Soil Decomposer Research Articles

Plant invasion down under: exploring the below-ground impact of invasive plant species on soil properties and invertebrate communities in the Central Plateau of New Zealand

AbstractThe impacts of invasive plants on arthropod communities are often reported to be negative and have predominantly been explored aboveground, but there is a paucity of information regarding what happens belowground. To address this gap, we compared soil properties and soil fauna communities associated with two native plant species (Leptospermum scoparium—mānuka and Chionochloa rubra—red tussock) and two invasive species (non-N-fixing Calluna vulgaris—European heather and N-fixing Cytisus scoparius—Scotch broom) in the Central Plateau of New Zealand. We expected that (1) at individual plant level soil properties would be different under invasive and native plant species, with higher soil nutrient concentrations under invasive species, especially N-fixing broom; (2) total abundance of soil fauna would be higher under invasive plant species, as generally positive impact of invasive plants on soil invertebrates is indicated in the literature; (3) invasive plants, and especially N-fixing broom, will be associated with greater abundances of soil decomposer groups. We found that soil properties and soil fauna assemblages did not cluster by plant invasive status as initially predicted. At individual plant level, there was similarity in soil conditions between mānuka and broom, and between red tussock and heather. The invasive N-fixer (broom) had positive effects on soil N availability, with higher N pool and lower C/N ratio in soil under this species. There were no consistent differences in total soil fauna abundance between invasive and native plants. Broom and mānuka were associated with higher abundances of Collembola, Oligochaeta and Diplopoda; heather and red tussock had higher abundances of Hymenoptera and Hemiptera. Significantly more Oligochaeta and Collembola under broom matched the prediction of invasive plants (and especially N-fixing invasives) being associated with greater abundances of decomposers. However, another important decomposer group—oribatid mites—did not show the same tendency. These results evidence that simplified generalizations regarding the impacts of invasive plants are unlikely to be justified, since the ecological effects of plant invasions are complex and do not always follow the same pattern. Therefore, we need to take into consideration the ecological context and the traits of individual plant species and target organisms in an unbiased manner to fully understand the impacts of plant invasions.

Recover of Soil Microbial Community Functions in Beech and Turkey Oak Forests After Coppicing Interventions

Forest management influences the occurrence of tree species, the organic matter input to the soil decomposer system, and hence, it can alter soil microbial community and key ecosystem functions it performs. In this study, we compared the potential effect of different forest management, coppice and high forest, on soil microbial functional diversity, enzyme activities and chemical-physical soil properties in two forests, turkey oak and beech, during summer and autumn. We hypothesized that coppicing influences soil microbial functional diversity with an overall decrease. Contrary to our hypothesis, in summer, the functional diversity of soil microbial community was higher in both coppice forests, suggesting a resilience response of the microbial communities in the soil after tree cutting, which occurred 15–20 years ago. In beech forest under coppice management, a higher content of soil organic matter (but also of soil recalcitrant and stable organic carbon) compared to high forest can explain the higher soil microbial functional diversity and metabolic activity. In turkey oak forest, although differences in functional diversity of soil microbial community between management were observed, for the other investigated parameters, the differences were mainly linked to seasonality. The findings highlight that the soil organic matter preservation depends on the type of forest, but the soil microbial community was able to recover after about 15 years from coppice intervention in both forest ecosystems. Thus, the type of management implemented in these forest ecosystems, not negatively affecting soil organic matter pool, preserving microbial community and potentially soil ecological functions, is sustainable in a scenario of climate change.

