further found a distance-decay effect of cover crops on natural enemy abundance across cover crop types. 4. The landscape context remarkably modulated the effects of local plant diversity on natural enemy abundance and predation rates. While predation rates were on average similar in the low and high cover crop diversity treatments across the experiment, diverse cover crops had higher positive effects on predation and natural enemies in simple (<50% semi-natural habitats) than complex landscapes. Predation rates increased from 11 to 42% in the high compared with low cover crop diversity treatments in simple landscapes. Synthesis and applications:Our study demonstrates the benefits of increasing plant diversity at the local scale to enhance the abundance of natural enemies as well as the level of biological pest control services in vineyard agroecosystems. Diverse cover crops mostly benefit natural enemies and biological pest control in simplifiedThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.