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Forest soil and litter is inhabited by a diverse community of animals, which directly and indirectly rely on dead organic matter as habitat and food resource. However, community composition may be driven by biotic or abiotic forces, and these vary with changes in habitat structure and resource supply associated with forest land use. To evaluate these changes, we compiled comprehensive data on the species composition of soil animal communities and environmental factors in forest types varying in land-use intensity in each of three regions in Germany, i.e., coniferous, young managed, old managed, and unmanaged beech forests. Coniferous forests featured high amounts of leaf litter and low microbial biomass concentrations contrasting in particular unmanaged beech forests. However, soil animal diversity and functional community composition differed little between forest types, indicating resilience against disturbance and forest land use. Structural equation modelling suggested that despite a significant influence of forest management on resource abundance and quality, the biomass of most soil fauna functional groups was not directly affected by forest management or resource abundance/quality, potentially because microorganisms hamper the propagation of nutrients to higher trophic levels. Instead, detritivore biomass depended heavily on soil pH. Macrofauna decomposers thrived at high pH, whereas mesofauna decomposers benefitted from low soil pH, but also from low biomass of macrofauna decomposers, potentially due to habitat modification by macrofauna decomposers. The strong influence of soil pH shows that decomposer communities are structured predominantly by regional abiotic factors exceeding the role of local biotic factors such as forest type. Supplementary Information The online version contains supplementary material available at 10.1007/s00442-021-04910-1.

Anthropogenic pressures alter the biodiversity, structure and organization of biological communities with severe consequences for ecosystem processes. Species invasion is such a human-induced ecosystem change with pronounced impacts on recipient ecosystems. Around the globe, earthworms invade habitats and impact abiotic soil conditions and a wide range of above- and belowground organisms. In northern North America, where earthworms have been largely absent since the last glaciation period and most earthworm species present today have only been (re-)introduced a few hundred years ago, invasion impacts have been intensively studied. However, despite several studies assessing impacts of invasive earthworms on soil fauna, studies have rarely investigated the simultaneous responses of different soil-fauna size groups and biodiversity facets which might respond differently to earthworm invasion and independently affect ecosystem processes. Our study goes beyond previously-established knowledge on earthworm-invasion effects by simultaneously assessing differences in four biodiversity facets, namely the abundance, biomass, richness and Shannon index of soil invertebrate macro-, meso- and microfauna communities between high- and low-invasion status plots (n = 80) and in relation to invasion intensity measured as earthworm biomass across four northern North American forests sampled between 2016 and 2017. Across forests and soil-fauna groups, we found reduced abundance (−33 to −45%) and richness (−18 to −25%) in high compared to low-invasion status areas. Additionally, meso- (−14%) and microfauna biomass (−38%) and macro- (−7%) and microfauna Shannon index (−8%) were reduced. Higher invasion intensity (earthworm biomass) was additionally related to reduced soil-fauna biodiversity. While the studied biodiversity facet was important for the soil fauna response, soil-fauna size group was comparably unimportant. Given the global ubiquity of earthworm invasion and the importance of soil fauna for key ecosystem processes, our observational results help to assess future impacts of this invasion and the consequences for anthropogenically-altered ecosystem functioning.

Herein, we update the diagnosis and description of the genus Krantzolaspina Datta & Bhattacharjee and provide a list of the three valid species including new combinations and synonyms, as follows: 1) Krantzolaspina angustatus (Ishikawa, 1987) comb. nov. (= Indutolaelaps jiroftensis Hajizadeh et al., 2017 syn. nov.), 2) K. rebatii Datta & Bhattacharjee, 1989 and 3) K. solimani (Metwali, 1983) comb. nov. Finally, we re-describe K. angustatus (Ishikawa, 1987) comb. nov. based on the holotype from Japan, voucher specimens from Iran and additional females that we found in soil samples from oil palm plantations in Sumatra, Indonesia.