Emerging Microplastics Alter the Influences of Soil Animals on the Fungal Community Structure in Determining the Litter Decomposition of a Deciduous Tree

Microplastics enter forest ecosystems in a variety of ways, including through atmospheric deposition, anthropogenic waste, and leaching. There is growing evidence of the ecotoxicity of microplastics to soil decomposers. Soil animals and microorganisms are the main decomposers of plant litter, and their interactions play important roles in determining the terrestrial biochemical cycle. However, how emerging microplastics in forests affect the influence of soil animals on the fungal community in decomposed litter is still unclear. Here, by constructing a rigorous mesocosm experiment, we investigated soil enzyme activities and the variation in fungal community characteristics in the leaf litter of a deciduous tree, Lindera glauca, which was decomposed by contrasting decomposer structures (with or without soil animals) under different contamination conditions (with or without microplastic contamination), aiming to determine the impacts of these factors on litter decomposition. We found that soil animals can significantly depress the litter decomposition rate by reducing fungal diversity and largely changing the community structure in the litter. However, these critical changes caused by soil animals were inhibited in the mesocosms contaminated with high-density polyethylene microplastics (HDPE−MPs), during which soil animal activities were significantly reduced. These findings represent a step forward in illustrating the potential effect of emerging contamination stress on forest litter decomposition and biogeochemical cycles under global environmental change.

Soil enzyme profile analysis for indicating decomposer micro-food web.

Highly diverse exoenzymes mediate the energy flow from substrates to the multitrophic microbiota within the soil decomposer micro-food web. Here, we used a "soil enzyme profile analysis" approach to establish a series of enzyme profile indices; those indices were hypothesized to reflect micro-food web features. We systematically evaluated the shifts in enzyme profile indices in relation to the micro-food web features in the restoration of an abandoned cropland to a natural area. We found that enzymatic C:N stoichiometry and decomposability index were significantly associated with substrate availability. Furthermore, the higher Shannon diversity index in the exoenzyme profile, especially for the C-degrading hydrolase, corresponded to a greater microbiota community diversity. The increased complexity and stability of the exoenzyme network reflected similar changes with the micro-food web networks. In addition, the gross activity of the enzyme profile as a parameter for soil multifunctionality, effectively predicted the substrate content, microbiota community size, diversity, and network complexity. Ultimately, the proposed enzymic channel index was closely associated with the traditional decomposition channel indices derived from microorganisms and nematodes. Our results showed that soil enzyme profile analysis reflected very well the decomposer food web features. Our study has important implications for projecting future climate change or anthropogenic disturbance impacts on soil decomposer micro-food web features by using soil enzyme profile analysis.

Community composition, and not species richness, of microbes influences decomposer functional diversity in soil

Diversity-function relationships in producers, and how these are influenced by consumers, are well known. However, these are not well known for microbial decomposers in soil. It is also unknown whether and how consumers such as large mammalian herbivores influence soil microbial decomposer diversity-function relationships. We used a 14-year-old herbivore-exclusion experiment in the Trans-Himalayan drylands of northern India to address whether microbial functions vary with microbial diversity (both species richness and composition), and whether herbivores alter the diversity-function relationships. We analyzed soils from n = 10 paired grazed-and-fenced plots three times during the growth season of 2019. Data were from 16S rDNA gene amplicon sequencing of 7.6 million reads covering 1937 operational taxonomic units (OTU) of bacteria across 47 phyla (of which 924 OTUs were identifiable to genus level), and 1800 catabolic profiles across 30 substrates related to carbon metabolism. We found that functional diversity was positively related to microbial community composition, but not to species richness; it was also unaffected by large mammalian herbivore-exclusion to indicate resilience and resistance. This positive relationship between community composition and functional diversity challenges the prevailing notion of functional redundancy in hyper-diverse soil microbial communities since certain combinations of species could outperform others and determine decomposition processes and services. Structural equation models suggested that the strength of this relationship is favoured by availability of soil moisture. Microbial functions varied more strongly with temporal variables (e.g., seasonality) than with spatial variables (e.g., edaphic factors such as soil texture and pH). Although interpretations can be constrained by which and how many functions are investigated, the relationship was generalizable and robust once 16 or more functions were quantified. Decomposition in drylands may be particularly susceptible to how the identity of the microbial species, and not the number of species, responds to rising precipitation variability under ongoing and projected climate change.

