Euedaphic Species Research Articles

Accumulation of free amino acids during exposure to drought in three springtail species

Springtails are closely related to insects, but they differ from these with respect to water balance, in particular because springtails are small and have high integumental permeability to water. Here we report a series of experiments addressing the dynamics of osmoregulation, water content and accumulation of free amino acids (FAAs) in three springtail species during exposure to a gradually increasing environmental desiccation simulating conditions in drought exposed soil. Folsomia candida and Protaphorura fimata (both living in the deeper soil layers; euedaphic species) were active throughout the 3week exposure, with the developing drought regime ending at −3.56MPa (the soil water activity at the permanent wilting point of plants is −1.5MPa) and remained hyperosmotic (having an body fluid osmolality higher than the corresponding environment) to their surrounding air. Sinella curviseta (living in upper soil/litter layers; hemiedaphic species) also survived this exposure, but remained hypoosmotic throughout (i.e. with lower osmolality than the environment). The body content of most FAAs increased in response to drought in all three species. Alanine, proline and arginine were the most significantly upregulated FAAs. By combining our results with data in the literature, we could account for 82% of the observed osmolality at −3.56MPa in F. candida and 92% in P. fimata. The osmolality of S. curviseta was only slightly increased under drought, but here FAAs were considerably more important as osmolytes than in the two other species. We propose that FAAs probably have general importance in drought tolerance of springtails.

Traits of collembolan life-form indicate land use types and soil properties across an European transect

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.

The impact of experimental forest fire on collembolan communities

Our study was carried out in fresh pine mixed forest, Biala Forest, near Warsaw (52°59’ N, 21°46’ E and 52°79’ N, 21°89’ E, Eastern Poland). Three experimental plots, 1m2 size, were chosen at random and burnt in June. The material was collected: just after the experimental fire (in June ), 30, 60, and 90 days after fire (respectively: in July, August, and September). On every sampling occasion 10 soil samples of an area of 10cm2 and a depth of 5 cm were taken in each sampling plots: burnt plots, in the border of burnt plots, and in surroundings of burnt plots. We found that experimental fire influenced on collembolan densities (Kruskall-Wallis test, H=8.29, P=0.01). Just after the experimental fire we found no collembolans in burnt plots. In a period of 90 days following the experimental fire densities of springtails of burnt and surroundings were similar. Euedaphic springtails were the dominating group in burnt plots and contrary to the border of burnt plots and surroundings, we noticed no epigeic springtails. Contribution of epigeic, hemiedaphic and euedaphic species in collembolan communities of investigated areas could point to different defense strategies of these invertebrates. Immature individuals of Collembola were the most numerous in burnt plots and at the border of burnt plots and this phenomenon is probably crucial for the reconstruction of collembolan communities after the fire.

Spruce monoculture establishment affects functional traits of soil microarthropod communities

Structure and density of soil microarthropod communities (Oribatida and Collembola) were studied in one natural beech forest and one spruce monoculture planted on a former beech stand in South Bohemia (Czech Republic). The spruce monoculture establishment increased microarthropod densities (93,000 ind. m−2 in the natural beech forest vs. 400,540 ind. m−2 in the spruce monoculture for Oribatida; 66,360 ind. m−2 in the natural beech forest vs. 136,360 ind. m−2 in the spruce monoculture for Collembola); additionally, it changed greatly the community structure in terms of species composition and functional traits. In the spruce monoculture, groups susceptible to disturbance were suppressed. The oribatid trophic structure changed as well with opportunistic herbifungivorous species increasing in the monoculture at the expense of fungivorous species. Similarly, hemiedaphic collembolans increased in the monoculture at the expense of euedaphic species. We conclude that the “functional approach” seems to be fruitful in revealing soil fauna response to environmental change.

Effects of Transgenic Bt Rice on Growth, Reproduction, and Superoxide Dismutase Activity of Folsomia candida (Collembola: Isotomidae) in Laboratory Studies

