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Forest ecosystems in central Europe are currently experiencing various environmental changes like ongoing nitrogen deposition, rising CO2 levels and more frequent summer droughts, with potential impacts on biogeochemical processes in soils. Monitoring of soil properties, especially sensitive indicators like the activities of extracellular enzymes, enables studying the net effect of different simultaneously ongoing global changes on soil processes. Therefore, we measured the potential activities of four extracellular enzymes related to the C, N, P and S cycle (beta-glucosidase, N-actetyl-glucosaminidase, acid phosphatase and sulfatase) of topsoils (0-10 cm of the mineral soil) from 150 forest plots under different management in three German regions as part of the Biodiversity Exploratories (https://www.biodiversity-exploratories.de/en/) project (Swabian Alb in the South, Hainich-Dün in the center and Schorfheide Chorin in the North of Germany) in May of 2011, 2014, 2017 and 2021. Analyzed soil samples were mixed samples composed of 14 soil cores (5 cm diameter) per plot, taken along two 40 m transects, sieved to < 2mm, and stored frozen before analyses. Additional information on soil C, N and pH was obtained for the same samples. Results revealed that the interannual variation of enzyme activities was about twice as high as that of soil organic carbon contents. Organic carbon, total nitrogen contents or soil pH showed no consistent trend over time across the regions. The same was true for the enzymes beta-glucosidase, N-acetyl-glucosaminidase and sulfates while acid phosphatase activity increased in all regions from 2011 to 2021 with the smallest absolute increase from on average 1290 to 2753 nmol MUF g−1 dw h−1 in the sandy and most acidic region Schorfheide Chorin, and the largest one in the loess-dominated silt-clay soils of the Hainich-Dün region (from 3474 to 5570 nmol MUF g−1 dw h−1). Accordingly, the ratio of carbon-to-phosphorus acquiring enzymes declined with time. Plots following Moorhead et al. (2016, http://dx.doi.org/10.1016/j.soilbio.2015.10.01) indicated a consistent shift from N- to P-limitation across regions, independent of their total P contents and for both, coniferous and deciduous forests. Forest ecosystems seem to need to acquire more P from organic sources but given that both, plants and microorganisms can produce acid phosphatase, we are currently not able to say, if the increased phosphatase activity was a direct plant response or one (potentially mediated) by microorganisms. However, elevated CO2 and N-deposition can both potentially lead to nutrient imbalances and thus increasing forest P requirements, and also summer droughts might reduce plant nutrient uptake, so that the observed trend might be an additive effect of all, rather than being attributable to one alone. As next steps we will test if changes in enzyme activities go along with changes in soil microbial communities and with leaf litter P contents.

Formation of mineral-associated organic matter (MAOM) supports accumulation and stabilization of carbon in soil, and thus, is a key factor in the global carbon cycle. Little is known about the interplay of mineral type, land use, and management intensity on the extent of MAOM formation. We addressed this research question by exposing mineral containers with pristine minerals (goethite, as a representative of oxide-type mineral phases, and illite, representing layered aluminosilicate minerals) for five years to ambient soil conditions at 5 cm depth in 150 grassland and 150 forest plots in three regions across Germany. After recovery, the content of organic carbon (OC) of the minerals was determined by dry combustion. Results show that irrespective of land use and management intensity, more OC accumulated on goethite than illite (on average 0.23 and 0.06 mg m-2 mineral surface, respectively), demonstrating that mineral type was the most crucial factor for MAOM formation. Carbon accumulation was consistently greater in coniferous forests than in deciduous forests and grasslands. Structural equation models revealed that in grasslands, fertilization had contradictory effects on carbon accumulation, with the positive effect being mediated by enhanced plant productivity and the negative effect by reduced plant species richness. Overall, our results suggest that OC stabilization in soil is primarily driven by mineral type, in particular iron and other metal oxides. The mineral-driven MAOM formation is further modified by land use and management intensity.

Soil respiration is rarely studied at the landscape scale where forest and soil properties can be important drivers. We performed forest and soil inventories in 150 temperate forest sites in three German landscapes and measured in situ soil CO2 efflux with the soda-lime method in early summer 2018 and 2019. Both years were affected by naturally occurring summer droughts. Our aim was to investigate the impact of forest structural and compositional properties, soil properties and climate on soil CO2 efflux at the landscape. Forest properties explained a large portion of soil CO2 efflux variance (i.e., 14% in 2018 and 20% in 2019), which was comparable or larger than the portion explained by soil properties (i.e., 15% in 2018 and 6% in 2019), and much larger than that of climate. Using Structural Equation Modeling, we found that forest structural properties, i.e., tree density and basal area, were negatively linked to soil CO2 efflux, while forest composition, i.e., conifer share and tree species richness, was not important. Forest structure effects on soil CO2 efflux were either direct or mediated by fine root biomass under dry summer conditions. Summer soil CO2 efflux was positively linked to fine root biomass but not related to total soil organic carbon stocks or climate. Forest structural properties influence soil CO2 efflux under drought events and should be considered when predicting soil respiration at the landscape scale.

