Oribatid Mite Communities Research Articles

Oribatid mite (Acari: Oribatida) communities of urban brownfields in Tallinn, Estonia, and their potential as bioindicators of wasteland successional stage

Urban brownfields are ecologically valuable ecosystems that have been and are under various anthropogenic influences. Because brownfields are subject to rapid development in urban areas, their biological communities, including soil mesofauna, are overlooked and seldom researched, even though they could provide valuable insight into the ecological functioning of these areas. This exploratory study describes the community characteristics of oribatid mite fauna of 12 brownfields in Tallinn, Estonia, and analyzes the potential of oribatid mites as bioindicators of brownfield successional stage. This study provides the first faunistic list of oribatid mites from the brownfields of Tallinn. No significant changes in species abundance or richness depending on the successional stage were discovered. While some changes in community structure were noted, due to low overall abundance, no clear indicators of brownfield successional stage were identified. For future research on urban brownfield oribatid fauna with the intention of finding potential bioindicators of brownfield properties, increasing the sampling size and inclusion of other groups of soil mesofauna is recommended.

Hydrology-driven environmental variability determines abiotic characteristics and Oribatida diversity patterns in a Sphagnum peatland system.

We investigated oribatid mite communities in a Sphagnum-dominated boreal peatland system characterised by a mosaic of oligotrophic and meso-eutrophic areas. We aimed to determine the relative importance of environmental factors (pH, Sphagnum nutrient content, water table level, diversity of vascular plants and bryophytes in the surrounding plant community) and spatial variation in influencing abundance, diversity and community composition of aquatic and terrestrial oribatid mites. Among environmental variables, water table level (micro-topography), pH, and K in Sphagnum tissues were the main predictors of Oribatida community structure. Aquatic species were associated with pools; two terrestrial species-Hoplophthiracarus illinoisensis and Nothrus pratensis-were associated with oligotrophic hummocks; the rest of terrestrial species were associated with dryer mesotrophic and eutrophic habitats. Low water table depth (hummocks), high local plant diversity, and high P in Sphagnum tissues were predictors of high abundance of terrestrial Oribatida. Species richness of terrestrial Oribatida was linked with low water table and high plant diversity. For aquatic Oribatida abundance, water table depth was the single most important predictor variable. Plot trophic class (its status on the peatland poor-rich gradient assigned based on plant indicator species) was also a significant predictor of terrestrial Oribatida abundance, richness, and community structure. Spatial structuring was important for terrestrial Oribatida community composition, weak (P < 0.10) for terrestrial Oribatida abundance and richness, and not significant for aquatic Oribatida.

Sixteen years of simulated summer and winter warming have contrasting effects on soil mite communities in a sub-Arctic peat bog

Northern peatlands are very sensitive to changes in climate. Impacts of increased temperatures on hydrology, vegetation structure and soil carbon are already well documented from northern peatlands. In contrast, effects of global warming on soil mites, and seasonal effects in particular, have received less attention, even though soil mites are an important component in ecosystems as they contribute to nutrient dynamics and decomposition. We investigated the impacts of long-term (16 years) experimental seasonal climate manipulations (summer warming, winter warming with snow accumulation, and year-round warming) on oribatid (Oribatida) and mesostigmatid (Mesostigmata) mite communities in a peat bog underlain by discontinuous permafrost, in Abisko, Northern Sweden. We found that (1) Year-round warming treatment had neither impact on life-history trait compositions nor on total abundances of oribatid mites, possibly because of opposite effects of summer and winter warming; (2) Small-bodied oribatid mites, in particular those belonging to genera Suctobelba, increased in abundance under the summer warming treatment; (3) The species richness of oribatid mites was negative affected by year-round warming; (4) Mesostigmatid mites, which were not identified to species level, were found to decrease in abundance under year-round warming. Because different mite taxa with different body sizes and diets play distinct roles in carbon and nutrient dynamics, the observed changes in mite communities may impact ecosystem functions in northern peatlands.