Transgenic rice expressing Bacillus thuringiensis (Bt) CrylAb protein is expected to be commercialized in China in the near future. The use of Bt rice for controlling insect pests sparks intensive debates regarding its biosafety. Folsomia candida is an euedaphic species and is often used as a "standard" test organism in assessing effects of environmental pollutants on soil organisms. In this study, growth, development, reproduction, and superoxide dismutase activity (SOD) of F. candida were investigated in the laboratory for populations reared on leaf tissue or leaf-soil mixtures of two CrylAb rice lines and a non-Bt rice isoline. Two independent tests were performed: 1) a 35-d test using petri dishes containing yeast diet (positive control) or fresh rice leaf tissue, and 2) a 28-d test in soil-litter microcosms containing yeast or a mixture of soil and rice leaf tissue. Biological parameters measured in both tests were number of progeny production, population growth rate, and SOD activity. For the petri dish test, data measured also included insect body length and number of exuviation. There were no significant differences between the populations reared on Bt and non-Bt rice leaf tissue in all measured parameters in both tests and for both Bt rice lines, suggesting no significant effects of the CrylAb protein in Bt rice on F. candida in the laboratory studies. Results of this study should add additional biosafety proofs for use of Bt rice to manage rice pests in China.

Wpływ doświadczalnych pożarów na zespoły mezofauny (Collembola i Acarina) dwóch typów łąk

The impact of experimental fires in grasslands on soil mesofauna was studied in the field experiment. The study was carried out on two kinds of meadows: on mineral (meadow I) and organic soils (meadow II), near Warsaw (52010’N; 20050’E). In November 2007 sampling plots, 1 m2 in size were chosen at random and burnt. Soil samples were taken just after fire and in April, July, and November 2008 to the depth of 10 cm from unburned places (control), at the border of fire and in burnt plots. The soil mesofauna was extracted from soil samples in the Tullgren apparatus. There were not found any effects of experimental fires on mesofauna densities. However, a slight increase of mesofauna abundance was s observed in burned plots 12 months after experimental fires on the meadow I and decrease on the meadow II. Just after fire, in burned plots, only euedaphic species of Collembola were present among mites communities dominated Oribatida, with thick cuticule.

Traits explain the responses of a sub-arctic Collembola community to climate manipulation

Ecosystems at high northern latitudes are subject to strong climate change. Soil processes, such as carbon and nutrient cycles, which determine the functioning of these ecosystems, are controlled by soil fauna. Thus assessing the responses of soil fauna communities to environmental change will improve the predictability of the climate change impacts on ecosystem functioning. For this purpose, trait assessment is a promising method compared to the traditional taxonomic approach, but it has not been applied earlier. In this study the response of a sub-arctic soil Collembola community to long-term (16 years) climate manipulation by open top chambers was assessed. The drought-susceptible Collembola community responded strongly to the climate manipulation, which substantially reduced soil moisture and slightly increased soil temperature. The total density of Collembola decreased by 51% and the average number of species was reduced from 14 to 12. Although community assessment showed species-specific responses, taxonomically based community indices, species diversity and evenness, were not affected. However, morphological and ecological trait assessments were more sensitive in revealing community responses. Drought-tolerant, larger-sized, epiedaphic species survived better under the climate manipulation than their counterparts, the meso-hydrophilic, smaller-sized and euedaphic species. Moreover it also explained the significant responses shown by four taxa. This study shows that trait analysis can both reveal responses in a soil fauna community to climate change and improve the understanding of the mechanisms behind them.

The rapid cold hardening response of Collembola is influenced by thermal variability of the habitat

Summary 1. It has been argued that species living under unpredictable thermal conditions need to have more flexible physiological capabilities to meet with thermal stress than species living in thermally stable environments. Here we investigate if the ability to rapidly cold-harden in Collembola is influenced by thermal conditions of the habitat. 2. Collembola exploit diverse habitats and are therefore exposed to different thermal environments: soil dwelling (euedaphic) species occupy relatively stable environments, whereas surface dwelling (epedaphic) species can be exposed to more fluctuating thermal environments, but a single species can also be found in diverse thermal habitats within its geographic distribution. 3. We compared the inherent cold shock tolerance and ability to rapidly cold-harden in three epedaphic, two near surface dwelling (hemiedaphic) and four euedaphic species of Collembola using a similar experimental approach for all species. Additionally we compared three populations of the epedaphic species, Orchesella cincta , sampled along a climatic gradient (Norway, Denmark, Italy). 4. Inherent cold shock tolerance was estimated as LT 50 by assaying cold shock survival following a 2 h exposure to a range of temperatures from 1 ° C to ‐12 ° C. Rapid cold-hardening (RCH) was induced by cooling individuals from 20 ° C to a temperature 7 ° C above the LT 50 during 80 min, followed by 1 h at the specific cold shock temperature, which was close to the LT 50 of the particular species. 5. There was large variation in cold shock survival among species. The capacity to rapidly coldharden was found in all three ecotypes. 6. Genetic difference in the ability to rapidly cold-harden was seen in O. cincta from different climatic regions, consistent with the predictability of the thermal environment of their habitat. Population differences matched the daily fluctuations in temperature (CV) recorded at the site of collection as well as the day-to-day predictability (autocorrelation). The role of phylogenetic inertia was tested using sequence data from the cytochrome- c oxidase I (COI) gene and no signal of phylogeny was detected that could explain these population differences. 7. Our results show that genetic differences in RCH ability exist, consistent with latitudinal gradients in thermal fluctuations and predictability; thus comparative studies can provide important insight when exploring the role of acclimation in the geographical distribution of species.