Understanding whether land use intensification causes regime shifts is of key importance for management, particularly if these shifts are associated with thresholds separating different ecosystem states and with hysteretic dynamics. Here we use a unique, long-term grassland database to identify thresholds in the response of 16 ecosystem functions and the diversities of 21 taxa to land use intensity. We show that aboveground diversity (5 of 10 taxa), shoot biomass and soil N retention showed threshold responses to land use intensity, i.e., abrupt changes between extensively and intensively managed grasslands. Time-series analysis revealed that ecosystem functions showed hysteresis around the threshold, while diversity did not. Shifting back to the functioning seen in extensively managed grasslands may therefore require larger reductions in land use intensity than shifting to the high intensity state. Identifying such thresholds along land use gradients is critical to prevent ecosystem degradation and conserve biodiversity and ecosystem functions.

Members of the verrucomicrobial clade 'Candidatus Udaeobacter' rank among the most dominant bacterial phylotypes in soil. Nevertheless, despite this global prevalence, in-depth analyses with respect to pH preferences of 'Ca. Udaeobacter' representatives are still lacking. Here, we utilized a recently designed primer pair, specifically targeting 'Ca. Udaeobacter', to investigate links between soil pH and the abundance as well as phylotype composition of this largely unexplored verrucomicrobial clade. Based on 150 forest and 150 grassland soils, comprising a broad pH range, we determined the highest total abundance of 'Ca. Udaeobacter' in strongly acidic soil (pH, ~5.1) and, noteworthy, in ultra-acidic soil (pH

Soil respiration is an important pathway of soil organic carbon losses in temperate grasslands; however, it is rarely studied across broad management intensity gradients in a landscape. Using the soda-lime method, we measured in-situ soil CO2 efflux with single measurements of long exposure time (i.e. 3 day long) in 150 grasslands in three German regions in early summer 2018 and 2019. The grasslands ranged from unfertilized and grazed grasslands to intensively fertilized and frequently harvested ones. To assess effects of grazing and fertilization intensities and plant diversity on soil CO2 efflux, we used Structural Equation Modeling to account for direct effects and indirect effects through soil and plant organic matter quantity and quality. Soil CO2 efflux was suppressed by limited water availability caused by naturally occurring droughts in both study years. Under the prevailing environmental conditions, grazing intensity, plant biomass and plant C:N ratio were not related to soil CO2 efflux. In contrast, fertilization intensity was positively associated with soil CO2 efflux (standardized coefficient of net effect: + 0.04 in 2018 and + 0.03 in 2019). This was because fertilization led to lower plant species richness and, thus, to lower C:N ratios in soils, which were associated with higher soil CO2 efflux (plant species richness net effect: −0.09 in 2018 and −0.18 in 2019; soil C:N ratio direct effect: −0.23 in 2018 and −0.33 in 2019). Intensively managed grasslands have higher soil respiration than extensively managed, plant species-rich grasslands even under the extreme conditions of natural droughts., Nutrient Cycling in Agroecosystems, 124, ISSN:1385-1314, ISSN:1573-0867

Background Forests perform various important ecosystem functions that contribute to ecosystem services. In many parts of the world, forest management has shifted from a focus on timber production to multi-purpose forestry, combining timber production with the supply of other forest ecosystem services. However, it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services. Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition, we develop models to predict the potential supply of 13 ecosystem services. We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data. Results Looking at the potential supply of ecosystem services, we found trade-offs (e.g. between both bark beetle control or dung decomposition and both productivity or soil carbon stocks) as well as synergies (e.g. for temperature regulation, carbon storage and culturally interesting plants) across the 53 most dominant forest types in Germany. No single forest type provided all ecosystem services equally. Some ecosystem services showed comparable levels across forest types (e.g. decomposition or richness of saprotrophs), while others varied strongly, depending on forest structural attributes (e.g. phosphorous availability or cover of edible plants) or tree species composition (e.g. potential nitrification activity). Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions. However, the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species. Conclusions Our results show that forest multifunctionality is limited to subsets of ecosystem services. The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level, when stands of complementary forest types are combined. These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales.

Root-associated fungi (RAF) link nutrient fluxes between soil and roots and thus play important roles in ecosystem functioning. To enhance our understanding of the factors that control RAF, we fitted statistical models to explain variation in RAF community structure using data from 150 temperate forest sites covering a broad range of environmental conditions and chemical root traits. We found that variation in RAF communities was related to both root traits (e.g., cations, carbohydrates, NO3 - ) and soil properties (pH, cations, moisture, C/N). The identified drivers were the combined result of distinct response patterns of fungal taxa (determined at the rank of orders) to biotic and abiotic factors. Our results support that RAF community variation is related to evolutionary adaptedness of fungal lineages and consequently, drivers of RAF communities are context-dependent.

Grassland management intensity influences nutrient cycling both directly, by changing nutrient inputs and outputs from the ecosystem, and indirectly, by altering the nutrient content, and the diversity and functional composition of plant and microbial communities. However, the relative importance of these direct and indirect processes for the leaching of multiple nutrients is poorly studied. We measured the annual leaching of nitrate, ammonium, phosphate and sulphate at a depth of 10 cm in 150 temperate managed grasslands using a resin method. Using Structural Equation Modeling, we distinguished between various direct and indirect effects of management intensity (i.e. grazing and fertilization) on nutrient leaching. We found that management intensity was positively associated with nitrate, ammonium and phosphate leaching risk both directly (i.e. via increased nutrient inputs) and indirectly, by changing the stoichiometry of soils, plants and microbes. In contrast, sulphate leaching risk was negatively associated with management intensity, presumably due to increased outputs with mowing and grazing. In addition, management intensification shifted plant communities towards an exploitative functional composition (characterized by high tissue turnover rates) and, thus, further promoted the leaching risk of inorganic nitrogen. Plant species richness was associated with lower inorganic nitrogen leaching risk, but most of its effects were mediated by stoichiometry and plant community functional traits. Maintaining and restoring diverse plant communities may therefore mitigate the increased leaching risk that management intensity imposes upon grasslands., Nutrient Cycling in Agroecosystems, 123 (3), ISSN:1385-1314, ISSN:1573-0867

