Collembolan Communities Research Articles

Effect of detrital subsidy on the Collembola community structure in winter wheat agroecosystems

Mulch is widely used for improving soil quality and maintaining crop productivity. The effects of mulch use in agroecosystems can be assessed by the state of the soil biota. Springtails (Collembola) are a representative group of soil animals in agroecosystems that survive well under agricultural field conditions. We assessed the effect of adding a detrital subsidy with different carbon to nitrogen ratio (C:N) on springtails in a 4-year series of field experiments in winter wheat agroecosystems located in two agroecological zones (broad-leaved forest and steppe). The mulch effect depended on weather conditions. In dry years, the addition of mulch led to an increase in the proportion of epedaphic (upper-litter dwellers) springtails in the broad-leaved forest zone and to an increase in the proportion of atmobiotic forms (mostly inhabiting macrophytes) in the steppe zone. These changes begin to manifest approximately 1.5 months after the detrital subsidy addition. In general, mulch application had a positive and stabilizing effect on the springtail community structure in winter wheat agroecosystems, regardless of the agroecological zone. Our study showed that the addition of detrital subsidy helps to increase the abundance and stabilize the diversity of the springtail community. Changes observed in the structure of the Collembola community can be an indicator of improved soil health, and springtails can be used in assessing the effectiveness of agricultural practices.

Attraction of pitfall trap preservation fluids complicates the estimation of Collembola density

Collembola (springtail) communities consist of three eco-morphologically defined life forms: the euedaphics dwell inside the soil matrix, the epedaphics (including atmobiotics) live on the ground and in vegetation, and the hemiedaphics are intermediate. The vast majority of springtail community studies focus on the belowground (eu- and hemiedaphic) forms that are generally collected by taking and extracting soil cores. Few investigations have dealt with epedaphic Collembola that are usually captured with pitfall traps, and only very few studies so far covered all three life forms. When epedaphic and belowground species are sampled using both methods simultaneously, core data (true densities, [individuals m-2]) and pitfall data (activity abundances, [individuals trap-1 length of trapping period-1]) may be analyzed independently, but are incompatible in a common statistical framework. As a remedy, two competing numerical approaches to estimate true densities from activity abundances have been described in literature: the nested-cross array and the two-circle method. Attraction or deterrence effects of trap preservation fluids bias the density estimation of the nested-cross array, but not of the two-circle method. To determine whether this bias may be expected for Collembola, and thus which of the two methods should be used in future studies, we experimentally tested potential effects of preservation fluids on trap catch rates. Three preservation fluids (sodium benzoate, propylene glycol, formaldehyde) and a detergent (Tween80) significantly increased the number of captured springtails, thus demonstrating an attraction effect and the deficiency of the nested-cross array. In future studies of collembolan communities, we therefore suggest complementing the traditional focus on the eu- and hemiedaphic life forms by sampling epedaphic species using pitfalls, and subsequently remodelling the trapping data with the two-circle method.

Habitat type controls microarthropod community changes across a Magellanic sub-Antarctic elevation gradient

IntroductionElevation gradients are often used as a proxy for climate change as they allow comparisons of ecological responses over much larger temporal and spatial scales than is possible through experimental manipulations.MethodsHere, we tested how microarthropod communities (Collembola and Acari) are affected by climatic differences between sea level and 600 m a.s.l. on Navarino Island, in the Magellanic sub-Antarctic ecoregion of southern Chile (mean annual temperatures of 5.6 vs 3.1°C, respectively). We quantified microarthropod abundance, richness and community trait characteristics in dominant moss (Racomitrium lanuginosum and Polytrichum strictum) and lichen (Usnea trachycarpa, Pseudocyphellaria freycinetii and Stereocaulon alpinum) vegetation growing at both elevations. These moss and lichen genera are characterized by large morphological differences and allow testing of how habitat characteristics affect microarthropod community response across elevation gradients.ResultsCollembola and Acari community composition differed between the low and high elevation sites. Total abundance levels of Acari were maintained in each habitat across elevation, whereas Collembola richness strongly declined (50%) at high elevation in the moss habitats. Acari community differences across elevation were driven by relative abundance changes whereas the Collembola community lost species at higher elevation. An anticipated decline of smaller eudaphic Collembola at high elevation was only observed in the moss Racomitrium, reflecting potentially lower temperature buffering capacity and shelter options compared to Polytrichum. Lichens mostly supported larger epigeic species irrespective of elevation. There were no consistent patterns linking microarthropod communities with habitat water holding capacity or water loss rates across the studied habitats and elevation.DiscussionHabitat type and the genus of moss or lichen were associated with microarthropod community changes across elevation, including examples of declines, increases and no change. These findings highlight that community responses across gradients may not always relate to the generally hypothesized environmental variables (e.g. temperature variability) and that habitat characteristics should be taken into account when using elevation as a proxy for climate change.