Atmospheric CO2 enrichment induces life strategy- and species-specific responses of collembolans in the rhizosphere of sugar beet and winter wheat

We studied atmospheric CO2 enrichment effects on life form types, species composition, dominance structure and individual density of collembolans under cultivation of sugar beet and winter wheat. The study was part of a long-term CO2 enrichment field experiment (FACE: Free Air CO2 Enrichment) at the Federal Agricultural Research Centre (FAL) in Braunschweig (Germany), using isotopically labelled CO2. The stable C-isotopic signature (δ13C) of collembolan species, plant material, and soil indicated CO2 impacts on C translocation. The δ13C values of both crops significantly increased from above-ground to below-ground plant parts and significantly decreased under FACE conditions. The δ13C values of collembolan species differed significantly depending on CO2 treatment and crop and showed a distinct tendency depending on plant growth stage. The extent, to which δ13C values of collembolans decreased under FACE conditions, was species- and life strategy-dependent. The stable C-isotopic signatures of euedaphic and hemiedaphic species were similar in the control, but, depending on crop, differently affected by atmospheric CO2 enrichment. Under winter wheat cultivation, hemiedaphic species showed more negative δ13C values than euedaphic ones under FACE conditions. CO2 enrichment effects on occurrence, density and dominance distribution of the collembolan species differed strongly between crops and their developmental stages, which reveal crop-specific below-ground effects due to different food qualities in the rhizosphere. CO2 impacts were stronger under sugar beet compared to winter wheat cultivation. Independent of crop, CO2 enrichment enhanced the diversity of collembolans before harvest and increased the proportion of hemiedaphic in relation to euedaphic species in a community. Our results on collembolan communities imply CO2-induced changes in the root-derived carbon resources used by the soil food web. The present study reveals atmospheric CO2 enrichment impacts to specifically affect collembolan species according to their food preferences.

Sex ratio and mode of reproduction in Collembola of an oak-beech forest

Summary Sex ratios of 31 species of Collembola of a temperate oak-beech forest were investigated in 2 months intervals during 1 year. For the estimation of population dynamics, the abundance and dominance of taxa in the litter (OL,F,H), the 0–3 and 3–6 cm soil layer (Ah) were assessed. A total of six species, including the abundant Mesaphorura machrochaeta, Parisotoma notabilis, Neanura muscorum and Isotomiella minor formed pure female populations suggesting that they reproduced by parthenogenesis. In three species, Lepidocyrtus cyaneus, Orchesella flavescens and Tomocerus longicornis, the mode of reproduction remained uncertain. The remaining 22 species including the widespread Folsomia quadrioculata, Protaphorura fimata and Lepidocyrtus lignorum formed bisexual populations, suggesting that sexual reproduction predominates in Collembola of the studied forest. Sex ratios of sexual species ranged between 33% and 90%. In five species the sex ratio was balanced (ca. 50%), in eight species males made up about one third of the population and in seven species males were rare constituting less than 25% of adults. Females generally comprised 77% of adult Collembola. Densities were highest in late summer and autumn. Except for M. machrochaeta, the density of Collembola deeper in soil (3–6 cm) was low. Consistent with earlier studies parthenogenetic species predominated deeper in the soil (euedaphic species), but some parthenogenetic species were hemiedaphic. The sex ratio of bisexual Collembola species in the litter layer generally was more female biased than that in 0–3 cm of the mineral soil. Presumably, females concentrate at sites with high density of resources whereas males are relatively more abundant at sites more favourable for spermatophore placement. Neither climatic factors (i.e. season) nor population parameters (i.e. density) correlated with the sex ratio of Collembola.

