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Soil fauna plays a key role in regulating biogeochemical cycles, but how multiple global change factors (GCFs) may affect faunal communities remains poorly studied. We conducted a meta-analysis using 1154 observations to evaluate the individual and combined effects of elevated CO

Terrestrial isopods and millipedes are key drivers of a litter decomposition in terrestrial ecosystems but the effects of litter chemistry on feeding preference and litter consumption rate as well as on the diversity and composition of gut and faecal microbiome still entails several challenges. We established a mesocosm experiment with terrestrial isopods (Oniscus asellus) and millipedes (Glomeris marginata) fed by leaf litter from six common European tree species (ash, maple, lime, beech, oak and Norway spruce) to reveal the effect of litter chemistry on consumption rate and feeding preference as well as on the compositions of gut and faecal microbiomes. The total percentage of consumed litter showed that O. asellus preferred nutrient-rich and labile-C litter of ash over more recalcitrant litter of oak, beech, and Norway spruce, while G. marginata preferred calcium-rich ash, maple and lime litter over beech and Norway spruce. Consumption of litter by O. asellus and G. marginata increased with concentrations of magnesium, sulphur and potassium but decreased with concentrations of iron, phosphorus, lignin, cellulose and TOC. The millipede G. marginata harboured higher bacterial OTU richness (73.5 ± 12.5) than the isopod O. asellus (49.1 ± 15.9), but fungal OTU richness was similar with 25.8 ± 6.7 in O. asellus and 25.7 ± 2.7 in G. marginata. In total, faeces of both animals hosted higher diversity than gut. In gut and faeces of O. asellus, the fungal OTU richness was highest for individuals fed by litter of Norway spruce, while lowest OTU richness was recorded for individuals fed by litter of more palatable ash. In contrast, the highest diversity of the fungal community in gut and faeces of G. marginata was recorded for individuals fed by palatable lime litter, while the lowest OTUs richness was recorded when millipedes were fed by maple and spruce. The structures of bacterial and fungal communities generally separated between O. asellus and G. marginata. The fungal community structure in gut and faeces differed between animals fed by different foliar litters, while the bacterial community structure mainly differed between gut and faeces regardless of the offered type of litter. The fungal community structure in gut and faeces of O. asellus and G. marginata were shaped by concentrations of magnesium, sulphur, lignin and cellulose. The bacterial communities in gut and faeces of both O. asellus and G. marginata were dominated by copiotrophic bacteria, while fungal communities were dominated by unspecified saprotrophs. Our study suggest that litter quality is a strong driver of feeding preference and consumption rates as well as composition of bacterial and fungal communities in gut and faeces of two species representing the main groups of litter feeding soil fauna in European forests.

Changes in precipitation regimes can strongly affect soil nitrogen (N) cycling in terrestrial ecosystems. However, whether altered precipitation regimes may differentially affect soil N cycling between arid and humid biomes at the global scale is unclear. We conducted a meta-analysis using 1036 pairwise observations collected from 194 publications to assess the effects of increased and decreased precipitation on the input (N return from plants), storage (various forms of N in soil), and output (gaseous N emissions) of soil N in arid versus humid biomes at the global scale. We found that (1) increased precipitation significantly increased N input (+12.1%) and output (+34.9%) but decreased N storage (-13.7%), while decreased precipitation significantly decreased N input (-10.7%) and output (-34.8%) but increased N storage (+11.1%); (2) the sensitivity of soil N cycling to increased precipitation was higher in arid regions than in humid regions, while that to decreased precipitation was lower in arid regions than in humid regions; (3) the effect of altered precipitation regimes on soil N cycling was independent of precipitation type (i.e., rainfall vs. snowfall); and (4) the mean annual precipitation regulated soil N cycling in precipitation alteration experiments at the global scale. Overall, our results clearly show that the response of soil N cycling to increased versus decreased precipitation differs between arid and humid regions, indicating the uneven effect of climate change on soil N cycling between these two contrasting climate regions. This implies that ecosystem models need to consider the differential responses of N cycling to altered precipitation regimes in different climatic conditions under future global change scenarios.