The impact of different urban conditions on structural characteristics of oribatid mite communities

Changes in the structure of oribatid mite communities were studied at six urban sites located in Bratislava, Slovakia (Central Europe). These differed in pattern and in the intensity of human impact. Soil samples were taken from each site at monthly intervals for a period of two years. A total of 139 species were identified, of which 64.8% occurred at the control site. Low numbers of species (18–26 spp.) were found at sites characterized by high anthropogenic pressure. The percentage of oribatid mites in acarocoenoses declined (in favour of other mite groups) at sites altered from their original biotope and influenced by permanent human intervention (from 70% to less than 25%). The highest abundance of mites (976.9 ind./dm2) was recorded at an urban site, where the oribatid mite percentage was only 21.2%. Species typical of wet forest and meadow habitats were found at sites with suburban and ruderal characteristics, where vegetation cover attenuates the heat island effect, whereas mainly xerothermophilous and eurypotent species formed oribatocoenoses in urban sites. Urban conditions resulted in distinctly lower values of diversity, species richness, and equitability. The species Epilohmannia cylindrica, Microppia minus, Oribatula tibialis, Protoribates capucinus, Rhysotritia ardua and Ramusella insculpta common in the European cities were recorded also in this study.

Seasonal dynamics and changing sea level as determinants of the community and trophic structure of oribatid mites in a salt marsh of the Wadden Sea.

Global change processes affect seasonal dynamics of salt marshes and thereby their plant and animal communities. However, these changes have been little investigated for microarthropod communities. We studied the effect of seasonality and changes in sea level on oribatid mites in the natural salt marsh and on artificial islands in the back-barrier environment of the island Spiekeroog (Wadden Sea, Germany). Three zones of the artificial islands were filled with transplanted sods from the lower salt marsh zone and thereby exposed to three different inundation frequencies. We hypothesized that oribatid mite communities will differ along the natural salt marsh vegetation zones [upper salt marsh (USM), lower salt marsh (LSM), pioneer zone (PZ)], which are influenced by different tidal regimes. Accordingly, total oribatid mite densities declined from the USM and LSM to the PZ. Similarly, oribatid mite species compositions changed along the salt marsh transect and also responded to variations in inundation frequency in LSM on artificial islands with typical species of the USM, LSM and PZ being Multioppia neglecta (USM), Hermannia pulchella (LSM), Zachvatkinibates quadrivertex (LSM, PZ) and Ameronothrus schneideri (LSM, PZ). Oribatid mite density in the salt marsh and on the artificial islands was at a maximum in winter and spring; this was due in part to high density of juveniles, pointing to two reproductive periods. We hypothesized that oribatid mite trophic structure changes due to variations in abiotic (e.g., tidal dynamics, temperature) and biotic conditions (e.g., resource availability). Stable isotope (15N, 13C) and neutral lipid fatty acid analyses indicated that oribatid mite species have different diets with e.g., Z. quadrivertex feeding on macroalgae and fungi, A. schneideri feeding on microalgae and bacteria, and Scheloribates laevigatus and M. neglecta feeding on dead organic matter, bacteria and fungi. Overall, the results indicate that oribatid mite species in salt marshes are affected by changes in environmental factors such as inundation intensity, with the effects being most pronounced in species with narrow trophic niches and limited niche plasticity. The results also indicate that oribatid mite communities of the LSM respond little to short-term (one year) changes in inundation frequency.

Oribatid mites of conventional and organic vineyards in the Valencian Community, Spain

In this study the oribatid mite communities of conventional and organic vineyards in theValencian Community (Spain) were compared. The soil samples were collected in El Poble Nou de Benitatxell in autumn 2014 and spring 2015 from four sites, treated as replicates, each including a conventional vineyard, an organic vineyard, and a control (natural habitat, i.e. in plots 1-3 an abandoned vineyard, in plot 4 an area never used in agriculture). Two parallel samples were collected in each vineyard from a zone between vine rows, driven by a tractor (Tr), a zone between vines (Vi), the border of the vineyard (Bo) and from a control, making a total of 112 samples. In total 3,225 oribatid mites were obtained represented by 59 species. No differences were found in density of Oribatida between the conventional, organic vineyards and the control, but the species diversity was higher in the control than in the vineyards. In the vineyards the density and species number of the oribatid mites were highest between vines (the average from all vineyards and both seasons was 4,400 individuals per 1 m2, 15 species), followed by the border of the vineyards (2,800 individuals per 1 m2, 14 species) and were lowest between vine rows (400 individuals per 1 m2, 6 species). The species diversity of Oribatida was higher in autumn than in spring, while the density followed this pattern only in the vineyards, but not in the control. In the vineyards Oribatula excavata dominated (D = 25), followed by Minunthozetes quadriareatus and Passalozetes africanus (D = 18 and 14, respectively), while in the control these species were not abundant. In the control the most abundant species was Oppiella subpectinata (D = 28), followed by Eremulus flagellifer (D = 20). Podoribates longipes and Steganacarus boulfekhari are reported for the first time in Spain. To conclude, the oribatid mites did not benefit from the organic cultivation of the vineyards, probably because they are tolerant to herbicides used in the conventional systems but sensitive to mechanical cultivation of soil, which was even more intense in organic vineyards than in the conventional ones.

