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Diana Harrison Wall passed away on 25 March 2024 in Fort Collins, CO, USA, her home for more than 25 years and where she was the Director of the School of Global Environmental Sustainability (SoGES) and Distinguished Professor of Biology at Colorado State University (CSU) after having been faculty at the Natural Resource Ecology Laboratory (NREL) there for more than a decade. While Diana was to become respected globally for her work in soil ecology, soil biodiversity, and sustainability science, she began her career as a nematologist, receiving her PhD from the University of Kentucky-Lexington in plant pathology. When faced with the challenges of being a woman scientist in a male-dominated era, Diana blazed trails. Undoubtedly, her early-career years were formative. The meticulousness and focus she honed-in her science during these early years extended to the expectations she held for her mentees, and in her approach to leadership as she progressed in her career. Those of us who were mentored by Diana wish to honor her and her legacy by providing a glimpse of not only her research and achievements, but what lessons she left us, her mentees, to carry with us through our careers and lives. Those of us who were close collaborators and co-editors wish to honor Diana’s exemplary approach to science, forward-looking approach, and impact on the science community as a whole.

The trait-based approach is increasingly used for soil invertebrates. Complementary to the taxonomy based approach, the trait-based approach can provide a more mechanistic understanding of the responses of organisms to environmental disturbances and of their effects on soil functioning. However, this approach has several limitations linked to the conceptual development of functional traits. There is a large ambiguity and variability in using the term "functional traits” by zoologists and ecologists working with soil invertebrates. In this study, we used a questionnaire and literature scanning to review the practical use of functional traits concept in soil ecology over the last decade. We clarifed and expanded the functional trait definition as "A functional trait is a measurable characteristic of an individual organism or its colony that has a clear link to the organism's fitness and/or its effect on other organisms and/or the environment”. We also reviewed existing trait databases showing a high amount, but also high heterogeneity and low accessibility of data on the functional traits of soil invertebrates. We suggest synthesising existing trait data and databases, using the functional trait-based approach consistently and reproducibly, and disseminating it to facilitate mechanistic research in soil ecology.

Abstract Fauna is highly abundant and diverse in soils worldwide, but surprisingly little is known about how it affects soil organic matter stabilization. Here, we review how the ecological strategies of a multitude of soil faunal taxa can affect the formation and persistence of labile (particulate organic matter, POM) and stabilized soil organic matter (mineral-associated organic matter, MAOM). We propose three major mechanisms - transformation, translocation, and grazing on microorganisms - by which soil fauna alters factors deemed essential in the formation of POM and MAOM, including the quantity and decomposability of organic matter, soil mineralogy, and the abundance, location, and composition of the microbial community. Determining the relevance of these mechanisms to POM and MAOM formation in cross-disciplinary studies that cover individual taxa and more complex faunal communities, and employ physical fractionation, isotopic, and microbiological approaches is essential to advance concepts, models, and policies focused on soil organic matter and effectively manage soils as carbon sinks, nutrient stores, and providers of food.

Recent research on earthworms has shed light on their global distribution, with high alpha richness in temperate zones and high beta diversity in tropical areas. Climate and agricultural practices, notably plowing and conservation methods, were shown to strongly influence earthworm communities. However, data gaps persist in regions like North Australia, Asia, Russia, and Africa, limiting our understanding of earthworm distribution and their responses to global changes. Understanding changes within earthworm communities is crucial given their profound influence on ecosystem functions such as soil structure, nutrient dynamics, and plant growth. Classifying earthworms into functional groups remains complex, prompting the adoption of a trait-based approach for a more comprehensive classification, but there is no representative global data on earthworm traits. To address these knowledge gaps, the Soil BON Earthworm initiative aims at creating a global community of earthworm experts, standardizing sampling methods and databases, collecting time series data on earthworm communities, and modeling future earthworm distributions under different climate scenarios. The initiative aims to address key questions, such as the dynamic of earthworm communities over time and their response to environmental factors and anthropogenic influences, their impact on ecosystem functioning, and the redefinition of functional groups based on traits. The consortium invites researchers worldwide to contribute to this endeavor and encourages the resampling of study sites, to expand currently limited time series datasets. To facilitate data collection, standardized protocols and data templates are proposed, ensuring data quality and interoperability. Furthermore, the initiative intends to make use of citizen science in expanding observations and improving taxonomic coverage, highlighting platforms like iNaturalist for community engagement. Soil BON Earthworm seeks to unite global expertise and foster collaborative research to address critical gaps in understanding earthworm ecology and its implications for ecosystems at a global scale.

Abstract Enhancing biodiversity in monoculture-dominated landscapes is a key sustainability challenge that requires considering the spatial organization of ecological communities (beta diversity). Here, we tested whether increasing landscape heterogeneity, through establishing 52 tree islands in an oil-palm landscape, is a suitable restoration strategy to enhance the diversity of six taxa (multi-taxa diversity). Further, we elucidated whether patterns in the spatial distribution of above- and below-ground taxa are related, and their role in shaping multi-taxa beta diversity. After five years, islands enhanced diversity at the landscape scale by fostering unique species (turnover). Partial correlation networks revealed that dissimilarity, in vegetation structural complexity and soil conditions, impacts multi-taxa beta diversity and turnover. In addition, soil fauna, bacteria, and fungi were more strongly associated with the overall community than aboveground taxa. Thus, strategies aiming to enhance multi-taxa diversity should consider the central role of landscape heterogeneity and soil biota.

