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Vegetation is widely used in the assessment of the quality of peatlands, while the invertebrate fauna of peatlands is relatively poorly studied. We compared the bioindicator values of vegetation with two arthropod groups widespread in peatlands, saprophagous Oribatida (Acariformes) and predatory Mesostigmata (Parasitiformes) mites. Samples were collected from ecotones at the edges of peatland ponds in Poland, including four in near-natural condition (i.e., peatlands unaffected by human activity) and three in previously disturbed but now recovering peatlands. A set of abiotic parameters was measured at each site: pond area, mean annual temperature, annual precipitation, and water parameters (pH, conductivity, colour, total nitrogen, phosphorus, calcium, and organic carbon). Overall, 63,635 specimens of Oribatida and 448 of Mesostigmata were recovered in the sampling. Species richness of Oribatida (56 species) was higher than that of flora (46) and Mesostigmata (15). Vegetation was significantly associated with annual precipitation in the years 1998–2007 which accounted for 29.1 % of the variation in vegetation communities. Oribatida variability was significantly associated with the content of organic carbon in water accounting for 32.4 % of variation. In contrast, variation in the Mesostigmata was not significantly associated with any of the abiotic parameters. Vegetation at ponds in previously disturbed and now recovering peatlands had higher bush cover than at near-natural ponds and the pond in the cutaway peat had lowest moss cover and the highest number of associate species (i.e., species with wide tolerance not characteristic of the certain community). Mite communities did not differ consistently between near-natural and recovering peatlands. Sphagnum divinum Flatberg et Hassel was recorded from Poland for the first time. publishedVersion

We performed a greenhouse experiment to test how the functional diversity of earthworms, the dominant group of soil macro-invertebrates in many terrestrial ecosystems, affects nitrogen cycling and plant growth. Three species were chosen to represent a range of functional traits: Lumbricus terrestris (large, mainly detritivorous, makes vertical permanent burrows open at the surface), Aporrectodea longa (medium-large, feeds on both detritus and soil, makes burrows more branched than L. terrestris), and Allolobophora chlorotica (small, geophagous, makes ephemeral burrows below the soil surface). Mesocosms with ryegrass (Lolium perenne) were inoculated with none to all three species (similar total biomass), using an experimental design (Simplex) suited to partition single species and diversity effects. Two contrasting N sources, urea or mammalian dung, were labelled with 15N so that the acquisition by plants and earthworms and recovery of applied 15N could be estimated. Over 3 months, plant production was higher with urea applications, but there were also species-specific earthworm effects: A. chlorotica and, to a lesser extent, A. longa increased shoot biomass, whereas L. terrestris increased root biomass. Earthworms did not affect soil N concentrations or leaching losses, whereas more N was leached under urea. A. chlorotica tended to increase dung-15N recovery in grass shoots, but in interaction with A. longa had the opposite effect, possibly through increased N immobilization in the microbial biomass. Earthworms assimilated negligible amounts of urea-15N but a substantial proportion (17% on average) of the dung-15N, with no clear-cut differences between species. Our findings show that earthworm species may have similar trophic response to N sources and yet different effects on plant N uptake and primary production, and that inter-specific earthworm interactions can result in non-additive diversity effects.

Land use changes are among the main factors shaping diversity patterns of soil fauna in European ecosystems. However, current knowledge on soil fauna biodiversity levels across land use types to establish baseline values with monitoring purposes are still lacking. Also, only few initiatives have been including functional components of soil fauna on biodiversity monitoring, despite the noticeable link between soil organisms and aboveground ecosystem services. Here, we analyzed the differences of collembolan taxonomic and functional diversity across an European transect with sites comprising different land use types (forests, grasslands and arable lands) and characteristics in terms of habitat conditions and soil properties. No clear relation was found between collembolan species richness and the site typology established in this study. However, community traits of life-forms responded to the gradient of site properties and indicated different land use types based on the higher proportion of eu-edaphic species in forested sites, in comparison to grasslands and arable lands. Among the environmental variables, pH was the main soil parameter influencing both collembolan richness and community weighted mean of life-forms, and was negatively correlated to both biodiversity components. The effects of pH may also reflect the influence of land use history and management practices in different European ecosystems and more suitable traits related to pH preferences, and tolerance should be further investigated for collembolan species. Our results suggest that functional diversity may provide a clearer picture on soil fauna diversity changes across different land use types and site properties. So components of functional diversity based on community traits should be included in the ‘indicator shopping basket’ of soil biodiversity monitoring studies across European ecosystems.

