Anecic Earthworm Lumbricus Terrestris Research Articles

The anecic earthworm Lumbricus terrestris can persist after introduction into permanent grassland on sandy soil

Grasslands are important water-regulating agro-ecosystems. Their ability to store and retain water is of vital importance under the current trend of increasing peak rains and droughts, which are events that can result in economic damage to infrastructure and crops. The presence of the anecic earthworm Lumbricus terrestris has a positive effect on the water regulation of the soil. This earthworm creates semi-permanent burrows with a depth of up to 2 m, which increase the water infiltration rate and capacity of the soil. The burrows can also facilitate plant root penetration into deeper soil layers, thus increasing drought resistance. The objective of this research was to explore the ability of L. terrestris to survive and reproduce after introduction into grasslands on sandy soils where they had been absent.We introduced L. terrestris into mesocosms on sandy soil under permanent grassland at two dairy farms in the Netherlands. Results showed that while L. terrestris was able to survive and produce cocoons, survival rate was low (32% after seven months, 6% after fifteen months) and the number of juveniles was low (2.6 and 2.7 ind. m−2 after seven and fifteen months, respectively). The causes of this low survival rate may be related to the life history of the earthworms introduced, the effects of soil moisture, interspecific competition for food with the native population of epigeic earthworms, and the risk of predation.We conclude that L. terrestris can survive and produce cocoons after introduction into permanent grassland on sandy soil, but only further experimental trials over greater time spans and in non-enclosed plots will determine whether there is realistic potential for L. terrestris to develop a stable population.

Soil grit influences the effects of earthworms (Lumbricus terrestris) on seed damage

Ingested soil grit is thought to enhance the grinding action of the earthworm gizzard but its role in earthworm-seed interactions is unknown. This study used feeding trials to investigate how different levels of supplemental soil grit (+0 %, +25 %, and +50 % sand additions by weight) influenced the impacts of the cosmopolitan anecic earthworm Lumbricus terrestris L. on seed ingestion, egestion, seed coat damage, and germination of garlic mustard (Alliaria petiolata). Added grit increased the amount of seed coat damage on garlic mustard seeds egested by L. terrestris. Earthworm egestion also increased the speed of garlic mustard germination (∼20 days control, ∼14 days with L. terrestris and +0 % grit, ∼11 days with L. terrestris and +25–50 % grit). The results demonstrate how earthworm ingestion and soil grit can modify the impacts of earthworms on seeds and highlight the importance of considering soil texture in field and laboratory earthworm experiments.

Three-dimensional mapping of earthworm (Lumbricus terrestris) seed transport

Transport by earthworms contributes to the secondary dispersal of seeds and influences patterns of plant community structure and function. To date, however, research on earthworm seed dispersal has focused primarily on vertical transport and the collection of seeds into middens at the soil surface, with no efforts to map horizontal distribution after burial. This study used an emergence depth assay and depth-stratified seedling emergence from soil microcosm cross-sections to map earthworm seed transport in three dimensions using commercial grass seed and the anecic earthworm Lumbricus terrestris L. While specific seed burial profiles should not be considered representative of burial under field conditions (due primarily to high earthworm densities under artificially limiting microcosm conditions), we created what we believe to be the first three-dimensional and most detailed map of earthworm seed burial, visualizing and quantifying the ability of L. terrestris to redistribute seed both vertically and horizontally throughout the soil profile. L. terrestris buried 6.5 to 17.4% of the total seeds and reduced aboveground grass biomass by 59–65 %. Vertically, L. terrestris buried seeds evenly across the 13 cm deep microcosms. Horizontally, L. terrestris aggregated seeds into small clusters aligned obliquely across soil depths, which suggest seeds being deposited in burrow walls (variance to mean ratio: 3.39 ± 2.49). Seeds were aggregated regardless of L. terrestris density but covered a greater cross-sectional area of the soil profile when more earthworms were present. Spatial patterning of shallow buried seed still capable of emergence is a newly described mechanism by which L. terrestris might influence the spatial structure of plant communities.