Plant litter is the major source of energy and nutrients in stream ecosystems and its decomposition is vital for ecosystem nutrient cycling and functioning. Invertebrates are key contributors to instream litter decomposition, yet quantification of their effects and drivers at the global scale remains lacking. Here, we systematically synthesized data comprising 2707 observations from 141 studies of stream litter decomposition to assess the contribution and drivers of invertebrates to the decomposition process across the globe. We found that (1) the presence of invertebrates enhanced instream litter decomposition globally by an average of 74%; (2) initial litter quality and stream water physicochemical properties were equal drivers of invertebrate effects on litter decomposition, while invertebrate effects on litter decomposition were not affected by climatic region, mesh size of coarse-mesh bags or mycorrhizal association of plants providing leaf litter; and (3) the contribution of invertebrates to litter decomposition was greatest during the early stages of litter mass loss (0-20%). Our results, besides quantitatively synthesizing the global pattern of invertebrate contribution to instream litter decomposition, highlight the most significant effects of invertebrates on litter decomposition at early rather than middle or late decomposition stages, providing support for the inclusion of invertebrates in global dynamic models of litter decomposition in streams to explore mechanisms and impacts of terrestrial, aquatic, and atmospheric carbon fluxes. ispartof: BIOLOGICAL REVIEWS vol:97 issue:6 pages:2023-2038 ispartof: location:England status: published

Ash is a fundamental component of plant litter and plays a vital role in regulating litter decomposition. However, to date, global patterns and underlying mechanisms of initial litter ash concentrations remain unclear. Here, we used 570 observations collected from 104 independent publications to assess the global patterns of initial plant litter ash concentrations and evaluated the effects of mycorrhizal association [arbuscular mycorrhiza (AM) vs. ectomycorrhiza (ECM)], taxon group (gymnosperm vs. angiosperm), life form (tree vs. shrub vs. herb), leaf type (broadleaf vs. needle), and environmental factors such as climate and soil properties on initial litter ash concentration. The results showed that (1) global average ash concentrations varied significantly among different plant tissues and were 7.3, 4.5, 3.7, 3.5, 3.1, 2.4, and 1.5% in leaf, root, bark, reproductive tissue (flower and fruit), branch, stem, and wood litter, respectively; (2) in leaf litter, the initial ash concentrations of AM plants and species associated with both AM and ECM fungi were higher than those of ECM plants, and those of the tree species were lower than those of the herbs and shrubs; in root litter, the initial ash concentrations of the AM plants were lower than those of the species associated with both AM and ECM fungi but higher than those of the ECM plants; in both leaf and root litter, the initial ash concentrations of the angiosperms and broadleaf trees were higher than those of the gymnosperms and needle trees, respectively, while the effect of plant traits on branch litter was not obvious; and (3) the initial ash concentration of leaf litter was predominantly driven by mycorrhizal association and taxon group, while that of root litter tended to be driven by mycorrhizal association well as soil organic carbon. Our study clearly assessed the global patterns and underlying mechanisms of initial plant litter ash concentrations, which could help in better understanding the role of ash in litter decomposition and the related processes of carbon and nutrient cycling.

Because climate change is predicted to have a strong impact on high-altitude ecosystems, a better knowledge of litter decomposition in alpine ecosystems is critical to improve our predictions of the effect of climate change on ecosystem processes and services such as nutrient cycling, carbon sequestration, and below-ground biodiversity. To evaluate the effects of vegetation types [alpine shrubland (AS) and alpine meadow (AM)] and litter quality on litter decomposition and related biochemical processes, the decomposition of leaf litter of two dominant shrub species, Sorbus rufopilosa (SR, high quality) and Rhododendron lapponicum (RL, low quality), was studied using the litterbag method in an alpine treeline ecotone on the eastern Tibetan Plateau. After 1 year of decomposition, cellulolytic enzyme activities and gram-negative bacterial biomass were higher in shrubland than in meadow. However, higher fungal biomass, fungal/bacteria ratio and ligninolytic activity were observed in meadow than in shrubland after 2 years of decomposition. During the first year of decomposition, litter decomposition was faster in shrubland than in meadow probably due to the home-field advantage (HFA) effect and the bacteria-dominated decomposition, whereas in later decomposition stages, litter decomposition was faster in meadow than in shrubland, as the HFA effect diminished and fungal-dominated decomposition of recalcitrant components took over. These results indicated that litter quality effects were generally strongest in the first year and diminished in later stages when the effect of vegetation type in incubation sites developed.