In determining the overall γ-diversity within a land use type or when assessing the impact of a land use on biodiversity one has to consider the hierarchically nested nature of the γ-diversity. In this study we used a hierarchical approach to examine the diversity of mites, Oribatei and Mesostigmata, in various forest types in Ireland. The study included sampling at regional, stand, individual tree and microhabitat scales. α- and β-diversity (species richness) was examined at each of these scales and the proportional contribution to the variation accounted for by each level of the hierarchy was quantified. β-Diversity generally accounted for at least 50% of the γ-diversity at all levels of the habitat hierarchy with average values varying from 34% between regions, to 57.5% between forest types within region, to 63% between trees within forest type and 63% between microhabitats within a forest type. Differences between the fauna of microhabitats within a forest type accounted for approximately 30% of the total variation while that of forest types within regions accounted for 10.5%. These results are similar to those reported in several other studies but the study quantifies the variation by examining the relative contributions of α- and β-diversity to species richness. Redundancy Analysis allowed the identification of the proportional contribution of the hierarchical components to the variation in community structure in a manner which has not been used before for these systems.

Extensive afforestation took place in Ireland during the twentieth century and the forest cover currently represents about 10% of the land area. However, approximately 50% of this forest is Sitka spruce, a non-native species introduced from the North Western United States of America. Little is known about the microarthopods of these forests and the current study examined the mites (Oribatida and Gamasina) occurring in the canopy, moss (both on the soil surface and in the canopy) and soil of oak, ash, Scots pine and Sitka spruce forests in Ireland to compare the mite assemblages in each and to determine the associations between forest type and the form of constituent microhabitats in determining the structure of this fauna. There were significant differences between the diversity and species composition of the assemblages in the different forest types with the largest species richness occurring in oak forest and the smallest in first rotation Sitka spruce forest. Analysis of our data, together with the results from other studies, suggest that the differences arise because the variation between the architecture of the tree species is reflected in the structure of microhabitats such as the form of the bark and the extent of moss cover. Thus while the ultimate factors affecting the variation in the mite fauna may be the form of the microhabitats, these are intrinsic properties of the forests associated directly with the species of tree. Finally, our results do not support the view that exotic species will necessarily have low biodiversity of mites than native forests.

Diversity of plant species and the species composition (identity) are known to influence below-ground diversity. In this paper we examine the effects of plant species diversity (richness and evenness), rates of nitrogen application and planting density, on earthworm community structure in grassland. The study was carried out at three sites in Ireland using a Simplex experimental design to define the compositions of the experimental plant communities used. A negative relationship was detected between diversity (evenness) of plant species and diversity of earthworms in the soils. However, plant species identity also affected the structure of the earthworm assemblage. In particular, the legume, Trifolium repens had a strong effect but this was conditional on the rate of nitrogen application. No earthworm species favoured communities dominated by slow growing grasses ( Phleum pratense and Dactylis glomerata ) ( P = 0.02). Higher N inputs reduced earthworm abundance and biomass under T . repens . Earthworm richness, was negatively influenced by elevated amounts of N inputs. No effect of planting density was detected but this factor also did not affect plant biomass production.

Important steps in developing reliable bioindicators for soil quality are characterising soil biodiversity and determining the response of its components to environmental factors across a range of land uses and soil types. Baseline data from a national survey in Ireland were used to explore relationships between diversity and composition of micro-organisms (bacteria, fungi, mycorrhiza), and micro-, meso- and macro-fauna (nematodes; mites; earthworms, ants) across a general gradient representing dominant land uses (arable, pasture, rough-grazing, forest and bogland). These diversity data were also linked to soil physico-chemical properties. Differences in diversity and composition of meso- and macro-fauna, but not microbes, were clear between agriculturally-managed (arable and pasture) and extensively-managed (rough-grazing and bogland) soils corresponding to a broad division between ‘mineral’ and ‘organic’ soils. The abundance, richness and composition of nematode and earthworm taxa were significantly congruent with a number of the other groups. Further analysis, using significant indicator species from each group, identified potential target taxa and linked them to soil environmental gradients. This study suggests that there is potential surrogacy between the diversity of key soil taxa groups and that different sets of bioindicators may be most effective under agricultural and extensive land use.

