Microarthropod Groups Research Articles

Biodiversity of a temperate karst landscape-ice cave collapse doline supports high α-diversity of the soil mesofauna.

Caves represent a specific environment with a special microclimate and fauna adapted to it. However, we have still a restricted knowledge on soil fauna communities in an environments with a marked microclimate gradient at the interface between cave and surface habitats. In the present study, we investigated the community patterns of dominant soil microarthropod group, oribatid mites, and their relationship to environmental factors across the microclimate gradient along a transect with seven study sites from cold and wet cave entrance zone to warm and drier deciduous forest. The cold and wet sites showed low oribatid abundances and a high spatial clustering of individuals in comparison to the warm sites. The oribatid mites showed significantly higher abundance and species richness at warm forest sites. Indicator species analysis indicated specific cold-tolerant species that dominated at cold sites of the gradient, but which were absent at the warmest sites. Variance analysis clarified that community composition at sites were significantly driven by environmental factors: temperature, soil moisture, pH and C/N ratio. The study underlines the importance of ice cave entrances as sources of high α-diversity of soil mesofauna and thus the conservation priority of these valuable habitats.

Collembola and ants: Influence of trails of red wood ants (Formica lugubris) on the community of soil springtails

Red wood ants are keystone species in forest ecosystems. Because ants are active polyphagous predators, they control the abundance of other arthropods. In addition to direct effects on other species, there are a number of indirect effects caused by ants. In our study, we investigated the influence of ants on springtails, which they rarely come into contact with. Springtails have been set as a model group to assess the state of soil animals, since they are one of the most numerous and widespread groups of soil microarthropods. They are characterized by high sensitivity to environmental changes. The basic characteristics (abundance, species richness, and species diversity) of the springtail community and the response of certain species to the presence of ant trails have been studied. The total abundance and species richness of springtails decreased along ant trails. Among occurred species Parisotoma ParIsotoma notabilis, Lepidacyrtus lignorum, Isotomiella minor, Desoria tigrina, and Pseudasinella alba are the most numerous species both along ant trails and in control samples. There are no significant changes in species diversity (assessed by the Shannon-Weaver index). Species structure of springtail communities along ant trails and in control is different. Two groups of common Collembola species are identified: (1) increasing their numbers in the presence of ants, (2) on the contrary, decreasing. The presence of ants in a forest ecosystem influences the soil springtail community, although ant-Collembola interactions are indirect.

Invasion by red imported fire ants depletes soil microarthropod communities in agricultural systems

AbstractBiological invasion is one of the major challenges to changing ecosystems worldwide. Red fire ants are a prime example of invasive soil animals. However, the impacts of their invasion on the native soil animal communities are still poorly understood. Here, we investigated how the biomass and diversity of soil microarthropods (incl., Collembola and Acari) vary between areas affected by red fire ants at different degrees (i.e., OA, occurrence area, 0–20 m from the nest; PCA, prevention and control area, 20–50 m; POA, potential occurrence area, 50–100 m). We also tested whether the potential effects of ant invasion on other animals are associated with changes in soil properties in the invaded areas. Our results showed a decline of 64% in species richness, 74% in density, and 72% in biomass of microarthropods in OA in comparison with POA. This reduction was mainly driven by the decrease of Acari, while no reduction in Collembola biomass was observed. Despite soil properties being significantly different between ant‐impacted areas, structural equation models indicated that the direct association of invasion with microarthropod communities is stronger than the indirect association mediated by soil properties. Therefore, we consider that direct biological interaction is more likely the major mechanism behind the observed changes in microarthropod communities. The effects of red fire ants were different among taxonomic and functional groups, with litter‐dwelling Collembola, Oribatida, and Mesostigmata (Acari) affected more negatively than soil‐dwelling and surface‐dwelling Collembola. Further, red fire ants affected the turnover component of beta‐diversity (i.e., replacement of species) for both Collembola and Acari. However, the impact on the nestedness component, which is related to species local extinction and population decline, was only detected for Acari. Our study shows that red fire ant invasion is associated with the depletion of soil microarthropod community, and especially highlights that Acari are more vulnerable to this invasion compared to Collembola. The divergent response between different taxonomic and functional groups of microarthropods and the consequent shift in microarthropod communities may have important significance to soil ecological functioning in the impacted areas.