Declining arthropod communities have recently gained a lot of attention, with climate and land-use change among the most frequently discussed drivers. Here, we focus on a seemingly underrepresented driver of arthropod community decline: biological invasions. For approximately 12 000 years, earthworms have been absent from wide parts of northern North America, but they have been re-introduced with dramatic consequences. Most studies investigating earthworm-invasion impacts focus on the belowground world, resulting in limited knowledge on aboveground-community changes. We present observational data on earthworm, plant and aboveground arthropod communities in 60 plots, distributed across areas with increasing invasion status (low, medium and high) in a Canadian forest. We analysed how earthworm-invasion status and biomass impact aboveground arthropod community abundance, biomass and species richness, and how earthworm impacts cascade across trophic levels. We sampled approximately 13 000 arthropods, dominated by Hemiptera, Diptera, Araneae, Thysanoptera and Hymenoptera. Total arthropod abundance, biomass and species richness declined significantly from areas of low to those with high invasion status, with reductions of 61, 27 and 18%, respectively. Structural equation models suggest that earthworms directly and indirectly impact arthropods across trophic levels. We show that earthworm invasion can alter aboveground multi-trophic arthropod communities and suggest that belowground invasions might be underappreciated drivers of aboveground arthropod decline.

Soil organisms drive major ecosystem functions by mineralising carbon and releasing nutrients during decomposition processes, which supports plant growth, aboveground biodiversity and, ultimately, human nutrition. Soil ecologists often operate with functional groups to infer the effects of individual taxa on ecosystem functions and services. Simultaneous assessment of the functional roles of multiple taxa is possible using food-web reconstructions, but our knowledge of the feeding habits of many taxa is insufficient and often based on limited evidence. Over the last two decades, molecular, biochemical and isotopic tools have improved our understanding of the feeding habits of various soil organisms, yet this knowledge is still to be synthesised into a common functional framework. Here, we provide a comprehensive review of the feeding habits of consumers in soil, including protists, micro-, meso- and macrofauna (invertebrates), and soil-associated vertebrates. We have integrated existing functional group classifications with findings gained with novel methods and compiled an overarching classification across taxa focusing on key universal traits such as food resource preferences, body masses, microhabitat specialisation, protection and hunting mechanisms. Our summary highlights various strands of evidence that many functional groups commonly used in soil ecology and food-web models are feeding on multiple types of food resources. In many cases, omnivory is observed down to the species level of taxonomic resolution, challenging realism of traditional soil food-web models based on distinct resource-based energy channels. Novel methods, such as stable isotope, fatty acid and DNA gut content analyses, have revealed previously hidden facets of trophic relationships of soil consumers, such as food assimilation, multichannel feeding across trophic levels, hidden trophic niche differentiation and the importance of alternative food/prey, as well as energy transfers across ecosystem compartments. Wider adoption of such tools and the development of open interoperable platforms that assemble morphological, ecological and trophic data as traits of soil taxa will enable the refinement and expansion of the multifunctional classification of consumers in soil. The compiled multifunctional classification of soil-associated consumers will serve as a reference for ecologists working with biodiversity changes and biodiversity–ecosystem functioning relationships, making soil food-web research more accessible and reproducible.

Many ecosystem functions depend on the structure of food webs, which heavily relies on the body size spectrum of the community. Despite that, little is known on how the size spectrum of soil animals responds to agricultural practices in tropical land-use systems and how these responses affect ecosystem functioning. We studied land-use-induced changes in below-ground communities in tropical lowland ecosystems in Sumatra (Jambi province, Indonesia), a hot spot of tropical rainforest conversion into rubber and oil palm plantations. The study included ca. 30,000 measured individuals from 33 high-order taxa of meso- and macrofauna spanning eight orders of magnitude in body mass. Using individual body masses, we calculated the metabolism of trophic guilds and used food web models to calculate energy fluxes and infer ecosystem functions, such as decomposition, herbivory, primary and intraguild predation. Land-use change was associated with reduced abundance and taxonomic diversity of soil invertebrates, but strong increase in total biomass and moderate changes in total energy flux. These changes were due to increased biomass of large-sized decomposers in soil, in particular earthworms, with their share in community metabolism increasing from 11% in rainforest to 59%-76% in jungle rubber, and rubber and oil palm plantations. Decomposition, that is the energy flux to decomposers, stayed unchanged, but herbivory, primary and intraguild predation decreased by an order of magnitude in plantation systems. Intraguild predation was very important, being responsible for 38% of the energy flux in rainforest according to our model. Conversion of rainforest into monoculture plantations is associated by an uneven loss of size classes and trophic levels of soil invertebrates resulting in sequestration of energy in large-sized primary consumers and restricted flux of energy to higher trophic levels. Pronounced differences between rainforest and jungle rubber reflect sensitivity of rainforest soil animal communities to moderate land-use changes. Soil communities in plantation systems sustained high total energy flux despite reduced biodiversity. The high energy flux into large decomposers but low energy fluxes into other trophic guilds suggests that trophic multifunctionality of below-ground communities is compromised in plantation systems.