Farmland birds have suffered a severe decline in recent years throughout Europe including Ireland. Agricultural intensification is believed to be the main cause and this has led to the introduction of agri-environmental schemes, of which set-aside is a part. Bird abundance and diversity were compared between set-aside and adjacent tillage or grassland at 18 locations. The set-aside sites were also assigned to one of four management types: rotational set-aside, non-rotational set-aside, first year set-aside that was productive grassland in the previous year, and long-term set-aside that was grazed by animals in winter. Species diversity and the abundances of skylark, meadow pipit and woodpigeon were significantly greater in set-aside sites. Species diversity was not significantly different between set-aside management types and meadow pipit, skylark, pheasant, house sparrow, magpie, snipe and starling were closely associated with non-rotational set-aside, which also contained significantly larger numbers of these species compared to the other set-aside types. This study shows that set-aside does enhance bird diversity and abundance and that, in Ireland, the most effective form of set-aside is non-rotational. It also shows that the most appropriate form of set-aside will vary from situation to situation and that a one size fits all view should not be taken in the development of agri-environmental schemes. Other funder Energy, Environment and Sustainable Development Programme TS 24.04.12

A novel experimental design, based on the simplex model, was used to study the effects of earthworm functional group diversity on nitrogen dynamics in soils. This mesocosm experiment was carried out at two densities of earthworm and at two levels of food supply. Leachate was collected and analysed over a 20-week period. Soil nitrogen content was measured when the soil columns were destructively sampled on week 30. Results showed the presence of variation among the functional groups in their effects on N dynamics and that both population densities and levels of resource availability were significant. Ammonium concentrations in leachate were generally higher with aneciques and endogees; the opposite was true for nitrate-N, which under certain circumstances was higher with epigees. A significant synergy between the endogees and aneciques was shown in terms of nitrate in soil. Earthworm biomass was important in some instances. For example, larger amounts of soil nitrate were present at higher densities of endogees. A varying effect of food supply was seen for the three functional groups. For example, there were reduced concentrations of nitrate-N in the leachate from the anecic monocultures at low levels of food supply, while increased amounts were leached from the epigees at low food supply. Greater concentrations of ammonium-N were leached from aneciques monocultures at low levels of food supply. Increased food supply resulted in increased amounts of soil nitrate-N in monocultures of both epigees and endogees. It was apparent that nitrogen transformations and amounts available in soil water are dependant on the composition of the earthworm community.

Summary Reduced biodiversity is associated with increased management intensity and reduced environmental heterogeneity but reduced tillage has been shown to lessen the severity of the effects. In this study we compare the effects, on the abundance and assemblage structure of Collembola, of conventional tillage with a form of reduced tillage management called ECOtillage and we examine the responses of the Collembola to straw incorporation into the soil. Conservation tillage (ECOtillage) resulted in elevated abundances of most collembolan species compared with conventional tillage practices but has little effect on species richness. The addition of straw residue did not enhance the diversity of Collembola and reduced overall abundances.

To study the effects of earthworm casting on organic matter dynamics, control soil and casts were added as a surface layer (Horizon I) to perspex cylinders containing a ‘base’ soil depleted in organic C (Horizon II). Three treatments with different Horizon I were used; a control containing uningested soil and oak litter (Quercus petraea (Mattuschka) Lieblein), cast derived from the same substrates, and a third (Ew+cast) where cast as well as endogeic (Aporrectodea caliginosa Savigny, Allolobophora chlorotica Savigny) and anecic (Lumbricus terrestris L.) earthworms were included. These were monitored over a 2 1 2 year period. Moisture fluctuations were reduced and higher amounts of organic matter and C were present in Horizon I with the cast treatment after 2 years. In addition, the proportion of clay C (and to a lesser extent light fraction) in Horizon I decreased significantly in the control and cast treatments while there was a corresponding increase in the proportions of silt C. Overall, earthworm activity had a limited effect on C distribution in the particle size fractions studied, though the dynamics of organic matter/particle associations may require more than 2 1 2 years before clear patterns emerge.