Evaluating small‐scale harvesting disturbance to the forest soil in Mediterranean beech high forests

AbstractEuropean beech (Fagus sylvatica L.) forests in Central and Southern Italy are managed applying the shelterwood system. Prior to the regeneration cut, it is common to apply 2–3 thinning interventions, aiming to obtain mostly firewood, considering the low dimension and poor quality of the stems. These interventions are usually carried out by local forest enterprises relying on a low or medium level of mechanization (small‐scale forestry). In particular, the short wood system is applied, thus processing the logs to 1 m length and extracting them with forestry‐fitted farm tractors equipped with forwarding bins. Despite the large application of this harvesting system in the Mediterranean forestry, no information is available in the literature about its possible disturbance to the forest soil. To fulfill this knowledge gap, we developed the first assessment of soil physicochemical (bulk density, penetration resistance, shear resistance, organic matter content) and biological (soil microarthropods biodiversity evaluated with the QBS‐ar index, that is, an index based on the idea that high‐quality soils have more groups of microarthropods that are morphologically better adapted to the soil than low‐quality soils) properties for this kind of logging operation. In three case study areas in Central Italy, we applied an experimental design to evaluate separately the impacts related to the passage of the machine and that of the silvicultural treatment itself. We further applied linear mixed‐effect models to investigate the relationship between changes in soil physicochemical and biological properties. We found the effect of the silvicultural treatment to be negligible, but there was a significant alteration of the investigated parameters in the soil affected by the passage of the machine. Soil penetration and shear resistance doubled in the forwarding trails (0.25 MPa and 4.02 t m−2, respectively) in comparison with the other two experimental treatments (control area and soil not affected by the machine passage; about 0.12 MPa and 2.10 t m−2, respectively). Soil organic matter and soil microarthropod biodiversity (QBS‐ar index) were reduced by 25% in the forwarding trails (about 30% and 92 respectively) in comparison with the soil not affected by the machine passage (about 39% and about 130, respectively). Such significant disturbance, which occurred even if the applied machinery had lower weight in comparison to other alternatives (forwarders), is related to the high number of machine passes needed to extract the woody material with forwarding bins applying the short wood system. We found a significant relationship between soil compaction and soil organic matter removal and microarthropod biodiversity, with the latter which resulted significantly lower in more compacted and organic matter‐poor soils. We demonstrated that this small‐scale extraction system can have a negative effect on soil features in the short term. We therefore recommend the application of best management practices, for instance placing brush mats and logging residues, on the forwarding trails to limit the soil disturbance within the framework of small‐scale forestry. We further recommend a wider application of aerial harvesting systems, which generally have lower impacts to the soil. However, this could happen only after an extensive training program aimed to increase the knowledge and skills of local loggers about aerial harvesting systems.

Diversity and Distribution of Mites (ACARI) Revealed by Contamination Survey in Public Genomic Databases.

Acari (mites and ticks) are a biodiverse group of microarthropods within the Arachnida. Because of their diminutive size, mites are often overlooked. We hypothesized that mites, like other closely related microorganisms, could also contaminate public genomic database. Here, using a strategy based on DNA barcodes previously reported, we scanned contaminations related to mites (Acari, exclusive of Ixodida) in Genbank WGS/TSA database. In 22,114 assemblies (17,845 animal and 4269 plant projects), 1717 contigs in 681 assemblies (3.1%) were detected as mite contaminations. Additional taxonomic analysis showed the following: (1) most of the contaminants (1445/1717) were from the specimens of Magnoliopsida, Insecta and Pinopsida; (2) the contamination rates were higher in plant or TSA projects; (3) mite distribution among different classes of hosts varied considerably. Additional phylogenetic analysis of these contaminated contigs further revealed complicated mite-host associations. Overall, we conducted a first systemic survey and analysis of mite contaminations in public genomic database, and these DNA barcode related mite contigs will provide a valuable resource of information for understanding the diversity and phylogeny of mites.

