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Alpine pastureland is increasingly abandoned, leading to shrub encroachment and to the accumulation of low-quality litter. Alpine key decomposers such as earthworms were found to feed on both low- and high-quality litter, but little is known how this might affect their life history traits. To fill this gap of knowledge, we conducted a laboratory experiment with the widespread earthworm species Lumbricus rubellus Hoffmeister, 1843. Hatchlings were provided with either of three aged litter types: grass and forb leaf litter as high-quality food sources and dwarf shrub leaves as low-quality food source. A control group was fed with aged cow dung. Biomass, days until (pre-)maturity, mortality, and reproduction rate were measured regularly to assess the impacts of food quality on earthworm development. We found pronounced impacts of food source quality on the fitness of L. rubellus. The low-quality litter led to significantly delayed development of up to 53 days, the lowest mean biomass (720 mg after 32 weeks) as well as a 50% drop of produced cocoons compared with the high-quality litter. However, the F2 generation showed the highest hatchling success in the shrub treatment. We conclude that the increased consumption of low-quality dwarf shrub litter led to negative effects on the development and reproduction of L. rubellus. Overall, this might be the main reason for declining earthworm densities in abandoned Alpine pasture soils, even though the biomass of the second generation was not significantly affected possibly due to a phenotypic variability in reproduction strategy. However, the decrease of such important decomposers and ecosystem engineers can have far reaching consequences for ecosystem processes such as litter accumulation and bioturbation and thus for the stability of Alpine soil ecosystems.

Earthworms have proved to contribute to plant health indirectly, by improvement of soil physical and chemical properties, as well as directly, through suppression of plant pathogens. Fusarium Head Blight, caused primarily by Fusarium graminearum, is one of the most important cereal diseases, with severe detrimental effects on yield and grain quality worldwide, and significant effect on grain safety due to the accumulation of mycotoxins produced by the fungus. Earthworms could reduce the residue-borne inoculum density of F. graminearum through different mechanisms, including direct competition by residue consumption, growth inhibition caused by the earthworm coelomic fluid, mechanical disruption of fungal hyphae, and burying crop residue which reduce the chances for the fungus to release spores for head infection. Thus, the aim of this study was to assess the effects of anecic and epigeic earthworms on wheat straw and on F. graminearum inoculum. For this, PVC cylinders (microcosms 14.5 cm diameter, 30 cm height) were filled with moist soil mix, wheat straw was evenly distributed on the soil surface (inoculated with Fusarium, soil microorganisms or sterile) and three earthworm species (Aporrectodea longa, Lumbricus rubellus or Lumbricus terrestris) were tested. Since the response of earthworms may change according to conditions of soil moisture and food availability, two different experiments were arranged. The first Experiment represented a sub-optimal situation for earthworms regarding soil moisture and feeding conditions, which was obtained by scarce watering of the microcosms with a consequent decrease in soil water content during incubation, and by not adding cow manure as supplementary food source. In the second experiment, soil was enriched with cow manure as feed for the earthworms and soil moisture was maintained above 25%. Results from qPCR analysis revealed that F. graminearum inoculum on straw was reduced to undetectable amounts by L. rubellus and A. longa when the feeding conditions were limited, while no significant differences compared with the control without earthworms were found when earthworms had high food availability (α = 0.05). Straw coverage on soil surface was reduced by L. rubellus (epigeic) in both experiments (p

Livestock farming produces slurry, which is normally recycled by land-spreading; but this raises questions about the long-term impact of slurry on soil fauna and soil processes. To examine the long-term effects of slurry on earthworms, cattle and pig excreta slurries and inorganic fertiliser were applied to a ryegrass silage sward for 33 years in a replicated experiment, and earthworms sampled for four consecutive years at three seasonal intervals (March, May and October). Animal slurries were applied at three rates (50, 100 and 200 m3 ha−1 yr−1) and inorganic fertiliser as 200 kg N, 32 kg P and 160 kg K ha−1 yr−1. Epigeic earthworms, Lumbricus rubellus, Lumbricus juveniles, and the endogeic Allolobophora chlorotica responded strongly and positively to cattle slurry inputs. In the case of L. rubellus, biomass was five times greater in the highest input cattle slurry plots than in the untreated controls. In contrast to Al. chlorotica adults, other endogeic earthworms and juvenile Allolobophora were more associated with the inorganic fertiliser treatment. Aporrectodea juveniles, in particular, had significantly greater biomass in the inorganic fertiliser treatment. However, no such response was demonstrated by adult Aporrectodea caliginosa, the commonest species found, suggesting niche separation between adults and juveniles. Pig slurry applications produced relatively little change in earthworm biomass compared to controls, despite residual copper concentrations; suggesting that organic matter input was counterbalancing the sublethal effects of copper.

Observations of earthworm colonization on sites where they were absent previously, such as on post-mining heaps, indicate that they may substantially alter soil conditions as well as soil microbial communities. However, long-term effects of earthworms on microbial activity of soil ecosystems remains poorly understood. To improve this situation, we set up microcosm experiments with clay only, with clay and litter, and with clay, litter and earthworms. Microcosms were sampled after 3, 60, 180 and 395 days of cultivation and divided into three subsamples: clay, litter, and drilosphere (earthworm tunnels and associates casts), when present. Microbial respiration, microbial biomass carbon, species composition, metabolic activity using BIOLOG, PLFA concentration, isoprenoid quinones content and DGGE fingerprints were analysed in all microcosms and at all subsamples. Microbial biomass carbon and basal soil respiration were significantly affected by type of microcosms and time of sampling. Microbial biomass in drilosphere was significantly higher than in clay and litter. The CFU (colony forming units) were significantly affected by presence of earthworms having significantly higher CFU in drilosphere than in all other subsamples. Analysis of PLFA indicated highest relative biomass of fungi and bacteria in clay from microcosms with earthworms. The DGGE analysis showed various compositions of microbial communities among subsamples from various treatments taken at different time. Finally, our results revealed significant effect of earthworms on activity and biomass of soil microbial community under long-term laboratory incubation.