Examining the Shift in the Decomposition Channel Structure of the Soil Decomposer Food Web: A Methods Comparison.

Selecting the appropriate indicators and measuring time point numbers is important for accurately examining the shift in soil gross decomposition channel structure. Through a selected case study on a natural forest vs. rainfed arable system over a two-month-long experiment, the utility of three commonly employed indicators (fungi to bacteria ratio (F:B), fungivore to bacterivore ratio (FF:BF), and glucosamine to muramic acid ratio (GlcN:MurN)) were compared to reflect the shift in soil gross decomposition channel structure. The requirement of measuring the time point numbers for the three indicators was also assessed, and we suggest a potential methodology. Our results revealed that the GlcN:MurN ratio was more reliable for assessing the shifts in gross decomposition channel structure for long-term land use changes, while it was less sensitive to short-term drought compared with the other two indicators. The F:B ratio was more applicable than the FF:BF ratio for reflecting both long- and short-term changes. Furthermore, the reliability of the GlcN:MurN ratio was the least dependent on measuring time point numbers. We suggest the use of multiple indicators and the adoption of multiple measuring time points for the overall methodology.

Responses of bulk and rhizosphere soil microbiomes to different cover crop inputs and their connection and contribution to soil fertility and plant growth

Bulk and rhizosphere soil microbiomes may be naturally linked and exhibit unique responses to different cover crop inputs during the early decomposition process. However, their relationship and contribution to soil carbon and nitrogen levels and plant growth during the decomposition process remain unclear. Herein, we performed a pot-based experiment to investigate the interactive effects of cover crops (rye, hairy vetch [HV], and a mixture of rye and HV [mix]) and soil microbial habitats (bulk and rhizosphere soils) on the microbial community. Additionally, we identified the hub taxa and evaluated their contributions to the microbial community, soil fertility, and plant growth. Lettuce was grown in soil exposed to control, rye, HV, or mixed cover crops. Bacterial 16S rRNA) and fungal (ITS) community structures were characterized in bulk and rhizosphere soils of lettuce plants using a DNA-based molecular approach. The results showed that cover crops and soil microbial habitats independently affected microbial community structures; the relative abundances of fungi and bacteria, known as decomposers in bulk soil and plant growth-promoting bacteria in rhizosphere soil, increased. The hub taxa under each treatment represented specific groups that connect bulk and rhizosphere microbiomes. Based on Mantel statistical analysis, hub taxa may maintain the bulk soil microbiome, within which the bacterial community in HV and mix treatments may contribute to the nitrogen supply from cover crop residues. Additionally, the bacterial community in rhizosphere soil in HV and mix treatments may contribute to nitrogen absorption by lettuce plants. These results add to the understanding of the early process of sustainable agriculture using cover crops.

Ecological significance of standing dead phytomass: Marcescence as a puzzle piece to the nutrient cycle in temperate ecosystems

Abstract The plant economics spectrum (PES) drives nutrient cycling through effects on soil decomposers. However, dead phytomass may remain standing or unshed (marcescent), hardly accessible to decomposers and be photodegraded. In arid zones, the significant part of marcescent phytomass can be decomposed without touching the ground. In temperate zones, photodegradation of marcescent phytomass is low but prompts important chemical changes, which affect its subsequent decomposability in the soil and alters the surrounding environment. It is unknown, however, how common marcescence is among different taxa and in which habitats, and how it is coordinated by PES traits. We sampled standing (marcescent) and lying (shed) dead phytomass from a broad spectrum of 127 herbaceous temperate species in a common garden experiment and related these parameters to PES traits, species ecological preferences and phylogeny. Nearly all species (97%) kept their phytomass marcescent. Tall species with a small leaf area and high leaf carbon had a high level of marcescence. Marcescent species also preferred sites affected by severe (but not necessarily frequent) disturbance. The degree of marcescence was considerably conserved in phylogeny. Synthesis. Marcescence extends PES trait effects on ecosystems, particularly in immature habitats, being a common but overlooked phenomenon of the temperate flora.