Assessing soil quality of Italian Western Alps protected areas by QBS-ar: impact of management and habitat type on soil microarthropods

Soil fauna has a crucial importance for the functioning of ecosystems and their conservation. Soil biota has a role in soil formation and distribution of organic matter, and groups like microarthropods can be used as indicators to assess soil quality and are often employed in monitoring programs. In the present study, the QBS-ar index, an index based on the presence/absence of microarthropod groups, was used to assess the level of soil quality in nine different sampling sites in the “Parco Naturale delle Alpi Marittime” and in the “Parco Naturale del Marguareis” (Cuneo, Piedmont). Forest soils, with different degree of management, and open environments (e.g., grasslands and peatlands) were analyzed comparatively, to investigate whether microarthropod fauna might be influenced by management and habitat type.The results show QBS-ar values are significantly higher in woodland soils compared to grasslands and peatlands (p < 0.05). The latter shows no significant difference between each other, although grasslands show a large range of values (108–214). Forest management does not seem to influence QBS-ar values (183–239), showing stable microarthropod communities both in the managed and unmanaged areas. In addition to this, QBS-ar values do not differ significantly in the different forest coenoses, confirming that woodlands have similar index values (p = 0.7).This study confirms that QBS-ar values in natural areas can vary depending on the environment. It is therefore important to consider clustering habitat types before assessing quality classes for QBS-ar values. Finally, sustainable forest management in the study area does not seem to affect significantly soil microarthropod presence in woodland sites.

Warming shifts the biomass distribution of soil microarthropod communities

Climate warming is often more detrimental to large body sized organisms than small body sized organisms. Yet, how such differential effects of warming at organismal levels affect aggregate community properties, such as community biomass, remains little understood. Here, using geothermally warmed sub-Arctic grassland soils, we investigate how total biomass (product of density and individual body mass) of two major groups of soil microarthropods (Collembola and mites), which are composed of both large and small body sized species, shift in warmed soils when warmed by ∼3–∼6 °C. Our results show that total biomass of Collembola significantly decreased in warmed soils predominantly due to a decline in the density of large body sized species. In contrast, total mite biomass showed a unimodal response to warming. As a result, there was a shift towards mite biomass dominated microarthropod communities in warmed soils. Within Collembola, the deep soil living eu-edaphic functional group declined the most in total biomass, whereas the unimodal response in mites was most pronounced in oribatid mites. Our study highlights that warming induced shifts in total community biomass of soil microarthropods are likely due to greater detrimental effects of warming on several large body sized Collembola.

Karst Ecosystems of Middle Timan, Russia: Soils, Plant Communities, and Soil Oribatid Mites

Oribatid mites are distinguished by high taxonomic diversity and abundance in almost all natural zones; they are used as an indicator group of microarthropods in the study of natural landscapes and anthropogenically disturbed ecosystems. In the karst landscapes of the North, the oribatid mites are very poorly studied. The aim of this study was to investigate the diversity of soil types, plant communities, and oribatid mites in karst relief forms in the conditions of the northern taiga forests. The material was collected in July 2020 in the karst landscapes of Timan Ridge, found in the European northeast of Russia. The research sites were located in the profile of the karst crater and in the profile of the slope in the Ukhta River Valley. A sedge wetland community, and pine–bilberry–green-moss forest, located in the depression between glacial hills and uplands were also examined. A total of seven sites were examined. Geobotanical descriptions were made by standard methods, descriptions of the soil profile, and samples of the soil microfauna; 12 in each site were collected. A total of 51 oribatid mite species from 39 genera and 31 families were found. The highest taxonomic diversity of oribatids was noted in forest phytocenoses located in the upper part of the karst crater slope, the lower part of the karst crater slope, and on rock outcrops in the lower part of the slope in Ukhta river valley. Ordination of the oribatid mite community by NMDS method showed the association of sites S3, S4, and S5 located on the slope of the karst crater in one group, and sites S6 and S7 located on a slope in the Ukhta River Valley, as well as S2 (pine–bilberry–green-moss forest located in the depression between glacial hills and uplands), in another group. The swamp community was located separately from other communities. Species of oribatid mites, which created the specifics of each community, were noted. The specifics of the population of oribatid mites of karst landscapes were that along with the features of fauna, characteristic for zonal north-taiga forests (the predominance of polyzonal widespread species) were found the “conditionally southern” species, the main area of distribution of which is located in lower latitudes. The study provides the basis for future studies of poorly known oribatid mites of karst landscapes of Northern Europe.