Field and laboratory responses of earthworms to use of wood ash as a forest soil amendment

Wood ash is produced by burning wood residues for energy and is often landfilled but can be more sustainably used as a forest soil amendment. We investigated how different fly and bottom wood ashes applied at a moderate 10 Mg∙ha−1 (dry) affected earthworms, a key group of forest soil biota. We conducted a field experiment with different wood ashes and application timings to determine the effects on population densities of different earthworm functional groups three weeks and one year post-amendment. We also used three laboratory microcosm experiments focused on the geographically widespread and ecologically influential anecic earthworm Lumbricus terrestris to test how wood ashes affect acute survivorship as well as habitat avoidance and surface feeding behaviors. In the field, wood ash amendment generally decreased or had no impact on earthworm densities in the first three weeks following amendment (with density decreases up to − 52 m−2), but had neutral or minor positive impacts one year later (up to + 21 m−2). In the laboratory, wood ashes generally had no effects on short-term earthworm survivorship or growth, but earthworms did respond behaviorally to certain wood ashes by habitat avoidance and reduced surface activity, with decreases in the overall frequency of aboveground events (−63%), the individual duration of each event (−63%), and the percentage of events that involved contact with litter (−53%). Across all experiments, fly ash tended to have a stronger effect than bottom ash. Overall, our study suggests that while some wood ashes may have limited short-term impacts on earthworm abundances, they may cause more subtle but ecologically important behavioral changes. Additionally, these earthworm-wood ash interactions are likely influenced by highly scenario-specific circumstances, including wood ash type, application site, and timing of application.

Effects of biocontrol bacteria and earthworms on Aphanomyces euteiches root-rot and growth of peas (Pisum sativum) studied in a pot experiment

ABSTRACT The role of below-ground interactions between microbial biocontrol agents and soil fauna for combatting soil-borne plant diseases have not been studied sufficiently. This study tested the hypothesis that the beneficial bacterium Bacillus velezensis UCMB5113 and the anecic earthworm Lumbricus terrestris positively influence health and growth of peas (Pisum sativum L.) infested with the pathogen Aphanomyces euteiches causing root-rot disease. A greenhouse fully factorial experiment studied the effects of A. euteches, B. velezensis and L. terrestris on the emergence, growth and health of pea plants. The factors B. velezensis and L. terrestris resulted in taller plants (p = .003 and p = .030). B. velezensis treatment resulted in a higher biomass of shoots and roots (p ≤ .001 and p = .005). The effects increased with the presence of both factors (p = .036). Earthworms reduced the disease symptoms significantly (p = .032). The decreased disease symptoms caused by the earthworms might be due to the consumption of A. euteiches (direct effect) as well as soil disturbance (indirect effect). Interactions between the microorganisms added and the earthworms were shown. B. velezensis and L. terrestris can be useful for enhancement of plant growth and for biological control of root-rot in peas.

Consistent seed ingestion preferences of earthworms (Lumbricus terrestris) between no-choice and choice feeding experiments

Summary Earthworm-seed interactions are increasingly recognized as ecologically important. Efforts to study these interactions make use of either no-choice or choice feeding trials due to logistical constraints or differing objectives, however, evidence is lacking regarding the consistency of feeding preferences by earthworms between these scenarios. We conducted a small-scale study in which we compared ingestion and egestion of eleven seed species by the anecic earthworm Lumbricus terrestris L. between no-choice and choice feeding dish trials. We found that seed ingestion and egestion differed between species and the seed ingestion preferences were relatively consistent (Pearson Correlation, r = 0.695) between the feeding trials. These results indicate that seeds preferred in isolation are similarly detectable and preferred alongside other options, aiding in the interpretation of results of other anecic earthworm-seed feeding experiments and suggesting that L. terrestris has a surprisingly strong ability to discriminate between and selectively consume specific seeds from a larger and diverse pool of species options.