Litter bags containing one of the following: earthworm cast, intact oak litter (Quercus petraea Matt., Liebl.) plus soil and shredded oak litter ( Earthworm casts (surface and buried) had reduced moisture fluctuations relative to non-cast (intact or shredded) treatments. Casts maintained higher levels of organic matter and carbon than non-cast treatments (surface or buried) after 2 years of decomposition. However, while both surface and buried casts maintained higher levels of organic matter, bacterial counts in buried cast remained higher than all other treatments (including surface cast) on five of the seven final sampling dates. Shredding and burial of organic matter did not affect total, cumulative loss of organic matter/carbon from the non-cast treatments. Potential mineralization rates (loss of CO2 at 20°C) from non-cast treatments was influenced by their placement. When temperature and/or moisture became limiting surface non-cast treatments showed reduced losses of CO2 by comparison with buried non-cast treatments. The reverse occurs when the moisture and temperature are not limiting, i.e. surface treatments have greater losses of CO2 than the buried treatments. Thus, both the micro-climatic and soil aggregate effects (and their interactions) were observed to influence the decay dynamics and are discussed in relation to nutrient stabilization/mobilization and microbial populations.

Two soils, one a silty loam soil (Kilkea) and the other a clayey soil (Leitrim), and stabilized earthworm cast derived from both soils, were subjected to two wet-drying regimes (4 d and 16 d wetting intervals) at two temperatures (10°C and 20°C). Each treatment was sampled regularly for CO2 emissions and dissolved organic carbon, ammonium and nitrate were measured in leachate. Production of CO2 from the clayey soil was 20–40% less than from the silty loam at both temperatures and under both cycles, while production was 40% less at the lower temperature. Amounts of dissolved organic carbon (DOC) in leachate from the silty loam soil were greater than from the clayey soil, while, in general, greater amounts of DOC leached from uningested soil than from earthworm cast. Treatments with the silty loam soil lost approximately 30–40 times more total N than corresponding clayey soils under the 4 d cycle, and 12–16 times more under the 16 d cycle, thus illustrating the extent of nutrient protection in clay soils, but also the reduction of this effect with super-saturation and prolonged drying (16 d cycle). Nutrient losses suggest greater protection of nutrients in cast at first, followed by a reduction in protection (weakening of aggregate structure) in later cycles. These results have important implications for nutrient losses in the field, since significant and complex interactions were evident between the experimental factors. To improve our understanding of soil organic matter (SOM) dynamics, interactions between climatic, soil and cast-mediated changes (i.e. increased organic–inorganic interaction and burial) need to be incorporated into future models of soil decomposition.

Arcitalitrus dorrieni (Hunt) is a euterrestrial amphipod, native to Australasia, which occurs in several woodland sites in Ireland and Britain. Experiments were carried out to estimate consumption, assimilation and egestion rates of A. dorrieni feeding on Lodgepole pine, Pinus contorta , litter. These figures, together with a model of weight-specific oxygen consumption, were used to estimate the annual percentage of litter fall or carbon utilized by A. dorrieni at a coniferous woodland site in Co. Galway, Ireland. Estimates of 25% suggest that these animals play an important role in mineralization and nutrient exchange in the habitats in which they occur.

Investigations of the structure, distribution and abundance of soil faunal communities have demonstrated three notable points. They are very diverse in numbers of species, highly spatially aggregated and appear to exhibit a low degree of food resource specialisation. In temperate regions these observations appear to be expressed to their greatest extent among the microarthropod assemblages of highly organic woodland soils. The species diversity of oribatid mites (Cryptostigmata: Acarina) in such environments can be bewildering and remains to be reconciled satisfactorily with classical Hutchinsonian niche theory. In this study the Shorrocks model is applied to a `fungivorous guild' composed of oppiid mites. The results indicate an aggregated pattern of oribatid distribution and abundance which may contribute to understanding the extraordinary diversity of soil microarthropods in temperate woodland soils. The datasets show that independent intraspecific aggregation of competing oppiid species over patches, alone, might be sufficient to stabilise coexistence and facilitate the high species diversity in this guild.

Ninety-one percent of Salix aquatica cv. gigantea litter disappeared within 6 months from experimental cages containing Lumbricus terrestris L. in reclaimed peat, compared with only 28% when L. terrestris was absent. Litter consumption rate was 6–9 mg dry wt g −1 fresh wt day −1 in the field and 10–15 mg g −1 fresh wt day −1 in the laboratory at 15°C. Maximum growth rate in the field was 4mg fresh wt g − day − and 4.55 mg in the laboratory. Cocoon production in the field was 1.3worm −1 month −1 and 2.1 in the laboratory. Mean gut contents were 48-23 mg dry wt g −1 fresh wt over the size range 1–6 g fresh wt and gut transit time was 10h. It was estimated that a Lumbricus biomass of 100gm −2 could consume 1.34 kg soil m −2 yr −1 .