Seasonal fluctuation of oribatid mite communities in forest microhabitats.

Oribatid mites are abundant and diverse decomposers in almost all terrestrial microhabitats, especially in temperate forests. Although their functional importance in the decomposition system in these forests has been investigated, spatio-temporal patterns of oribatid mite communities inhabiting different microhabitats have largely been neglected. Therefore, we (i) investigated seasonal fluctuation (monthly over one year) in oribatid-mite community structure and specificity to three microhabitats (moss, dead wood and litter) and (ii) analyzed the influence of air temperature and overall air humidity on seasonal community changes. In total, 57,398 adult oribatid mite individuals were collected. Total abundance, species richness and diversity differed among microhabitats. Seasonal changes were most pronounced in moss and least in litter. While overall air humidity had no influence on species distribution and community changes, air temperature positively influenced species richness and diversity, again most pronounced in moss. The calculated environmental temperature occurrence niche showed that 35% of adult oribatid mite species occurred at higher air temperatures. Furthermore, interaction/bipartite networks were more generalized—i.e., species were more equally distributed among moss, dead wood and litter—when ambient air temperatures were higher. This pattern is probably due to the dispersal ability of adult oribatid mites, i.e., species enter a dispersal mode only at higher air temperatures.

Oribatid mites communities (Acari: Oribatida) and their distribution in the tea (Camellia sinensis) plantation at Moc Chau plateau, Son La province

In the period of 2014-2015, oribatid mite community (Acari: Oribatida) was investigated according to four seasons and three vertical layers in the soil ecosystem of the tea plantation (Camellia sinensis) at Moc Chau Plateau, province of Son La. Identifies are 68 oribatid species, including 6 sp., belonging to 45 genera and 29 families. Among them 57 species are recorded for the first time for the study area, including 26 species are recorded new for Vietnam. The oribatid mite systematic structure of study area is not diverse. Tweenty out of 29 families identified were recorded with only one genus, and each genus recorded with one to two species. The family Oppiidae Grandjean, 1951 is the most diversified recocorded with 7 genera and 10 species. According to seasons, oribatid species richness decreases in the following order: Spring &gt;Winter &gt;Autumn &gt;Summer, respectively identified 35 &gt;32 &gt;31 &gt;21 species. According to soil vertical layers, it decreases in the following order: (-1) &gt;(-3) &gt;(-2), respectively identified 43 &gt;40 &gt;32 species. The only species S. mahunkai, is recorded in all four seasons, and all three soil layers studied.

Oribatid mite recovery along a chronosequence of afforested boreal sites following oil sands mining

Bitumen extraction via surface mining has affected nearly 1000 km2 of boreal forest habitat in the Athabasca oil sands region of Alberta, Canada, pushing entire ecosystems back to the primary stages of forest and soil succession. Previous work in the Athabasca oil sands region has investigated the influence of vegetation, mineral reclamation material, and peat cover soil on microbial communities and the quality of soil carbon. No research has been conducted to assess the bioindicator potential of soil fauna, specifically oribatid mites, in these reclaimed soils. This study investigated the influence of time-since-reclamation (8–31 yrs.) and canopy type (white spruce (Picea glauca (Moench) Voss), trembling aspen (Populus tremuloides, Michx)) on the abundance and diversity of oribatid mite adults ≥300 μm in size after land reclamation in the Athabasca Oil Sands Region. Thickness of the forest floor accumulating on top of the peat cover soil at the reclaimed sites was the most powerful predictor of oribatid mite richness, and was a better predictor than time-since-reclamation. A forest floor with a thickness ≥2 cm strongly increased oribatid mite abundance to levels higher than those found in the forest floors of natural, undisturbed stands in the area. Species richness in the (≥2 cm thick) forest floor within reclaimed stands was slightly lower than within natural stands but was notably higher than in the peat cover soil. Assemblage diversity followed the same trend as species richness, and mite diversity in the forest floor with a thickness ≥2 cm in reclaimed stands was the most similar to natural stands. Four of the six reclaimed stands with a forest floor thickness ≥2 cm were aspen stands, and increased aspen density may aid in faster reestablishment of oribatid mite communities after oil sands mining.