Impact of different earthworm ecotypes on water stable aggregates and soil water holding capacity

We carried out mesocosm experiments using either the anecic earthworm Lumbricus terrestris or the endogeic earthworm Allolobophora chlorotica and loam, silt loam and sandy loam soils to investigate the differing impact of these earthworm of different ecotypes on aggregate formation (percentage water stable aggregates, %WSA) and soil water holding capacity (WHC), two soil properties that underpin many of the ecosystem services provided by soils. Earthworms significantly increased %WSA (by 16–56% and 19–63% relative to earthworm-free controls for L. terrestris and A. chlorotica, respectively). For L. terrestris, this increase was significantly greater in the upper 6.5 cm of the soil where their casts were more obviously present. Allobophora chlorotica treatments significantly increased WHC by 7–16%. L. terrestris only caused a significant increase in WHC (of 11%) in the upper 6.5 cm of the sandy loam soil. Linear regression indicated a consistent relationship between increases in %WSA and WHC for both earthworm species. However, for a given %WSA, WHC was higher for A. chlorotica than L. terrestris likely due to the known differences in their burrow structure. Overall, earthworms increased soil %WSA and WHC but the significant species/ecotype differences need to be considered in discussions of the beneficial impacts of earthworms to soil properties.

Anecic earthworms (Lumbricus terrestris) facilitate the burial of surface-applied wood ash

The purpose of our study was to determine whether earthworms facilitate the burial of surface-applied wood ash. We mixed a fluorescent tracer powder with fly ash from a commercial biomass boiler to track and quantify ash burial in microcosms containing different densities of the deep-burrowing anecic earthworm Lumbricus terrestris L. While passive incorporation of the wood ash-tracer mix from the surface in the absence of earthworms was limited (rarely penetrating more than 2 cm below the surface), earthworms increased the amount of ash-tracer found belowground and the maximum depths at which ash-tracer was observed (up to 16 cm deep). We suspect that earthworms facilitated wood ash burial primarily by creating burrows down which wood ash could be carried by water and by burying wood ash-covered leaf litter. Earthworms may help increase the efficacy of wood ash amendment in ecosystems where it is impractical to manually mix amendments into the soil (e.g. forests).

Improving Complementarity Effect of Legume Intercrop by Earthworm Facilitation for Wheat Performance

Intercrops and crop mixtures are considered to be a way to increase nitrogen use efficiency by promoting niche complementarity and facilitation, reducing the input of fertilizers and herbicides, which are important factors when considering the effects of climate change. However, interactions between crop communities and soil functional diversity also have major effects on crop cover function. Our study aimed to investigate the simultaneous effects of plant composition and presence of earthworms on the growth (roots and shoots) of wheat (Triticum aestivum L.). Mesocosms filled with soil were sown with either 6 wheat plants of the same cultivar, or 6 plants of 3 different wheat cultivars, or 3 wheat plants of 3 different cultivars with 3 clover plants (Trifolium hybridum L.). A part of the mesocosms was inoculated with either endogeic earthworms (Aporrectodea caliginosa S.) or a mixture of endogeic and anecic earthworms (Lumbricus terrestris S.). A relative interaction index was calculated to highlight competition strength between plants with or without earthworms. The presence of different cultivars had no influence on wheat performance, but with clover, plant competition decreased to the benefit of wheat biomass and N accumulation. Earthworms also reduced the competitive strength between wheat plants in mixed-cultivar mesocosms and in intercropping. In intercrops with clover, wheat performance was improved as a result of niche complementarity and earthworm facilitation for N resource. Our results suggest that the plant functional group, such as legumes, and earthworm communities work synergistically to improve wheat yields.