The impact of local biodiversity loss on ecosystem functioning is well established, but the role of larger-scale biodiversity dynamics in the delivery of ecosystem services remains poorly understood. Here we address this gap using a comprehensive dataset describing the supply of 16 cultural, regulating and provisioning ecosystem services in 150 European agricultural grassland plots, and detailed multi-scale data on land use and plant diversity. After controlling for land-use and abiotic factors, we show that both plot-level and surrounding plant diversity play an important role in the supply of cultural and aboveground regulating ecosystem services. In contrast, provisioning and belowground regulating ecosystem services are more strongly driven by field-level management and abiotic factors. Structural equation models revealed that surrounding plant diversity promotes ecosystem services both directly, probably by fostering the spill-over of ecosystem service providers from surrounding areas, and indirectly, by maintaining plot-level diversity. By influencing the ecosystem services that local stakeholders prioritized, biodiversity at different scales was also shown to positively influence a wide range of stakeholder groups. These results provide a comprehensive picture of which ecosystem services rely most strongly on biodiversity, and the respective scales of biodiversity that drive these services. This key information is required for the upscaling of biodiversity–ecosystem service relationships, and the informed management of biodiversity within agricultural landscapes.

Land‐use intensification drives changes in microbial communities and the soil functions they regulate, but the mechanisms underlying these changes are poorly understood as land use can affect soil communities both directly (e.g. via changes in soil fertility) and indirectly (e.g. via changes in plant inputs). The speed of microbial responses is also poorly understood. For instance, whether it is long‐term legacies or short‐term changes in land‐use intensity that drive changes in microbial communities. To address these topics, we measured multiple microbial functions, bacterial and fungal biomass and abiotic soil properties at two time intervals 3 years apart. This was performed in 150 grassland sites differing greatly in management intensity across three German regions. Observed changes in microbial soil properties were related to both long‐term means and short‐term changes in: abiotic soil properties, land‐use intensity, community abundance‐weighted means of plant functional traits and plant biomass properties in regression and structural equation models. Plant traits, particularly leaf phosphorus, and soil pH were the best predictors of change in soil microbial function, as well as fungal and bacterial biomass, while land‐use intensity showed weaker effects. Indirect legacy effects, in which microbial change was explained by the effects of long‐term land‐use intensity on plant traits, were important, thus indicating a time lag between plant community and microbial change. Whenever the effects of short‐term changes in land‐use intensity were present, they acted directly on soil microorganisms. Synthesis. The results provide new evidence that soil communities and their functioning respond to short‐term changes in land‐use intensity, but that both rapid and longer time‐scale responses to changes in plant functional traits are at least of equal importance. This suggests that management which shapes plant communities may be an effective means of managing soil communities and the functions and services they provide.

Functionally, ectomycorrhizal (ECM) and saprotrophic (SAP) fungi belong to different guilds, and they play contrasting roles in forest ecosystem C-cycling. SAP fungi acquire C by degrading the soil organic material, which precipitates massive CO2 release, whereas, as plant symbionts, ECM fungi receive C from plants representing a channel of recently assimilated C to the soil. In this study, we aim to measure the amounts and identify the drivers of ECM and SAP fungal biomass in temperate forest topsoil. To this end, we measured ECM and SAP fungal biomass in mineral topsoils (0–12 cm depth) of different forest types (pure European beech, pure conifers, and mixed European beech with other broadleaf trees or conifers) in a range of about 800 km across Germany; moreover, we conducted multi-model inference analyses using variables for forest and vegetation, nutritive resources from soil and roots, and soil conditions as potential drivers of fungal biomass. Total fungal biomass ranged from 2.4 ± 0.3 mg g−1 (soil dry weight) in pure European beech to 5.2 ± 0.8 mg g−1 in pure conifer forests. Forest type, particularly the conifer presence, had a strong effect on SAP biomass, which ranged from a mean value of 1.5 ± 0.1 mg g−1 in broadleaf to 3.3 ± 0.6 mg g−1 in conifer forests. The European beech forests had the lowest ECM fungal biomass (1.1 ± 0.3 mg g−1), but in mixtures with other broadleaf species, ECM biomass had the highest value (2.3 ± 0.2 mg g−1) among other forest types. Resources from soil and roots such as N and C concentrations or C:N ratios were the most influential variables for both SAP and ECM biomass. Furthermore, SAP biomass were driven by factors related to forest structure and vegetation, whereas ECM biomass was mainly influenced by factors related to soil conditions, such as soil temperature, moisture, and pH. Our results show that we need to consider a complex of factors differentially affecting biomass of soil fungal functional groups and highlight the potential of forest management to control forest C-storage and the consequences of changes in soil fungal biomass.