Humus Forms and Organic Matter Decomposition in the Swiss Alps

Humus forms and organic matter decomposition are influenced by climate, plants and soil decomposers. Yet, whether different humus forms could be experimentally linked to litter decomposition has still to be fully assessed. To assess the link between humus systems and organic matter decomposition, we worked in two regions of the Swiss Alps (Valais and Ticino) along elevational gradients by following a north/south exposure design. We quantified humus forms macrorests proportion types by the Ponge small-volume method and measured the decomposition of green tea and rooibos tea within the Parasystems and Terrosystems. We found that Parasystems and Terrosystems differed in tea decomposition rates, with a slower decomposition in Parasystems than in Terrosystems. We also observed that elevation, and hence, vegetation type (i.e., forest in the subalpine versus grassland in the alpine), drove humus form distribution, with Parasystems found in the alpine and subalpine in Ticino, while in Valais Parasystems were only found in the alpine and Terrosystems in the subalpine levels. Further analyses are however needed to identify other variables that best correlate with variation in decomposition processes within humus systems, such as soil decomposer community composition.

Neutral Dietary Effects of Two MicroRNAs, Csu-Novel-260 and Csu-Mir-14, on the Non-Target Arthropod Folsomia candida.

RNA interference (RNAi) that is triggered by small or short RNAs has shown enormous potential in the development of pest control strategies. Two microRNAs (miRNAs), Csu-novel-260 and Csu-miR-14, were used in insect-resistant genetically engineered (IRGE) rice lines to confer resistance to Chilo suppressalis. However, a risk assessment of RNAi-based products is essential to determine the safety of a biopesticide or IRGE crop for commercialization. The non-target organism Folsomia candida, which plays an important ecological role as a soil decomposer in agricultural ecosystems, was used to assess the risk of miRNAs Csu-novel-260 and Csu-miR-14. In this study, a dietary miRNA toxicity assay system was established in F. candida. The expression levels of target genes, survival rate, fecundity and body size were investigated to evaluate the effects of the miRNAs on F. candida under the worst-case scenario. The results showed that the dietary miRNA toxicity assay system could be used for risk assessment of miRNA in F. candida. The target genes of miRNAs were influenced by miRNA at some time points. However, no significant differences were observed in the life-table parameters in F. candida fed with a diet containing miRNAs. The dietary effects of two miRNAs on F. candida are neutral.

Role of carbohydrate-active enzymes in mycorrhizal symbioses.

Mycorrhizal fungi form mutually beneficial interactions with a wide range of terrestrial plants. During this symbiosis, the associated fungus provides mineral nutrients, such as phosphorus and nitrogen, to its host plant in exchange of photosynthesis-derived carbohydrates. Genome sequencing of mycorrhizal fungi has shown that arbuscular mycorrhizal fungi and ectomycorrhizal fungi have a restricted set of plant-cell wall degrading enzymes (PCWDE) genes, while orchid and ericoid mycorrhizal fungi have an extended PCWDE repertoire similar to soil decomposers and wood-decay fungi. On the other hand, mycorrhizal fungi have retained a substantial set of carbohydrate active enzymes (CAZymes) acting on microbial polysaccharides. Functional analysis has shown that several of the remaining PCWDEs are involved in the fungal root colonization and establishment of the symbiotic interface. In this review, we highlight the current knowledge on the evolution and function of PCWDEs in mycorrhizal fungi.