We investigated how the land-use change from rainforest into jungle rubber, intensive rubber and oil palm plantations affects decomposers and litter decomposition in Sumatra, Indonesia. Litterbags containing three litter types were placed into four land-use systems and harvested after 6 and 12 months. Litter mass loss and litter element concentrations were measured, and different microbial groups including bacteria, fungi and testate amoebae were studied. After 12 months 81, 65, 63 and 53% of litter exposed in rainforest, jungle rubber in oil palm and rubber plantations was decomposed. In addition to land use, litter decomposition varied strongly with litter type and short-term effects differed markedly from long-term effects. After 6 months, oil palm and rubber litter decomposed faster than rainforest litter, but after 12 months, decomposition of rainforest litter exceeded that of oil palm and rubber litter, reflecting adaptation of bacteria and fungi to decompose structural compounds in rainforest litter but not (or less) in rubber and oil palm litter. Bacterial and fungal community composition and testate amoeba species number and density varied strongly with litter type, but little with land use. However, community composition of testate amoebae was mainly affected by land use. Generally, changes in bacteria, fungi and testate amoebae were linked to changes in litter element concentrations, suggesting that element ratios of litter material as basal resource for the decomposer food web shape the structure of decomposer communities and decomposition processes via bottom-up forces. Overall, changing rainforest to monoculture plantations shifts the decomposer community structure and negatively affects litter decomposition.

Deforestation and land-use change in tropical regions result in habitat loss and extinction of species that are unable to adapt to the conditions in agricultural landscapes. If the associated loss of functional diversity is not compensated by species colonizing the converted habitats, extinctions might be followed by a reduction or loss of ecosystem functions including biological control. To date, little is known on how land-use change in the tropics alters the functional diversity of invertebrate predators and which key environmental factors may mitigate the decline in functional diversity and predation in litter and soil communities. We applied litter sieving and heat extraction to study ground spider communities and assessed structural characteristics of vegetation and parameters of litter in rainforest and agricultural land-use systems (jungle rubber, rubber and oil palm monocultures) in a Southeast Asian hotspot of rainforest conversion: Sumatra, Indonesia. We found that (1) spider density, species richness, functional diversity and community predation (energy flux to spiders) were reduced by 57-98% from rainforest to oil palm monoculture; (2) jungle rubber and rubber monoculture sustained relatively high diversity and predation in ground spiders, but small cryptic spider species strongly declined; (3) high species turnover compensated losses of some functional trait combinations, but did not compensate for the overall loss of functional diversity and predation per unit area; (4) spider diversity was related to habitat structure such as amount of litter, understory density and understory height, while spider predation was better explained by plant diversity. Management practices that increase habitat structural complexity and plant diversity such as mulching, reduced weeding, and intercropping monocultures with other plants may contribute to maintaining functional diversity of and predation services provided by ground invertebrate communities in plantations.

