Aim: Biodiversity is increasingly threatened by human impacts. While abiotic conditions are well known to shape species richness, the role of human activities remains less clear. We examined how abiotic and human factors influence terrestrial and limnic species richness in a densely populated region with a long land-use history. Location: Germany. Time Period: 1900-2023 (varies by taxonomic group). Major Taxa Studied: Mammals, breeding birds, fishes, amphibians, reptiles, butterflies, dragonflies, fungi, vascular plants. Methods: Species richness data were aggregated in 11 & times; 11 km grid cells and related to abiotic (climate, soil) and human drivers (land use, protection status). We applied a two-step approach: (1) Boosted Regression Trees (BRTs) to select relevant predictor variables and (2) Generalised Additive Models (GAMs) to test their effects, accounting for spatial autocorrelation. Results: Land-use and climate were similarly important for species richness (26% vs. 21% in BRTs), while protection status and soil contributed less (8% and 9%). GAMs showed positive effects of temperature across many groups. Among land-use factors, human footprint, urban open spaces and water bodies consistently enhanced richness. Protected areas were positively related to richness, whereas soil variables had mixed effects. Main Conclusions: In Germany, species richness peaks not only in semi-natural, protected areas but also along water bodies and within settlement open spaces. These results suggest that conservation strategies should integrate both traditional protected areas and human-modified habitats that sustain high biodiversity.

Plant litter decomposition governs how much carbon soils store and emit, yet the microbial traits that shape ecosystem-scale decay remain unresolved. Metagenomes can quantify genes encoding plant cell-wall-degrading enzymes, but it is unclear whether ecosystem differences in decay reflect distinct enzymatic repertoires, and whether these data improve prediction beyond climate and soil properties. We paired standardized green and rooibos tea-bag decomposition assays across 3–24 months with 295 soil metagenomes from 264 global sites. Using 196 European plots for primary inference, we built a stage-resolved catalogue of 17.6 million carbohydrate-active enzyme (CAZyme) genes. Forest microbiomes decomposed tea faster than grasslands, but this was not explained by greater CAZyme family richness. Instead, ecosystems differed in CAZyme abundance, subfamily and protein-sequence variation, and allocation across biochemical stages of plant cell-wall decay, with evidence of ecosystem-specific selection. CAZyme profiles added explanatory power for 24-month mass loss and improved within-ecosystem prediction but generalized poorly across ecosystems and continents. By showing that ecosystem differences in decomposition arise from the stage-specific distribution of shared enzymatic functions rather than their presence alone, this work shifts microbial trait inference beyond gene inventories and provides a mechanistic genomic framework for carbon-cycle modelling within defined environmental limits.

Temperate agricultural landscapes are experiencing unprecedented biodiversity declines. Landscape simplification is commonly identified as a driver of species loss across taxonomic groups, but the contribution of crop and non-crop habitats to farmland biodiversity conservation is surprisingly poorly known. Using 86 paired permanent grasslands and oilseed rape fields in five European countries, we assess how habitat type shaped plant, butterfly, wild bee, and carabid assemblages and whether increasing grassland amount in surrounding landscapes fosters the spillover of grassland-associated biodiversity to oilseed rape fields. We find habitat type rather than landscape-level grassland amount determines diversity and shapes species assemblages: plants and butterflies are more diverse in grasslands, while wild bees and carabids are equally or more diverse in oilseed rape fields. Increasing landscape-level grassland amount affects species assemblage composition but only reduces turnover between habitats in wild bees. Overall, both grasslands and oilseed rape fields harbour distinct sets of species, together contributing complementarily to regional diversity. Safeguarding biodiversity in agricultural landscapes therefore requires not only the conservation of permanent semi-natural habitats but also biodiversity-friendly management of disturbed habitats such as crop fields that can contribute valuable species.