Intercropping outweighs straw incorporation driving community and functional diversity of microarthropods after 5 years of tillage practices

Crop-leguminous intercropping and straw incorporation are considerable approaches to sustainable agriculture and have been widely used as a coping strategy to mitigate the negative effects caused by intensive agriculture. Yet, as a sustainable agriculture requires a deeper understanding of the impacts of conservation tillage practices on soil fauna, such as collembolans and acarid mites. These organisms are considered the most abundant and functionally critical soil fauna in many terrestrial natural, agricultural, and urban systems. In the present study, we assessed the responses of the community and functional diversity of collembolan and acarid mite assemblages to long-term intercropping and straw incorporation practices in a temperate farming land, in China. The experimental site was established with a full-factorial design of conservation managements (maize monocropping, maize-peanut intercropping, without maize straw addition, and with maize straw addition) over five consecutive years. Results showed that intercropping doubled collembolan and acarid density. Most of the enriched species in the intercropping field were euedaphic collembolans and cleptoparasitic mites. Nonetheless, the density of most phoretic species decreased, resulting in a negative effect of intercropping on acarid diversity. Despite straw incorporation additionally boosting the intercropping-induced increases in biomass, richness, and density of the collembolan community, the effects of straw incorporation on the community structure of collembolans and acarid mites were negligible. Similarly, intercropping affected the functional composition of collembolans and mites differently. Intercropping favored euedaphic collembolans characterized by less-developed furca, ocelli and sexual reproduction, but fungivorous, and benefited the cleptoparasitic mites that might be transported by their provisional hosts during pollinating peanut flowers. Moreover, intercropping decreased the functional dispersion of acarid mites, resulting in an acarid community with a homogenized ecological niche of acarid mites. In contrast, the ecological niche was more differentiated. Similar to intercropping, the ecological niche of collembolans in the field with straw was relatively higher, as well as the functional divergence, suggesting more intense resource competition between collembolans. In conclusion, intercropping has species-specific effects on the community and functional diversity of collembolans and mites and is relatively beneficial to collembolans, whereas straw incorporation has a marginal advantage on collembolans and acarid mites.

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.

Impacts of Millipedes on Acari and Collembola Communities-A Microcosm Experiment.

Ecosystem engineers influence the structure and function of soil food webs through non-trophic interactions. The activity of large soil animals, such as earthworms, has a significant impact on the soil microarthropod community. However, the influence of millipedes on soil microarthropod communities remains largely unknown. In this microcosm experiment, we examined the effects of adding, removing, and restricting millipede activity on Acari and Collembola communities in litter and soil by conducting two destructive sampling sessions on days 10 and 30, respectively. At the time of the first sampling event (10 d), Acari and Collembola abundance was shown to increase and the alpha diversity went higher in the treatments with millipedes. At the time of the second sampling event (30 d), millipedes significantly reduced the Collembola abundance and alpha diversity. The results were even more pronounced as the millipedes moved through the soil, which caused the collembolans to be more inclined to inhabit the litter, which in turn resulted in the increase in the abundance and diversity of Acari in the soil. The rapid growth of Collembola in the absence of millipedes significantly inhibited the abundance of Acari. The presence of millipedes altered the community structure of Acari and Collembola, leading to a stronger correlation between the two communities. Changes in these communities were driven by the dominant taxa of Acari and Collembola. These findings suggest that millipedes, as key ecosystem engineers, have varying impacts on different soil microarthropods. This study enhances our understanding of biological interactions and offers a theoretical foundation for soil biodiversity conservation.