Land-use intensification is a major driver of biodiversity loss. However, understanding how different components of land use drive biodiversity loss requires the investigation of multiple trophic levels across spatial scales. Using data from 150 agricultural grasslands in central Europe, we assess the influence of multiple components of local- and landscape-level land use on more than 4,000 above- and belowground taxa, spanning 20 trophic groups. Plot-level land-use intensity is strongly and negatively associated with aboveground trophic groups, but positively or not associated with belowground trophic groups. Meanwhile, both above- and belowground trophic groups respond to landscape-level land use, but to different drivers: aboveground diversity of grasslands is promoted by diverse surrounding land-cover, while belowground diversity is positively related to a high permanent forest cover in the surrounding landscape. These results highlight a role of landscape-level land use in shaping belowground communities, and suggest that revised agroecosystem management strategies are needed to conserve whole-ecosystem biodiversity., Nature Communications, 12 (1), ISSN:2041-1723

Evidence from experimental and established grasslands indicates that plant biodiversity can modify the water cycle. One suspected mechanism behind this is a higher infiltration capacity (νB) and hydraulic conductivity (K) of the soil on species‐rich grasslands. However, in established and agriculturally managed grasslands, biodiversity effects cannot be studied independent of land‐use effects. Therefore, we investigated in established grassland systems how land‐use intensity and associated biodiversity of plants and soil animals affect νB and K at and close to saturation. On 50 grassland plots along a land‐use intensity gradient in the Biodiversity Exploratory Schwäbische Alb, Germany, we measured νB with a hood infiltrometer at several matrix potentials and calculated the saturated and unsaturated K. We statistically analysed the relationship between νB or K and land‐use information (e.g., fertilising intensity), abiotic (e.g., soil texture) and biotic data (e.g., plant species richness, earthworm abundance). Land‐use intensity decreased and plant species richness increased νB and K, while the direction of the effects of soil animals was inconsistent. The effect of land‐use intensity on νB and K was mainly attributable to its negative effect on plant species richness. Our results demonstrate that plant species richness was a better predictor of νB and K at and close to saturation than land‐use intensity or soil physical properties in the established grassland systems of the Schwäbische Alb., Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659, Stiftung Landesbank Baden‐Württemberg, Swiss National Science Foundation http://dx.doi.org/10.13039/501100001711, http://doi.org/10.17616/R32P9Q

Acidobacteria occur in a large variety of ecosystems worldwide and are particularly abundant and highly diverse in soils. In spite of their diversity, only few species have been characterized to date which makes

Grassland management can influence nitrogen leaching by changing respective inputs (like fertilization) and outputs (e.g. harvest) from the ecosystem but also through changes in plant and microbial communities and their interactions with the soil. Yet the mechanisms of these processes and their importance for nitrate (NO3-) and ammonium (NH4+) are poorly researched. Although temperate grassland management can cause a high leaching risk, studies measuring annual soil nitrogen fluxes and covering a high number of sites are limited. Using a resin method, we measured annual leaching fluxes of NO3-N and NH4-N in 150 grassland sites in three German regions from spring 2018 to spring 2019 at a depth of 10 cm. We used Structural Equation Modeling to identify direct and indirect management effects on nitrogen leaching. Both fertilization and grazing intensities increased NO3-N leaching to almost the same extent. Fertilization intensity increased NO3-N leaching directly and indirectly i) by decreasing the negative effect of plant richness on NO3-N leaching and ii) by increasing the positive effect of legume cover on NO3-N leaching. Similarly, grazing intensity increased NO3-N directly and indirectly i) by increasing the positive effect of legume cover on NO3-N leaching and ii) by decreasing the negative effect of grass cover on NO3-N leaching. Microbial biomass (nitrogen) increased NO3-N leaching and it was not controlled by management. Fertilization strongly increased NH4-N leaching, both by a direct effect and indirectly by increasing the positive effect of plant nitrogen on NH4-N. Grazing intensity and plant richness had no direct effects on NH4-N leaching. We have shown that grassland management considerably influences inorganic nitrogen leaching in the annual basis, and that fertilization intensity is more important than grazing, especially for NH4-N leaching. Moreover, we found that plant diversity decreases NO3-N leaching, but this effect is controlled by fertilization leading to increased leaching risks. Thus, reducing the management intensity, both in meadows and pastures, can be used as a mitigation tool for inorganic nitrogen leaching.

Land-use intensification can increase provisioning ecosystem services, such as food and timber production, but it also drives changes in ecosystem functioning and biodiversity loss, which may ultimately compromise human wellbeing. To understand how changes in land-use intensity affect the relationships between biodiversity, ecosystem functions, and services, we built networks from correlations between the species richness of 16 trophic groups, 10 ecosystem functions, and 15 ecosystem services. We evaluated how the properties of these networks varied across land-use intensity gradients for 150 forests and 150 grasslands. Land-use intensity significantly affected network structure in both habitats. Changes in connectance were larger in forests, while changes in modularity and evenness were more evident in grasslands. Our results show that increasing land-use intensity leads to more homogeneous networks with less integration within modules in both habitats, driven by the belowground compartment in grasslands, while forest responses to land management were more complex. Land-use intensity strongly altered hub identity and module composition in both habitats, showing that the positive correlations of provisioning services with biodiversity and ecosystem functions found at low land-use intensity levels, decline at higher intensity levels. Our approach provides a comprehensive view of the relationships between multiple components of biodiversity, ecosystem functions, and ecosystem services and how they respond to land use. This can be used to identify overall changes in the ecosystem, to derive mechanistic hypotheses, and it can be readily applied to further global change drivers. The work has been supported by the DFG Priority Program 1374 “Infrastructure-Biodiversity-Exploratories”. S.S. was supported by the Spanish Government under Ramón y Cajal Contract RYC-2016-20604.