Growing evidence has shown that, apart from local environmental factors, changes in landscape-level factors by accelerated land-use change can also shape soil pathogenic fungal diversity. However, the global representativeness of such patterns remains unclear. Here, we assess how pathogenic fungal diversity in 511 soil samples worldwide responds to landscape factors, including landscape complexity index based on eight landscape metrics and quantity of different land cover types across six spatial scales (i.e., surrounding landscape, 250 m to 10,000 m radii from the sampling coordinate). We find that while soil variables explain over half of the variance, pathogenic fungal alpha diversity increases with landscape complexity and crop cover proportion, but decreases with grass and tree cover proportion, together explaining 23.4% of the total variance. Landscape factors have weaker impacts on beta diversity, explaining 13.0% of the variance. Across spatial scales, grassland ecosystems exhibit increasingly stronger responses to landscape variables compared to forest ecosystems. Landscape factors have a higher relative contribution to root-associated fungi than leaf/fruit/seed-associated fungi. Our results emphasize the importance of local factors and the complementary role of landscape patterns in shaping global soil pathogenic fungal distributions, highlighting scale-dependent effects across ecosystems and fungal functional groups.

1. As there is growing interest among non-specialists in participating in pollinator conservation initiatives, developing proxies for wild bee species richness that could be potentially used by non-experts can aid conservation, decision support systems for managers and policymakers, and create entry points for future taxonomists. 2. We used data from 63 independent studies in which wild bees were sampled, covering all main European habitats and climates. We tested two proxies for wild bee species richness: abundance of all wild bees (excluding the honeybee) and abundance of bumblebees. These proxies require basic taxonomic training and have the potential for routine implementation by non-experts. 3. Within-region, the abundance of wild bees was a strong predictor of wild bee species richness at the local scale, with an average correlation exceeding 0.80. Bumblebee abundance was a poorer proxy for total wild bee species richness (correlation coefficient of similar to 0.55) and was unsuitable for warm-temperate and Mediterranean climates. Observed abundance-richness correlations were consistent across climates, habitats and sampling methods, suggesting that, after a simple training, counting all bee individuals in transect walks provides a non-lethal, robust estimate of wild bee species richness. We observed a weak negative relationship between sample coverage and the strength of the abundance-richness correlation. 4. Synthesis and applications. The use of a simple but effective proxy could be an important starting point for the expansion of wild bee monitoring initiatives at the regional scale, particularly given the growing involvement of non-specialists. We provided here a simple implementation framework to use this proxy in rapid biodiversity assessments, such as the evaluation of payment-by-result schemes by farmers and measuring the efficacy of conservation actions in urban green areas or protected areas by citizens and site managers, respectively. It is important to stress that we are not advocating for the replacement of the urgently needed long-term monitoring of pollinator status and trends. Instead, we propose that employing an effective proxy for non-experts could enhance the evaluation of many local and regional conservation initiatives that currently lack any basic assessment schemes.

Healthy soils and the biodiversity therein are the prerequisite for the supply of manifold ecosystem services that are essential for human well-being. Detailed knowledge, especially at the national level, is important for effective policy-making to safeguard healthy functional soils for future generations. Hence, synthesis of the state of soil biodiversity and related ecosystem functions, the driving forces affecting the soil as a habitat, avenues for sustainable soil management, and the role of stakeholders at different levels is required. Here, we present the eleven key messages of the first comprehensive soil biodiversity assessment in Germany, based on the currently available and accessible literature and expert knowledge. Among others, we highlight the high biodiversity of soils in Germany, their role for climate regulation and other ecosystem services, the impact of multiple concurrent drivers, as well as actions and schemes already in place to sustainably manage soil biodiversity and to raise awareness in different groups of the public. We conclude that national assessments of the available literature and data are an important step towards the incorporation of soil biodiversity in national policies and to provide the basis for national long-term systematic monitoring.