We present an evaluation of earthworm fauna in Sao Miguel Island (Azores, Portugal) revealing that it is rich in species in relation to its size and nature. Four families (Acanthodrilidae, Lumbricidae, Megascolecidae and Rhinodrilidae), 15 genera and 27 species were inventoried. About 74% were Palearctic species and 26% were Intertropical, mainly invasive earthworms originating from South-East Asia, of which Amynthas corticis Kingberg, 1867 was most dominant. The first comprehensive checklist of Sao Miguel earthworms is detailed, and the outdated nomenclature is improved, unifying synonymous taxa such as Lumbricus azoricus Eisen, 1869 and Allolobophoridella eiseni Levinsen, 1884. Seven new earthworm species records are given, highlighting Lumbricus friendi Cognetti, 1904 and Amynthas diffringens Baird, 1869 as cited for the first time in Macaronesia, and therefore expanding their known geographic range to the northern border of this region. Moreover, richness and composition of species were evaluated in relation to environmental and anthropogenic characteristics, including soil properties, altitude, land use intensity or distance to urban nuclei. Our results demonstrated that soil pH affected the establishment of species and that organic matter is positively associated with abundance of some non-native lumbricids (e.g. the anecic Octodrilus complanatus Duges, 1828) and negatively related to richness and abundance of exotic species such as Amynthas corticis, Amynthas gracilis Kingberg, 1867 and Pontoscolex corethrurus Muller, 1857. Results suggested that land use intensity, represented as five categories ranging from undisturbed sites with native vegetation to sites under intensive agriculture exploitation, is a good predictor of species composition. Higher values of diversity and density of Intertropical species were found in more intensively exploited locations. Moreover, the Palearctic lumbricids, although present in all the disturbance categories tested, were the most diverse group at higher altitudes. The species Dendrodrilus rubidus tenuis Eisen, 1864 and Lumbricus rubellus Hoffmeister, 1843, with narrow distribution range, showed a trend towards natural, non-intensive (NI) and low intensity (LI) systems. Our results indicate that anthropogenic disturbance and altitude are the main drivers of earthworm diversity on the island of Sao Miguel, making these animals good indicators for land use intensity. Therefore, earthworm surveys may help design conservation programs in protected areas.

Invasive earthworms alter the structure of soils in northern hardwood forests, but the quantitative impacts on litter-dwelling invertebrates are unclear. Litter loss should reduce the habitat space, but nutrient-rich earthworm burrows might provide food resources. We investigated the impact of invasive earthworms on populations of Ixodes scapularis (black-legged ticks) and other litter-dwelling arthropods to determine the impact of a reduced litter environment. We used five pairs of one-hectare sites (earthworm invaded versus reference) within four separate contiguous forests in New York state. The presence of earthworms decreased the density of nymphal I. scapularis by 46.1% and larval I. scapularis by 29.3%. We also observed a dramatic decline in the total abundance of litter-dwelling arthropods with 69.9% of the arthropod population disappearing in the presence of earthworms. Additionally, litter arthropod populations declined disproportionately to leaf litter mass reduction indicating that the quality of the remaining litter material in the earthworm sites was poor. The impact of earthworm invasion on the litter environment and implications for the position of an important disease vector ( I. scapularis ) within the litter ecosystem are explored.

The aim of the study was to investigate the impact of the cultivation of newly introduced perennial bioenergy crops on earthworm species composition, number and biomass at an experimental site in Western Germany. The included crops were Szarvazi ( Agropyron elongatum ), Switchgras ( Panicum virgatum ), Sida ( Sida hermaphrodita ), Silphie ( Silphium perfolatum ), Igniscum ( Fallopia sachalinensis ), and a wild flower mix (WFM) relative to silage ( Zea maize ). In sum, earthworm population at that site consisted of 8 species, Lumbricus rubellus and Allolobophora cupulifera being dominant species. Species number varied in a range of WPM (8) > Szarvazi (7) > Sida (6) > Silphie, Igniscum (5) > Switchgras, Maize (4). Earthworm number and biomass significantly increased in all newly introduced energy crops. On comparison within the perennial crops, it was found that earthworm number was significantly highest in Sida and lowest in Switchgras plots. The differences within the remaining crops were small and not significant. From an agro-ecological point of view and deduction from earthworm population data, it might be concluded that Szarvasi, Sida and wild flower mix can be seen as important energy crops in future bioenergy production in Western Germany.

a b s t r a c t This study investigated the possibility of a facilitative relationship between Chinese privet (Ligustrum sinense) and exotic earthworms, in the southeastern region of the USA. Earthworms and selected soil properties were sampled five years after experimental removal of privet from flood plain forests of the Georgia Piedmont region. The earthworm communities and soil properties were compared between sites with privet, privet removal sites, and reference sites where privet had never established. Results showed that introduced European earthworms (Aporrectodea caliginosa, Lumbricus rubellus, and Octolasion tyr- taeum) were more prevalent under privet cover, and privet removal reduced their relative abundance (from >90% to ∼70%) in the community. Conversely, the relative abundance of native species (Diplocardia michaelsenii) increased fourfold with privet removal and was highest in reference sites. Soils under privet were characterized by significantly higher pH relative to reference plots and privet removal facilitated a significant reduction in pH. These results suggest that privet-mediated effects on soil pH may confer a competitive advantage to European lumbricid earthworms. Furthermore, removal of the invasive shrub appears to reverse the changes in soil pH, and may allow for recovery of native earthworm fauna. Published by Elsevier B.V.

