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

Bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment

Biodiversity is rapidly declining1, and this may negatively affect ecosystem processes, including economically important ecosystem services. Previous studies have shown that biodiversity has positive effects on organisms and processes4 across trophic levels. However, only a few studies have so far incorporated an explicit food-web perspective. In an eight-year biodiversity experiment, we studied an unprecedented range of above- and below-ground organisms and multitrophic interactions. A multitrophic data set originating from a single long-term experiment allows mechanistic insights that would not be gained from meta-analysis of different experiments. Here we show that plant diversity effects dampen with increasing trophic level and degree of omnivory. This was true both for abundance and species richness of organisms. Furthermore, we present comprehensive above-ground/below-ground biodiversity food webs. Both above ground and below ground, herbivores responded more strongly to changes in plant diversity than did carnivores or omnivores. Density and richness of carnivorous taxa was independent of vegetation structure. Below-ground responses to plant diversity were consistently weaker than above-ground responses. Responses to increasing plant diversity were generally positive, but were negative for biological invasion, pathogen infestation and hyperparasitism. Our results suggest that plant diversity has strong bottom-up effects on multitrophic interaction networks, with particularly strong effects on lower trophic levels. Effects on higher trophic levels are indirectly mediated through bottom-up trophic cascades

Diversity Promotes Temporal Stability across Levels of Ecosystem Organization in Experimental Grasslands

The diversity–stability hypothesis states that current losses of biodiversity can impair the ability of an ecosystem to dampen the effect of environmental perturbations on its functioning. Using data from a long-term and comprehensive biodiversity experiment, we quantified the temporal stability of 42 variables characterizing twelve ecological functions in managed grassland plots varying in plant species richness. We demonstrate that diversity increases stability i) across trophic levels (producer, consumer), ii) at both the system (community, ecosystem) and the component levels (population, functional group, phylogenetic clade), and iii) primarily for aboveground rather than belowground processes. Temporal synchronization across studied variables was mostly unaffected with increasing species richness. This study provides the strongest empirical support so far that diversity promotes stability across different ecological functions and levels of ecosystem organization in grasslands

A comparison of the strength of biodiversity effects across multiple functions

In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45% of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combinatio

Globally invariant metabolism but density-diversity mismatch in springtails.

Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning

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.</p

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

Vacht, Piret, Niglas, Helin, Kuu, Annely, Koff, Tiiu, Kutti, Sander, Raamets, Jane (2019): Oribatid mite (Acari: Oribatida) communities of urban brownfields in Tallinn, Estonia, and their potential as bioindicators of wasteland successional stage. Acarologia 59 (1): 26-32, DOI: 10.24349/acarologia/2019431

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