Recently, biomass of invertebrates has declined substantially at many locations with the implications of this biodiversity loss for ecosystems yet unknown. Through multitrophic interactions, plant- and soil-associated microbiomes might be altered, causing a cascade of changes on diverse ecosystem processes. We simulated aboveground invertebrate decline in grassland ecosystems with two levels of invertebrate biomass (36% and 100% of current ambient conditions), plus a control with no invertebrates present. Each standardised grassland mesocosm additionally contained one clonal Quercus robur L. sapling to investigate the extent of invertebrate decline effects exceeding grasslands. We investigated oak biomass partitioning and mycorrhiza formation, oak leaf transcriptome and microbiome composition of leaves, roots and rhizosphere. While invertebrate decline did not significantly affect oak performance and herbivory-related gene expression, fungal communities presented an increase of saprotrophs and pathogens, especially in leaves. Among leaf-inhabiting bacteria, Proteobacteria and Actinobacteria increased under invertebrate decline. The belowground microbiome was only little affected. But, invertebrate decline came along with a reduced influence on predators leading to an elevated aphids infestation that proofed able to alter microbiota. Our findings establish a strong difference between above- and belowground, with the impacts of invertebrate decline being more pronounced in the leaf microbiome.

Human activities cause substantial changes in biodiversity.1,2 Despite ongoing concern about the implications of invertebrate decline,3,4,5,6,7 few empirical studies have examined the ecosystem consequences of invertebrate biomass loss. Here, we test the responses of six ecosystem services informed by 30 above- and belowground ecosystem variables to three levels of aboveground (i.e., vegetation associated) invertebrate community biomass (100%, 36%, and 0% of ambient biomass) in experimental grassland mesocosms in a controlled Ecotron facility. In line with recent reports on invertebrate biomass loss over the last decade, our 36% biomass treatment also represented a decrease in invertebrate abundance (-70%) and richness (-44%). Moreover, we simulated the pronounced change in invertebrate biomass and turnover in community composition across the season. We found that the loss of invertebrate biomass decreases ecosystem multifunctionality, including two critical ecosystem services, aboveground pest control and belowground decomposition, while harvested plant biomass increases, likely because less energy was channeled up the food chain. Moreover, communities and ecosystem functions become decoupled with a lower biomass of invertebrates. Our study shows that invertebrate loss threatens the integrity of grasslands by decoupling ecosystem processes and decreasing ecosystem-service supply.

Litter decomposition is a key ecosystem function in forests and varies in response to a range of climatic, edaphic, and local stand characteristics. Disentangling the relative contribution of these factors is challenging, especially along large environmental gradients. In particular, knowledge of the effect of management options, such as tree planting density and species composition, on litter decomposition would be highly valuable in forestry. In this study, we made use of 15 tree diversity experiments spread over eight countries and three continents within the global TreeDivNet network. We evaluated the effects of overstory composition (tree identity, species/mixture composition and species richness), plantation conditions (density and age), and climate (temperature and precipitation) on mass loss (after 3 months and 1 year) of two standardized litters: high-quality green tea and low-quality rooibos tea. Across continents, we found that early-stage decomposition of the low-quality rooibos tea was influenced locally by overstory tree identity. Mass loss of rooibos litter was higher under young gymnosperm overstories compared to angiosperm overstories, but this trend reversed with age of the experiment. Tree species richness did not influence decomposition and explained almost no variation in our multi-continent dataset. Hence, in the young plantations of our study, overstory composition effects on decomposition were mainly driven by tree species identity on decomposer communities and forest microclimates. After 12 months of incubation, mass loss of the high-quality green tea litter was mainly influenced by temperature whereas the low-quality rooibos tea litter decomposition showed stronger relationships with overstory composition and stand age. Our findings highlight that decomposition dynamics are not only affected by climate but also by management options, via litter quality of the identity of planted trees but also by overstory composition and structure.