The response of decomposers (earthworms, springtails and microorganisms) to variations in species and functional group diversity of plants

The responses of three decomposer groups (earthworms, springtails and microorganisms) to manipulations in plant species diversity (1, 2, 4, 8), plant functional group diversity (1, 2, 3, 4) and functional group identity (grasses, legumes, small herbs, tall herbs) were studied in a microcosm experiment. Separate and combined treatments with earthworms and springtails were set up. Two earthworm species representing major functional groups of earthworms in grasslands were investigated, the endogeic speciesAporrectodea caliginosa(Savigny) and the anecic speciesLumbricus terrestrisL. For springtails three species were investigated, the hemiedaphic speciesHeteromurus nitidus(Leleup), Folsomia candida(Willem) and the euedaphic speciesProtaphorura fimata(Gisin). Plant species and functional group diversity beneficially affectedA. caliginosa(increase in body weight and incorporation of15N from labelled litter) andP. fimata(density), presumably by changing the quality of belowground resources. In contrast, the biomass ofL. terrestrisdecreased with plant species diversity but only in presence of legumes. ForH. nitidusandF. candidathe identity of plant functional groups was more important than plant species diversity per se. Also, the response ofF. candidadepended on earthworms. Microbial respiration was reduced by earthworms in more diverse plant communities, which correlated with root biomass. In contrast, microbial biomass was not affected by plant species diversity. The results suggest that belowground resource inputs from plant roots strongly modify decomposer performance and that the quality of the resources that enter the belowground subsystem is more important than their quantity. The responses of decomposers generally were not correlated with below‐ or aboveground plant productivity. In addition, the results document that effects of plant community composition on the performance of decomposer species depend on the presence of other decomposers.

Global warming affect Collembola community: A long-term study

Summary Long-term (1992–2002) effects of climate changes on soil Collembola in Scots pine Pinus sylvestris forests in North Vidzeme Biosphere Reserve (northern Latvia) are investigated. The study was carried out in three forest stands of different age, young (30–40 years), middle aged (50–70 years), and old (150–200 years). One hundred soil samples were collected within each sampling site once a year in autumn over a period of 11 years. In total, 66 species of Collembola were found. Species richness varied between 47 and 56 and density of Collembola from 7300 to 8300 ind m−2. A statistically significant increase in the sums of positive air temperatures (⩾4 °C) was recorded during the period of investigation. Precipitation and thereby soil moisture showed considerable year-to-year fluctuations. Non-metric Multidimensional Scaling of the data yielded two axes explaining 48.6% and 38.6% of the variation. Axis 1 coincided with the trend of sums of positive air temperature ( r = 0.66 ). Axis 1 corresponded best with the negative impact of warming of climate on Collembola, mainly on the euedaphic species inhabiting the deeper layers of the organic soil horizon. Axis 2 was considered reflecting the effect of soil moisture fluctuations (correlation with moisture r = - 0.62 ) on litter dwelling, mostly hemiedaphic Collembola. Species richness tended to decrease gradually in all forest sites during the study period from 29–36 to 13–26 species. Correlation between axes ( r = 0.455 ) indicated interaction effects between positive air temperatures and soil moisture. Forest age showed no substantial effect on the community structure, therefore the changes observed cannot be explained by ecological succession.

A Comparative Study of the Effects of Metal Contamination on Collembola in the Field and in the Laboratory

We examined the species diversity and abundance of Collembola at 32 sampling points along a gradient of metal contamination in a rough grassland site (Wolverhampton, England), formerly used for the disposal of metal-rich smelting waste. Differences in the concentrations of Cd, Cu, Pb and Zn between the least and most contaminated part of the 35 metre transect were more than one order of magnitude. A gradient of Zn concentrations from 597 to 9080 microg g(-1) dry soil was found. A comparison between field concentrations of the four metals and previous studies on their relative toxicities to Collembola, suggested that Zn is likely to be responsible for any ecotoxicological effects on springtails at this site. Euedaphic (soil dwelling) Collembola were extracted by placing soil cores into Tullgren funnels and epedaphic (surface dwelling) species were sampled using pitfall traps. There was no obvious relationship between the total abundance, or a range of commonly used diversity indices, and Zn levels in soils. However, individual species showed considerable differences in abundance. Metal "tolerant" (e.g., Ceratophysella denticulata) and metal "sensitive" (e.g., Cryptopygus thermophilus) species could be identified. Epedaphic species appeared to be influenced less by metal contamination than euedaphic species. This difference is probably due to the higher mobility and lower contact with the soil pore water of epedaphic springtails in comparison to euedaphic Collembola. In an experiment exposing the standard test springtail, Folsomia candida, to soils from all 32 sampling points, adult survival and reproduction showed small but significant negative relationships with total Zn concentrations. Nevertheless, juveniles were still produced from eggs laid by females in the most contaminated soils with 9080 microg g(-1) Zn. Folsomia candida is much more sensitive to equivalent concentrations of Zn in the standard OECD soil. Thus, care should be taken in extrapolating the results of laboratory toxicity tests on metals in OECD soil to field soils, in which, the biological availability of contaminants is likely to be lower. Our studies have shown the importance of ecotoxicological effects at the species level. Although there may be no differences in overall abundance, sensitive species that are numerous in contaminated sites, and which may play important roles in decomposition ("keystone species") can be greatly reduced in numbers by pollution.