Variability in terrestrial litter decomposition can be explained by nutrient allocation strategies among soil decomposer communities

Abstract Leaf litter decomposition is a key process for nutrient cycling with broad ecosystem‐level consequences. However, we still cannot explain an important amount of the observed variability in decomposition rates. Therefore, a mechanistic model of how litter quality impacts the metabolic capacity of microbial decomposers to degrade litter at a given rate could improve our understanding of litter decomposition. Elemental imbalances between leaf litter and microbial decomposers can lead to nutrient‐limited decomposition. Microbial decomposers can deal with elemental imbalances via three main physiological mechanisms; by adjusting their carbon use efficiency (i.e. the proportion of assimilated carbon that is not respired), accumulating nitrogen or adjusting extracellular enzyme allocation between carbon (C) and nitrogen (N). Therefore, decomposer communities that adjust to elemental imbalances using these strategies should decompose litter faster than those unable to adjust. In this study, in a reciprocal transplant microcosm, we experimentally evaluated whether differences in the capacity of decomposers to reduce elemental imbalances help explain variability in decomposition rates. We used litter and soils from three coexisting woody species with contrasting litter C:N. Throughout the decomposition experiment, we quantified litter biomass loss, the allocation to β‐1,4‐glucosidase and β‐N‐acetylglucosaminidase (i.e. C and N degrading enzymes), and N accumulation. These data allowed us to identify the main strategies through which decomposers deal with elemental imbalances and their concomitant effects on litter decomposition rates. Our results confirm that litter decomposition rates are strongly controlled by litter quality, but differences in decay rates are a function of C and N demands of decomposers. Here, decomposers dealt with elemental imbalances mainly through N accumulation and, to a lesser extent, through extracellular enzyme allocation and lower carbon use efficiency. However, when enzymatic allocation and N accumulation were insufficient to reduce elemental imbalances, decomposition rates were slower irrespective of litter quality. Finally, we show that the effectiveness of physiological strategies used by decomposers to reduce elemental imbalances will affect decomposition rates, a key ecosystem process. Read the free Plain Language Summary for this article on the Journal blog.

Impacts of plant domestication on soil microbial and nematode communities during litter decomposition

PurposePlant domestication altered leaf litter quality. Since litter traits relate to soil functions and organisms (i.e., litter decomposition and soil decomposer communities), in this study we explore if domestication-induced changes in litter quality have affected their decomposability, and bacterial, fungal, and nematode communities in the soil.MethodsWe collected leaf litter from herbaceous crops and their wild progenitors, and measured litter chemical and physical traits. Then, we performed a litter decomposition assay on a common soil. After three months of litter incubation, we measured mass loss, nematode richness and community composition in ten crops. We also measured soil bacterial and fungal richness and community composition in six crops.ResultsDomesticated litters had less carbon (C) and leaf dry matter content (LDMC), which accelerated decomposition in comparison to wild litters. Fungal richness was higher in microcosms incubated with domesticated litters, while the effects of domestication on bacterial richness differed among crops. Domestication did not affect nematode richness. The effects of domestication on bacterial and fungal community compositions differed among crops. Soils with domesticated litters tended to have nematode communities with a higher abundance of bacterial feeding nematodes, in comparison to soils fed with wild litters.ConclusionDomestication altered decomposition at different levels. Leaf litter decomposability increased with domestication, which might alter resource inputs into the soil. Feeding soils with domesticated litters had idiosyncratic effects on soil microbes, but consistent effects on soil nematodes. Overall, domestication altered the linkages between crop residues and soil communities differently for bacteria, fungi, and nematodes.

Regulation of agronomic traits of bean by soil decomposer animals depends on cropping system and genotype

Regulation of agronomic traits of bean by soil decomposer animals depends on cropping system and genotype

Synergic chitin degradation by Streptomyces sp. SCUT-3 chitinases and their applications in chitinous waste recycling and pathogenic fungi biocontrol