Soil fauna is one of the key drivers of the litter decomposition at both local and global scales, yet the role of tree species in mediating the effects of soil fauna on litter decomposition remains elusive. We conducted a field experiment using litterbags with three different mesh sizes that allowed access of microfauna (0.1 mm), micro- and mesofauna (2 mm), and total soil fauna (5 mm) to evaluate the decomposition of foliar litter of two tree species associated with arbuscular mycorrhizal (AM) fungi and three tree species associated with ectomycorrhizal (ECM) fungi in six Danish common garden sites. We also assessed how differences in initial litter quality, soil properties, and microbial community composition among the tree species may affect litter decomposition as well as soil fauna effects on litter decomposition. Results showed that (1) litter mass loss varied significantly among different mesh sizes and tree species, with litter decomposition rates (k) ranging from 0.273 to 3.482; (2) the access of mesofauna significantly increased litter k of 0.658 for AM and 0.396 for ECM tree species with no access of soil fauna 255 and 92%, respectively, while the access of both meso- and macrofauna increased k by 265 and 108% for AM and ECM trees, respectively; (3) tree species identity, mycorrhizal association, initial litter quality, soil properties, microbial community composition, and ambient soil fauna biomass were all significantly influencing factors on litter decomposition, but tree species identity was the dominant factor regardless of litterbag mesh size; and (4) the effects of mesofauna on litter decomposition were predominantly controlled by tree species identity, initial litter Mg concentration and lignin:N ratio, while the small additional impact of macrofauna access was not well explained by any of the assessed factors. Overall, our results suggest that tree species affect litter decomposition via different stimulation of soil fauna functioning, and that AM and ECM associated tree species differ in the degree to which soil fauna stimulates litter decomposition. However, the pattern was not entirely consistent as litter decomposition rates for the ECM associated lime were stimulated to the same extent as rates for the AM associated tree species ash and maple. Overall, our results suggested that soil meso- and macrofauna communities may enhance tree species effects on litter decomposition as well as incorporation of litter C into mineral soil.

Plant litter decomposition is not only the major source of soil carbon and macronutrients, but also an important process for the biogeochemical cycling of trace elements such as iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu). The concentrations of plant litter trace elements can influence litter decomposition and element cycling across the plant and soil systems. Yet, a global perspective of the patterns and driving factors of trace elements in plant litter is missing. To bridge this knowledge gap, we quantitatively assessed the concentrations of four common trace elements, namely Fe, Mn, Zn, and Cu, of freshly fallen plant litter with 1411 observations extracted from 175 publications across the globe. Results showed that (1) the median of the average concentrations of litter Fe, Mn, Zn, and Cu were 0.200, 0.555, 0.032, and 0.006 g/kg, respectively, across litter types; (2) litter concentrations of Fe, Zn, and Cu were generally stable regardless of variations in multiple biotic and abiotic factors (e.g., plant taxonomy, climate, and soil properties); and (3) litter Mn concentration was more sensitive to environmental conditions and influenced by multiple factors, but mycorrhizal association and soil pH and nitrogen concentration were the most important ones. Overall, our study provides a clear global picture of plant litter Fe, Mn, Zn, and Cu concentrations and their driving factors, which is important for improving our understanding on their biogeochemical cycling along with litter decomposition processes.

Nutrient resource availability is a crucial environmental factor in determining soil bacterial community assembly. However, the effects of nutrient availability on niche differentiation and temporal co-occurrence patterns of bacterial communities remain elusive. Here, we retrieved sequencing datasets (105 amplicon samples of bacterial 16S rRNA genes and 60 bacterial metagenomic samples) from a laboratory incubation experiment and a coastal wetland study, to elucidate the effects of nutrient availability on niche differentiation and co-occurrence patterns of bacterial communities. Niche differentiation within bacterial communities, indicated by nearest taxon index and niche breadth of bacterial communities, did not significantly correlate with nutrient availability gradients in either environment, even though deterministic processes dominated bacterial community assembly. Network analyses revealed that co-occurrence patterns of bacterial OTUs over incubation time changed across nutrient availability gradients, and were likely to be mediated by environmental selection. There were more co-occurrences of metabolic genes under higher nutrient levels. This study revealed the non-significant correlation between nutrient availability gradients and niche differentiation within bacterial communities, not only in a natural environment but also in a laboratory modified environment where the nutrient availability gradient was the sole environmental variable. These findings boost the understanding of bacterial community assembly along environmental nutrient availability gradients.