Earthworms play an important role in many soil functions and are affected by soil tillage in agricultural soils. However, effects of tillage on earthworms are often studied without considering species and their interactions with soil properties. Furthermore, many field studies are based on one-time samplings that do not allow for characterisation of temporal variation. The current study monitored the short (up to 53 days) and medium term (up to 4 years) effects of soil tillage on earthworms in conventional and organic farming. Earthworm abundances decreased one and three weeks after mouldboard ploughing in both conventional and organic farming, suggesting direct and indirect mechanisms. However, the medium-term study revealed that earthworm populations in mouldboard ploughing systems recovered by spring. The endogeic species Aporrectodea caliginosa strongly dominated the earthworm community (76%), whereas anecic species remained −2 ) than mouldboard ploughing (MP; 130 m −2 ). However, reduced tillage in conventional farming significantly increased the epigeic species Lumbricus rubellus from 0.1 m −2 in mouldboard ploughing to 9 m −2 averaged over 4 years. Contrastingly, in organic farming mean total earthworm abundance was 45% lower in reduced tillage (297 m −2 ) than MP (430 m −2 ), across all sampling dates over the medium-term study (significant at 3 of 6 sampling dates). Reduced tillage in organic farming decreased A. caliginosa from 304 m −2 in mouldboard ploughing to 169 m −2 averaged over 4 years (significant at all sampling dates). Multivariate analysis revealed clear separation between farming and tillage systems. Earthworm species abundances, soil moisture, and soil organic matter were positively correlated, whereas earthworm abundances and penetration resistance where negatively correlated. Variability demonstrated between sampling dates highlights the importance of multiple samplings in time to ascertain management effects on earthworms. Findings indicate that a reduction in tillage intensity in conventional farming affects earthworms differently than in organic farming. Differing earthworm species or ecological group response to interactions between soil tillage, crop, and organic matter management in conventional and organic farming has implications for management to maximise soil ecosystem functions.

Earthworms and arbuscular mycorrhizal fungi (AMF) are known to independently affect soil microbial and biochemical properties, in particular soil microbial biomass (SMB) and enzymes. However, less information is available about their interactive effects, particularly in soils contaminated with heavy metals such as cadmium (Cd). The amount of soil microbial biomass C (MBC), the rate of soil respiration (SRR) and the activities of urease and alkaline phosphatase (ALP) were measured in a calcareous soil artificially spiked with Cd (10 and 20 mg Cd kg −1 ), inoculated with earthworm ( Lumbricus rubellus L.), and AMF ( Glomus intraradices and Glomus mosseae species) under maize ( Zea mays L.) crop for 60 days. Results showed that the quantity of MBC, SRR and enzyme activities decreased with increasing Cd levels as a result of the elevated exchangeable Cd concentration. Earthworm addition increased soil exchangeable Cd levels, while AMF and their interaction with earthworms had no influence on this fraction of Cd. Earthworm activity resulted in no change in soil MBC, while inoculation with both AMF species significantly enhanced soil MBC contents. However, the presence of earthworms lowered soil MBC when inoculated with G. mosseae fungi, showing an interaction between the two organisms. Soil enzyme activities and SRR values tended to increase considerably with the inoculation of both earthworms and AMF. Nevertheless, earthworm activity did not affect ALP activity when inoculated with G. mosseae fungi, while the presence of earthworm enhanced urease activity only with G. intraradices species. The increases in enzyme activities and SRR were better ascribed to changes in soil organic carbon (OC), MBC and dissolved organic carbon (DOC) contents. In summary, results demonstrated that the influence of earthworms alone on Cd availability is more important than that of AMF in Cd-polluted soils; and that the interaction effects between these organisms on soil microorganism are much more important than on Cd availability. Thus, the presence of both earthworms and AMF could alleviate Cd effects on soil microbial life.

Earthworms can have a profound effect on a myriad of soil physical, chemical and microbial parameters. To better understand their role in the soil, they are often studied under controlled conditions. However, a persistent problem in such controlled experiments is the ability of earthworms to escape from experimental units with open tops (e.g. for plant growth). Here, we tested whether adhesive hook tape applied to the inside of mesocosms is effective in confining them to their experimental units. A mesocosm study was set up with hook tape treatments (control, one layer, two layers), mesocosm material (polyvinylchloride – PVC, polypropylene – PP) and earthworm species (Lumbricus rubellus (Hoffmeister), Aporrectodea caliginosa (Savigny), Lumbricus terrestris (L.) + Aporrectodea longa (Ude)) as different factors to study the escape of earthworms during 24 h. In the treatments without hook tape, individuals of L. rubellus and A. caliginosa escaped, with highest escape rates (80%) for L. rubellus from the PP mesocosms, and lowest escape rates (20%) for A. caliginosa from the PVC mesocosms. When hook tape was applied, in either one or two layers, no individuals of those species escaped. The two anecic earthworm species, L. terrestris and A. longa did not escape from any mesocosms, irrespective of the presence of hook tape. As not a single earthworm escaped from the hook tape treatments, we conclude that applying hook tape is a simple, inexpensive and effective method to keep earthworms confined to experimental units.

The ranges of exotic earthworms have been expanding into previously earthworm-free areas in temperate forests of North America. These earthworms can have profound effects on soil properties and biogeochemical processes, but the rate and patterns of earthworm range expansion has received limited study. We assessed long-term (2001–2011) changes in earthworm distributions along two belt transects (60–75 m long) in a northern hardwood forest in central New York. We expected long-term increases in earthworm abundance at the presumed earthworm invasion front. We also quantified earthworm populations in seven monospecific plantations of different tree species. We expected higher earthworm abundance in hardwood than conifer forests. We observed large annual fluctuations in earthworm abundance along both transects but no evidence of increasing abundance or range expansion at the earthworm fronts. At the plantation site we observed significant variation in earthworm abundance both within and among plantations, but the patterns were not consistently related to tree species composition; rather, earthworm abundance was highest in areas of higher soil pH and topographically wetter soils. Further study of environmental and biotic factors controlling the range expansion of exotic earthworms is needed at both local and regional scale.