The genus Streptomyces comprises the most important chitin decomposers in soil and revealing their chitinolytic machinery is beneficial for the conversion of chitinous wastes. Streptomyces sp. SCUT-3, a chitin-hydrolyzing and a robust feather-degrading bacterium, was isolated previously. The potential chitin-degrading enzymes produced by SCUT-3 were analyzed in the present study. Among these enzymes, three chitinases were successfully expressed in Pichia pastoris at comparatively high yields of 4.8 U/mL (SsExoChi18A), 11.2 U/mL (SsExoChi18B), and 17.8 U/mL (SsEndoChi19). Conserved motifs and constructive 3D structures of these three exo- and endochitinases were also analyzed. These chitinases hydrolyzed colloidal chitin to chitin oligomers. SsExoChi18A showed apparent synergic effects with SsEndoChi19 in colloidal chitin and shrimp shell hydrolysis, with an improvement of 29.3 % and 124.9 %, respectively. Compared with SsExoChi18B and SsEndoChi19, SsExoChi18A exhibited the strongest antifungal effects against four plant pathogens by inhibiting mycelial growth and spore germination. This study provided good candidates for chitinous waste-processing enzymes and antifungal biocontrol agents. These synergic chitin-degrading enzymes of SCUT-3 are good targets for its further genetical modification to construct super chitinous waste-degrading bacteria with strong abilities to hydrolyze both protein and chitin, thereby providing a direction for the future path of the chitinous waste recycling industry.

Crop productivity, resource allocation and nitrogen concentration as affected by soil decomposers, mixed cropping and crop genotype

Mixed cropping, crop breeding and soil biodiversity all serve as promising strategies for the management of agroecosystems, but empirical evidence for their synergies and trade-offs remains little explored. Here, we studied the effects of two main soil decomposers, collembolans and earthworms, on 15N uptake from organic residues, crop production, resource allocation and shoot-root C/N ratio of two bean genotypes (S-62 and S-69) in monoculture and mixture with wheat in a microcosm experiment. Soil decomposers mainly increased the productivity of wheat and little that of beans, but their effects on wheat varied with bean genotype. Earthworms increased the biomass of reproductive (+231%) and vegetative (+36%) organs as well as that of roots (+56%) of wheat in mixtures with S-62. Conversely, neither collembolans nor earthworms significantly affected wheat biomass when cultivated with S-69. Effects of decomposers on crop C/N ratio were pronounced in beans, but varied between cropping systems as well as between genotypes. In monoculture, collembolans decreased shoot C/N ratio of S-69 by 10%, whereas in mixture they increased it by 11% in S-62 irrespective of the presence of earthworms. 15N uptake by crop species was mainly affected by mixed cropping and earthworms; mixed cropping generally reduced the uptake of litter 15N by both crops, whereas earthworms generally increased it. The results document that soil decomposers differentially affect different genotypes of crops in particular in mixture and indicate that wheat benefits more from decomposers than beans. Both the non-uniform and complementary effects of soil decomposers on crop performance suggest that maintaining soil biodiversity may help in establishing sustainable cropping systems and this may be particularly important in mixture. The differential response of different genotypes to soil decomposers suggests that breeding programs targeting at establishing plant genotypes responsive to decomposer-mediated changes in plant performance may help in the establishment of sustainable monoculture but particularly mixed cropping systems in future.

Response of soil Collembola to nitrogen and phosphorus deposition: A review

Collembola are among the most abundant and integral group in soil decomposers. They channel C and nutrients from basic food resources to higher trophic levels, and therefore play an irreplaceable role in the underground food web. Collembola community would be altered dramatically by increasing N and P deposition. However, we still know little about how Collembola respond to N and P inputs, which will largely retard our steps to understand the ecological functions of collembolans, material circulation and energy flow of the underground food web, and even C cycling in terrestrial ecosystem. The different classification rules for Collembola functional groups have led to poor comparability of research results in the literature. This review proposed three taxonomic criteria of Collembola and four common research means on trophic relationships, summarized the mechanisms underlying the responses of Collembola to N and P addition alone and coadded. Overall, Collembola generally shows a negative response to N addition namely community density decreases, while a positive response to P addition in most ecosystems. The situation was more complicated under the combined N and P application. In the future, the research of Collembola response to N and P deposition should focus on the scientific taxa of Collembola functional groups, improving the research methods of trophic structure of Collembola, and the mechanism underlying the impacts of N and P interaction on Collembola community.