Response of oribatid mites to reforestation of degraded tropical montane pastureland

Tropical montane forests are being turned into pastures for cattle at an unprecedented rate. However, efforts are being made to reforest pastures in particular if invaded by weeds of low nutritional value, but until today little is known on the response of the decomposer system to reforestation. We focused on the response of soil fauna, specifically oribatid mites, which play an important role in the breakdown of organic matter. In the south Ecuadorian Andes we chose two sites with distinct vegetation: one pasture site invaded by Setaria sphacelata (grass pasture) and another invaded by Pteridium arachnoideum (bracken pasture). At both sites plots reforested with native (Alnus accuminata) and exotic tree species (Pinus patula and Eucalyptus saligna) were established. We hypothesized that oribatid mite abundance, species richness and community structure differ between reforestation treatments. To identify driving factors for oribatid mite community structure, we measured environmental variables, e.g. C-to-N ratio, water content, and microbial biomass. Overall, 65 species of oribatid mites were found with small species such as Suctobelbidae and Rostrozetes ovulum dominating. In contrast to our hypotheses, the abundance and species richness of oribatid mites differed more between pasture types than between reforestation treatments. This resembled the response of soil microbial biomass. Presumably, the duration of the experiment of seven years was too short to allow establishment of forest specific oribatid mite and microbial communities, suggesting that oribatid mites and microorganisms respond slowly to reforestation and changes in plant cover, reflecting long lasting legacy effects of previous land use.

Distribution of oribatid mites is moisture-related within red wood ant Formica polyctena nest mounds

Abundant and species rich oribatid mite faunas live as ant associates in red wood ant nest mounds. Distribution of oribatids (as of many other groups) within mounds is unknown, yet there is an indication that many oribatid species favor moist microclimates. The ant mounds typically have a relatively dry core covered by a moister surface layer, but the moisture variance of mound parts has rarely been verified by measurements. We measured the moisture variance of nine Formica polyctena mounds (surface, rim, core) located in three different forest types in Finland. The moisture may affect the mounds’ temperature maintenance, and we further investigated this relationship. We also hypothesised that the abundance, species richness and community composition of oribatids may be related to the moisture, and investigated these differences between the mound parts and forest types. The moisture varied significantly between the mound parts; moisture was highest in surface followed by rim and core. The surface moisture had a positive relationship with nest core temperature. A total of 18,614 oribatid mites belonging to 93 species and one higher taxon were recorded. The oribatids occurred predominantly on the surface (77.9%), followed by the rim (16.6%) and the core (5.5%) of the ant nest mounds. The abundance and species richness of oribatids was positively related to moisture and differed significantly between the mound parts and forest types. The mound volume had no effect on moisture, temperature or mite community composition. The results indicate that the moisture harbored in the surface layer of ant nest mounds is a vital factor for maintaining rich oribatid mite communities within mounds.

Bringing multivariate support to multiscale codependence analysis: Assessing the drivers of community structure across spatial scales

Abstract Multiscale codependence analysis (MCA) quantifies the joint spatial distribution of a pair of variables in order to provide a spatially explicit assessment of their relationships to one another. For the sake of simplicity, the original definition of MCA only considered a single response variable (e.g. a single species). However, that definition would limit the application of MCA when many response variables are studied jointly, for example when one wants to study the effect of the environment on the spatial organisation of a multi‐species community in an explicit manner. In the present paper, we generalise MCA to multiple response variables. We conducted a simulation study to assess the statistical properties (i.e. type I error rate and statistical power) of multivariate MCA (mMCA) and found that it had honest type I error rate and sufficient statistical power for practical purposes, even with modest sample sizes. We also exemplified mMCA by applying it to two ecological datasets. The simulation study confirmed the adequacy of mMCA from a statistical standpoint: it has honest type I error rates and sufficient power to be useful in practice. Using mMCA, we were able to detect variation in fish community structure along the Doubs River (in France), which was associated with large spatial structures in the variation of physical and chemical variables related to water quality. Also, mMCA usefully described the spatial variation of an Oribatid mite community structure associated with a gradient of water content superimposed on various smaller‐scale spatial features associated with vegetation cover in the peat blanket surrounding Lac Geai (in Québec, Canada). In addition to demonstrating the soundness of mMCA in theory and practice, we further discuss the strengths and assumptions of mMCA and describe other potential scenarios where it would be helpful to biologists interested in assessing influence of environmental conditions on community structure in a spatially explicit way.