Aerated topsoils are important sinks for atmospheric methane (CH4) via oxidation by CH4‐oxidizing bacteria (MOB). However, intensified management of grasslands and forests may reduce the CH4 sink capacity of soils. We investigated the influence of grassland land‐use intensity (150 sites) and forest management type (149 sites) on potential atmospheric CH4 oxidation rates (PMORs) and the abundance and diversity of MOB (with qPCR) in topsoils of three temperate regions in Germany. PMORs measurements in microcosms under defined conditions yielded approximately twice as much CH4 oxidation in forest than in grassland soils. High land‐use intensity of grasslands had a negative effect on PMORs (−40%) in almost all regions and fertilization was the predominant factor of grassland land‐use intensity leading to PMOR reduction by 20%. In contrast, forest management did not affect PMORs in forest soils. Upland soil cluster (USC)‐α was the dominant group of MOBs in the forests. In contrast, USC‐γ was absent in more than half of the forest soils but present in almost all grassland soils. USC‐α abundance had a direct positive effect on PMOR in forest, while in grasslands USC‐α and USC‐γ abundance affected PMOR positively with a more pronounced contribution of USC‐γ than USC‐α. Soil bulk density negatively influenced PMOR in both forests and grasslands. We further found that the response of the PMORs to pH, soil texture, soil water holding capacity and organic carbon and nitrogen content differ between temperate forest and grassland soils. pH had no direct effects on PMOR, but indirect ones via the MOB abundances, showing a negative effect on USC‐α, and a positive on USC‐γ abundance. We conclude that reduction in grassland land‐use intensity and afforestation has the potential to increase the CH4 sink function of soils and that different parameters determine the microbial methane sink in forest and grassland soils. Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659 ESF Ministry of Education, Science and Culture of Mecklenburg‐Western Pomerania

Nutrient contents of soil organic matter in forests vary with regional differences in soil types and parent material, and can be modified by forest type and management intensity. Variation of organic carbon (OC)-to-nutrient ratios in soils supposedly alters microbial carbon and nutrient use efficiencies and the rates of OC-to-nutrient mineralization. Here, we studied mineralization rates of carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) for topsoil samples from differently managed forest plots in Germany. Samples were incubated for two weeks in microlysimeters under controlled conditions. CO2 respiration, leachable dissolved organic carbon (DOC), nitrate (NO3–), ammonium (NH4+), sulfate (SO42–), and phosphate (PO43–) were determined as net organic C (OC) and nutrient mineralization rates. We hypothesized that in soils with high C-to-nutrient ratios, soil microbes may mobilize relatively more OC as CO2 or DOC than nutrients to meet their nutrient requirements. Further, we hypothesized that forest management practices, such as tree species selection and harvest intensity, potentially affect the stoichiometry of SOM mineralization by altering the ratios of C-to-nutrients in soils. Results showed that CO2-release rates were proportional to soil OC, but when normalized to microbial biomass C, they increased, similar to DOC leaching rates, with soil OC-to-N ratios. However, contrary to our expectation, higher soil OC-to-nutrient ratios did not go along with reduced nutrient leaching. Instead, when normalized to soil OC, the largest amounts of N, P, and S were leached in the most nutrient poor region, so that sites with highest soil OC-to-nutrient ratios had the smallest OC-to-nutrient mineralization ratio. Forest type and tree species selection affected soil stoichiometry only in the most nutrient poor region with higher OC-to-nutrient ratios under coniferous than deciduous forest sites. This potentially caused the significantly enhanced OC-normalized DOC leaching rates under coniferous forests. However, in the two other study regions tree species had a significant effect on N and S leaching rates and the ratio of OC-to-nutrient leaching despite similar stoichiometry. Overall, our study suggests that increasing nutrient scarcity enhances microbial based CO2 and DOC production, possibly because of increased energy demand for enzyme production and to remove excess OC to reach and mobilize more nutrients, thereby allowing for high nutrient leaching rates despite small total stocks. Forest management affected OC-to-nutrient mineralization rates mostly via tree species selection, but observed differences were not obviously caused by soil stoichiometry but rather by other ecological differences between forest types.

Land-use intensification has contrasting effects on different ecosystem services, often leading to land-use conflicts. While multiple studies have demonstrated how landscape-scale strategies can minimise the trade-off between agricultural production and biodiversity conservation, little is known about which land-use strategies maximise the landscape-level supply of multiple ecosystem services (landscape multifunctionality), a common goal of stakeholder communities.We combine comprehensive data collected from 150 German grassland sites with a simulation approach to identify landscape compositions, with differing proportions of low-, medium-, and high-intensity grasslands, that minimise trade-offs between the six main grassland ecosystem services prioritised by local stakeholders: biodiversity conservation, aesthetic value, productivity, carbon storage, foraging, and regional identity. Results are made accessible through an online tool that provides information on which compositions best meet any combination of user-defined priorities (https://neyret.shinyapps.io/landscape_composition_for_multifunctionality/).Results show that an optimal landscape composition can be identified for any pattern of ecosystem service priorities. However, multifunctionality was similar and low for all landscape compositions in cases where there are strong trade-offs between services (e.g. aesthetic value and fodder production), where many services were prioritised, and where drivers other than land use played an important role. We also found that if moderate service levels are deemed acceptable, then strategies in which both high and low intensity grasslands are present can deliver landscape multifunctionality. The tool presented can aid informed decision-making by predicting the impact of future changes in landscape composition, and by allowing for the relative roles of stakeholder priorities and biophysical trade-offs to be understood by scientists and practitioners alike.HighlightsAn online tool identifies optimal landscape compositions for desired ecosystem servicesWhen the desired services are synergic, the optimum is their common best landscape compositionWhen the desired services trade-off, a mix of grassland intensity is most multifunctionalSuch tools could support decision-making processes and aid conflict resolutionGraphical abstract