Optimal soil water content and temperature sensitivity differ among heterotrophic and autotrophic respiration from oasis agroecosystems

Soil respiration (Rs), which consists of heterotrophic respiration (Rh) by soil decomposers and autotrophic respiration (Ra) by roots, plays a critical role in the climate–carbon cycle feedback. However, the magnitudes, patterns and drivers of Rs and its components remain unclear in agroecosystems in arid regions. In this study, we conducted a two-year program of continuous measurement of Rs, Rh, Ra, soil water content (SWC5), and soil temperature (Ts5) at a 5-cm depth in an irrigated vineyard in Northwest China. The results showed that the mean annual Rs was 688.03 ± 8.59 g C m−2 yr−1 (mean ± standard deviation), of which 67.9 ± 0.5 % was dependent on Rh and 32.1 ± 0.5 % was dependent on Ra. In addition, the contribution of Rs during the non-growing season (NGS) to the annual values was 19.9 ± 2.3 %. We found that Rh and Ra responded asynchronously to SWC5 and Ts5. During the growing season (GS), the optimal SWC5 (20.0 %) and temperature sensitivity (Q10 = 1.93 ± 1.38) for Ra were higher than that for Rh (19.0 % and 0.97 ± 0.76). They were affected by the plant growth stages to a certain extent. During the NGS, the Q10 for Rh (1.52 ± 0.95) was higher than that for Ra (1.51 ± 1.27). These results underscore the importance of including the NGS emissions for reliably quantifying annual Rs and its components from arid agroecosystems. Meanwhile, Rh and Ra should be considered separately in Earth system models. The different optimal soil water content and temperature sensitivity for Rh and Ra should be used when predicting the effects of climate change.

Northward range expansion of rooting ungulates decreases detritivore and predatory mite abundances in boreal forests.

In the last few decades wild boar populations have expanded northwards, colonizing boreal forests. The soil disturbances caused by wild boar rooting may have an impact on soil organisms that play a key role in organic matter turnover. However, the impact of wild boar colonization on boreal forest ecosystems and soil organisms remains largely unknown. We investigated the effect of natural and simulated rooting on decomposer and predatory soil mites (total, adult and juvenile abundances; and adult–juvenile proportion). Our simulated rooting experiment aimed to disentangle the effects of (i) bioturbation due to soil mixing and (ii) removing organic material (wild boar food resources) on soil mites. Our results showed a decline in the abundance of adult soil mites in response to both natural and artificial rooting, while juvenile abundance and the relative proportion of adults and juveniles were not affected. The expansion of wild boar northwards and into new habitats has negative effects on soil decomposer abundances in boreal forests which may cascade through the soil food web ultimately affecting ecosystem processes. Our study also suggests that a combined use of natural and controlled experimental approaches is the way forward to reveal any subtle interaction between aboveground and belowground organisms and the ecosystem functions they drive.

Phylotype diversity within soil fungal functional groups drives ecosystem stability.

Soil fungi are fundamental to plant productivity, yet their influence on the temporal stability of global terrestrial ecosystems, and their capacity to buffer plant productivity against extreme drought events, remain uncertain. Here we combined three independent global field surveys of soil fungi with a satellite-derived temporal assessment of plant productivity, and report that phylotype richness within particular fungal functional groups drives the stability of terrestrial ecosystems. The richness of fungal decomposers was consistently and positively associated with ecosystem stability worldwide, while the opposite pattern was found for the richness of fungal plant pathogens, particularly in grasslands. We further demonstrated that the richness of soil decomposers was consistently positively linked with higher resistance of plant productivity in response to extreme drought events, while that of fungal plant pathogens showed a general negative relationship with plant productivity resilience/resistance patterns. Together, our work provides evidence supporting the critical role of soil fungal diversity to secure stable plant production over time in global ecosystems, and to buffer against extreme climate events.