Anthropogenic global warming has major implications for mobile terrestrial insects, including long-term effects from constant warming, for example, on species distribution patterns, and short-term effects from heat extremes that induce immediate physiological responses. To cope with heat extremes, they either have to reduce their activity or move to preferable microhabitats. The availability of favorable microhabitat conditions is strongly promoted by the spatial heterogeneity of habitats, which is often reduced by anthropogenic land transformation. Thus, it is decisive to understand the combined effects of these global change drivers on insect activity. Here, we assessed the movement activity of six insect species (from three orders) in response to heat stress using a unique tracking approach via radio frequency identification. We tracked 465 individuals at the iDiv Ecotron across a temperature gradient up to 38.7°C. In addition, we varied microhabitat conditions by adding leaf litter from four different tree species to the experimental units, either spatially separated or well mixed. Our results show opposing effects of heat extremes on insect activity depending on the microhabitat conditions. The insect community significantly decreased its activity in the mixed litter scenario, while we found a strong positive effect on activity in the separated litter scenario. We hypothesize that the simultaneous availability of thermal refugia as well as resources provided by the mixed litter scenario allows animals to reduce their activity and save energy in response to heat stress. Contrary, the spatial separation of beneficial microclimatic conditions and resources forces animals to increase their activity to fulfill their energetic needs. Thus, our study highlights the importance of habitat heterogeneity on smaller scales, because it may buffer the consequences of extreme temperatures of insect performance and survival under global change.

Abstract Across the globe, ecological communities are confronted with multiple global environmental change drivers, and they are responding in complex ways ranging from behavioral, physiological, and morphological changes within populations to changes in community composition and food web structure with consequences for ecosystem functioning. A better understanding of global change‐induced alterations of multitrophic biodiversity and the ecosystem‐level responses in terrestrial ecosystems requires holistic and integrative experimental approaches to manipulate and study complex communities and processes above and below the ground. We argue that mesocosm experiments fill a critical gap in this context, especially when based on ecological theory and coupled with microcosm experiments, field experiments, and observational studies of macroecological patterns. We describe the design and specifications of a novel terrestrial mesocosm facility, the iDiv Ecotron. It was developed to allow the setup and maintenance of complex communities and the manipulation of several abiotic factors in a near‐natural way, while simultaneously measuring multiple ecosystem functions. To demonstrate the capabilities of the facility, we provide a case study. This study shows that changes in aboveground multitrophic interactions caused by decreased predator densities can have cascading effects on the composition of belowground communities. The iDiv Ecotrons technical features, which allow for the assembly of an endless spectrum of ecosystem components, create the opportunity for collaboration among researchers with an equally broad spectrum of expertise. In the last part, we outline some of such components that will be implemented in future ecological experiments to be realized in the iDiv Ecotron.

Ecosystems integrity and services are threatened by anthropogenic global changes. Mitigating and adapting to these changes require knowledge of ecosystem functioning in the expected novel environments, informed in large part through experimentation and modelling. This paper describes 13 advanced controlled environment facilities for experimental ecosystem studies, herein termed ecotrons, open to the international community. Ecotrons enable simulation of a wide range of natural environmental conditions in replicated and independent experimental units while measuring various ecosystem processes. This capacity to realistically control ecosystem environments is used to emulate a variety of climatic scenarios and soil conditions, in natural sunlight or through broad‐spectrum lighting. The use of large ecosystem samples, intact or reconstructed, minimizes border effects and increases biological and physical complexity. Measurements of concentrations of greenhouse trace gases as well as their net exchange between the ecosystem and the atmosphere are performed in most ecotrons, often quasi continuously. The flow of matter is often tracked with the use of stable isotope tracers of carbon and other elements. Equipment is available for measurements of soil water status as well as root and canopy growth. The experiments ran so far emphasize the diversity of the hosted research. Half of them concern global changes, often with a manipulation of more than one driver. About a quarter deal with the impact of biodiversity loss on ecosystem functioning and one quarter with ecosystem or plant physiology. We discuss how the methodology for environmental simulation and process measurements, especially in soil, can be improved and stress the need to establish stronger links with modelling in future projects. These developments will enable further improvements in mechanistic understanding and predictive capacity of ecotron research which will play, in complementarity with field experimentation and monitoring, a crucial role in exploring the ecosystem consequences of environmental changes.