Karst landforms as microrefugia for soil Collembola: Open versus forested dolines

Enclosed surficial karst dolines are geomorphologically diverse habitats with the potential to strongly shape community structure and the distribution of functional groups of organisms. Forest habitats in karst landscapes are characterized by lower soil temperatures and microclimatic fluctuations compared to open habitats; therefore, they may provide favorable conditions for cold-adapted/psychrophilic species, which are highly vulnerable to climate warming. We compared the diversity and structure of soil Collembola communities at sites along microclimatic gradients in open and forested karst dolines. The effect of topography and related environmental conditions on the distribution of ecological groups of soil Collembola was analyzed, and the function of the dolines as potential climate refugia for psychrophilic arthropods was assessed. The karst dolines revealed significant habitat heterogeneity, including warm plateaus and S-facing slopes and colder and wetter bottoms and N-facing slopes. The inner sites of the dolines had an overall higher abundance and species richness compared to the plateau sites. Nonmetric multidimensional scaling ordination revealed a clear delimitation of Collembola communities in terms of warmer and cooler sites in the open dolines, while the forested dolines did not reveal such a clear pattern. The studied dolines showed a potential to serve as microrefugia in the context of global climate change. Dolines could support the long-term persistence of at least some species such as cold-adapted species. Karst dolines in the temperate zone play a key role in maintaining biodiversity; therefore, they should be central in biodiversity conservation programs.

Trophic niches of Collembola communities change with elevation, but also with body size and life form

Climate change will likely increase habitat loss of endemic tree species and drives forest conversion in mountainous forests. Elevation gradients provide the opportunity to predict possible consequences of such changes. While species compositions of various taxa have been investigated along elevation gradients, data on trophic changes in soil-dwelling organisms are scarce. Here, we investigated trophic changes of the Collembola communities along the northern slope of Changbai Mountain, China. We sampled Collembola in primary forests at seven elevations (800–1700 m asl). We measured individual body lengths and bulk stable isotopes on species level. We further categorized Collembola species into life forms. The community-weighted means of Δ15N and Δ13C values as well as minimum Δ15N values and isotopic uniqueness of Collembola communities increased with increasing elevation, while the range of Δ15N values decreased. Maximum and minimum of Δ13C values differed between elevations but showed no linear trend. Further, Δ15N values of Collembola species occurring across all elevations increased with elevation. Changes in Δ15N values with elevation were most pronounced in hemiedaphic species, while Δ13C values increased strongest with elevation in euedaphic species. Δ15N values increased with decreasing body size in hemiedaphic and euedaphic species. Overall, the results suggest that Collembola species functioning as primary decomposers at lower elevations shift towards functioning as secondary decomposers or even predators or scavengers at higher elevation forests. The results further indicate that access to alternative food resources depends on Collembola life form as well as body size and varies between ecosystems.

Asymmetric environmental selection on intraspecific body size in Collembola communities along an elevational gradient in northern Japan

Body size is a crucial functional trait that influences the environmental filtering processes of animal communities. However, the role of intraspecific variations in soil invertebrate communities remains poorly understood. In this study, we investigated the influence of environmental changes on intraspecific body size variations in Collembola communities along an elevational gradient in northern Japan, using potential body length in the literature cited and realized body length actually measured. Our hypothesis posits that environmental conditions selectively filtered out smaller nymphs while sparing larger adults of Collembola, as stress tolerance, survival and mortality are directly influenced by body size in response to environmental severity. Calculating size quantiles based on observed realized individual body lengths, we found a stable size hierarchy among species across elevational sites. Species composition was significantly related with elevational gradient, with community-weighted means of smaller quantiles in body length increasing at higher elevations, while those of larger quantiles and adult body size remained unaffected. This suggests that environmental filtering predominantly influences the body size of smaller individuals, such as nymphs, but not larger adults within species. Our findings reveal asymmetric size selection among different life stages in soil animal communities.

