Diatom and microarthropod communities of three airfields in Estonia – Their differences and similarities and possible linkages to airfield properties

Even though airfields, which are often anthropologically modified natural areas, are continuously influenced by human activities, their soils are still dynamic ecosystems containing various habitats for microscopic groups of organisms which are often ignored. In this exploratory study, the microarthropod fauna, Collembola (Hexapoda) and oribatid mites (Acari: Oribatida), and diatom (Bacillariophyta) flora were identified in three Estonian airfields, both runway sides and snow-melting sites were investigated. The communities of these airfields shared approximately 10–60% of the species belonging to each studied bioindicator group. The shared species were generally characteristic of a broad habitat spectrum. Communities were also characterized based on their species richness and diversity and in relation to location and the purpose of different airfield areas (e.g. snow-melting sites vs. runway sides). Also, species indicative of a specific airfield or purpose of the area within the airfield were identified using Indicator Species Analysis. Some possible linkages between airfield properties and communities,  e.g. airfield that had highest pollutant concentrations had also maintained high diversity and species richness, were noted. Despite the contamination levels the airfield soils had still maintained a functioning soil ecosystem

Seasonal change of oribatid mite communities (Acari, Oribatida) in three different types of microhabitats in an oak forest

Oribatid mites are one of the most abundant groups of the ground-dwelling mesofauna. They can be found in almost every terrestrial habitat all over the world and they are characterized by great species richness and great number of individuals. In spite of that not enough is known about their behaviour on community level and their spatial and temporal pattern in different habitats of the world. In our present study the seasonal behaviour of oribatid mite communities was analysed in three types of microhabitats in a temperate deciduous forest: in leaf litter, soil and moss. Samples were collected at a given site in a year and a half and the oribatid mite communities living there were studied on genus level along with the changes of meteorological factors characteristic of the area. The results show that corresponding to similar previous researches, the communities in our study do not have a seasonally changing, returning pattern either. Based on this, we can conclude that climatic differences and differences in other seasonally changing factors between the seasons do not have a significant role in the annual change of communities. Besides that we discovered that the communities of the three microhabitats are not completely the same. It is the oribatid mite community of the moss which differs mostly from communities in the leaf litter and in the soil. Our study calls attention among others to the fact that compositional changes of the oribatid mite communities living all over the world and their causes are unclear to date

Biodiversity and Ecology of Soil Oribatid Mites (Acari: Oribatida) in the Grassland Habitats of Eastern Mongolia

Composition, abundance, distribution, and diversity of oribatid mite communities were investigated at five study areas in Eastern Mongolia. A total of 88 species of oribatid mites were recorded from the studied areas. The largest number of species (51 spp.) was found in the habitats of river valleys, while the plain steppe which covers the largest area contained the lowest species richness (24 spp.). Three other sub-regions with similar landscape types show approximately the same species richness (39 to 45 spp.), although they are located relatively far from each other. The oribatid mite faunas of all sub-regions were essentially similar to each other. The abundances of oribatid mites were higher in mountain-steppes (5,240 to 9,800 ind./m2), and lower in the plain steppe and river basins (3,520 to 3,535 ind./m2). Oribatid mite communities were characterized by species with relatively similar abundances. The results of species diversity and evenness indices indicate species-rich assemblages with low dominance

Indication strength of coenological similarity patterns based on genus-level taxon lists and prevalence distribution

Several methods and indicators can be used to evaluate the coenological state of a given habitat, the ones which can be created simply, quickly, standardizably and reliably and which can be used to exactly quantify the state of a given habitat in point of numbers can be of outstanding practical importance in ecology. One possible method is the examination of the genera which can be found in a given habitat in great abundance and have little number of species and various ecological characteristics. For this purpose one of the most appropriate groups is that of ground-dwelling oribatid mites (Acari: Oribatida). In our research, joining the bioindication methodological project of the “Adaptation to Climate Change” Research Group of the Hungarian Academy of Sciences, the indication strength of genus-level taxon lists and the effects of the main pattern-generating factors creating similarity patterns were analysed with the help of data series on oribatid mites collected by us and originating from literature. Our aim was to develop a method with the help of which the difference expressed with distance functions between two oribatid mite genus lists originating from any sources can correspond to spatial and temporal scales. Our results prove that these genus lists are able to express the spatial distance of the habitats. With the help of this base of comparison changes in disturbed or transformed habitats can be expressed by means of oribatid mite communities, with spatial and temporal distances

Invasion by Exotic Earthworms Alters Litter- and Soil-dwelling Oribatid Mites

Exotic earthworms are drivers of biotic communities in invaded North American forest stands. Here we used ecologically important oribatid mite (Arachnida: Acari) communities, as model organisms to study the responses of litter- and soil-dwelling microarthropod communities to exotic earthworm invasion in a northern temperate forest. Litter- and soil-dwelling mites were sampled in 2008–2009 from forest areas: (1) with no earthworms; (2) those with epigeic and endogeic species, including Lumbricus rubellus Hoffmeister; and (3) those with epigeic, endogeic, and anecic earthworms including L. terrestris L. Species richness and diversity of litter- and soil-dwelling (0–2 cm soil depth) oribatid mites was 1–2 times higher in sites without earthworms than in sites with worms. Similarly, litter-dwelling oribatid mites were between 72 and 1,210 times more abundant in earthworm-free sites than in sites with worms. Among earthworm invaded sites, abundance of litter-dwelling oribatid mites in sites without the anecic L. terrestris was twice as high in May and 28 times higher in October, compared to sites with L. terrestris. Species richness, diversity, and abundance of oribatid mites were greater in litter-layers than in the soil-layers that showed a varied response to earthworm invasion. Species compositions of both litter- and soil-dwelling oribatid mite communities of forests with no earthworms were markedly different from those with earthworms. We conclude that exotic earthworm invasions are associated with significant declines of species diversity, numbers, and compositional shifts in litter- and soil-inhabiting communities. These faunal shifts may contribute to earthworm effects on soil processes and food web dynamics in historically earthworm-free, northern temperate forests