Selection of appropriate tree species is an important forest management decision that may affect sequestration of carbon (C) in soil. However, information about tree species effects on soil C stocks at the global scale remains unclear. Here, we quantitatively synthesized 850 observations from field studies that were conducted in a common garden or monoculture plantations to assess how tree species type (broadleaf vs. conifer), mycorrhizal association (arbuscular mycorrhizal (AM) vs. ectomycorrhizal (ECM)), and N-fixing ability (N-fixing vs. non-N-fixing), directly and indirectly, affect topsoil (with a median depth of 10 cm) C concentration and stock, and how such effects were influenced by environmental factors such as geographical location and climate. We found that (1) tree species type, mycorrhizal association, and N-fixing ability were all important factors affecting soil C, with lower forest floor C stocks under broadleaved (44%), AM (39%), or N-fixing (28%) trees respectively, but higher mineral soil C concentration (11%, 22%, and 156%) and stock (9%, 10%, and 6%) under broadleaved, AM, and N-fixing trees respectively; (2) tree species type, mycorrhizal association, and N-fixing ability affected forest floor C stock and mineral soil C concentration and stock directly or indirectly through impacting soil properties such as microbial biomass C and nitrogen; (3) tree species effects on mineral soil C concentration and stock were mediated by latitude, MAT, MAP, and forest stand age. These results reveal how tree species and their specific traits influence forest floor C stock and mineral soil C concentration and stock at a global scale. Insights into the underlying mechanisms of tree species effects found in our study would be useful to inform tree species selection in forest management or afforestation aiming to sequester more atmospheric C in soil for mitigation of climate change., Authors Accepted Manuscript

Microbial interconnections in soil are pivotal to ecosystem services and restoration. However, little is known about how soil microbial interconnections respond to slash-and-burn agriculture and to the subsequent ecosystem restoration after the practice. Here, we used amplicon sequencing and co-occurrence network analyses to explore the interconnections within soil bacterial and fungal communities in response to slash-and-burn practice and a spontaneous restoration (spanning ca. 60 years) of tropical forests after the practice, in Papua New Guinea. We found significantly higher complexity and greater variations in fungal networks than in those of bacteria, despite no significant changes observed in bacterial or fungal networks across successional stages. Within most successional stages, bacterial core co-occurrences (co-occurrences consistently present across all sub-networks in a stage) were more frequent than those of fungi, indicating higher stability of interconnections between bacteria along succession. The stable interconnections occurred frequently between bacterial taxa (i.e. Sporosarcina, Acidimicrobiale and Bacillaceae) and between ectomycorrhizal fungi (Boletaceae and Russula ochroleuca), implying important ecological roles of these taxa in the ecosystem restoration. Collectively, our results provide new insight into microbial interconnections in response to slash-and-burn agriculture and the subsequent ecosystem restoration, thus promoting a better understanding of microbial roles in ecosystem services and restoration.

Moisture is recognized as a key factor shaping the structure of soil microbial community and its function in soil ecosystem. However, the temporal response patterns of soil microbes under various moisture regimes remain poorly understood. Therefore, the main objective of our study was to reveal how moisture regulates prokaryotic community structure, diversity, phylogenetic structure and finally how moisture regulates greenhouse gas emissions, as an indicator of microbial community function. We monitored prokaryotic community in soil incubated under an artificial moisture gradient for three months. We observed robust effects of both moisture gradient and incubation time on increased greenhouse gas emissions (methane, carbon dioxide and nitrous oxide). Furthermore, the moisture gradient as well as the incubation time exerted significant effects on species turnover of the soil prokaryotic community. In contrast, the artificial moisture gradient did not show any significant effects on prokaryotic alpha diversity. Alpha diversity of the soil prokaryotic community decreased significantly with incubation time. Different community assembly patterns were observed (based on both the mean nearest relatedness index (NRI) and nearest taxon index (NTI)). The mean NRI exhibited the dominance of stochastic factors, while the NTI indicated the dominance of deterministic factors. The prokaryotic communities in soils with less moisture tended to be controlled by stochastic factors, while prokaryotes in soils with higher moisture (60%) were controlled by deterministic factors. Relative abundances of oligotrophs and copiotrophs did not change significantly along the artificial moisture gradient, while the relative abundances of some prokaryotic taxa did vary significantly along the artificial moisture gradient.