Exploring the pathways of earthworm-induced phosphorus availability

As many soils are unable to supply sufficient amounts of phosphorus (P) to plants, P availability is often a growth-limiting factor. Literature shows that levels of readily available P can be considerably higher in earthworm casts than in the surrounding bulk soil, possibly resulting in increased plant P uptake. However, the underlying mechanisms through which this increase of readily available P occurs are unclear. In a greenhouse pot experiment with annual ryegrass (Lolium multiflorum) on a soil with low P availability, we tested whether the presence of the anecic earthworm Lumbricus terrestris resulted in increased grass growth and P uptake and explored the possible mechanisms behind such an effect. During the pot experiment, earthworm casts were collected and analysed for water-extractable P as well as for most other relevant ions. The earthworm's presence significantly increased grass yield from 9.80 to 10.80g dry matter per pot (p=0.044) and P uptake from 6.32 to 8.04mg per pot (p=0.002). Due to increased microbial activity, the solution chemistry in the water extracts of the casts was dramatically changed compared to the bulk soil samples. The concentrations of dissolved inorganic P in cast were enhanced by a factor ~30–1000 compared to the levels found in bulk soil. The pH in earthworm casts increased from 5.9 to values between 7.4 and 9.0 and the Ca concentrations decreased by about a factor ~2-3 compared to bulk soil samples. In addition, there was an increase in dissolved organic carbon (35mgL−1 in casts versus 3mgL−1 in soil). Surface complexation modelling, using the Charge Distribution model, suggests that, besides an increase in pH, particularly an enhanced interaction of dissolved organic matter with reactive surface of metal (hydr)oxides is likely to be a major driving force for the augmented release of orthophosphate (PO4) via competitive adsorption and desorption. This competition for adsorption sites is an alternative pathway, next to mineralisation of organic matter, through which earthworms can increase soil fertility.

Incorporation of microplastics from litter into burrows of Lumbricus terrestris

Pollution caused by plastic debris is an urgent environmental problem. Here, we assessed the effects of microplastics in the soil surface litter on the formation and characterization of burrows built by the anecic earthworm Lumbricus terrestris in soil and quantified the amount of microplastics that was transported and deposited in L. terrestris burrows.Worms were exposed to soil surface litter treatments containing microplastics (Low Density Polyethylene) for 2 weeks at concentrations of 0%, 7%, 28%, 45% and 60%. The latter representing environmentally realistic concentrations found in hot spot soil locations. There were significantly more burrows found when soil was exposed to the surface treatment composed of 7% microplastics than in all other treatments. The highest amount of organic matter in the walls of the burrows was observed after using the treatments containing 28 and 45% microplastics. The highest microplastic bioturbation efficiency ratio (total microplastics (mg) in burrow walls/initial total surface litter microplastics (mg)) was found using the concentration of 7% microplastics, where L. terrestris introduced 73.5% of the surface microplastics into the burrow walls. The highest burrow wall microplastic content per unit weight of soil (11.8 ± 4.8 g kg-1) was found using a concentration of 60% microplastics. L. terrestris was responsible for size-selective downward transport when exposed to concentrations of 7, 28 and 45% microplastics in the surface litter, as the fraction ≤50 μm microplastics in burrow walls increased by 65% compared to this fraction in the original surface litter plastic. We conclude that the high biogenic incorporation rate of the small-fraction microplastics from surface litter into burrow walls causes a risk of leaching through preferential flow into groundwater bodies. Furthermore, this leaching may have implications for the subsequent availability of microplastics to terrestrial organisms or for the transport of plastic-associated organic contaminants in soil.

Biocontrol of eyespot disease on two winter wheat cultivars by an anecic earthworm (Lumbricus terrestris)

Eyespot is a major fungal disease of winter wheat, mostly affecting the base of the stem. The development of biological control approaches, using organisms such as earthworms, represents a potential alternative strategy for eyespot control. In a greenhouse experiment, we analyzed the response of two wheat cultivars (Soissons and Aubusson) to the presence of the pathogenic fungus Oculimacula yallundae and the anecic earthworm Lumbricus terrestris, alone and in combination. We assessed necrosis frequency, necrosis severity, wheat biomass, resource allocation and soil mineral concentrations. Disease incidence was lower in the presence of earthworms: the frequency of necrosis was 44% lower for Soissons and 70% lower for Aubusson. Necrosis severity was also lower for both cultivars (50% lower for Soissons and 80% lower for Aubusson) in the presence of earthworms. Earthworms had no detectable effect on the shoot and root biomasses of plants exposed to the fungus, but they modified resource allocation between plant organs and nutrient translocation within the plant. Our results suggest that earthworms are a potentially effective biocontrol agent for eyespot, and we discuss the possible underlying mechanisms.