Soil bacteria have been investigated for more than a century, but one of the most dominant terrestrial groups on Earth, “Candidatus Udaeobacter,” remains elusive and largely unexplored. Its natural habitat is considered a major reservoir of antibiotics, which directly or indirectly impact phylogenetically diverse microorganisms. Here, we found that “Ca. Udaeobacter” representatives exhibit multidrug resistance and not only evade harmful effects of antimicrobials but even benefit from antibiotic pressure in soil. Therefore, “Ca. Udaeobacter” evidently affects the composition of soil resistomes worldwide and might represent a winner of rising environmental pollution with antimicrobials. In addition, our study indicates that “Ca. Udaeobacter” representatives utilize H2 and thereby contribute to global hydrogen cycling. The here-reported findings provide insights into elementary lifestyle features of “Ca. Udaeobacter,” potentially contributing to its successful global dissemination., Verrucomicrobia affiliated with “Candidatus Udaeobacter” belong to the most abundant soil bacteria worldwide. Although the synthesis of antibiotics presumably evolved in soil, and environmental pollution with antimicrobials increases, the impact of these complex molecules on “Ca. Udaeobacter” remains to be elucidated. In this study, we demonstrate that “Ca. Udaeobacter” representatives residing in grassland as well as forest soil ecosystems show multidrug resistance and even take advantage of antibiotics release. Soils treated with up to six different antibiotics exhibited a higher “Ca. Udaeobacter” abundance than corresponding controls after 3, 8, and 20 days of incubation. In this context, we provide evidence that “Ca. Udaeobacter” representatives may utilize nutrients which are released due to antibiotic-driven lysis of other soil microbes and thereby reduce energetically expensive synthesis of required biomolecules. Moreover, genomic analysis revealed the presence of genes conferring resistance to multiple classes of antibiotics and indicated that “Ca. Udaeobacter” representatives most likely oxidize the trace gas H2 to generate energy. This energy might be required for long-term persistence in terrestrial habitats, as already suggested for other dominant soil bacteria. Our study illustrates, for the first time, that globally abundant “Ca. Udaeobacter” benefits from release of antibiotics, which confers advantages over other soil bacteria and represents a so-far overlooked fundamental lifestyle feature of this poorly characterized verrucomicrobial genus. Furthermore, our study suggests that “Ca. Udaeobacter” representatives can utilize H2 as an alternative electron donor. IMPORTANCE Soil bacteria have been investigated for more than a century, but one of the most dominant terrestrial groups on Earth, “Candidatus Udaeobacter,” remains elusive and largely unexplored. Its natural habitat is considered a major reservoir of antibiotics, which directly or indirectly impact phylogenetically diverse microorganisms. Here, we found that “Ca. Udaeobacter” representatives exhibit multidrug resistance and not only evade harmful effects of antimicrobials but even benefit from antibiotic pressure in soil. Therefore, “Ca. Udaeobacter” evidently affects the composition of soil resistomes worldwide and might represent a winner of rising environmental pollution with antimicrobials. In addition, our study indicates that “Ca. Udaeobacter” representatives utilize H2 and thereby contribute to global hydrogen cycling. The here-reported findings provide insights into elementary lifestyle features of “Ca. Udaeobacter,” potentially contributing to its successful global dissemination.

Root-associated mycobiomes (RAMs) link plant and soil ecological processes, thereby supporting ecosystem functions. Understanding the forces that govern the assembly of RAMs is key to sustainable ecosystem management. Here, we dissected RAMs according to functional guilds and combined phylogenetic and multivariate analyses to distinguish and quantify the forces driving RAM assembly processes. Across large biogeographic scales (>1,000 km) in temperate forests (>100 plots), RAMs were taxonomically highly distinct but composed of a stable trophic structure encompassing symbiotrophic, ectomycorrhizal (55%), saprotrophic (7%), endotrophic (3%) and pathotrophic fungi (

1.Rapid growth of the world's human population has increased pressure on landscapes to deliver high levels of multiple ecosystem services, including food and fibre production, carbon storage, biodiversity conservation and recreation. However, we currently lack general principles describing how to achieve this landscape multifunctionality. 2.We combine theoretical simulations and empirical data on 14 ecosystem services measured across 150 grasslands in three German regions. In doing so, we investigate the circumstances under which spatial heterogeneity in a driver of ecosystem functioning (an ‘ecosystem‐driver,’ e.g. the presence of keystone species, land‐use intensification or habitat types) increases landscape‐level ecosystem multifunctionality. 3.Simulations based on theoretical data demonstrated that relationships between heterogeneity and landscape multifunctionality are highly variable and can range from non‐significant to strongly positive. Despite this variability, we could identify criteria under which heterogeneity‐landscape multifunctionality relationships were most strongly positive: this happened when multiple ecosystem services responded contrastingly (both positively and negatively) to an ecosystem‐driver. 4.These findings were confirmed using empirical data, which showed that heterogeneity in land‐use intensity promoted landscape multifunctionality in cases where functions with both positive (e.g. plant biomass) and negative (e.g. flower cover) responses to land use intensification were included. For example, the simultaneous provisioning of ecosystem functions related to forage production (generally profiting from land‐use intensification), biodiversity conservation and recreation (generally decreasing with land‐use intensification) was highest in landscapes consisting of sites varying in land‐use intensity. 5.Synthesis and applications. Our findings show that there are general principles governing landscape multifunctionality. A knowledge of these principles may support land management decisions. For example, knowledge of relationships between ecosystem services and their drivers, such as land use type, can help estimate the consequences of increasing or decreasing heterogeneity for landscape‐level ecosystem service supply, although interactions between landscape units (e.g. the movement of pollinators) must also be considered.