Soil pH plays an important role in shaping the structure and diversity of prokaryotic community. Altered pH regimes may change prokaryotic community composition by selecting species or groups with different ecological strategies to optimize their fitness. However, it remains unresolved whether prokaryotic communities exhibit deterministic (phylogenetically conserved) or stochastic (phylogenetically overdispersed) responses to pH. In this study we investigated the responses of greenhouse gas emissions and prokaryotic community structure to pH using three-month incubation experiments by adjusting an artificial pH gradient from 4.5 to 8.5. We found decreasing OTUs richness after three months of incubation. Phylogenetic clustering of the prokaryotic community was observed at earlier incubation times whereas greater phylogenetic distance of the prokaryotic community was found at later incubation time. Our results evidenced differential responses of various soil bacterial taxa to the changes in pH. Relative abundances of bacterial phyla and classes of main ecological groups of soil prokaryotes, oligotrophs and copiotrophs, changed significantly along an artificial pH gradient at various incubation times. Relative abundance of Acidobacteria significantly increased with pH at the start of experiment, while opposite trend was observed after 90 days of incubation. In contrast, the relative abundance of Bacteroidetes showed opposite response as Acidobacteria to elevated pH gradient during various incubation time. Methane emissions increased with pH as well as with incubation time, but carbon dioxide and nitrous oxide only increased with incubation time.

Understanding the differentiation of soil bacterial communities under precipitation and temperature gradients is crucial for assessing the impacts of environmental filters on ecosystem structure and function. Here we investigated spatial variations of bacterial communities along a precipitation and temperature transect in the eastern Inner Mongolia steppe, China. The aims are to understand the biogeographic pattern and key drivers shaping soil bacterial communities along the transect. Our results showed that the soil bacterial community along the 451-km transect exhibited the distance-decay relationship, decreasing in community similarity with geographic distance. Obvious changes in the bacterial community structure occurred at an annual precipitation from 215 to 261 mm, which was close to the boundary between arid and semi-arid systems. The relative abundances of Proteobacteria, Bacteroidetes, and Acidobacteria increased with precipitation, while those of Actinobacteria, Chloroflexi, and Gemmatimonadetes decreased. Environmental filtering was observed to be the key in shaping bacterial biogeographic patterns, and climate conditions exert indirect effects on soil bacterial communities mainly through direct effects on soil properties. Soil pH and plant coverage were important to soil bacterial communities in both arid and semi-arid steppes. Our findings provided insights for understanding the linkages among geographic distance, environmental filters, and soil bacterial communities in Eurasian steppe ecosystems.

Topsoil layer contains various components of soil organic matter such as branches, leaves, bark, or metabolites and residues of soil biota. Soil organic matter (SOM) in forest ecosystems consists mostly of lignin, cellulose, chitin and other hydrocarbons. These compounds are decomposed mainly by soil fungi which produce extracellular enzymes to decompose wide range of organic residues. These enzymes may alter nutrient cycling and change soil properties such as water retention capacity, ion exchange capacity, formation of soil microstructure, soil microbial respiration, etc. In this study, we studied enzyme activity in the topsoil layer of postmining spoil heaps near Sokolov, Czech Republic. We investigated the effect of the following factors and their combinations on enzyme activity: i) dominant vegetation, ii) time of sampling, iii) reclamation, and iv) soil macrofauna.We measured enzyme activity in plastic mesocosms with autochthonous litter deposited on reclaimed and unreclaimed post-mining sites. We used mesocosms accessible for macrofauna (mesh size > 2 mm) and mesocosms inaccessible for macrofauna (mesh size < 2 mm). Under laboratory conditions, we measured enzyme activity (laccase, oxidase, peroxidase, Mn-peroxidase, alkaline phosphatase, acid phosphatase, endoglucanase, xylanase, cellobiohydrolase, glucosidase, xylosidase and chitinase) using buffer extraction method followed by spectrophotometric assay. We did not find any statistically significant difference between mesocosms accessible and inaccessible for fauna. However, we found significant effect of time of sampling on enzyme activity. Our results showed significant difference between reclaimed and unreclaimed post-mining sites. Reclaimed sites showed significantly higher enzyme activity than unreclaimed sites.