Feeding on a variety of resources, collembolans have been assumed to be food generalists. However, recent stable isotope analyses documented that collembolan species occupy different trophic levels, but detailed studies on species-specific food resources are sparse. Further, it still is little understood whether food resources of collembolan species are constant or shift, e.g., with habitats. Fatty acid (FA) and stable isotope analysis allow insight into utilisation of basal resources and trophic levels of consumers, respectively. We combined these methods to investigate variations in trophic niches of six collembolan species (Lepidocyrtus lanuginosus, Folsomia quadrioculata, Parisotoma notabilis, Ceratophysella denticulata, Isotomiella minor and Protaphorura armata) in beech and spruce forests. We correlated collembolan FAs with that of litter microorganisms at the respective study sites to identify links to resources. FA composition and stable isotope signatures in collembolan species did not differ significantly between forest types but between species suggesting pronounced trophic niche differentiation between species. The trophic niche of C. denticulata and P. armata was similar and significantly differed from the other species with 13C and 15N signatures being least depleted. We suggest that C. denticulata has a predatory life style feeding on nematodes. Due to intermediate to low 13C and 15N levels and specific FA compositions the other collembolan species could be ascribed to secondary decomposers with I. minor being more closely associated with bacterial resources and F. quadrioculata, L. lanuginosus and P. notabilis with fungal resources. However, dietary niches presumably comprise a mixture of resources rather than single resources. FAs in collembolan species correlated poorly with those in litter suggesting that the diet of collembolan species is rather independent of the structure of microbial communities in bulk litter. The results suggest that collembolans consume resources of microsites rather than bulk material thereby benefitting from the small-scale heterogeneity in resource distribution in soil. Low variation in trophic niches with forest type suggests that these microsites are similar across different forests and provide similar food resources despite marked differences in e.g., litter materials and humus structure.

Mesofauna taxa fill key trophic positions in soil food webs, even in terrestrial-marine boundary habitats characterized by frequent natural disturbances. Salt marshes represent such boundary habitats, characterized by frequent inundations increasing from the terrestrial upper to the marine pioneer zone. Despite the high abundance of soil mesofauna in salt marshes and their important function by facilitating energy and carbon flows, the structure, trophic ecology and habitat-related diet shifts of mesofauna species in natural salt marsh habitats is virtually unknown. Therefore, we investigated the effects of natural disturbance (inundation frequency) on community structure, food web complexity and resource use of soil mesofauna using stable isotope analysis (15N, 13C) in three salt marsh zones. In this intertidal habitat, the pioneer zone is exposed to inundations twice a day, but lower and upper salt marshes are less frequently inundated based on shore height. The mesofauna comprised 86 species / taxa dominated by Collembola, Oribatida and Mesostigmata. Shifts in environmental disturbances influenced the structure of food webs, diversity and density declined strongly from the land to the sea pointing to the importance of increasing levels of inundation frequency. Accordingly, the reduced diversity and density was associated by a simplification of the food web in the pioneer zone as compared to the less inundated lower and upper salt marsh with a higher number of trophic levels. Strong variations in δ15N signatures demonstrated that mesofauna species are feeding at multiple trophic levels. Primary decomposers were low and most mesofauna species functioned as secondary decomposers or predators including second order predators or scavengers. The results document that major decomposer taxa, such as Collembola and Oribatida, are more diverse than previously assumed and predominantly dwell on autochthonous resources of the respective salt marsh zone. The results further suggest that Mesostigmata mostly adopt an intraguild predation lifestyle. The high trophic position of a large number of predators suggests that intraguild predation is of significant importance in salt marsh food webs. Presumably, intraguild predation contributes to stabilizing the salt marsh food web against disturbances.