Global fine-resolution data on springtail abundance and community structure

Springtails (Collembola) inhabit soils from the Arctic to the Antarctic and comprise an estimated ~32% of all terrestrial arthropods on Earth. Here, we present a global, spatially-explicit database on springtail communities that includes 249,912 occurrences from 44,999 samples and 2,990 sites. These data are mainly raw sample-level records at the species level collected predominantly from private archives of the authors that were quality-controlled and taxonomically-standardised. Despite covering all continents, most of the sample-level data come from the European continent (82.5% of all samples) and represent four habitats: woodlands (57.4%), grasslands (14.0%), agrosystems (13.7%) and scrublands (9.0%). We included sampling by soil layers, and across seasons and years, representing temporal and spatial within-site variation in springtail communities. We also provided data use and sharing guidelines and R code to facilitate the use of the database by other researchers. This data paper describes a static version of the database at the publication date, but the database will be further expanded to include underrepresented regions and linked with trait data.

THE FORMATION OF SPRINGTAIL ASSEMBLAGES (HEXAPODA, COLLEMBOLA) ALONG A RETREATING TSEY GLACIER, NORTH OSSETIA – ALANIA

Successional changes in springtail communities were studied along a retreating Tsey Glacier at 2336 to 2071 m a.s.l. Springtails were collected from 10 sites of different ages ranging from 1 to 170 years. The sites covered the main stages of surface overgrowth, from a bare ground through a grassy-shrub stage to mixed and then mature pine forests. Springtails appeared already during the first year after the glacier’s retreat and were represented by a species of the genus Desoria, a peculiar inhabitant of bare rocky-sandy soils. During the first 7–14 years of succession, rapid changes in population and species composition repeatedly occurred. Both abundance and species diversity of springtails sharply increased at the grassy-shrub stage (14 years) and reached their maximum at later ones. Starting with this intermediate stage, springtail assemblages were primarily composed of widespread generalists belonging to euedaphic and hemiedaphic life forms. Beginning from this point, the pace of succession gradually slowed down. Approximately 100 years since, springtail communities reached a level of diversity similar to that found in mature mountain forest communities in the region. However, their species composition and structure remained quite distinctive. A comparison with similar foreign studies showed the composition of periglacial springtail communities to exhibit high-level regional specificity.

Structure of Collembola Communities in the Urban Gradient of Rīga City

Abstract The world’s increasing urbanisation and the deterioration of human quality of life in major cities have redirected the focus of urban planning toward green infrastructure improvement and, as a result, increased the research of urban ecosystems. This article analyses changes in the structure of Collembola communities in soil in the urban-rural gradient in the city of Rīga, Latvia. Soil samples were collected in 21 randomly selected sample plots within six urban habitats: street edge grasslands, downtown parks, private houses, cemetery grasslands, and urban and suburban forests. Soil samples were taken at the end of September/beginning of October 2017. A steel soil corer (D 50 mm, surface area 19.6 cm2, depth 10 cm) was used. In each plot, three soil samples were taken with a soil corer. Collembola were extracted from pooled samples from each habitat using a Berlese-Tullgren extractor. Nonmetric Multidimensional Scaling (NMS) ordination of Collembola data in sample plots yielded three statistically significant axes (p < 0.01). The first axis explaining 49% of the data variation coincided with the urban-rural gradient. Species richness declined towards the city centre, while the Simpson’s Dominance Index increased. The species Mesaphorura macrochaeta predominates in the central habitats, while Parisotoma notabilis dominates in suburban forests.