A high diversity of Apicomplexa was recently found in tropical soils presumably reflecting the diversity of their invertebrate hosts, but such patterns have not been explored in colder regions. We analysed the diversity of Apicomplexa and their potential metazoan hosts in litter and mosses collected in 11 different alpine habitats using an eDNA metabarcoding approach. The abundance and diversity of Apicomplexa phylotypes and of their potential invertebrate hosts were positively correlated. This confirms that eDNA metabarcoding is a useful tool to explore the unknown biodiversity of free-living eukaryotes, as well as potential host-parasite interactions. Future studies should aim at describing this diversity using a combination of morphological and molecular approaches.

Observations of earthworm colonization on sites where they were absent previously, such as on post-mining heaps, indicate that they may substantially alter soil conditions as well as soil microbial communities. However, long-term effects of earthworms on microbial activity of soil ecosystems remains poorly understood. To improve this situation, we set up microcosm experiments with clay only, with clay and litter, and with clay, litter and earthworms. Microcosms were sampled after 3, 60, 180 and 395 days of cultivation and divided into three subsamples: clay, litter, and drilosphere (earthworm tunnels and associates casts), when present. Microbial respiration, microbial biomass carbon, species composition, metabolic activity using BIOLOG, PLFA concentration, isoprenoid quinones content and DGGE fingerprints were analysed in all microcosms and at all subsamples. Microbial biomass carbon and basal soil respiration were significantly affected by type of microcosms and time of sampling. Microbial biomass in drilosphere was significantly higher than in clay and litter. The CFU (colony forming units) were significantly affected by presence of earthworms having significantly higher CFU in drilosphere than in all other subsamples. Analysis of PLFA indicated highest relative biomass of fungi and bacteria in clay from microcosms with earthworms. The DGGE analysis showed various compositions of microbial communities among subsamples from various treatments taken at different time. Finally, our results revealed significant effect of earthworms on activity and biomass of soil microbial community under long-term laboratory incubation.

Soil microorganisms are recognized as key players in all biogeochemical cycles. However, little effort has been paid to incorporate them in predictive models for future climate change. Here, we investigated the variation of prokaryotic community composition in alpine meadow soil from the Qinghai-Tibet Plateau under dry-rewetting stress using MiSeq sequencing approach. We incubated soils treated by various frequencies of rewetting and durations of desiccation. Emission rates of methane, carbon dioxide and nitrous oxide were measured every week during five months of incubation, and soil samples were taken each month for community composition analysis. Our results revealed that soil prokaryotic community showed different response patterns to dry-wetting cycles. Diversity indices significantly increased in soils under short-term drought and soils rewetted after long-term drought. Higher niche partitioning was promoted by higher frequencies of disturbance and rapid physiological activation of inactive microbial communities during desiccation, allowing colonization by a diverse array of organisms. Null model percentage of NTI revealed a strong phylogenetic relatedness of soil prokaryotic communities across all treatments and incubation times, suggesting that desiccation and rewetting events were strong biological filters shaping community assemblies. Our results also indicated different responses of various genera belonging to same phylum. These results suggest that prokaryotes that are well adapted to extremely stressful conditions such as long-term desiccation may release more greenhouse gasses in a positive feedback loop and that this prospect should be considered when modeling climate change.

Our study is focused on the effects of long-term cultivation of hybrid sorrel on basal soil respiration, specific microbial respiration, microbial biomass carbon, the composition of the cultivable soil fungal community, and the composition of soil meso- and macrofauna communities. In a split-plot field experiment in Chotýsany near Vlasim (Central Bohemia, Czech Republic), fields with hybrid sorrel (2 and 10 years old), oilseed rape/wheat rotation (>10 years old), and cultural meadow (>10 years old) were compared. The density and composition of soil meso- and macrofauna communities differed among fields. Soil meso- and macrofauna density were lowest in soils covered by oilseed rape/wheat rotation, while highest density was found in soil overgrown by cultural meadow species. Hybrid sorrel fields contained more pathogenic fungi than oilseed rape/wheat fields or cultural meadows but the difference was only marginally significant. Basal soil respiration and specific microbial respiration (qCO2) were highest in oilseed rape/wheat fields, and microbial biomass was highest in cultural meadows. In conclusion results show that long term effect of hybrid sorrel cultivation alters soil community structure, however the range is in the variation between existing annual and perennial landscape cover. Only exception is higher occurrence of pathogenic fungi but its ecological relevance require future attention.