To maintain constant chemical composition, i.e. elemental homeostasis, organisms have to consume resources of sufficient quality to meet their own specific stoichiometric demand. Therefore, concentrations of elements indicate resource quality, and rare elements in the environment may act as limiting factors for individual organisms scaling up to constrain population densities. We investigated how the biomass densities of invertebrate populations of temperate forest soil communities depend on 1) the stoichiometry of the basal litter according to ecological stoichiometry concepts and 2) the population average body mass as predicted by metabolic theory. We used a large data set on biomass densities of 4959 populations across 48 forests in three regions of Germany. Following various ecological stoichiometry hypotheses, we tested for effects of the carbon-to-element ratios of 10 elements. Additionally, we included the abiotic litter characteristics habitat size (represented by litter depth), litter diversity and pH, as well as forest type as an indicator for human management. Across 12 species groups, we found that the biomass densities scaled significantly with population-averaged body masses thus supporting metabolic theory. Additionally, 10 of these allometric scaling relationships exhibited interactions with stoichiometric and abiotic co-variables. The four most frequent co-variables were 1) forest type, 2) the carbon-to-phosphorus ratio (C:P), 3) the carbon-to-sodium ratio (C:Na), and the carbon-to-nitrogen ratio (C:N). Hence, our analyses support the sodium shortage hypothesis for microbi-detritivores, the structural elements hypothesis for some predator groups (concerning N), and the secondary productivity hypothesis (concerning P) across all trophic groups in our data. In contrast, the ecosystem size hypothesis was only supported for some meso- and macrofauna detritivores. Our study is thus providing a comprehensive analysis how the elemental stoichiometry of the litter as the basal resource constrain population densities across multiple trophic levels of soil communities.

Food web topologies depict the community structure as distributions of feeding interactions across populations. Although the soil ecosystem provides important functions for aboveground ecosystems, data on complex soil food webs is notoriously scarce, most likely due to the difficulty of sampling and characterizing the system. To fill this gap we assembled the complex food webs of 48 forest soil communities. The food webs comprise 89 to 168 taxa and 729 to 3344 feeding interactions. The feeding links were established by combining several molecular methods (stable isotope, fatty acid and molecular gut content analyses) with feeding trials and literature data. First, we addressed whether soil food webs (n = 48) differ significantly from those of other ecosystem types (aquatic and terrestrial aboveground, n = 77) by comparing 22 food web parameters. We found that our soil food webs are characterized by many omnivorous and cannibalistic species, more trophic chains and intraguild-predation motifs than other food webs and high average and maximum trophic levels. Despite this, we also found that soil food webs have a similar connectance as other ecosystems, but interestingly a higher link density and clustering coefficient. These differences in network structure to other ecosystem types may be a result of ecosystem specific constraints on hunting and feeding characteristics of the species that emerge as network parameters at the food-web level. In a second analysis of land-use effects, we found significant but only small differences of soil food web structure between different beech and coniferous forest types, which may be explained by generally strong selection effects of the soil that are independent of human land use. Overall, our study has unravelled some systematic structures of soil food-webs, which extends our mechanistic understanding how environmental characteristics of the soil ecosystem determine patterns at the community level.

Anthropogenic land use shapes the dynamics and composition of central European forests and changes the quality and availability of resources of the decomposer system. These changes likely alter the structure and functioning of soil animal food webs. Using stable isotope analysis (13C, 15N) we investigated the trophic position and resource use of soil animal species in each of four forest types (coniferous, young managed beech, old managed beech and unmanaged beech forests) across three regions in Germany. Twenty-eight species of soil invertebrates were analyzed covering three consumer levels and a representative spectrum of feeding types and morphologies. Data on stable isotope signatures of leaf litter, fine roots and soil were included to evaluate to which extent signatures of soil animals vary with those of local resources. Soil animal d15N and d13C signatures varied with the respective signatures of leaf litter and fine roots. After calibration to leaf litter signatures, soil animal stable isotope signatures of the different beech forests did not differ significantly. However, thick leaf litter layers, such as those in coniferous forests, were associated with low animal stable isotope signatures presumably due to reduced access of decomposer animals to root-derived resources, suggesting that the decomposer food web is shifted towards leaf litter based energy pathways with the shift affecting all consumer levels. Variation in stable isotope signatures of soil animal species with litter quality parameters suggests that nutrition of third level but not first and second level consumers is related to litter quality, potentially due to microorganisms locking up litter resources thereby hampering their propagation to higher trophic levels.