Previous field observations indicated that earthworms promote late-successional plant species and reduce collembolan numbers at post-mining sites in the Sokolov coal mining district (Czech Republic). Here, we established a laboratory pot experiment to test the effect of earthworms ( Aporrectodea caliginosa Savigny and Lumbricus rubellus Hoffm.) and litter of low, medium, and high quality (the grass Calamagrostis epigejos , the willow Salix caprea , and the alder Alnus glutinosa , respectively) on late successional plants (grasses Arrhenatherum elatius and Agrostis capillaris , legumes Lotus corniculatus and Trifolium medium , and non-leguminous dicots Centaurea jacea and Plantago lanceolata ) in spoil substrate originating from Sokolov post-mining sites and naturally inhabited by abundant numbers of Collembola. The earthworms increased plant biomass, especially that of the large-seeded A. elatius , but reduced the number of plant individuals, mainly that of the small-seeded A. capillaris and both legumes. Litter quality affected plant biomass, which was highest with S. caprea litter, but did not change the number of plant individuals. Litter quality did not modify the effect of earthworms on plants; the effect of litter quality and earthworms was only additive. Species composition of Collembola community was altered by litter quality, but earthworms reduced the number of individuals, increased the number of species, and increased species evenness consistently across the litter qualities. Because the results of this experiment were consistent with the field observations, we conclude that earthworms help drive succession of both plant and Collembola communities on post-mining sites.

Dwarf shrub litter is thought to be of poor quality and palatability for macro-decomposers. In laboratory feeding experiments, however, it was found that this litter type represents a potential food source for earthworms and millipedes. Here we tested whether this is true under natural conditions by conducting a 1 year field experiment on an abandoned alpine pasture in Tyrol (Austria). As the natural isotopic signatures of plant litter do not allow discriminating between different plant species, dwarf shrub litter, artificially enriched in 15 N, was offered in experimental plots to the macro-decomposer community. Both the earthworm Lumbricus rubellus and the millipede Cylindrojulus fulviceps fed on dwarf shrub litter as indicated by their increased δ 15 N signatures, but IsoError analysis indicated a clear preference for grass litter for all macro-decomposer species investigated. Soil δ 15 N signatures were only marginally affected by the experimental provision of 15 N-enriched dwarf shrub litter, whereas litter from other, unlabelled, plants became enriched by the isotopic tracer to some extent. Except for one grass species, plants harvested at the end of the experiment were not enriched in 15 N, suggesting that the N-uptake from decomposing litter material by plants on abandoned alpine pastureland is slow.

In freshly deposited dredged sediment contaminated with PAHs, we followed the colonization of earthworm species by monthly monitoring over two years. Already five months after deposition the first species, Lumbricus castaneus, appeared, although only temporarily. The first permanent colonizing species was L. rubellus, soon followed by Aporrectodea caliginosa and L. castaneus, and a few months later Eiseniella tetraeda. At the end of the two-year observation period some first few specimen of Allolobophora rosea were present. These earthworm species colonized the deposited sediment apparently in succession. The colonization of each individual species did not show a gradual influx from the bordering dikes at both sides of the deposit, but a fast colonization over the whole width, presumably by surface dispersal, although at low and variable numbers, followed by a gradual increase of population numbers. Modeling the dispersal showed that diffusion was the primary driving factor. Also juvenile earthworms were observed locally in high numbers, so reproduction did occur. Total earthworm numbers in the deposit reached a maximum of 80% of the numbers in the bordering dikes consisting of loamy and clayey soils. Numbers were highest in periods with warm and rainy weather. The appearance of earthworms improved the soil development, stimulated a faster desiccation and aeration of the sediment and may have contributed to the increased degradation of PAHs, especially three- and four-ring PAHs. © 2009 Elsevier B.V. All rights reserved.

Earthworms are known to influence water infiltration in soils, but most of the existing knowledge relates to grasslands and arable systems; little is known on the role of earthworms for water infiltration in forests. We studied earthworm populations and water infiltration rates in woodland flooding sites used for groundwater recharge and the production of drinking water. Intensive flooding may detrimentally affect earthworm populations and simultaneously result in clogging of the topsoil, with the latter being a common problem in groundwater recharge systems. However, clogging does not occur at our study site, the “Lange Erlen” (Basel, Switzerland) and total earthworm numbers and biomass in flooded sites exceeded those of non-flooded sites (+51% and +71%, respectively). Total earthworm numbers ( r = 0.85***), numbers of endogeic ( r = 0.64*) and epigeic ( r = 0.81**) earthworms and numbers of two species ( Lumbricus rubellus, r = 0.62* and Allolobophora chlorotica, r = 0.77**) significantly correlated with water infiltration rates. The results suggest that short-term flooding (max. 10 days) interrupted by longer recovery periods favor earthworm populations which likely contribute to the long-term (ca. 100 years) sustainability of the studied forest groundwater recharge system and thereby to effective and cost efficient drinking water production.