Ecological intensification alters the trait-based responses of soil microarthropods to extreme precipitation in agroecosystem

Soil biodiversity is of key importance to many essential ecosystem functions, but currently it is severely threatened by both intensive agriculture and climate changes. Ecological intensification, including organic amendments and less disturbance, is expected to buffer the degradation of biodiversity and ecosystem functioning induced by intensive agriculture, but its effects in the context of climate changes are poorly understood. In the present work, we studied the responses of agricultural soil biodiversity to ecological intensification under different natural rainfall intensities in a subtropical field. We focused on a numerically dominant group of soil microarthropods, the Collembola, and three conservation managements, i.e., straw, manure, and no-tillage. The experimental site was established with a full-factorial design of different managements. Soil physiochemical parameters and the density, taxonomic diversity, and morpho-functional traits of the collembolan community were measured over three consecutive years. Results showed that rainfall intensification markedly reduced collembolan density and had severe impact on large euedaphic species. Straw amendment buffered the detrimental effect of dense rainfall on collembolan density, but aggravated the body size reduction caused by the rainfall. Manure input and no-tillage mainly affected the community functional composition, in which manure favours more active and mobile species characterised by a well-developed furca, whereas no-tillage favoured surface-dwelling species. These results support the hypothesis that external resource enrichment and reduced disturbance would shape the functional traits of soil fauna, and further modified their response to climate change events. Our findings call for more attention on the functional consequences of ecological intensification and the interactions among soil biodiversity, agricultural managements and climate changes.

Changes in the Structure of Microarthropods Population in Relation to Edaphic Factors in a Managed Ecosystem of Cachar District, North East India

Micro-arthropods are important bio-indicators of soil health and are an integral part of food web in soil ecosystems. The present study elucidates the extent to which the various soil parameters influence the structure of soil microarthropod community. Soil sampling was done on monthly intervals and modified Berlese Tullgren funnel method was applied for the extraction of soil microarthropods. Soil temperature was noted on the study sites while other parameters of soil were analyzed. Results showed that the Collembola was the most dominant microarthropod and the density of microarthropods was recorded highest in July 2016 and lowest in September 2016. Soil organic carbon showed a significant positive correlation while other parameters revealed a weak correlation with the microarthropods density. CCA analyses revealed the occurrence of the different microarthropod groups in correspondence with the various abiotic variables and were discussed based on the microarthropods position in the CCA plot. The relation of the different edaphic variables with the microarthropods indicates that the potential contribution of all these variables should be considered for assessing the different aspects of microarthropods ecology

ПРАКТИЧЕСКИЕ АСПЕКТЫ ПРИМЕНЕНИЯ БИОУДОБРЕНИЯ «ВЕСНА» КАК ФАКТОР ЗАЩИТЫ ПОЧВЕННОГО ПЛОДОРОДИЯ

The article is devoted to the study of the effect of biofertilizers on the number of different groups of soil microarthropods of chernozem of ordinary agrocenosis of perennial grasses in the condi-tions of the Lower Don. Most groups of mites and collembolus on the agrocenosis of perennial grasses, being saprophages by the nature of nutrition, undoubtedly play an important role in the circulation of substances, indirectly affecting the productivity of the agrocenosis. It was found that when applying the biofertilizer "Vesna", the number of all groups of microarthropods at the exper-imental site exceeded the control indicators by 1.5 times. All groups of ticks showed a large num-ber, gamase and shell ticks prevailed. The number of leg-tails was less than the number of ticks in the experimental area, but it turned out to be higher than the number of leg-tails in the control ar-ea. The vertical distribution of microarthropods in the horizon of 0-20 cm of the chernozem of the ordinary agrocenosis of perennial grasses was characterized by an uneven distribution: basically all groups of ticks and longtails are concentrated in the horizon of 0-10 cm, which is determined by the gradient of hydrothermal conditions and the distribution of root systems of plants of agro-cenosis.