The impact of soil compaction on euedaphic Collembola

Tillage operations and field traffic may cause soil compaction and alter the pore characteristics in soil. These practices often lead to a reduction in habitable pore space for the soil mesofauna. In the present study the abundance of some euedaphic species of Collembola was investigated under a range of soil bulk densities normally found in agricultural soils. The study was performed using containers with defaunated soil that was compressed to six levels of bulk density in the range 1.02–1.56 g cm −3. One of the following species was added to a separate series: Mesaphorura macrochaeta, Protaphorura armata, and Folsomia fimetaria. The number of individuals and the concentration of ergosterol (used to estimate fungal biomass) were measured after each experiment and related to bulk density and pore size distribution. A series of experiments in which straw was added to the soil in order to increase microbial life was also included. Only F. fimetaria was used in the straw amended series. In the soil experiments without straw amendments, the numbers of M. macrochaeta and P. armata, were significantly reduced when bulk densities increased from 1.37 to 1.47 g cm −3. F. fimetaria did not exhibit any significant response to compaction. The ergosterol concentration was independent of bulk density. When straw was added, the abundance of F. fimetaria declined significantly with increasing bulk density from 1.21 g cm −3. The decline in collembolan numbers was probably due to the decline in coarse pores (>120 μm) because the ergosterol concentration was independent of bulk density. These results show that soil structure and decline in habitable pore space are the key parameters in the abundance of euedaphic Collembola in soil.

The importance of cuticular permeability, osmolyte production and body size for the desiccation resistance of nine species of Collembola

Euedaphic collembolans have recently been shown to actively regulate internal osmotic pressure by means of sugars and polyols in response to desiccation. In contrast, studies of cuticular permeability have shown that some, especially epedaphic, species of collembolans may primarily rely on a low cuticular permeability to survive desiccation. To elucidate to what extent these strategies are important for desiccation resistance, the survival of 7-day acute desiccation stress (LRH 50), the cuticular water conductance constant and osmolyte production were investigated in nine species of collembolans, covering euedaphic, hemiedaphic and epedaphic species. The LRH 50 values ranging from 98.8% to 95.2% RH showed no correlation with the vertical distribution of species, since both the highest and lowest values were found in epedaphic species. The water conductance varied from 698±141 to 41±13 μg h −1 cm −2 mmHg −1 and showed good agreement with the vertical distribution of species in their natural habitats. Modelling the drying curves showed that, in addition to cuticular permeability and osmolyte production, body size also plays an important role in the survival of short-term severe desiccation stress. Furthermore, the model pointed to the need for behavioural responses to desiccation, particularly in epedaphic species. Thus, in keeping with expected humidity regimes in their respective microhabitats, euedaphic species rely on small body size, high cuticular permeability and the ability to actively regulate the osmotic pressure of their body fluids, hemiedaphic species have similar strategies but with reduced cuticular permeability, whereas in epedaphic species, active regulation of osmotic pressure is replaced by combinations of greatly reduced cuticular permeability or greatly reduced surface area to volume ratio combined with behavioural responses to desiccation.

Successional changes of Collembola and soil microbiota during forest rotation.