Finding the optimal strategy for quantitative sampling of springtails community (Hexapoda: Collembola) in glacial lithosols

Springtails (Hexapoda: Collembola) play a key role in biological community in glacial ecosystems and represent important ecological indicators in such threatened habitats. An effective sampling protocol for springtail community that optimizes sampling effort in the peculiar conditions of glacial lithosols is not available. We tested three sampling methods on the Sforzellina glacier (Central Italian Alps) in 21 sampling points. For each sampling point, we performed: 1. Tullgren funnels; 2. Flotation method; 3. Pitfall trapping. The potential effect of different sampling methods on species detection was evaluated by ANOVA and by N-mixture models for Flotation method and Tullgren funnels. The incidence coverage estimator (ICE) was used to test the performance of each sampling method comparing the observed vs estimated species richness. Our analysis showed that the sampling method affected the number of species and individuals recorded. Tullgren funnels collected the highest number of species, pitfall trapping the highest average number of species, but did not detect soil species. The observed/estimated species ratio was higher for pitfall trapping and Tullgren funnels than for flotation. The combination of pitfall trapping with Tullgren funnels or flotation method resulted optimal in terms of number of species and functional types recorded. Flotation method collected more than twice the number of specimens obtained with Tullgren, indicating a higher ability to extract springtails from mineral soil. Flotation method and Tullgren funnels detected the same community, from a functional point of view, but only flotation method collected all the most abundant species. These results indicate that a combination of pitfall trapping and flotation should be evaluated in order to maximize the obtained information in terms of specie assemblage composition and functional categories.

Ecological monitoring using Collembola metabarcoding with extremely low bycatch amplification

Collembola are used widely to monitor soil health and functional parameters. Recent developments in high throughput sequencing (especially metabarcoding) have substantially increased their potential for these ends. Collembola are especially amenable to metabarcoding because of their small size, high abundance, and ubiquity in most habitat types. However, most Collembola sampling protocols collect a substantial and highly varied bycatch that can be a considerable impediment to metabarcoding, especially because of data lost to non-target species. We designed a primer set amplifying the D2 expansion segment of ribosomal DNA that is highly conserved across Collembola and successfully excludes from amplification nearly all other invertebrate taxa. We tested the diagnostic power of the primer set by clearly distinguishing Collembola communities between forest sites with differing habitat qualities in São Paulo State, Brazil. The oligos amplified all Collembola orders previously encountered in the sampling locations, with no non-target amplification, and also excluded the closely related Protura and Diplura. Alpha diversity (OTU count) and phylogenetic diversity was significantly higher in high quality habitats. Moreover, the beta diversity indices successfully differentiated high and low-quality habitats. This new addition to the biomonitoring toolbox greatly increases the accessibility of Collembola metabarcoding for various types of habitat assessments.

Elevational changes in canopy Collembola community composition are primarily driven by species turnover on Changbai Mountain, northeastern China

Forest canopies harbor extraordinary biodiversity, with Collembola being one of the most abundant arthropod taxa. However, much of the research on canopy biodiversity has focused on tropical and subtropical regions, leaving a gap in our understanding of canopy communities in temperate and boreal forests. Studying canopy Collembola along elevational gradients can be particularly informative because several environmental factors change with elevation, and these changes may mirror those seen along latitudinal gradients. To better understand and conserve canopy Collembola diversity along elevational gradients, natural forests are of particular interest. In this study, we used canopy fogging to sample canopy Collembola at four elevation sites (800–1700 m a.s.l.) on Changbai Mountain, northeastern China, representing three natural forest types. We examined changes in species richness, abundance and composition of canopy Collembola, and partitioned beta diversity into nestedness and turnover to identify processes driving changes in community composition. We identified 53 morphospecies among 10,191 individuals, with Entomobryidae and Hypogastruridae being the dominant families. The highest abundance and species richness were observed at 1400 m and remained at similar levels at 1700 m, indicating an increasing pattern with elevation. Species turnover was the main driver of changes in community composition with elevation. Our results provide insights into the shift of canopy Collembola communities across an elevational gradient in temperate boreal forests.

Impact of forest disturbance on microarthropod communities depends on underlying ecological gradients and species traits.