Scavenging beetles control the temporal response of soil communities to carrion decomposition

Abstract Carrion is a frequent but overlooked source of nutrients to the soil. The decomposition of carrion is accelerated by invertebrate scavengers, but the impact of the scavengers on below‐ground biota and its functions is scarcely known. We conducted a laboratory experiment to investigate the effects of the burying beetle Nicrophorus vespilloides on the soil community of a temperate broadleaved forest. We assembled microcosms from soil collected from an oak woodland and treated them with mouse Mus musculus carcasses and mating pairs of burying beetles (♀+♂) in a factorial design with control soils. We sampled independent replicates over time to investigate how the beetles affect soil microarthropods and microbial biomass (bacteria and fungi) in relation to soil pH and organic matter content. The beetle treatment initially reduced the total microbial biomass and abundance of major groups of microarthropods relative to the control soil. At the same time, organic matter increased in the beetle treatment and then dropped to the pre‐beetle level (i.e. soil baseline) at the end of the beetle breeding cycle (2 weeks). The rapid temporal changes in organic matter were mimicked by the relative abundances of the dominant microarthropod groups, with Oribatida relatively more abundant than Collembola and predaceous mites in the beetle treatment. The overall final effect of the beetle (relative to the laboratory control) on microarthropods was negative but the beetle kept these variables within the levels observed for freshly collected soil (baseline), while the final effect on pH was positive, and most likely driven by the surplus of nutrients from the carcass and biochemical changes triggered by the decomposition process. In nature, scavenging invertebrates are widespread. Our study demonstrates that beetles breeding in carcasses regulate the dynamics of key components of the soil food web, including microbial biomass, changes in the relative abundances of dominant microarthropods and soil organic matter and pH. Given the abundance of these beetles in nature, the study implies that the distribution of these beetles is a key driver of variation in soil nutrient cycling in woodlands. A free Plain Language Summary can be found within the Supporting Information of this article.

Stable isotopes of amino acids indicate that soil decomposer microarthropods predominantly feed on saprotrophic fungi

AbstractSoil microarthropods are essential for nutrient cycling in forest ecosystems as they are integral components of decomposer food webs. They channel carbon and nutrients from leaf litter and roots to higher trophic levels; however, knowledge on the relative importance of different channels and on their variation with forest type is lacking. Although the importance of root‐derived inputs for sustaining soil food webs is increasingly recognized, the pathways by which they are channeled to higher trophic levels are little understood. For the channeling, ectomycorrhizal fungi may play a significant role, but until now methods allowing to separate the contribution of ectomycorrhizal and saprotrophic fungi to the nutrition of soil animal communities are lacking. Using dual analysis of 15N and 13C in amino acids (AAs), we investigated trophic positions and basal resources of two major groups of soil microarthropods, Collembola and Oribatida, in beech and spruce forests in Germany. By applying a 13C fingerprinting approach and Bayesian mixing models, we separated in a first step the relative contribution of bacteria, fungi, and plants to the nutrition of soil microarthropods. As fungi were identified as the major food source, in a second step we attempted to separate the contribution of ectomycorrhizal vs. saprotrophic fungi. For the first time, we provide direct evidence that soil microarthropods mainly rely on saprotrophic fungi, whereas ectomycorrhizal fungi are consumed by only few species. While trophic niches of Collembola and Oribatida species generally varied little between beech and spruce forests, plant detritus as basal resource of soil microarthropods was somewhat more important in beech forests, whereas in spruce forests microbial resources dominated. Overall, the dual analysis of carbon and nitrogen in AAs provided insight into food web structure of soil microarthropods in unprecedented detail, and for the first time allowed to estimate the relative importance of mycorrhizal and saprotrophic fungi for soil food web nutrition, a long‐standing riddle in soil food web ecology. The technique provides the perspective for a comprehensive understanding of the trophic structure and energy channeling in soil food webs.