A clear understanding of the size and structure of earthworm communities is important to sports turf facilities managers if they are to control the activity of earthworms within the soil. Earthworms are directly linked to a wide range of biogeochemical nutrient cycles, and are frequently described as ecosystem engineers. In this role they assist land managers in maintaining a healthy turf sward. Despite this, earthworm populations in sports turf were frequently suppressed using organochloride based vermicides prior to such compounds being banned in the UK. A survey of earthworm species diversity was carried out over 1 year, using mustard extraction at five golf courses in Bedfordshire and Buckinghamshire, UK, to investigate how species diversity varied temporally and was influenced by the physical environment within different course surfaces. Rank–abundance analysis indicated that four species of earthworm (Aporrectodea rosea, Lumbricus rubellus, Aporrectodea longa and Lumbricus terrestris) were more dominant in the community than any other. The endemic earthworm population number of the five study sites was found to differ significantly (p

Epigeic earthworms are detritivorous organisms that live and feed in the soil litter layer. These earthworms exert important effects on the presence of decomposer micro-organisms and their microbial grazers, which lead to changes in the rate of decomposition of the organic matter. To assess the effect of the transit through the gut of epigeic earthworms on the decomposer organisms, we analysed the gut contents of four epigeic species reared under laboratory conditions, with pig slurry as food source. The numbers of nematodes, protozoa (flagellates, testate and naked amoebae) and total coliforms in the hindgut of the earthworm species, Eisenia fetida , Eisenia andrei , Lumbricus rubellus and Eudrilus eugeniae , were compared with the numbers of the same organisms in the pig slurry. No nematodes were found after transit through the gut of the earthworms and there was a decrease between 85% and 98% in the numbers of total coliforms of the pig slurry (723 ± 125 × 10 3 CFU g −1 dw). The effect on the numbers of protozoa depended on both groups of protozoa and species of earthworm considered. The numbers of flagellates were greater in the gut samples of E. fetida and E. andrei (363 ± 46 × 10 3 MPN g −1 dw) than in the ones of L. rubellus and E. eugeniae (105 ± 26 × 10 3 MPN g −1 dw). The density of testate amoebae was not affected by the transit through the gut of earthworms, and the numbers of naked amoebae were greater in the gut samples of L. rubellus (2500 ± 780 × 10 3 MPN g −1 dw) than in the fresh pig slurry (755 ± 311 × 10 3 MPN g −1 dw). The results indicate that short-time effects associated with the digestive activity in the earthworm gut play an important role in the changes that epigeic species exert on the decomposer community.

Earthworm (Lumbricidae) populations were assessed in three replicated, field experiments with different management intensities conducted on grassland research farms on medium-textured mineral soils, located at Solohead (Co. Tipperary), Grange (Co. Meath) and Johnstown Castle (Co. Wexford), Ireland. The experiment at Solohead involved four levels of mineral fertilizer application (80, 175, 225 and 350 kg N ha−1), and the plots were rotationally grazed by dairy cows. Three levels of mineral fertilizer application were compared at Johnstown Castle (0, 225 and 390 kg N ha−1) and two at Grange (100 and 225 kg N ha−1), and the plots at these sites were rotationally grazed by suckler cows and followers or dry cattle. Between 10 and 15 earthworm species were recorded per site, with Allolobophora chlorotica and Aporrectodea caliginosa being dominant. Other abundant species included Aporrectodea rosea, Aporrectodea longa, Lumbricus terrestris, Lumbricus friendi, Lumbricus festivus, Lumbricus rubellus and Satchellius mammalis. Mean earthworm population densities per treatment ranged from 203 to 324 individuals m−2 and biomass from 60 to 176 g m−2. ANCOVA revealed significant overall positive relationships between management intensity (as indicated by N application rate) and earthworm abundance (F = 4.47, p

Anecic earthworm species function as ecosystem engineers by structuring the soil environment, incorporating large amounts of litter and seeds into soil and, thereby influence the composition of plant communities. The aim of the present greenhouse experiment was to investigate the effects of three apparently anecic earthworm species on wheat seed burial, seedling establishment, wheat growth and litter incorporation. The three species differed substantially in their behavior and effect on plant establishment. Aporrectodea longa did not incorporate litter into the soil while Lumbricus terrestris (−69%) and Lumbricus rubellus friendoides (−75%) reduced the litter layer considerably during 9 weeks of incubation. Moreover, L. terrestris and L. rubellus friendoides buried more wheat seeds than A. longa. Fewer seeds germinated when buried by A. longa compared to L. terrestris. The behavior of L. terrestris and L. rubellus friendoides was characteristic for anecic earthworm species whereas that of A. longa rather resembled that of endogeic species. The present study is the first experimental evidence for anecic behavior in L. rubellus friendoides.

To analyse decomposition dynamics on abandoned alpine pastureland where organic material accumulates on the soil surface a mesocosm experiment was conducted. Twelve treatments were set up in a two-factorial design analysing food preferences (grass or dwarf shrub litter) of primary (Lumbricus rubellus, Dendrobaena octaedra, Cylindroiulus fulviceps) and secondary macro-decomposers (Octolasion lacteum, Enantiulus nanus), and their effect on decomposition processes, soil and microbial parameters (pH, soil organic matter content, C/N ratio, soil aggregate stability, basal respiration, microbial biomass). The primary decomposers L. rubellus and C. fulviceps strongly increased decomposition, while secondary decomposers and the presence of both a primary and a secondary decomposer had no or even negative effects on litter breakdown. Surprisingly, L. rubellus and C. fulviceps preferentially fed on dwarf shrub litter which we assumed to be of low food quality. It is concluded that factors other than the quality of the litter material are responsible for the reduced litter decomposition on abandoned alpine pastureland. Most soil parameters (pH, soil organic matter content, C/N ratio, basal respiration) were only slightly affected by the presence of decomposer species. Effects of interactions between earthworms significantly increased soil aggregate stability by 10–15% and microbial biomass by up to 121%. On the other hand the presence of millipedes significantly decreased soil aggregate stability and microbial biomass. Although most soil chemical and microbial parameters were only slightly affected by the presence of soil animals, presumably due to the short incubation time, statistical analyses showed the presence of macro-decomposers to be an important factor for litter decomposition.