Landslide Effect on an Oribatid-Mite Community in a Monsoon Forest

Landslide-caused erosion of soil alters above ground plant cover and primary production, and is a major disturbance in forests and agro ecosystems in Taiwan. Bimonthly litter collections were conducted for one year, with oribatid mites studied at landslide sites and on the undisturbed forest floor. We hypothesized that landslide soil erosion would decrease oribatid-mite abundance and diversity and alter its community structure compared with control site.

Mesovoid shallow substratum as a biodiversity hotspot for conservation priorities: analysis of oribatid mite (Acari: Oribatida) fauna

The mesovoid shallow substratum (MSS) is a unique habitat that shelters and serves as a microrefuge for epigean, endogean and hypogean invertebrate species. Understanding the MSS community′s spatio-temporal structure and species diversity patterns in relation to the environmental parameters plays a crucial role in conservation. In this study we investigated: i) the diversity and community structure of oribatid mites from edaphic habitat, superficial MSS (i.e., the upper layer of MSS) and deep MSS (i.e., lower layer of MSS) in an alpine region of Southern Carpathians, Romania, and ii) the relationships between the oribatid mite communities and the environmental variables, such as temperature and humidity. The composition and the structure of oribatid communities differed along the three habitats indicating possible habitat specialization. The structure of the oribatid community was influenced by temperature and humidity. The rich and mixed oribatid communities in the MSS and the oribatid communities' response to surface and subsurface environmental variables suggest that the MSS may offer a micro-refuge for edaphic species when the conditions in the surface habitats become too harsh. Thus, we suggest that MSS should be prioritized for conservation because it may be the key component in maintaining biodiversity.

Patterns of oribatid mite species diversity: testing the effects of elevation, area and sampling effort.

Elevational gradients in species diversity and species area relationships are two well established patterns that are not mutually exclusive in space and time. Elevation and area are both considered as good proxies to detect and characterize the patterns of species diversity distribution. However, such studies are hampered by the incomplete biodiversity data available for ecologists, which may affect the pattern perceptions. Using the large dataset of oribatid mite communities sampled in Georgia, we tested the effects of altitude and area on species distribution using various approaches, while explicitly considering the biases from sampling effort. Our results showed that elevation and area are strongly correlated (with increasing absolute elevation, land area decreases) and both have strong linear effects on species diversity distribution when studied separately. Approaches based on multiple regression and direct removal of co-varied factors, indicated that the effect of area can actually override the effect of elevation in describing the oribatid species diversity distribution along with elevation. On the other hand, the bias of sampling proved significant in perception of elevational species richness pattern with less effect on elevational species area relationship. We suggest that the sampling alone may be responsible for patterns observed and thus should be considered in ecological studies when eligible.

Communities of oribatid mites (Acari: Oribatida) of naturally regenerating and salvage-logged montane spruce forests of Šumava Mountains

AbstractThe main aim of this study was to describe and compare communities of oribatid mites of selected areas in montane spruce forests near Březník in the Šumava National Park, where different management strategies were used after the spruce dieback caused by massive bark beetle gradation more than 15 years ago. Naturally regenerating and salvage-logged areas were compared. Significant differences were found in the oribatid mite community composition between differently managed areas. The oribatid mite community in naturally regenerating areas was in better shape and its abundance and species composition was similar to the community of a control area in a mature and healthy spruce forest.

Comparing the natural variation of oribatid mite communities with their changes associated with anthropogenic disturbance.

Several organism communities serve as ecological and environmental indicators to detect changes in human-impacted habitats. However, the composition of indicator communities may vary because of natural variation in addition to the changes associated with human disturbances. This meta-analysis compared the natural variation of oribatid mite assemblages, a good indicator model group in soil ecosystems, with their deviations associated with disturbance using diversity and dissimilarity indices and three human disturbance types. Literature data were collected about oribatid mite assemblages from natural and disturbed habitats. Human disturbances consisted of agriculture, heavy metal pollution and forest management. Biodiversity indices (Shannon and Berger-Parker) and dissimilarity indices (Jaccard and Bray-Curtis) were calculated among natural habitats and between disturbed and control habitats at the species and genus level. We considered oribatid mite assemblages as effective community-level indicators when the methods separated the differences of assemblages between disturbed and control habitats from their varieties among natural habitats. In addition, the study analysed the correlation between these indices and environmental variables of the study sites. Oribatid mite assemblages performed high indication strength with Bray-Curtis index for agricultural disturbances since dissimilarity values between disturbed and control habitats were as high as between different natural habitats and higher than among the same types of natural habitats. Genus-level values showed similar results to the species level. This approach may be useful to test the effectiveness of other indicator groups and methods.