Ecological communities consist of small abundant and large non-abundant species. The energetic equivalence rule is an often-observed pattern that could be explained by equal energy usage among abundant small organisms and non-abundant large organisms. To generate this pattern, metabolism (as an indicator of individual energy use) and abundance have to scale inversely with body mass, and cancel each other out. In contrast, the pattern referred to as biomass equivalence states that the biomass of all species in an area should be constant across the body-mass range. In this study, we investigated forest soil communities with respect to metabolism, abundance, population energy use, and biomass. We focused on four land-use types in three different landscape blocks (Biodiversity Exploratories). The soil samples contained 870 species across 12 phylogenetic groups. Our results indicated positive sublinear metabolic scaling and negative sublinear abundance scaling with species body mass. The relationships varied mainly due to differences among phylogenetic groups or feeding types, and only marginally due to land-use type. However, these scaling relationships were not exactly inverse to each other, resulting in increasing population energy use and biomass with increasing body mass for most combinations of phylogenetic group or feeding type with land-use type. Thus, our results are mostly inconsistent with the classic perception of energetic equivalence, and reject the biomass equivalence hypothesis while documenting a specific and nonrandom pattern of how abundance, energy use, and biomass are distributed across size classes. However, these patterns are consistent with two alternative predictions: the resource-thinning hypothesis, which states that abundance decreases with trophic level, and the allometric degree hypothesis, which states that population energy use should increase with population average body mass, due to correlations with the number of links of consumers and resources. Overall, our results suggest that a synthesis of food web structures with metabolic theory may be most promising for predicting natural patterns of abundance, biomass, and energy use.

Living organisms are constrained by both resource quantity and quality. Ecological stoichiometry offers important insights into how the elemental composition of resources affects their consumers. If resource quality decreases, consumers can respond by shifting their body stoichiometry, avoiding low-quality resources, or up-regulating feeding rates to maintain the supply of required elements while excreting excess carbon (i.e., compensatory feeding). We analyzed multitrophic consumer body stoichiometry, biomass, and feeding rates along a resource-quality gradient in the litter of tropical forest and rubber and oil-palm plantations. Specifically, we calculated macroinvertebrate feeding rates based on consumer metabolic demand and assimilation efficiency. Using linear mixed effects models, we assessed resource-quality effects on macroinvertebrate detritivore and predator communities. We did not detect shifts in consumer body stoichiometry or decreases in consumer biomass in response to declining resource quality, as indicated by increasing carbon-to-nitrogen ratios. However, across trophic levels, we found a strong indication of decreasing resource quality leading to increased consumer feeding rates through altered assimilation efficiency and community body size structure. Our study reveals the influence of resource quality on multitrophic consumer feeding rates and suggests compensatory feeding to be more common across consumer trophic levels than was formerly known.

Conversion of tropical rainforests into plantations fundamentally alters ecological niches of animal species. Generalist predators such as centipedes (Chilopoda) may be able to persist in converted ecosystems due to their ability to adapt and switch to alternative prey populations. We investigated variations in community composition and trophic niches of soil and litter living centipedes in a range of ecosystems including rainforests, jungle rubber agroforests, and rubber and oil palm monocultures in two landscapes in Sumatra, Indonesia. Including information on environmental factors in the soil and litter habitat, we explored drivers shaping ecological niches of soil living invertebrate predators in one of the world’s hotspots of rainforest conversion. Conversion of rainforests into agroforests and plantations was associated with a marked change in the composition of centipede communities. However, irrespective of major differences in habitat characteristics, changes in total abundances were small and the overall diversity and biomass of centipedes was similar in each of the systems investigated, suggesting that the number of ecological niches for this group of predators remains unchanged. By using stable isotope analysis (15N and 13C), we investigated trophic niche shifts of the centipede community; lower δ13C values of centipedes in oil palm plantations as compared to other ecosystems suggests that centipedes switch from decomposer prey to other prey, presumably understory associated herbivores, due to reduced availability of litter associated prey species. The results suggest that the ability to utilize alternative prey is a key feature enabling invertebrate predators to persist in ecosystems undergoing major structural changes due to anthropogenic land use change.