Soil biodiversity does not only represent a major share of the total Earth’s biodiversity, but has also major importance for the functioning of terrestrial ecosystems. This realization has triggered an unprecedented scientific, public, and political interest in the distribution, drivers, trends, and conservation measures of soil biodiversity. Here, we outline the role of the journal Soil Organisms in this rapidly developing field and our planned approaches to address the most pressing scientific and societal issues related to soil biodiversity. In the last couple of years, Soil Organisms has played a pioneering role in the movement to mobilize soil biodiversity and function data, with the goal to become the hub for unbiased soil biodiversity knowledge publishing. We plan to follow this successful route and introduce new approaches, such as requiring authors to share their raw data and statistical code along with the results to ensure reproducibility, we will accept submissions of manuscripts published as preprints, and we invite authors to submit their rejected papers along with their responses to reviewers’ comments from other journals. Next to the already existing and successful paper formats of Research Articles, Invited Reviews, and Calls for collaboration, we will introduce Editors‘ Highlights and Invited Comments to complement the journal’s portfolio in a way that ensures fast information flow on important developments related to soil organisms. Together with our Editorial Board of international specialists in soil biodiversity, ecology, and taxonomy, representing expertise across taxa, scientific disciplines, and research approaches, we aim to further establish Soil Organisms as a globally recognized and esteemed scientific platform, serving as a worldwide forum for researchers in the fields of soil organismic and functional biodiversity.

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.

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.

Information about soil scale insect (Hemiptera: Coccomorpha) diversity, although fragmented, had been progressively improved for Asia, especially in the southern countries such as Indonesia. Recent works recorded 365 species in the country, 21 of which in below ground habit. In this paper, we contribute to the knowledge of Indonesian scale insect diversity by analyzing specimens collected from rainforest, rubber and oil palm plantations in the Province of Jambi and Sumatra, Indonesia. The results include the new records of Rhizoecus americanus, Rhizoecus omphalius, Ripersiella bacorum, Ripersiella cryphia and Ripersiella sabahica (Rhizoecidae) with description of new intraspecific variations. Pseudococcus saccharicola (Pseudococcidae), Geococcus coffeae, and Rhizoecus pignerator (Rhizoecidae) were also collected in this study. With these species, the known Indonesian scale insect fauna increases to 370 species.

Abstract Deforestation and agricultural expansion in the tropics affect local and regional climatic conditions, leading to synergistic negative impacts on land ecosystems. Climatic changes manifest in increased inter‐ and intraseasonal variations and frequency of extreme climatic events (i.e., droughts and floods), which have evident consequences for aboveground biodiversity. However, until today, there have been no studies on how land use affects seasonal variations below ground in tropical ecosystems, which may be more buffered against climatic variation. Here, we analyzed seasonal variations in soil parameters, basal respiration, microbial communities, and abundances of soil invertebrates along with microclimatic conditions in rainforest and monocultures of oil palm and rubber in Sumatra, Indonesia. About 75% (20 out of 26) of the measured litter and soil, microbial, and animal parameters varied with season, with seasonal changes in 50% of the parameters depending on land use. Land use affected seasonal variations in microbial indicators associated with carbon availability and cycling rate. The magnitude of seasonal variations in microbial parameters in the soil of monocultures was almost 40% higher than in the soil of rainforest. Measured parameters were associated with short‐term climatic conditions (3‐day period air humidity) in plantations, but not in rainforest, confirming a reduced soil buffering ability in plantations. Overall, our findings suggest that land use temporally shifts and increases the magnitude of seasonal variations of the belowground ecosystem compartment, with microbial communities responding most strongly. The increased seasonal variations in soil biota in plantations likely translate into more pronounced fluctuations in essential ecosystem functions such as nutrient cycling and carbon sequestration, and these ramifications ultimately may compromise the stability of tropical ecosystems in the long term. As the observed seasonal dynamics is likely to increase with both local and global climate change, these shifts need closer attention for the long‐term sustainable management of plantation systems in the tropics.

Agricultural expansion is among the main threats to biodiversity and functions of tropical ecosystems. It has been shown that conversion of rainforest into plantations erodes biodiversity, but further consequences for food-web structure and energetics of belowground communities remains little explored. We used a unique combination of stable isotope analysis and food-web energetics to analyze in a comprehensive way consequences of the conversion of rainforest into oil palm and rubber plantations on the structure of and channeling of energy through soil animal food webs in Sumatra, Indonesia. Across the animal groups studied, most of the taxa had lower litter-calibrated Δ13C values in plantations than in rainforests, suggesting that they switched to freshly-fixed plant carbon ('fast' energy channeling) in plantations from the detrital C pathway ('slow' energy channeling) in rainforests. These shifts led to changes in isotopic divergence, dispersion, evenness, and uniqueness. However, earthworms as major detritivores stayed unchanged in their trophic niche and monopolized the detrital pathway in plantations, resulting in similar energetic metrics across land-use systems. Functional diversity metrics of soil food webs were associated with reduced amount of litter, tree density, and species richness in plantations, providing guidelines on how to improve the complexity of the structure of and channeling of energy through soil food webs. Our results highlight the strong restructuring of soil food webs with the conversion of rainforest into plantations threatening soil functioning and ecosystem stability in the long term.