Arbuscular mycorrhizal (AM) mycelia are dependent on contact with plant roots for spore formation. In this study, earthworms and collembolans were regarded as potential dispersal vectors of AM fungal spores and hyphae, and we determined how they influenced the extension of AM fungi from host plant roots. Plantago lanceolata seedlings were grown in a mesh bag with an AM inoculurn of dried soil and root pieces from a set-aside agricultural field. The bag was placed in a growth box that was filled with a mixture of irradiated soil and sand, into which fungal hyphae could grow while roots were retained by the mesh. Three treatments with 15 replicates each were established with an addition of either Lumbricus rubellus, Folsomia candida or no soil fauna into the root-free soil. Five replicates of each treatment were harvested after 6, 10 and 15 weeks. The extension of the AM fungi was determined by measuring PLFA 16:1w5 and NLFA 16:1w5 as signature compounds of AM fungal biomass, spore production and mycorrhizal inoculum potential on P lanceolata seedlings. After 10 weeks, all indicators of AM fungal growth showed that the fungi had extended into the whole growth box. Plant shoot biomass of the host plants was greater in the presence of earthworms than other treatments, and the contents of PLFA 16:1w5 were greater in the earthworm than in the collembolan treatment. The reduced amount of PLFA 18:2w6,9 in the collembolan treatment relative to other treatments suggests that saprophytic fungi provided a food source for the collembolans. Spore production and mycorrhizal inoculurn potential were not affected by the presence of soil fauna. We conclude that the biomass of AM fungi was stimulated by earthworms, but that fungal dispersal over 20 cm was not influenced. (C) 2004 Elsevier B.V. All rights reserved. (Less)

Although it is known that deep-burrowing earthworms can increase the depth of penetration of solutes in soil, their comparative effect on solute transport when they are added to communities composed solely of epigeic and endogeic species is not clear. Ionic tracers were applied as artificial rainfall to the surface of plots with or without added deep-burrowing earthworms (n=3). We determined the soil water content, total nitrogen, soil organic carbon (SOC), strontium, and bromide concentrations in soil samples taken from a 320 mm ×380 mm, 56-position grid with 40 mm sample spacing. Earthworm inoculations increased populations of deep-burrowing Lumbricus terrestris L., and decreased those of the surface-dwelling L. rubellus Hoffmeister, and had no impact on geophagous species; compared to the earthworm communities in control plots. The average soil concentrations of SOC, bromide and strontium were higher where earthworms were inoculated compared to controls. Solute concentrations, SOC, and soil water content all decreased with depth. Synthetic data derived from multivariate analyses were used as an index of solute transport intensity. Solute transport intensity was greater at any given depth in response to earthworm inoculations, compared to that in controls. Although we observed a characteristic breakthrough of solutes to greater depths where deep-burrowing earthworms were inoculated, there were no differences in the spatial distribution of solutes between the two earthworm communities studied. We concluded that although the activity of deep-burrowing species allowed solute breakthrough to greater depth, the more diffuse distribution of solutes was the result of the dominant random burrowing activity of epigeic and endogeic earthworm species, which comprised the larger proportion of earthworms in these communities.

In a field trial (1985–1996) on a sandy loam soil the effects of tractor traffic and fertilisation on earthworm populations were investigated. The tractor traffic treatments compared normal farm practice (`normal') with reduced tractor traffic (`low'). In the fertilisation treatments, three different cattle-manure management methods were compared. The cattle manure was applied as diluted slurry, as aerated slurry, or as separated manure with the composted faeces being applied to tilled land, while the urine was applied to ley. The different cattle manure management methods were compared at two different application levels. In addition, there were an unfertilised control and a higher application level with diluted slurry and mineral fertiliser treatments. The endogeic species, Aporrectodea caliginosa and A. rosea constituted 67% and 7% of the population density, respectively, and 78% and 3% of the mass in the period 1993–1996. The epigeic species, Lumbricus rubellus, constituted 25% of the population density and 19% of the mass. The population density, but not the species composition, was strongly affected by tractor traffic. In the years 1987–1989, there was an average of 160 earthworms/m2 after normal, and 680 earthworms/m2 after low, tractor traffic. During the experimental period, the earthworm population decreased in treatments with low tractor traffic. Important reasons for the reduction in earthworm population are likely to be soil acidification and reduced manure application. In 1995, the differences in population density and mass between treatments with normal, and low, tractor traffic were no longer statistically significant (140 and 250 earthworms/m2, respectively). In 1996, when there was no tractor traffic or fertilisation carried out, the corresponding population densities were 200 and 280 earthworms/m2. The population density and mass of earthworms were highest in manured soil. Increasing the amount of slurry applied was associated with a higher earthworm population in some years and a lower population in others. Increasing slurry application was most favourable for endogeic species and most destructive for epigeic species. Neither the average total population density nor mass of earthworms was affected by whether the manure was treated as slurry, or separated. However, more earthworms were found after addition of solid manure than of urine. Aerated slurry did not result in a higher earthworm population than diluted slurry.

The metal (Cd, Cu, Pb, Zn and Ca) concentrations in the tissues, ingesta (crop contents) and egesta (faeces) were investigated in two physiologically contrasting earthworm species (Lumbricus rubellus and Aporrectodea caliginosa) inhabiting soils exhibiting various levels of heavy metal contamination. In addition, a complementary soil layering experiment, conducted under laboratory conditions, was undertaken to investigate whether the distribution of Pb within a soil vertical profile influenced the relative metal accumulation patterns of these species. Generally, the Cd, Cu and Pb concentrations of field populations of A. caliginosa were significantly greater than in L. rubellus, a pattern reversed for Ca. Concentrations of Zn were significantly greater in A. caliginosa in soils containing the lowest Zn concentrations, but no species differences were apparent at high soil concentrations of this metal. Comparisons of metal concentrations between ingesta and soils indicate that both species selectively ingest material from the soil matrix, although no significant correlations were found between tissue metal and ingesta metal concentrations. Differences in concentrations of Cd, Pb and Zn between the ingesta of the species were, however, concomitant with observed differences in tissue concentrations of the respective metals, which cannot be explained by excretion via the egesta. The soil stratification experiment indicated that Pb distribution within a soil profile affected the pattern of species differences in tissue metal concentrations observed in field populations. The evidence therefore suggests that the difference in dietary intakes of these metals is an important factor in contributing to observed differences between these species, although other factors are also contributory. The observations are discussed in the context of soil hazard assessment monitoring, and in particular, the role of concentration factors in such applied surveys.