Ecosystems integrity and services are threatened by anthropogenic global changes. Mitigating and adapting to these changes require knowledge of ecosystem functioning in the expected novel environments, informed in large part through experimentation and modelling. This paper describes 13 advanced controlled environment facilities for experimental ecosystem studies, herein termed ecotrons, open to the international community. Ecotrons enable simulation of a wide range of natural environmental conditions in replicated and independent experimental units while measuring various ecosystem processes. This capacity to realistically control ecosystem environments is used to emulate a variety of climatic scenarios and soil conditions, in natural sunlight or through broad-spectrum lighting. The use of large ecosystem samples, intact or reconstructed, minimizes border effects and increases biological and physical complexity. Measurements of concentrations of greenhouse trace gases as well as their net exchange between the ecosystem and the atmosphere are performed in most ecotrons, often quasi continuously. The flow of matter is often tracked with the use of stable isotope tracers of carbon and other elements. Equipment is available for measurements of soil water status as well as root and canopy growth. The experiments ran so far emphasize the diversity of the hosted research. Half of them concern global changes, often with a manipulation of more than one driver. About a quarter deal with the impact of biodiversity loss on ecosystem functioning and one quarter with ecosystem or plant physiology. We discuss how the methodology for environmental simulation and process measurements, especially in soil, can be improved and stress the need to establish stronger links with modelling in future projects. These developments will enable further improvements in mechanistic understanding and predictive capacity of ecotron research which will play, in complementarity with field experimentation and monitoring, a crucial role in exploring the ecosystem consequences of environmental changes.

Defaunation including invertebrate decline is one of the major consequences of anthropogenic alterations of the environment. Despite recent reports of ubiquitous invertebrate decline, the ecosystem consequences have been rarely documented. We exposed standardized plant communities grown in the iDiv Ecotron to different levels of invertebrate numbers and biomass and tracked effects on the diversity and composition of bacterial communities associated with flowers and leaves of Scorzoneroides autumnalis and Trifolium pratense using next-generation 16S rRNA gene amplicon sequencing. Our data indicate that invertebrate decline reduces bacterial richness and β-diversity and alters community composition. These effects may result from direct effects of invertebrates that may serve as dispersal agents of bacteria; or from indirect effects where animal-induced changes in the plant's phenotype shape the niches plants provide for bacterial colonizers. Because bacteria are usually not dispersal limited and because species sorting, i.e. niche-based processes, has been shown to be a dominant process in bacterial community assembly, indirect effects may be more likely. Given that a healthy microbiome is of fundamental importance for the well-being of plants, animals (including humans) and ecosystems, a loss of bacterial diversity may be a dramatic yet previously unknown consequence of current invertebrate decline.

Climate and land-use change lead to decreasing invertebrate biomass and alter invertebrate communities. These biotic changes may affect plant species abundance and phenology. Using 24 controlled experimental units in the iDiv Ecotron, we assessed the effects of invertebrate decline on an artificial grassland community formed by 12 herbaceous plant species. More specifically, we used Malaise traps and sweep nets to collect invertebrates from a local tall oatgrass meadow and included them in our Ecotron units at two different invertebrate densities: 100% (no invertebrate decline) and 25% (invertebrate decline of 75%). Another eight EcoUnits received no fauna and served as a control. Plant species abundance and flowering phenology was observed weekly over a period of 18 weeks. Our results showed that invertebrate densities affected the abundance and phenology of plant species. We observed a distinct species abundance shift with respect to the invertebrate treatment. Notably, this shift included a reduction in the abundance of the dominant plant species, Trifolium pratense, when invertebrates were present. Additionally, we found that the species shifted their flowering phenology as a response to the different invertebrate treatments, e.g. with decreasing invertebrate biomass Lotus corniculatus showed a later peak flowering time. We demonstrated that in addition to already well-studied abiotic drivers, biotic components may also drive phenological changes in plant communities. This study clearly suggests that invertebrate decline may contribute to already observed mismatches between plants and animals, with potential negative consequences for ecosystem services like food provision and pollination success. This deterioration of ecosystem function could enhance the loss of insects and plant biodiversity.