Windstorms and salvage logging lead to huge soil disturbance in alpine spruce forests, potentially affecting soil-living arthropods. However, the impacts of forest loss and possible interactions with underlying ecological gradients on soil microarthropod communities remain little known, especially across different environmental conditions. Here we used DNA metabarcoding approach to study wind-induced disturbances on forest communities of springtails and soil mites. In particular, we aimed to test the effect of forest soil disturbance on the abundance, richness, species composition, and functional guilds of microarthropods. We sampled 29 pairs of windfall-forest sites across gradients of elevation, precipitation, aspect and slope, 2 years after a massive windstorm, named Vaia, which hit North-Eastern Italy in October 2018. Our results showed that wind-induced disturbances led to detrimental impacts on soil-living communities. Abundance of microarthropods decreased in windfalls, but with interacting effects with precipitation gradients. Operative Taxonomic Units (OTU) richness strongly decreased in post-disturbance sites, particularly affecting plant-feeder trophic guilds. Furthermore, species composition analyses revealed that communities occurring in post-disturbance sites were different to those in undisturbed forests (i.e., stands without wind damage). However, variables at different spatial scales played different roles depending on the considered taxon. Our study contributes to shed light on the impacts on important, but often neglected arthropod communities after windstorm in spruce forests. Effects of forest disturbance are often mediated by underlying large scale ecological gradients, such as precipitation and topography. Massive impacts of stronger and more frequent windstorms are expected to hit forests in the future; given the response we recorded, mediated by environmental features, forest managers need to take site-specific conservation measures.

Downed deadwood habitat heterogeneity drives trophic niche diversity of soil-dwelling animals

Habitat heterogeneity is one of the important drivers of biodiversity, but the underlying mechanisms are still vague. Increasing habitat heterogeneity often coincides with greater habitat space and/or greater food availability for organisms, but it is unclear whether and how these components are related to habitat selection. Downed dead wood (i.e., dead wood laying on the ground) is an important but understudied component of dead plant matter that creates spatial habitat heterogeneity for soil fauna on the ground. To unravel the role of dead wood for providing niche dimensionality for soil fauna via variance in resource use, we sampled Collembola communities from moss growing on bark and from bark on the logs of two tree species (pedunculate oak and Norway spruce) and from soil next to the logs. We assessed habitat selection of Collembola species combining abundance data with trophic position data using stable isotope ratios (i.e., δ13C and δ15N). Based on the Bray-Curtis dissimilarity, Collembola community composition differed significantly among the three habitats (i.e., moss, bark and soil). Collembola community-weighted mean δ13C and δ15N values also differed among the three habitats (average δ13C values of moss: −25.94‰, bark: −25.30‰, soil: −25.60‰; average δ15N values of moss: −4.80‰, bark: −3.83‰, soil: −5.11‰), partly reflecting isotopic differences of the habitats themselves (δ13C of moss: −29.83‰, bark: −28.26‰, soil: −29.04‰; δ15N of moss: −7.59‰, bark: −4.18‰, soil: −7.84‰). These findings indicate that Collembola depend on food sources derived from the habitats they inhabit at least at the community level. Collembola community-weighted variance of both δ13C and δ15N values ranked as bark > moss > soil. Species-level data suggested that the bark community included both bark-specific food specialists as well as species which likely use bark only as a temporary habitat based on their morphological traits supporting high mobility. These findings together indicate that the trophic niche variation of the Collembola community is larger in bark than in soil. Our results stress the importance of downed dead wood as a source of habitat heterogeneity, which in turn promotes soil animal diversity, likely via heterogeneity in food sources. Furthermore, the presence of dead wood on the ground could have consequences for organic matter processing by the soil animal community through sustaining a larger trophic niche variation even at a small spatial scale.