Contribution of anecic earthworms to biopore formation during cultivation of perennial ley crops

Abstract Large sized biopores (diameter >2 mm) in the subsoil can be created by tap roots, which leave voids after their decay, or by the burrowing activity of anecic earthworms which may benefit from the temporary lack in tillage in perennial cropping systems. However, the interactions between root growth and earthworm activity in the process of biopore formation during perennial ley cropping are not well understood. The aim of this field study was to quantify the development of the abundance of the anecic earthworm Lumbricus terrestris and the biopore density during the cultivation of lucerne ( Medicago sativa L.), chicory ( Cichorium intybus L.) and tall fescue ( Festuca arundinacea Schreb.) grown for either one, two or three years. An increased abundance of L. terrestris was already recorded after two years of continuous ley when compared with one year cultivation. The ley crop species had only minor influence on the abundance of L. terrestris . Biopore densities of both diameter classes under study (2–5 mm and >5 mm) were not significantly affected by the duration of ley cropping. In contrast, biopore densities were influenced by ley crop species. More biopores of diameter class 2–5 mm were recorded after chicory than after fescue. Lucerne cropping resulted in intermediate biopore density. Additionally, in an incubation experiment under field conditions, we quantified whether L. terrestris preferentially created new biopores or colonized abandoned, previously existing ones. After three weeks of incubation, one third of the adult individuals incubated in the experimental area created new biopores at 0.4 m soil depth. A similar percentage of individuals colonized previously existing biopores, partially widening the lumen of smaller sized biopores. The remaining individuals remained in the topsoil. Sub-adult individuals rarely formed new pores. Half of the introduced sub-adults remained in the topsoil. We conclude that in crop rotations new biopores can be generated during perennial ley cropping by taproot systems of ley crops, but that a two to three- year period without tillage is not sufficient for populations of anecic earthworms to make a marked contribution to biopore density in the subsoil. The relevance of anecic earthworms for altering physical and chemical properties of biopores during ley cropping still needs further investigation.

Earthworm invasion alters enchytraeid community composition and individual biomass in northern hardwood forests of North America

European earthworms are invading many ecosystems worldwide and fundamentally transform habitats by acting as dominant ecosystem engineers. However, there is little knowledge of the consequences of earthworm invasion on the composition and diversity of native soil organisms. Particularly functionally similar groups, such as enchytraeids (Annelida: Enchytraeidae), may be affected through changes in the chemical and physical properties of the soil, but also due to competition for resources. In 2010–2011, we studied the impact of earthworm invasion on enchytraeids at two sites in the northern hardwood forests of North America: one site within the Chippewa National Forest in northern Minnesota and one site in the Chequamegon-Nicolet National Forest in northern Wisconsin, USA. At each site, three plots were sampled along a transect, representing (1) a non-invaded or very slightly invaded area, (2) the leading edge of earthworm invasion and (3) a heavily invaded area with an established population of the anecic earthworm Lumbricus terrestris (among other species). In total, 29 enchytraeid (morpho)species were identified (some yet to be formally described, several first or second records for the continent); of those 24 occurred at the Minnesota site and 17 at the Wisconsin site. The structure of enchytraeid assemblages differed significantly among the three invasion stages, although this was not equally pronounced at the two sites. Each stage was characterized by one or several indicator species. Mean enchytraeid densities (10,700–30,400individuals/m2) did not differ significantly among the invasion stages, but were lowest at the leading edge of earthworm invasion at both sites. In the heavily invaded plot at the Minnesota site, the mean enchytraeid density and biomass in L. terrestris middens were significantly higher than in soil in-between the middens. This was due to a pronounced effect of L. terrestris middens in the uppermost 3cm of soil. Differences in biomass among earthworm invasion stages were most apparent for mean individual biomass. This was significantly higher in the heavily invaded area than at the leading edge or in the non-invaded area at the Minnesota site. Compositional changes of the enchytraeid assemblage are likely to result in changes in the functioning of soil foods webs. Our results suggest that earthworm invasions can cause a loss of native species in soil, including heretofore unknown ones, that might go unnoticed.