Dynamics of soil microarthropod populations affected by a combination of extreme climatic events in tropical home gardens of Kerala, India

Climate change is predicted to increase drought and flooding events in the coming decades, especially in the tropics; we need to understand the short-term responses of plant community and soil microarthropods populations to these extreme events.Yet most of our current knowledge on this comes from manipulative studies in temperate regions. The present study reports the impact of a severe summer drought followed by a catastrophic flood in 2018 on soil microarthropod density and biological soil quality across 25 tropical home gardens. Drought reduced the density of organisms six-fold and flooding caused a further threefold reduction. Biological soil quality in the home gardens that were not flooded was restored during the monsoon season but this was just partially possible for microarthropod population size. Three months after flooding, the microarthropod groups encountered were generally able to re-establish their population to the condition prior to flooding. However, none of the group recovered to the mean seasonal values. The severity of previous drought seemed to have overridden any possible adaptation to annual summer water scarcity. Plant species richness in home gardens played a key role towards mitigation and possible resilience to disturbance of these ancient agroecosystems. The capacity of the soil microarthropod communities to recover over the long term after extreme climatic events and its relevance to maintaining ecosystem functions and services in home gardens through soil fertility warrant further investigation.

Effects of Livestock Pressure and Vegetation Cover on the Spatial and Temporal Structure of Soil Microarthropod Communities in Iberian Rangelands

Forests, including their soils, play an important role since they represent a large reservoir of biodiversity. Current studies show that the diversity of soil fauna provides multiple ecosystem functions and services across biomes. However, anthropogenic practices often pose a threat to soil fauna because of changes in land use and soil mismanagement. In these terms, rangelands in the southwest of Spain present several problems of soil degradation related to livestock activity and soil erosion, the intensity of which compromises the soil fauna’s functions in the ecosystem. Therefore, the aim of this study is to evaluate the response of community metrics and the spatial distribution of soil microarthropods to livestock activity and vegetation in such ecosystems. A photo interpretation analysis of an experimental catchment used as a study area was developed to identify and classify the intensity of livestock pressure. A total of 150 soil samples were collected throughout 2018. Soil biological (CO2 efflux) and physical-chemical parameters (pH, bulk density, organic matter, and water contents), and such meteorological variables as precipitation, temperature, and evapotranspiration were considered as variables affecting the composition of microarthropod communities in terms of taxa diversity, abundances, and their adaptation to soil environment (evaluated by QBS-ar index). Results showed higher abundance of microarthropods and higher adaptation to soil environment outside the influence of trees rather than beneath tree canopies. Moreover, the classification of livestock pressure revealed by the photo interpretation analysis showed low correlations with community structure, as well as with the occurrence of well-adapted microarthropod groups that were found less frequently in areas with evidence of intense livestock activity. Furthermore, abundances and adaptations followed different spatial patterns. Due to future climate changes and increasing anthropogenic pressure, it is necessary to continue the study of soil fauna communities to determine their degree of sensitivity to such changes.

Variation in trophic niches of oribatid mites in temperate forest ecosystems as indicated by neutral lipid fatty acid patterns

Shifting of trophic niches of soil microarthropods may allow them to adapt to changing resource conditions as induced by global change processes. However, the capability of microarthropods to shift their trophic niches is little studied. Whereas some studies based on stable isotopes (15N/13C) point to distinct and narrow trophic niches, others indicate that trophic niches are plastic. Here, we investigated shifts in trophic niches of oribatid mites (Oribatida, Acari), a major soil detritivore microarthropod group, due to forest management, i.e., plantation of beech and spruce forests in Central Europe, using neutral lipid fatty acid (NLFA) markers. Due to differential microbial communities, we expected a fungi-based diet of oribatid mites in beech forest, but more bacterial contributions to the diet in spruce forest. Supporting these hypotheses, NLFA markers indicated that the trophic niches of each of the studied oribatid mite species differed between beech and spruce forests and shifted from feeding predominantly on litter and fungi in beech forest to more intensively feeding on bacteria in spruce forest. Oribatid mite species with the most pronounced differences in trophic niches included Achipteria coleoptrata, Eupelops hirtus, Eupelops plicatus and Liacarus xylariae, which had been classified as primary or secondary decomposers in previous studies. Overall, the results indicate that the ability of oribatid mite species to colonize different habitats and ecosystems is due to their ability to adjust their diet, i.e., to trophic plasticity. Changes in trophic niches in each of the studied oribatid mite species suggest that detritivores in soil may better cope with future changes in environmental conditions and associated changes in resource composition than species above the ground.