The tropics as an ancient cradle of oribatid mite diversity

Diversity of most animal and plant taxa increases towards the equator. The reasons for this pattern are manifold, but their relative importance is controversial. Understanding of the radiation of animal taxa is needed to uncover the mechanisms underlying latitudinal gradients in biodiversity. Species may have evolved more quickly in tropical regions, suggesting that the tropics function as cradle of diversity, or they may have survived in the tropics for longer periods of time as compared to higher latitude biomes, suggesting that the tropics function as museum of diversity. We used oribatid mites as a model group to investigate if the high species number of this mainly soil-living taxon can be explained by the cradle or museum hypothesis. We analyzed oribatid mite communities in tropical and temperate forest ecosystems, sequenced 18S and part of the 28S rDNA of common species, and constructed phylogenetic trees using Bayesian Inference and Maximum Likelihood algorithms. Then, we mapped the distribution of species (tropical, temperate, cosmopolitan) onto the phylogenetic tree. Most tropical oribatid mite taxa formed terminal branches indicating that the high diversity of oribatid mites in tropical regions is due to recent radiation, supporting the hypothesis that the tropics function as cradle of oribatid mite diversity. Further, the results suggest that most early-derivative oribatid mite taxa are cosmopolitan indicating that they evolved on a large ancient continent. Overall, our results support the view that oribatid mites are a very old taxon which radiated intensively in tropical regions, but their origin predates the existence of the tropical regions of today.

Estudio de la comunidad de oribátidos (Acari: Oribatida) en dos parches de tala (Celtis ehrenbergiana) del sudeste bonaerense

Study of the oribatid mite (Acari: Oribatida) community from two patches of tala (Celtis ehrenbergiana) from the southern of Buenos Aires. “Talares” are xeric forests located along the coast of Buenos Aires province, Argentina. Since >400 years ago, they have been subject of a severe degradation, resulting in a fragmentary landscape of forest patches surrounded by a grassland matrix. The aims of this study were: a) to enhance the knowledge of oribatid mites in the talares, and b) to analyze the effect of habitat fragmentation on diversity, richness, abundance and structure of the oribatid mite community. I analyzed oribatids in three sites: two different-size close forest patches (big: Gr, small: Ch) and the surrounded grassland matrix (Ma) in Laguna de los Padres reserve, Mar del Plata. A total of 51 species of oribatids were identified, with similar values of richness in all sites. Oppiidae y Scheloribatidae were the families with more species. Diversity (H’) was greater in the forest patches (Gr=1.58; Ch=1.59) than in the matrix (Ma=0.91). Density of oribatid mites was higher in Gr (36500 individuals/m2); in Ch and Ma, densities were 50% and 75% lower. This global difference is a consequence of reduced population sizes in most species. According to seasonal variations, in Gr there were more “ubiquitous” species (20) than in Ch y Ma (10). Summarizing, the community of oribatid mites were primarily conditioned by the type of environment (grassland vs. forest), with similar distribution patterns of species but with a marked seasonality in the grassland matrix. Among forest patches, area did affect oribatid mites density through a reduction in most population sizes. The evaluation of the fragility of these populations could be a starting point to undertake conservation programs.

Relative importance of local habitat complexity and regional factors for assemblages of oribatid mites (Acari: Oribatida) in Sphagnum peat bogs.

We investigated communities of oribatid mites in five peat bogs in the north-west of the East European plain. We aimed to determine the extent to which geographic factors (latitude, separation distance), local environment (Sphagnum moss species, ground water level, biogeochemistry) and local habitat complexity (diversity of vascular plants and bryophytes in the surrounding plant community) influence diversity and community composition of Oribatida. There was a significant north-to-south increase in Oribatida abundance. In the variance partitioning, spatial factors explained 33.1% of variability in abundance across samples; none of the environmental factors were significant. Across all bogs, Oribatida species richness and community composition were similar in Sphagnum rubellum and Sphagnum magellanicum, but significantly different and less diverse in Sphagnum cuspidatum. Sphagnum microhabitat explained 52.2% of variability in Oribatida species richness, whereas spatial variables explained only 8.7%. There was no distance decay in community similarity between bogs with increased geographical distance. The environmental variables explained 34.9% of the variance in community structure, with vascular plants diversity, bryophytes diversity, and ground water level all contributing significantly; spatial variables explained 15.1% of the total variance. Overall, only 50% of the Oribatida community variance was explained by the spatial structure and environmental variables. We discuss relative importance of spatial and local environmental factors, and make general inferences about the formation of fauna in Sphagnum bogs.