Soil organisms are important drivers of the functioning of terrestrial ecosystems and co-determine how these ecosystems respond to human-induced changes in climate and land use. In the present study, we assessed the interacting effects of these two global change drivers on soil faunal communities. We carried out an experimental field study within the framework of the Global Change Experimental Facility (GCEF) manipulating (1) two climatic conditions (ambient vs. future) and (2) five land-use regimes (with two croplands: conventional farming and organic farming; and three grasslands: intensively-used meadow, extensively-used meadow and extensivelyused pasture). The future climate treatment is characterized by a slight increase of soil temperature (similar to 0.5 degrees C), whereas precipitation was strongly decreased during the summer (by similar to 20%) but moderately increased during spring and autumn (by similar to 10%). Soil fauna was sampled in two consecutive years in spring and autumn. Overall, future climate tented to have negative effects on soil fauna communities. For specific taxa, the detrimental effects of climate change were only evident for Isotomidae (Collembola) and Chilopoda. In general, soil faunal composition differed strongly between grasslands and croplands, with a higher number of macrofauna taxa and generally higher abundances of meso- and macrofauna in grasslands. However, land-use intensity within these land-use types had no further effect. Likewise, there were negligible interactive effects of climate and land use, and short-term effects of projected climate change on the community compositions of soil fauna were found to be more subtle than land-use effects. Land-use effects on soil fauna are therefore equally strong under ambient and future climatic conditions.

Litter decomposition is a key process determining the cycling of nutrients in ecosystems. Soil fauna plays an essential role in this process, e.g., by fragmenting and burrowing surface litter material, and thereby enhancing microbial decomposition. However, soil fauna-mediated decomposition might be influenced by interacting factors of environmental changes. Here we used a large-scale global change field experiment to test potential interacting effects between land-use type (croplands and grasslands differing in management intensity) and projected climate change on litter decomposition rates over a period of two years. For that, climate and land-use treatments were orthogonally crossed: (1) two climate scenarios: ambient vs. future; and (2) five land-use regimes: conventional fanning, organic farming, intensively used meadow, extensively used meadow, and extensively used pasture. Litterbags with two mesh sizes (5 mm and 0.02 mm) were used to differentiate contributions of microbes and fauna to the mass loss of standardized crop residues. Soil fauna accounted for more than 68% of surface litter mass loss. Future climate treatment decreased decomposition rates as a result of reduced precipitation and elevated temperature during summer months. Litter decomposition and the contribution of soil fauna to it were significantly higher in croplands than in grasslands, but did not differ due to management intensity within these land-use types. In grasslands, faunal contribution to decomposition decreased under future climate. There were no interacting effects between climate change and land use on decomposition rates. These findings indicate that predicted changes in precipitation patterns and temperature will consistently decelerate litter decomposition across land-used types via both microbial and faunal effects.

Collembola are highly abundant and diverse soil animals and play key roles in litter decomposition and nutrient cycling. Given their functional significance, it is important to understand their responses to human-induced global changes, such as climate change and land-use intensification. Here, we utilized an experimental field study, to test the interactive effects of climate (ambient vs. future) and land use (five land-use regimes, from extensively-used meadow to conventional farming) on three eco-morphological life forms of Collembola: epedaphic, hemiedaphic, and euedaphic species. We found that the effects of climate change on Collembola density were modulated by land use, and that the responses of different life forms to climate x land use interaction differed in magnitude and/or direction. The densities of total and hemiedaphic Collembola significantly decreased under organic farming and marginally increased in grasslands under future climatic conditions, whereas epedaphic Collembola tended to decrease their density with climate change in grasslands. In contrast, the density of euedaphic Collembola significantly increased with climate change in intensively-used grasslands. Further, we found that grasslands (especially extensively-used meadow) support the most abundant Collembola communities, with high species richness but low evenness. Multivariate analyses revealed independent effects of climate change and land-use intensification on Collembola community composition. Together, our findings indicate that the effects of climate change on Collembola communities depend on their life forms and land-use types. Surface-dwelling Collembola are more vulnerable to land use and climate change than those living in deeper soil layers. This may slow down the process of soil-surface litter decomposition in a changing world.