A large number of predatory mesostigmatid mite species populate forest soils in high densities. The present study investigates the trophic structure of the Mesostigmata community of old growth beech stands in Central Germany and identifies potential prey groups using natural variations in stable isotope ratios ( 13 C/ 12 C and 15 N/ 14 N). Data on relative abundances and body mass were included for each of the 40 species studied to analyze functional aspects in Mesostigmata feeding ecology. The results indicate that Mesostigmata predominantly feed on secondary decomposers, whereas primary decomposer and intra-guild prey are of minor importance. Dominant species featured high δ 13 C signatures suggesting that they predominantly feed on species relying on root derived resources such as bacterial feeding nematodes. Less abundant species where characterized by lower δ 13 C values suggesting that they predominantly feed on prey relying on litter derived resources such as fungal feeding Collembola. Related taxa often had distinctively different isotope ratios suggesting that trophic niche partitioning facilitates coexistence of morphologically similar species. Unexpectedly, the trophic position of Mesostigmata species was not related to body size reflecting the varying trophic position of their main prey, nematodes and Collembola, suggesting that body size is a poor predictor of trophic position in soil food webs.

Background and Aims The response of forest ecosystems to continuous nitrogen (N) deposition is still uncertain. We investigated imports and exports of dissolved N from mull-type organic layers to identify the controls of N leaching in Central European beech forests under continuous N deposition. Methods Dissolved N fluxes with through fall and through mull-type organic layers (litter leachate) were measured continuously in 12 beech forests on calcareous soil in two regions in Germany over three consecutive growing seasons. Results Mean growing season net (i.e. litter leachate – throughfall flux) fluxes of total dissolved N (TDN) from the organic layer were low (2.3 ± 5.6 kg ha⁻¹) but varied widely from 12.9 kg ha⁻¹ to–8.3kgha⁻¹. The small increase of dissolved N fluxes during the water passage through mull-type organic layers suggested that high turnover rates coincided with high microbial N assimilation and plant N uptake. Stand basal area had a positive feedback on N fluxes by providing litter for soil organic matter formation. Plant diversity, especially herb diversity, reduced dissolved N fluxes. Soil fauna biomass increased NO−3 -N fluxes with litter leachate by stimulating mineralization. Microbial biomass measures were not related to dissolved N fluxes. Conclusions Our results show that dissolved N exports from organic layers contain significant amounts of throughfall-derived N (mainly NO−3 -N) that flushes through the organic layer but also highlight that N leaching from organic layers is driven by the complex interplay of plants, animals and microbes. Furthermore, diverse understories reduce N leaching from Central European beech forests.

Tropical lowland rainforests are increasingly threatened by the expansion of agriculture and the extraction of natural resources. In Jambi Province, Indonesia, the interdisciplinary EFForTS project focuses on the ecological and socio-economic dimensions of rainforest conversion to jungle rubber agroforests and monoculture plantations of rubber and oil palm. Our data confirm that rainforest transformation and land use intensification lead to substantial losses in biodiversity and related ecosystem functions, such as decreased above- and below-ground carbon stocks. Owing to rapid step-wise transformation from forests to agroforests to monoculture plantations and renewal of each plantation type every few decades, the converted land use systems are continuously dynamic, thus hampering the adaptation of animal and plant communities. On the other hand, agricultural rainforest transformation systems provide increased income and access to education, especially for migrant smallholders. Jungle rubber and rubber monocultures are associated with higher financial land productivity but lower financial labour productivity compared to oil palm, which influences crop choice: smallholders that are labour-scarce would prefer oil palm while land-scarce smallholders would prefer rubber. Collecting long-term data in an interdisciplinary context enables us to provide decision-makers and stakeholders with scientific insights to facilitate the reconciliation between economic interests and ecological sustainability in tropical agricultural landscapes.