Collembola taxonomic and functional diversity in conventional, organic and conservation cropping systems

Intensive agriculture has been demonstrated to be a main threat to soil biodiversity through physical and chemical disturbances of soil. Alternative systems based on lower disturbances may help to promote soil biodiversity and its role in soil functioning. However, the effects of alternative systems on soil biodiversity are still poorly understood, especially regarding soil mesofauna. In this study, we aimed to assess the effects of alternative cropping systems and practice intensity on the taxonomic and functional diversity of Collembola. Collembola were sampled for two consecutive years in 21 fields (3 plots per field) under conventional or alternative systems, namely conservation or organic systems either stable (≥7 years) or in transition (≤3 years). Indicators and indices were computed to characterize separately tillage, pesticide treatments and organic fertilization in each field. Collembola species and functional traits were investigated. Functional diversity of Collembola was assessed using species traits (i.e. traits from the literature) and by conducting length measurements directly on collected Collembola individuals (body, head, leg, antenna and furca length). Collembola diversity was highly variable between and within cropping systems and years. Species richness was notably higher in conservation than in conventional systems in the second year of the study. More specifically, low tillage and high pesticide treatment intensities increased taxonomic and functional diversity and affected species with traits adapted to the surface (i.e. scales, trichobothria). Measured Collembola body length additionally revealed the presence of larger individuals under low tillage and high pesticide treatment intensities, with similar results for other length traits. Overall, our results revealed that 1) taxonomic and functional diversity are complementary to understand the effects of agricultural practices and systems on Collembola and 2) measurement of body length is relevant to assess the effects of disturbances on the local Collembola community.

Collembola community contains larger species in frequently flooded soil

Climate change is increasingly affecting biotic communities, including soil fauna. Extreme weather events such as the incidence of heavy rainfall or prolonged drought can cause strong fluctuations in soil moisture. In river floodplains such extreme events determine the flooding intensity of the river bank grassland soils, and their communities. The diversity and distribution of many soil fauna groups depends on soil moisture content, so changes in inundation frequency and duration will impact soil fauna communities. We used the natural fluctuations in water levels of large Dutch rivers to investigate the effect of flooding intensity on the composition and traits of Collembola species, a key group of the soil fauna community. At five locations along large rivers in The Netherlands, we sampled Collembola communities at six levels of decreasing elevation and increasing flooding intensity. We identified all Collembola to species level and calculated species richness, composition and abundance values. Moreover, to understand the observed taxonomic changes across elevation we used the traits body size and life form to explain the change in Collembola community composition. Our results show that high flooding intensity favors larger Collembola species in the community. We hypothesize that high soil moisture in frequently flooded soil favors larger Collembola, which tolerate flooding. Life form, i.e. the preferred depth in the soil column, was significantly correlated with flooding intensity. There is an optimum in species richness and abundance at intermediate flooding intensity. These results can help predict the impact of climate change on soil fauna.

Soil Springtail Communities Are Resilient to Forest Tent Caterpillar Defoliation in Quebec Mixed Hardwood Forests

Outbreaks of defoliator insects are important natural disturbances in boreal forests, but their increasing frequency under warming climate conditions is of concern. Outbreak events can shape ecosystem dynamics with cascading effects through trophic networks. Caterpillar defoliation can alter tree physiology, increase sunlight to the understory, and result in the deposition of large amounts of leaf litter and caterpillar frass to the forest floor. These modifications can thus affect soil organisms through direct (e.g., changes in soil temperature or moisture) or indirect (e.g., changes in detrital and root food webs) mechanisms. We assessed whether a recent (2015 to 2017) outbreak of the forest tent caterpillar (Malacosoma disstria) at the Lake Duparquet Teaching and Research Forest (Abitibi, QC, Canada) affected soil springtail communities, abundant microarthropods in forest soils. In 2018 and 2019, we sampled litter and soil (0–10 cm depth) at eight sites each in aspen-dominated (Populus tremuloides Michx) stands that were undefoliated or had a recent defoliation history. We found no significant difference in springtail abundance (specimens cm−2) or alpha diversity indices between undefoliated sites and those with defoliation history. However, we observed a transient change in springtail community composition 1 year after the outbreak (2018) with the absence of Folsomia nivalis, Anurophorus sp1, and Xenylla christianseni in sites with defoliation history, but no compositional differences were observed in 2019. Certain soil nutrients (P, C, Mg, Mn) were significant predictors of springtail community composition, but soil microbial biomass was not, despite its significant decrease in sites with defoliation history. Our results show that soil springtail communities respond in the short-term to the forest tent caterpillar outbreak with compositional shifts, but seem ultimately resilient to these events.