Ecotoxicological effects of an aged TiO 2 nanocomposite measured as apoptosis in the anecic earthworm Lumbricus terrestris after exposure through water, food and soil

Titanium dioxide nanoparticles seem to have a low toxicity to terrestrial organisms, though few studies are published in this area. TiO 2 used in sunscreens are nanocomposites where TiO 2 has been coated with magnesium, silica or alumina, as well as amphiphilic organics like polydimethyl siloxane (PDMS), and these coatings are modified by ageing. We assessed the ecotoxicity and propensity for bioaccumulation of an aged TiO 2 nanocomposite used in sunscreen cosmetics, and its potential effect on the frequency of apoptosis in different earthworm tissues. The earthworm Lumbricus terrestris was exposed to the TiO 2 nanocomposite for 7 days in water or 2–8 weeks in soil with the nanocomposite mixed either into food or soil at concentrations ranging from 0 to 100 mg kg − 1 . Apoptosis was then measured by immunohistochemistry and Ti localized by XRF microscopy. Results showed no mortality, but an enhanced apoptotic frequency which was higher in the cuticule, intestinal epithelium and chloragogenous tissue than in the longitudinal and circular musculature. TiO 2 nanoparticles did not seem to cross the intestinal epithelium/chloragogenous matrix barrier to enter the coelomic liquid, or the cuticule barrier to reach the muscular layers. No bioaccumulation of TiO 2 nanocomposites could thus be observed.

Clostridiaceae and Enterobacteriaceae as active fermenters in earthworm gut content.

The earthworm gut provides ideal in situ conditions for ingested heterotrophic soil bacteria capable of anaerobiosis. High amounts of mucus- and plant-derived saccharides such as glucose are abundant in the earthworm alimentary canal, and high concentrations of molecular hydrogen (H(2)) and organic acids in the alimentary canal are indicative of ongoing fermentations. Thus, the central objective of this study was to resolve potential links between fermentations and active fermenters in gut content of the anecic earthworm Lumbricus terrestris by 16S ribosomal RNA (rRNA)-based stable isotope probing, with [(13)C]glucose as a model substrate. Glucose consumption in anoxic gut content microcosms was rapid and yielded soluble organic compounds (acetate, butyrate, formate, lactate, propionate, succinate and ethanol) and gases (carbon dioxide and H(2)), products indicative of diverse fermentations in the alimentary canal. Clostridiaceae and Enterobacteriaceae were users of glucose-derived carbon. On the basis of the detection of 16S rRNA, active phyla in gut contents included Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Gemmatimonadetes, Nitrospirae, Planctomycetes, Proteobacteria, Tenericutes and Verrucomicrobia, taxa common to soils. On the basis of a 16S rRNA gene similarity cutoff of 87.5%, 82 families were detected, 17 of which were novel family-level groups. These findings (a) show the large diversity of soil taxa that might be active during gut passage, (b) show that Clostridiaceae and Enterobacteriaceae (fermentative subsets of these taxa) are selectively stimulated by glucose and might therefore be capable of consuming mucus- and plant-derived saccharides during gut passage and (c) indicate that ingested obligate anaerobes and facultative aerobes from soil can concomitantly metabolize the same source of carbon.

Site Classification to Predict the Abundance of the Deep‐Burrowing Earthworm Lumbricus terrestris L.