Microorganisms in forest soils provide essential ecosystem services, such as decomposition of organic matter and nutrient mineralization. However, microbial community structure and function can be affected by environmental conditions, such as regional climate and soil properties and, moreover, by human activity through forest management. We examined the biomass and composition of microbial assemblages in 150 forest stands in the organic layer (Oi, Oe, Oa) and upper mineral soil (0–10 cm) in three regions across Germany (Schwabische Alb, Hainich-Dun, Schorfheide-Chorin) by phospholipid fatty acid (PLFA) analysis. Different explanatory environmental variables (total C, N, S, P, organic C, inorganic C, pH, water content) were identified. The intensity of land use was characterized with the Forest Management Intensity Index (ForMI). The total amount of PLFAs, as measure for microbial biomass, was different among the three regions both in the organic layer and mineral soil. In the organic layer, total PLFAs decreased from Schwabische Alb over Hainich-Dun to Schorfheide-Chorin, with the latter comprising a fourfold and twofold lower amount in fungal and bacterial PLFAs, respectively. In contrast, in the mineral soil the forests in the Hainich-Dun showed the highest microbial biomass. Discriminant function analysis of PLFA pattern indicated that Gram-positive bacteria and fungi accounted mainly for the regional differences in the organic layer, whereas in the mineral soil additionally Gram-negative and actinobacteria were important. Redundancy analysis showed that PLFA profiles were predominantly affected by sampling site and environmental variables, with the water content in the organic layer and the soil texture in the mineral soil explaining most of the variability in microbial communities between the three regions. Additionally, forest stands were classified into four management groups (conifer; deciduous with low, medium, and high intensity) based on the ForMI. In the mineral soil, forest management accounted for a small proportion of the observed regional differences. Within regions, fungal biomass in the organic layer decreased with management intensity at the Schwabische Alb and increased in the mineral soils of Hainich-Dun region. Microbial community structure discriminated coniferous and deciduous forests in all three regions, and moreover showed a separation based on forest management intensity in the Schorfheide-Chorin. In conclusion, microbial biomass and community composition in forest organic layer and mineral soil were more influenced by regional conditions, including environmental properties such as moisture, soil texture, C/N ratio and pH, than by forest management intensity. However, within given environments, microbial assemblages can be influenced by forest management, in particular through changes in the tree species composition.

In this study, we investigated how co-occurrence patters of ammonia and nitrite oxidizers, which drive autotrophic nitrification, are influenced by tree species composition as well as soil pH in different forest soils. We expected that a decline of ammonia oxidizers in coniferous forests, as a result of excreted nitrification inhibitors and at acidic sites with low availability of ammonia, would reduce the abundance of nitrite-oxidizing bacteria (NOB). To detect shifts in co-occurrence patterns, the abundance of key players was measured at 50 forest plots with coniferous respectively deciduous vegetation and different soil pH levels in the region Schwabische Alb (Germany). We found ammonia-oxidizing archaea (AOA) and Nitrospira-like NOB (NS) to be dominating in numbers over their counterparts across all forest types. AOA co-occurred mostly with NS, while bacterial ammonia oxidizers (AOB) were correlated with Nitrobacter-like NOB (NB). Co-occurrence patterns changed from tight significant relationships of all ammonia and nitrite oxidizers in deciduous forests to a significant relationship of AOB and NB in coniferous forests, where AOA abundance was reduced. Surprisingly, no co-occurrence structures between ammonia and nitrite oxidizers could be determined at acidic sites, although abundances were correlated to the respective nitrogen pools. This raises the question whether interactions with heterotrophic nitrifiers may occur, which needs to be addressed in future studies.

Forest soils play an important role in the active carbon (C) cycle of terrestrial ecosystems as they store one third of the global organic carbon. Therefore, the sequestration of atmospheric carbon in soils as stable organic matter is discussed as a potential contribution to mitigate atmospheric CO2 concentrations. The carbon dynamic in forest ecosystems is expected to be a result of environmental as well as human-induced factors. Germany’s forest soils contained in the organic layer and the mineral soil down to 90 cm on average 117.1 ± 1.7 Mg C ha–1 which has been increased significantly since the NFSI I by 0.75 ± 0.09 Mg C ha–1 year–1 resulting in a total increase of 11.3 Mg C ha–1. Structural equation modelling was performed to analyze direct and indirect factors affecting organic carbon stocks and organic carbon stock changes. The pathway analyses revealed a variation of carbon stocks in the organic layer that was especially controlled by tree species. Organic layers under broadleaf trees stored less carbon than under coniferous trees, while tree species effects on carbon stocks of mineral soil were comparatively less pronounced. Soil carbon stocks were furthermore affected by site conditions. An effective selection of tree species combined with specific site conditions may therefore enhance carbon sequestration potential of soils. We found specific effects of nitrogen deposition and forest liming on carbon stock changes. The additional nitrogen has the potential to increase sequestering carbon by an increase in productivity and accumulation of soil organic matter through increased litter production, while liming may both stimulate and inhibit soil respiration depending on various environmental conditions. Altogether, the results showed that further research is needed to identify the most important factors affecting turnover of soil organic matter in respect to the impact of anthropogenic effects as forest stand management, liming, or atmospheric nitrogen deposition especially on dynamics of microbial communities as well as on recalcitrance and stabilization of soil organic matter.