Adult earthworms (Lumbricus rubellus), sampled from a metal-contaminated site (Cwmystwyth Cottage) and two reference sites (acidic, Caerffili; calcareous, Dinas Powys), were maintained on metalliferous Cwmystwyth Cottage soil in the laboratory for up to 90 days. All three populations accumulated Cd, Pb and Zn for at least the first 60 days of laboratory exposure, while Cu and Ca concentrations were maintained fairly constant throughout. The experiment did not prove conclusively that the native worms maintained on their own contaminated soil had the capacity to accumulate higher burdens of non-essential toxic metals (Cd and Pb) than the introduced reference worms. Finally, the reference population naturally inhabiting the Ca-poor acidic soil (Caerffili) accumulated or maintained tissue Ca concentrations more efficiently than the second reference population (Dinas Powys) and `native' population (Cwmystwyth Cottage), both naturally inhabiting relatively Ca-rich soils.

The accumulated metal (Ca, Cd, Cu, Pb, Zn) concentrations in seven different populations of the earthworm, Lumbricus rubellus, maintained in the laboratory for 90 days on their `own' native polluted soils were compared with those accumulated by two reference populations (sampled from uncontaminated calcareous and acidic sites, respectively), maintained for the same period on the same series of seven polluted soils. Worms native to the more heavily polluted soils accumulated higher Cd and Zn concentrations than their reference counterparts, the striking exception being worms maintained on the exceptionally acidic, Ca-poor, Cwmystwyth Stream soil; tissue Cu concentrations were consistently low and similar in `native' and reference worms; tissue Pb concentrations were significantly higher in only one population of native worms, a site (Wemyss) that did not contain the highest soil Pb concentration; Ca concentrations were generally similar in native and reference worms, but reference worms normally inhabiting an acidic soil, Caerffili (CF) tended to accumulate Ca more efficiently than reference worms derived from a more calcareous soil, Dinas Powys (DP). These observations indicated that differentiation between natural populations as expressed by metal accumulation patterns is probably a commoner earthworm response to Cd- or Zn-exposures than it is to Pb- or perhaps Cu-exposures. Measuring and comparing accumulated metal concentrations is a crude method of early-stage screening for metal-tolerant ecotypes; having identified candidate tolerant populations more definitive genetic tests must be undertaken.

The burrowing characteristics of three common introduced European lumbricid earthworm species were studied in New Zealand agricultural soils. Large (30 cm internal diameter×50 cm high) cylinders were filled with topsoil (0–25 cm) and subsoil (25–50 cm), sieved to remove earthworms and other soil macrofauna. Cylinders were inoculated with either mature Aporrectodea caliginosa, Octolasion cyaneum (both endogeic species) or Lumbricus rubellus (an epigeic species) at the rates of 300 and 600 m−2. Additional control (nil earthworms) and mixed species treatments were also included in the experiment. Cylinders were buried in the field for six months before sampling. After six months, most of the introduced O. Cyaneum and L. rubellus earthworms had died, but significant populations of A. caliginosa were present in all treatments. However, it appears that the different species of inoculated earthworms had created contrasting burrowing patterns. L. rubellus was most active in the top 10 cm of the topsoil, although it did create burrows to at least 21 cm depth. L. rubellus did not create any burrows in the subsoil. Both A. caliginosa and O. cyaneum burrowed relatively evenly throughout the topsoil. Both species also created burrows at all depths sampled in the subsoil. Under saturated conditions, most water flow occurred through earthworm burrows. In the topsoil, burrows of A. caliginosa were more continuous and better connected to the soil surface than burrows of O. cyaneum. In contrast, O. cyaneum created the most continuous burrows through the subsoil.

Laboratory experiments were conducted with Lumbricus terrestris , Lumbricus rubellus and Dendrobaena octaedra to study the effects of different food sources on physical and chemical cast properties. Earthworm species were kept separately in special microcosms filled with a loamy soil and offered leaves of dandelion ( Taraxacum officinale ), lupin ( Lupinus polyphyllus ), rye ( Secale cereale ), alder ( Alnus glutinosa ), beech ( Fagus sylvatica ) and larch ( Larix decidua ), diets which differed in palatability, C/N-ratios and secondary plant compounds. Cast production was monitored in relation to earthworm species and food. Enzyme activities (acid and alkaline phosphomonesterase), texture, water stable aggregation and tensile strength of casts were compared with those of the soil. Water stable aggregation was influenced by the food source and the earthworm species. The tensile strength of the casts was also species specific. Although D. octaedra produced the highest and L. terrestris the lowest amount of water stable aggregates, the tensile strength of the casts was lowest for D. octaedra and highest for L. terrestris .

Adult earthworms, Lumbricus rubellus, sampled from an acidic site (Caerffili, CF) and a relatively calcareous site (Dinas Powys, DP) were maintained in the laboratory for either 18 days (Expt. 1) or 28 days (Expt. 2) on their `own' soils, on their counterparts' soil, and on Ca/Sr-rich (Yate) soils from a region rich in Triassic celestite (SrSO4) deposits. CF and DP earthworms had similar tissue Ca concentrations on their `own' soils. CF earthworms accumulated Sr, a calcium analogue, to a greater extent than DP earthworms when transferred to Yate soils; CF earthworms also increased their tissue Ca when transferred to Yate or DP soils. DP earthworms lost tissue Ca when transferred to CF soils. These observations suggest that intra-species, inter-population differentiation in nutrient acquisition efficiency exists in earthworms, and enables them to adapt to specific habitat conditions.