Channels made by deep‐burrowing (anecic) earthworms are known to strongly affect soil water flow and increase the leaching risk of agricultural pollutants. A classification tree that predicts the abundance of the anecic earthworm Lumbricus terrestris L. from readily available survey information (land use, management practices, and soil texture) was derived from literature data (n = 86). The most important factors favoring L. terrestris were perennial land use, no‐till arable cropping, organic additions (i.e., manure), and medium‐textured soil. The classification scheme correctly predicted earthworm abundance for 71% of the studies in the database. Among other potential applications, the classification tree could be used to identify areas at risk from groundwater pollution in agricultural landscapes and to support catchment‐ and regional‐scale models of contaminant leaching in the vadose zone.

Field investigations of Lumbricus terrestris spatial distribution and dispersal through monitoring of manipulated, enclosed plots

A field experiment in managed woodland was set up to examine the effects of manipulated population density and resource availability on spatial distribution and dispersal of the anecic earthworm Lumbricus terrestris. Experiments over 2 years, made use of 1 m 2 field enclosures with associated trapping units to assess emigration rates at control and enhanced L. terrestris densities and different levels of leaf litter availability. Densities were manipulated twice; at the outset and again after 1 year when visually tagged animals obtained from 2 origins were introduced. Population density had a significant effect on dispersal ( p < 0.01, p < 0.05 in Year 1 and Year 2 respectively) with more captures (pro rata) at the higher density compared with controls over the experimental period. Food availability only had a significant effect during the initial week of the experiment. L. terrestris midden arrangement was found to be regular across 1 m 2 plots and regularity increased with an increase in midden number. Mean (±S.E.) midden number was 30.34 ± 0.77 m −2 and 28.06 ± 0.5 m −2, during the first and second year of the experiment respectively and this was unaffected by additions. Inter-midden distance was recorded at 0.13 ± 0.0014 m. Results suggest that L. terrestris dispersal can be affected by population density and resource availability.

The earthworm Lumbricus terrestris favours the establishment of Lolium perenne over Agrostis capillaris seedlings through seed consumption and burial

We studied the effects of the anecic earthworm Lumbricus terrestris L. on seed germination of two plant species to understand the mechanisms underlying earthworm–seed interactions. We set up microcosms with seeds of Lolium perenne L. (large seeds) and Agrostis capillaris L. (small seeds), in a loam based compost, with and without earthworms. We buried seeds at three depths and recorded their germination, we also examined to what depth earthworms buried seeds, and we studied seed viability after transit through the gut of earthworms. Earthworms dramatically reduced the numbers of A. capillaris seeds germinating, but did not modify the germination of L. perenne seeds. Earthworms did, however, increase the biomass of L. perenne seedlings. When we buried the seeds, those from A. capillaris rarely germinated when they were placed below 7 cm, unlike L. perenne seeds. Earthworms buried the seeds of L. perenne to a depth of 15 cm. Passage of seeds through the gut of earthworms had a detrimental effect on A. capillaris seed viability, while L. perenne seeds remained unaffected. While our results show that earthworm activity can strongly influence grass seed germination and plant establishment in microcosm experiments, further work is needed to asses the implications of earthworm–seed interactions for vegetation dynamics in the field.

White-tailed deer (Odocoileus virginianus) fecal pellet decomposition is accelerated by the invasive earthworm Lumbricus terrestris

Exotic European earthworms have expanded into worm-free forests of the United States. Concurrently, populations of the white-tailed deer, Odocoileus virginianus, have also increased. During winter, deer use hemlock stands for cover while browsing elsewhere, creating a net organic matter flux into these stands. Deer fecal pellets can provide annual inputs of 48.1 kg C, 1.4 kg N, and 1.3 kg Ca per hectare. We tested the hypothesis that these pellets were readily consumed by invading earth- worms. The litter-feeding anecic earthworm Lumbricus terrestris redistributed fecal pellets and accelerated mass and nutrient loss rates. These losses are likely due to the combination of enhanced fragmentation and decomposition as earthworms drag pellets into their burrows for consumption. This nutrient subsidy may be an important source of high quality ''litter'' input to hemlock stands, which may in turn facilitate the invasion of these stands by earthworms under high deer densities.