Dynamic approaches to forest ecosystems are surprisingly rare. Here we report about successional changes in collembolan community structure and microbial performances during forest rotation. The study was carried out in a chronosequence of four spruce forest stands (5-, 25-, 45-, and 95 years old; Tharandter forest, Germany). CO2 release significantly increased after clear-cutting and the amount of C stored in the organic layer subsequently declined. The early phase of forest rotation was characterized by a very active decomposer microflora, stimulation of both fungi and bacteria as well as by a high abundance of surface-oriented Collembola. In addition, collembolan species turnover was accelerated. While the biomass of fungi further increased at intermediate stages of forest rotation, the metabolic activity of the microflora was low, the functional diversity of bacteria declined and the collembolan community became impoverished. Euedaphic species dominated during this stage of forest development. These changes can be explained by both reduction in microhabitat diversity and depletion of food sources associated with an accumulation of recalcitrant soil organic matter. Results of the General Regression Model procedure indicate a shift from specific associations between collembolan functional groups and microbiota at the early stage of forest rotation to a more diffuse pattern at intermediate stages. Though the hypothesis that Collembola are relatively responsive to changes in environmental conditions is confirmed, consistently high community similarity suggests a remarkable persistence of some components of microarthropod assemblages. Our study provides evidence for substantial ecosystem-level implications of changes in the soil food web during forest rotation. Moreover, correlations between bacterial parameters and Collembola point to the overarching impact of differences in the composition of the microbial community on microarthropods.

Collembola of pulverised fuel ash sites in east London

Collembola were extracted from surface layers of four lagoons in east London (UK) of the industrial waste pulverised fuel ash (PFA). One lagoon was subject to seasonal inundation, while the other lagoons were dry, and ranged from 4 to 40 years. Twenty-one species were recorded, with both species richness and community diversity increasing steadily with site age. Early successional species were primarily epi-edaphic, while eu-edaphic species were largely confined to the woodland phase of the succession. The first axis of a canonical correspondence analysis detected the difference between early and late stage sites, while the second axis separated out the wet lagoon community from the dry sites. The data include the first record of Isotoma riparia Nicolet for the UK.

Collembola communities along a European transect

The impact of changing environmental factors on Collembola communities was studied using a N–S transect formed by four European coniferous forests: Åheden (northern Sweden), Skogaby (southern Sweden), Waldstein (Germany) and Aubure (France). The similarity between Collembola communities gradually decreased with increasing distance suggesting a significant impact of geographical factors on species composition. While the data show a northward decrease of collembolan abundance, no consistent trend in species richness, diversity, and evenness was detected. However, the dominance of Collembola life forms (eu-, hemi-, epedaphic) markedly changed along the transect, with euedaphic species dominating at the southernmost site and epedaphic species dominating at the northernmost site. In addition, the share of detritivorous species increased and that of fungivorous species decreased from south to north. It is concluded that latitudinal changes in environmental conditions have a strong impact on both abundance and functional structure of collembolan communities, but act within a framework set of geographical and historical impacts on the species composition.

Response types in Collembola towards copper in the microenvironment

Laboratory studies were carried out to cast light on differences in density responses among collembolan species to copper (Cu)-polluted environments. In a recolonisation experiment, mesofauna originating from a copper (Cupolluted arable field were allowed to colonise defaunated Cu-contaminated and uncontaminated soil cores for 3 months. The abundances of Pseudosinella alba and gamasid mites were higher in the uncontaminated soil, whereas the majority of other collembolans tended to be more abundant in the Cu-enriched soil. Behavioural experiments were conducted to test the ability of single Collembola species to distinguish between filter paper and food soaked in water, Cu, and calcium (Ca) solutions. Onychiurus armatus avoided both Cu and Ca, whereas Folsomia quadrioculata and Folsomia manolachei showed a significant preference for Cu. Isotomurus palustris was not able to distinguish between Cu and water. The results are compared and discussed with regard to other studies on the occurrence and behaviour of Collembola in Cu-contaminated environments. We suggest that microsite selection according to preference or avoidance of high salinity of pore water may partly explain the community structure of Collembola in Cu-polluted soils which are characterised by an increase of euedaphic species. More studies have to be carried out to generalise this concept and to explore to what extent reduced predation by gamasid mites contribute to the success of certain Collembola in Cu-contaminated sites.

Influence of agricultural traffic and crop management on collembola and microbial biomass in arable soil

Collembola and microbial biomass C were investigated in a field experiment with controlled agricultural traffic and crop rotation over a period of 27 months. The wheel-induced compactive efforts were applied according to management practices within the crop rotation of sugar beet, winter wheat, and winter barley. Increasing wheel traffic produced increasing soil compaction, mainly due to a reduction in surface soil porosity. Increasing soil compaction was accompanied by a decrease in microbial biomass C and the density of collembola. The influence of soil compaction on microbial biomass C was smaller than that of the standing crop. However, for collembola, especially euedaphic species, a reduction in pore space appeared to be of more importance than the effects of a standing crop. Within the crop rotation, microbial biomass C and the density of collembola increased in the order sugar beet, winter wheat, and winter barley.