Soil organic matter (SOM) content and composition may be affected by geographic region, land use (grassland vs. forest) and management intensity (intensive vs. extensive). To asses these effects SOM of 300 German soils was characterized using soil color analyses (L*,a*,b*-values) and Fourier transform infrared (FTIR) spectroscopy. Soil lightness (L*-value) was strongly negatively correlated with the soil organic carbon content and this relationship was stronger when the previously sieved soils were ground. Using the band at wavenumber 1634 cm − 1 (as determined by FTIR) as a proxy for aromaticity of SOM the L*-value was negatively correlated with aromaticity. Geographic region as well as land use affected L*-, a*- and b*-values. FTIR results suggested that particularly amides and polysaccharides were affected by geographic region, while mainly polysaccharides were affected by land use. We conclude that soil color analysis can provide additional information on environmental circumstances/site effects which may affect SOM composition. A few only weak correlations of soil color/SOM composition parameters with management intensity indicate that either changes in SOM parameters were too small or that the applied management indices were not sensitive enough to management effects.

Many experiments have shown that loss of biodiversity reduces the capacity of ecosystems to provide the multiple services on which humans depend. However, experiments necessarily simplify the complexity of natural ecosystems and will normally control for other important drivers of ecosystem functioning, such as the environment or land use. In addition, existing studies typically focus on the diversity of single trophic groups, neglecting the fact that biodiversity loss occurs across many taxa and that the functional effects of any trophic group may depend on the abundance and diversity of others. Here we report analysis of the relationships between the species richness and abundance of nine trophic groups, including 4,600 above- and below-ground taxa, and 14 ecosystem services and functions and with their simultaneous provision (or multifunctionality) in 150 grasslands. We show that high species richness in multiple trophic groups (multitrophic richness) had stronger positive effects on ecosystem services than richness in any individual trophic group; this includes plant species richness, the most widely used measure of biodiversity. On average, three trophic groups influenced each ecosystem service, with each trophic group influencing at least one service. Multitrophic richness was particularly beneficial for 'regulating' and 'cultural' services, and for multifunctionality, whereas a change in the total abundance of species or biomass in multiple trophic groups (the multitrophic abundance) positively affected supporting services. Multitrophic richness and abundance drove ecosystem functioning as strongly as abiotic conditions and land-use intensity, extending previous experimental results to real-world ecosystems. Primary producers, herbivorous insects and microbial decomposers seem to be particularly important drivers of ecosystem functioning, as shown by the strong and frequent positive associations of their richness or abundance with multiple ecosystem services. Our results show that multitrophic richness and abundance support ecosystem functioning, and demonstrate that a focus on single groups has led to researchers to greatly underestimate the functional importance of biodiversity.

The microbiota in three distinct terrestrial habitats (biological soil crusts – BSC, crust-adhering soil beneath BSC – trans, and crust-free soil close to BSC – soil) was studied in 33 temperate forest stands differing in management intensity (ForMI). Specific lipid fractions and respective marker fatty acids were used to determine microbial biomass and community structure (phospholipid fatty acids – PLFA), energy reserves (neutral lipid fatty acids – NLFA), and community level lipid profiles (CLLP) of nematodes and enchytraeids. The density and diversity of nematode fauna were additionally determined morphologically. The highest total amounts of PLFA and NLFA occurred in the BSC, followed by soil and trans habitats, indicating stronger effects of habitats than forest management intensity. This corresponds to the distribution pattern of bacterial PLFA that dominated the soil microbiota. The highest nematode population density occurred in the BSC, followed by soil and trans. The BSC was dominated by bacterial feeders and omnivores, while plant feeding nematodes were most frequent in the crust-free soil habitat. The highest biomass of photoautotrophs also occurred in the BSC, followed by the crust-adhering and crust-free soil habitats. Redundancy analysis indicated strong effect of ForMI and total N on soil PFLAs and NFLAs across habitats. The C:N and C:S ratios were important for the separation of NLFAs while P:S accounted for the separation of PLFAs. Bacterial and fungal PLFAs largely separated the microbial community across habitats, and particularly between BSC and trans habitats. The separation of nematodes and enchytraeids by CLLP was less pronounced, and most distinct between the crust-free soil and BSC or crust-adhering soil habitats. Overall, BSC and crust-adhering soil habitats provide different suitability for microbiota, resulting in specifically adapted communities that are shaped by the management intensity and nutrient availability.

Fine roots support the water and nutrient demands of plants and supply carbon to soils. Quantifying turnover times of fine roots is crucial for modeling soil organic matter dynamics and constraining carbon cycle–climate feedbacks. Here we challenge widely used isotope-based estimates suggesting the turnover of fine roots of trees to be as slow as a decade. By recording annual growth rings of roots from woody plant species, we show that mean chronological ages of fine roots vary from, Fine-root lifetimes and carbon inputs from roots into soil impact carbon cycle-climate feedbacks yet remain poorly constrained. Here, using annual-growth rings and radiocarbon dating, the authors show that the chronological age of fine roots is substantially younger than that of the carbon used for their growth.