Smallholder-dominated agricultural mosaic landscapes are highlighted as model production systems that deliver both economic and ecological goods in tropical agricultural landscapes, but trade-offs underlying current land-use dynamics are poorly known. Here, using the most comprehensive quantification of land-use change and associated bundles of ecosystem functions, services and economic benefits to date, we show that Indonesian smallholders predominantly choose farm portfolios with high economic productivity but low ecological value. The more profitable oil palm and rubber monocultures replace forests and agroforests critical for maintaining above- and below-ground ecological functions and the diversity of most taxa. Between the monocultures, the higher economic performance of oil palm over rubber comes with the reliance on fertilizer inputs and with increased nutrient leaching losses. Strategies to achieve an ecological-economic balance and a sustainable management of tropical smallholder landscapes must be prioritized to avoid further environmental degradation., Small-scale farmers in Southeast Asia are increasingly turning to monocultures of oil palm and rubber to maximize income. Clough and colleagues demonstrate that this land-use change in Indonesia comes at a cost to a wide array of ecosystem functions and biodiversity.

Seven new species of oribatid mites of the genus Galumna are described from litter and soil materials of Sumatra, Indonesia. A new subgenus, Galumna (Atypicogalumna) subgen. n., is proposed; it differs from all galumnid genera and subgenera by the simultaneous presence of porose areas and sacculi on the notogaster (vs. either porose areas or sacculi present). Galumna (Galumna) calva Starý, 1997 is recorded for the first time in the Oriental region, and Galumna (Galumna) sabahna Mahunka, 1995 is recorded for the first time in the Indonesian fauna.

Very few principles have been unraveled that explain the relationship between soil properties and soil biota across large spatial scales and different land-use types. Here, we seek these general relationships using data from 52 differently managed grassland and forest soils in three study regions spanning a latitudinal gradient in Germany. We hypothesize that, after extraction of variation that is explained by location and land-use type, soil properties still explain significant proportions of variation in the abundance and diversity of soil biota. If the relationships between predictors and soil organisms were analyzed individually for each predictor group, soil properties explained the highest amount of variation in soil biota abundance and diversity, followed by land-use type and sampling location. After extraction of variation that originated from location or land-use, abiotic soil properties explained significant amounts of variation in fungal, meso- and macrofauna, but not in yeast or bacterial biomass or diversity. Nitrate or nitrogen concentration and fungal biomass were positively related, but nitrate concentration was negatively related to the abundances of Collembola and mites and to the myriapod species richness across a range of forest and grassland soils. The species richness of earthworms was positively correlated with clay content of soils independent of sample location and land-use type. Our study indicates that after accounting for heterogeneity resulting from large scale differences among sampling locations and land-use types, soil properties still explain significant proportions of variation in fungal and soil fauna abundance or diversity. However, soil biota was also related to processes that act at larger spatial scales and bacteria or soil yeasts only showed weak relationships to soil properties. We therefore argue that more general relationships between soil properties and soil biota can only be derived from future studies that consider larger spatial scales and different land-use types. peerReviewed

Background: One of the most significant consequences of contemporary global change is the rapid decline of biodiversity in many ecosystems. Knowledge of the consequences of biodiversity loss in terrestrial ecosystems is largely restricted to single ecosystem functions. Impacts of key plant functional groups on soil biota are considered to be more important than those of plant diversity; however, current knowledge mainly relies on short-term experiments. Methodology/Principal Findings: We studied changes in the impacts of plant diversity and presence of key functional groups on soil biota by investigating the performance of soil microorganisms and soil fauna two, four and six years after the establishment of model grasslands. The results indicate that temporal changes of plant community effects depend on the trophic affiliation of soil animals: plant diversity effects on decomposers only occurred after six years, changed little in herbivores, but occurred in predators after two years. The results suggest that plant diversity, in terms of species and functional group richness, is the most important plant community property affecting soil biota, exceeding the relevance of plant above- and belowground productivity and the presence of key plant functional groups, i.e. grasses and legumes, with the relevance of the latter decreasing in time. Conclusions/Significance: Plant diversity effects on biota are not only due to the presence of key plant functional groups or plant productivity highlighting the importance of diverse and high-quality plant derived resources, and supporting the validity of the singular hypothesis for soil biota. Our results demonstrate that in the long term plant diversity essentially drives the performance of soil biota questioning the paradigm that belowground communities are not affected by plant diversity and reinforcing the importance of biodiversity for ecosystem functioning. peerReviewed