The European earthworm, Aporrectodea trapezoides (Lumbricidae), is one of the most common species of earthworms in pasture soils in southern Australia. A survey of 163 pastures in southwestern Victoria yielded A. trapezoides at 81% of sites (mean density=33.1 m−2). A. trapezoides was more abundant in light clay soils than in sandy and clay loams (i.e. more abundant where clay content was higher). Other common species were A. caliginosa, A. rosea and Lumbricus rubellus (Lumbricidae) and Spenceriella sp. and Gemascolex octothecatus (Megascolecidae). A field trial in the southeast of South Australia, in which varying amounts of clay had been added to a non-wetting sandy soil beneath a pasture, further demonstrated that the abundance (and biomass) of A. trapezoides is influenced by the clay content of the soil. No changes in the abundance of A. trapezoides were recorded in response to fertiliser (superphosphate) application or rotary hoeing.

Earthworms are widely exploited as test organisms to assess terrestrial pollution. However, it has been shown that some earthworm populations can tolerate heavy metal concentrations well above the critical concentration known to induce lethal effects in more typical populations. By fingerprinting amplified messenger RNA (mRNA) species by the technique of directed differential display, it has been possible to pinpoint genes up-regulated in a population of earthworms adapted to exceptionally high levels of heavy metals. The full characterisation of these genes will further our understanding of the mechanism(s) involved in heavy metal tolerance in earthworms and thus make it possible to validate current toxicity tests.

The effects of metal contaminants on the population density and species composition of earthworms were studied at 22 sites around a primary smelting works situated at Avonmouth, southwest England. All worms were absent from six sites within 1 km of the factory and numbers were also reduced significantly at an additional four sites 2 km from the plant. Total earthworm density was found to be inversely related to concentrations of metals in soils. some species of earthworms were found to be more ‘sensitive’ to metals and were absent from sites where more ‘tolerant’ species persisted. For example, Lumbricus rubellus, Lumbricus castaneus and Lumbricus terrestris were all present at sites close to the smelter where Aporrectodea rosea, Aporrectodea caliginosa and Allolobophora chlorotica were absent. The first three ‘tolerant’ species have more active calcium secretion glands in their gut than the three ‘sensitive’ worms. Calcium is known to be involved in the sequestration and elimination of various metals through the chlorogogenous tissue. Toxicity tests were carried out with a ‘sensitive’ and a ‘non-sensitive’ earthworm species ( Lumbricus rubellus and Aporrectodea rosea respectively) to examine if earthworm species distribution could be related to their susceptibility to the metals. In addition, the OECD recommended species Eisenia fetida was tested, to compare the sensitivity of this worm to the two commonly occurring soil species. Zinc was the metal used for these tests, since earlier comparisons of metal toxicity between the laboratory and field have shown that of the four metals released from the smelting works (Cd, Cu, Pb, Zn), it is zinc that is limiting the distribution of worms. Test results indicated that Aporrectodea rosea is more sensitive to the effects of zinc than Lumbricus rubellus . Thus, it appears that differences in the distribution of species of earthworms around the smelter can be related to variation in sensitivity to zinc. Both species were affected by zinc at lower concentrations than Eisenia fetida .

The effects of previous cropping history (varying periods of pasture or arable management) on soil organic C and microbial biomass C content and on the size and composition of earthworm populations were investigated on a range of mixed cropping (arable in rotation with pasture) farms. Some 105 fields located at 24 different commercial farms across the Canterbury Plains of New Zealand were sampled during spring. No native megascolecid earthworms were recorded. Up to five introduced European species were identified at sample sites. Overall, about 80% of earthworms were Aporrectodea caliginosa ,10% were Aporrectodea trapezoides and 5% were Lumbricus rubellus . The remaining 5% were Octolasion cyaneum and Aporrectodea rosea . All five species were found under long-term pasture. As the length of time under arable production increased, the number of species declined until, under continuous arable production, only A. caliginosa and A. trapezoides were recovered. Although soil organic C content was not greatly affected by cropping history, microbial biomass C content generally increased with time under pasture and decreased with time under arable. Earthworm numbers and biomass showed a similar but more pronounced trend to that of microbial biomass. This trend is reflected in the increased organic matter inputs under pasture and decreased inputs and increased decomposition under arable. In mixed cropping rotations, earthworm populations varied greatly with cropping history. Populations reached their maximum (over 800 m −2 ) after about 3 years under pasture whilst with more than 3 years under arable they were less than 400 m −2 . With continuous arable production for more than 9 years, populations fell to below 100 m −2 . Similar trends were found for earthworm biomass.

Earthworm populations were measured over a 7 year period in areas of a kiwifruit orchard with two different managements, (1) completely undisturbed and (2) organically managed, i.e. commercially, with only organic fertilisers and no synthetic biocides. Earthworms present were Aporrectodea caliginosa, Aporrectodea longa, and Lumbricus rubellus with an initial population of 400–500 m−2. After 7 years, the earthworm population in the undisturbed plot was zero; there was no significant reduction on the managed plot. After 7 years, water infiltration and air permeability were greater within the vine rows in the managed than the undisturbed plot, and smaller where the soil had been compacted by traffic, soil respiration was least in the undisturbed orchard. After 7 years, surface venting soil macropores were absent in the undisturbed plot. On the managed plot macropores tended to be vertically aligned in the sward between the vine rows and horizontally aligned within the vine rows. Soil chemical properties, measured four times during the 7 years, were similar in both managed and undisturbed plots. The importance of using measurements of biological, physical and chemical soil properties when describing a soil is discussed. Dependence only on assessment of chemical fertility in decision making may result in early stages of soil degradation being unnoticed.