We present a meta-analysis of experiments in which researchers used litter bags or similar enclosures to explore three questions: Do soil macrofauna increase the removal of litter from the soil surface? How is this mass loss of litter by macrofauna affected by climate and litter quality? To what extent does litter loss from litter layer by macrofauna correspond with litter mineralization? In total, we found 132 published field experiments in which authors compared litter bags with mesh sizes that did permit or not permit access by soil fauna. Meta-analysis of these experiments indicated that litter removal was significantly greater from bags that did permitted rather than did not permitted soil macrofauna access. When we divided these studies according to climate, a significant positive effect of soil fauna on litter removal was only evident from the warm humid, temperate regions with correspond to deciduous forest zone. When studies from this climate zone were sorted according to litter C:N ratio, the effect of fauna was significant in all cases except when the ratio was low (

Serious nitrogen (N) deposition in terrestrial ecosystems causes soil acidification and changes the structure and function of the microbial community. However, it is unclear how these changes are dependent on N deposition rates, other factors induced by N (e.g., pH), and their interactions. In this study, we investigated the responses of soil prokaryotic community structure and stability after a 13-year N addition in the semi-arid Leymus chinensis steppe in Inner Mongolia, China. Our results demonstrated that the prokaryotic community structure changed at the low N addition rate of 1.75 g N m � 2 yr � 1 ; however, dramatic changes in microbial abundance, respiratory quotient, and prokaryotic diversity occurred at N addition rates of more than 5.25 g N m � 2 yr � 1 when the soil pH dropped below 6.0. The two patterns indicated the difference in driving forces for different microbial properties. The N-driven and pH-driven processes are likely the most important mechanisms determining the responses of bacterial community to N. Some copiotrophic/oligotrophic bacteria, e.g., Proteobacteria and Acidobacteria, changed their relative abundances with the N addition continuously even at a low rate, indicating that they were more sensitive to N directly. Some bacterial groups significantly changed their relative abundance at a high N addition rate when pH dropped below 6.0, e.g., Verrucomicrobia and Armatimonadetes, indicating that they were more sensitive to pH below 6.0. N addition altered the prokaryotic community structure through enrichment of copiotrophic bacteria (species adjustment) at low N addition rates and through enrichment of nitrophilous taxa and significant loss of diversity at high N rates. The results also demonstrated that a high N addition diminished the stability of the prokaryotic community structure and activity through reduction in species diversity and bacterial interaction. Overall, this study supported the hypothesis that the responses of prokaryota to N were dependent on deposition rates, and N-driven and pH-driven processes were the important mechanisms to control the shift of the prokaryotic community.

Biofuel crops as an alternative to fossil fuels are a component of the energy mix in many countries. Many of them are introduced plants, so they pose a serious threat of biological invasions. Production of allelopathic compounds can increase invasion success by limiting co-occurring species in the invaded environment (novel weapons hypothesis). In this study, we focused on plant chemistry and production of allelopathic compounds by biofuel crops (hybrid sorrel Rumex tianschanicus x Rumex patientia and miscanthus Miscanthus sinensis) in comparison with invasive knotweed (Fallopia sachalinensis) and cultural meadow species. First, we tested the impact of leachates isolated from hybrid sorrel, miscanthus, knotweed and cultural meadow species compared to deionized water, used as a control, on seed germination of mustard (Sinapis arvensis) and wheat (Triticum aestivum) cultivated on sand and soil. Secondly, we studied the effect of leachates on the growth of soil fungal pathogens Fusarium culmorum, Rhizoctonia solani, Sclerotinia solani and Cochliobolus sativus. Finally, we tested the effect of litter of hybrid sorrel, miscanthus, knotweed and cultural meadow litter mixed with soil on population growth of Enchytraeus crypticus and Folsomia candida. Miscanthus and knotweed litter had a higher C:N ratio than the control meadow and hybrid sorrel litter. Miscanthus and hybrid sorrel litter had a higher content of phenols than knotweed and cultural meadow litter. Leachates from hybrid sorrel, miscanthus and knotweed biomass significantly decreased seed germination of wheat and mustard in both substrates. Soil fungal pathogens grew less vigorously on agar enriched by leachates from both biofuel crops than on agar enriched by knotweed and leachates. Litter from hybrid sorrel, miscanthus and knotweed significantly altered (both ways) the population growth of the soil mesofauna.