Get a grip-evolution of claw shape in relation to microhabitat use in intertidal arthropods (Acari, Oribatida).

Claws may be the most common biological attachment devices in animals but relatively few studies have examined the ecological and evolutionary significance of their morphology. We performed the first geometric morphometric investigation of arthropod claws using 15 intertidal oribatid mite species from two different families living in three different habitat types to determine if claw shape is correlated with ecology. Our results show that species living on rocky shores show remarkably high and strongly curved claws while species from mangrove habitats show significantly lower and less curved claws. Euryoecious species are able to dwell in a wide range of habitats and show an intermediate claw type. These results indicate a strong relationship between claw shape and microhabitat and the best predictors of microhabitat use seem to be claw height and curvature. Claw length varied to some degree among the species but without any noticeable ecological pattern. A comparison with terrestrial and freshwater aquatic oribatid mite species, on the other hand, confirms that their claws are only half as long as that of intertidal mites and it is suggested that tidal flooding and wave action strongly selects for long claws. In this microarthropod group which occupies a vast array of microhabitats, claw morphology may play an important role in niche separation and hence demonstrate the importance of ecomorphological studies.

Move or change, an eco-evolutionary dilemma: The case of Collembola

The present opinion paper suggests that springtails, which can live above- and/or belowground according to species requirements, have two strategies at their disposal to face environmental hazards, called ‘move’ or ‘change’. Species with poor dispersal capacity, often parthenogenetic, and living mainly in a confined environment, have to adapt themselves by increasing their phenotypic plasticity or letting the environment selecting or adding favourable mutations. Conversely, species with a high dispersal capacity, often sexual and living in a more open environment, may emigrate and immigrate without the need to become better adapted to changing environmental conditions. Advantages and disadvantages of these two tactics are reviewed and their prospective responses to global changes are compared on the light of existing knowledge on this microarthropod group.

Soil Health and Arthropods: From Complex System to Worthwhile Investigation.

The dramatic increase in soil degradation in the last few decades has led to the need to identify methods to define not only soil quality but also, in a holistic approach, soil health. In the past twenty years, indices based on living communities have been proposed alongside the already proven physical-chemical methods. Among them, some soil invertebrates have been included in monitoring programs as bioindicators of soil quality. Being an important portion of soil fauna, soil arthropods are involved in many soil processes such as organic matter decomposition and translocation, nutrient cycling, microflora activity regulation and bioturbation. Many studies have reported the use of soil arthropods to define soil quality; among taxa, some have been explored more in depth, typically Acari and Collembola, while generally less abundant groups, such as Palpigradi or Embioptera, have not been investigated much. This paper aims to evaluate and compare the use of different soil microarthropod taxa in soil degradation/quality studies to highlight which groups are the most reported for soil monitoring and which are the most sensitive to soil degradation. We have decided not to include the two most present and abundant taxa, Acari and Collembola, in this paper in consideration of the vast amount of existing literature and focus the discussion on the other microarthropod groups. We reported some studies for each taxon highlighting the use of the group as soil quality indicator. A brief section reporting some indices based on soil microarthropods is proposed at the end of this specific discussion. This paper can be considered as a reference point in the use of soil arthropods to estimate soil quality and health.

Recovery Successions of Soil Microfauna in Oil-Polluted Ecosystems of the European Subarctic

The dependence of recovery of the soil zoocoenosis on succession of the plant community after soil remediation was examined. An increase in the population density of invertebrates was registered in the following phytocoenotic succession on the “agrochemical techniques” experimental site: no plants—low projective cover—high projective cover (5100 ± 1340, 12 400 ± 2823, and 22 040 ± 3008 ind./m2, respectively). Various trends in the microarthropod population density were identified: a reduction of the parameter values for dipterous larvae and mesostigmatic mites over time and, conversely, an increase in the population densities of collembolans and oribatid mites; these trends determine the dynamics of the grouping structure and changes in the dominant taxa. Demutation of the zoocoenosis has been divided into three stages; taxonomic groups of microarthropods acting as biomarkers of succession stages were identified: larvae of Diptera and mesostigmatic mites at the first stage, collembola at the second stage, and oribatid mites at the third stage.