Biofuel crops are an accepted alternative to fossil fuels, but little is known about the ecological impact of their production. The aim of this contribution is to study the effect of native (Salix viminalis and Phalaris arundinacea) and introduced (Helianthus tuberosus, Reynoutria sachalinensis and Silphium perfoliatum) biofuel crop plantations on the soil biota in comparison with cultural meadow vegetation used as control. The study was performed as part of a split plot field experiment of the Crop Research Institute in the city of Chomutov (Czech Republic). The composition of the soil meso- and macrofauna community, composition of the cultivable fraction of the soil fungal community, cellulose decomposition (using litter bags), microbial biomass, basal soil respiration and PLFA composition (incl. F/B ratio) were studied in each site. The C:N ratio and content of polyphenols differed among plant species, but these results could not be considered significant between introduced and native plant species. Abundance of the soil meso- and macrofauna was higher in field sites planted with S. viminalis and P. arundinacea than those planted with S. perfoliatum, H. tuberosus and R. sachalinensis. RDA and Monte Carlo Permutation Test showed that the composition of the faunal community differed significantly between various native and introduced plants. Significantly different basal soil respiration was found in sites planted with various energy crops; however, this difference was not significant between native and introduced species. Microbial biomass carbon and cellulose decomposition did not exhibit any statistical differences among the biofuel crops. The largest statistically significant difference we found was in the content of actinobacterial and bacterial (bacteria, G+ bacteria and G− bacteria) PLFA in sites overgrown by P. arundinacea compared to introduced as well as native biofuel crops. In conclusion, certain parameters significantly differ between various native and introduced species of biofuel crops; however, the functional importance of these differences requires further research.

Soil fungi are important food resources for soil fauna. Here we ask whether the collembolan Folsomia candida shows selectivity in grazing between four saprophytic fungi ( Penicillium chrysogenum , Penicillium expansum , Absidia glauca , and Cladosporium herbarum ), whether grazing preference corresponds to effects on collembolan reproduction, and whether the effects of fungi on grazing and reproduction depends on the fungal substrate, which included three kinds of litter ( Alnus glutinosa , Salix caprea , and Quercus robur ) and one kind of agar (yeast extract). On agar, C. herbarum and A. glauca were the most preferred fungi and supported the highest collembolan reproduction. On fungal-colonized litter, grazing preference was more affected by litter type than by fungal species whereas collembolan reproduction was affected by both litter type and fungal species. On fungal-colonized litter, the litter type that was most preferred for grazing did not support the highest reproduction, i.e., there was an inconsistency between food preference and suitability. Alder and willow were preferred over oak for grazing, but alder supported the least reproduction.

Recent studies have revealed effects of various tree species on soil physical and chemical properties. However, effects of various tree species on composition and activity of soil microbiota and the relevant controls remain poorly understood. We evaluated the influence of tree species associated with two different mycorrhizal types, ectomycorrhiza (EcM) and arbuscular mycorrhiza (AM), on growth, biomass and metabolic activity of soil fungal and bacterial communities using common garden tree species experiments throughout Denmark. The soil microbial communities differed between six European tree species as well as between EcM (beech, lime, oak and spruce) and AM (ash and maple) tree species. The EcM tree species had higher fungal biomass, fungal growth and bacterial biomass, while AM species showed higher bacterial growth. The results indicated that microbial community composition and functioning differed between groups of tree species with distinct litter qualities that generate soil C/N ratio and soil pH differences. The mycorrhizal association only partly explained litter quality and soil microbial species differences since lime was more similar to AM tree species. In addition, our results indicated that tree species-mediated soil pH and C/N ratio were the most important variables shaping microbial communities with a positive effect on bacterial and a negative effect on fungal growth rates. The results suggest that tree species-mediated microbial community composition and activity may be important drivers of the different vertical soil C distribution previously observed in AM and EcM tree species., Authors Accepted Manuscript