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A test of 'hot' mustard extraction method of sampling earthworms

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Abstract

Earthworm densities in soil are difficult to quantify. Part of the problem is that they are incorporated closely into the soil structure, which makes their extraction tedious and time consuming (Edwards, 1991). In addition, earthworms have widely varying patterns of activity and occupy a range of soil depths depending upon season, species, and life history stage (Bouche and Gardner, 1984). Behavioral methods, which involve stimulating earthworms with a chemical or other expellant (e.g. an electrical shock) and collecting them as they emerge at the surface, have been proposed as efficient extraction methods that do not require physical disruption of the soil system. We examined the effectiveness of one such technique: the non-toxic ‘hot’ mustard extraction method. We compare hot mustard extraction with digging and hand-sorting, and conclude that it provides a consistent index of earthworm abundance across a range of soil and land-use types.

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... Bartlett et al. (2006) estimated that mustard extraction accounted for 35.7% of the available population, with results varying by species. Lawrence and Bowers (2002) estimated that 61.4% of earthworms were extracted using mustard solution. ...
... We used a concentration of 40 g dry mustard flour/3.79 L of water, similar to other studies from the Great Lakes Region (Lawrence and Bowers 2002, Hale et al. 2005, Loss et al. 2012). We first sifted through and removed leaf litter from the mesocosm surface (0.144 m 2 ), looking for earthworms. ...
... On average, mustard extraction produced a third to half of the individuals available for capture. These density results are consistent with other studies and our study is one of few that controlled potential exodus of worms out of the treated area (e.g., Lawrence andBowers 2002, Bartlett et al. 2006). Future studies should include control mesocosms to account for the possibility of some worms dying before treatment. ...
Article
We examined efficacy of a mustard extraction technique for quantifying earthworm occupancy and density using a mesocosm experiment. In May 2017, we placed 12 earthworms from 2 ecological groups (6 surface dwelling [epigeic] and 6 deep dwelling [anecic]) into mesocosms (0.144 m2 surface area) constructed from soils typically found in northern hardwood forests of Michigan, USA. We evaluated 2 soil depths (15 and 30 cm) and a soil moisture gradient (dry to wet). We found occupancy of epigeic earthworms was accurately portrayed 92% of the time through leaf searches, and subsequent mustard phase did not improve accuracy. For anecic earthworms, we found that occupancy was accurately portrayed 50% of the time through leaf searches and mustard phase increased accuracy to 92%. We found that mustard extraction produced 0–83% (median = 50%) of epigeic earthworms available for capture, with most recovered through leaf searches (median = 42%). We found that mustard extraction produced 0–67% (median = 33%) of anecic earthworms available for capture, with most (median = 20%) recovered during the mustard phase. Our results lend support for using mustard extraction as a technique for quantifying occupancy of epigeic and anecic earthworms, but caution that density estimates are likely low. © 2019 The Wildlife Society. We tested mustard extraction on 2 different groups of earthworms. We found that mustard extraction as a technique for quantifying occupancy of epigeic and anecic earthworms can be reliable, but researchers should use caution when trying to estimate density.
... The mesofauna activity was assessed using the bait lamina method (Törne, 1990;Kratz, 1998;Griffiths et al., 2016). We completed the assessment at the macrofauna level by extracting earthworms using the combined mustard flour and hand sorting procedure (Lawrence and Bowers, 2002). ...
... After 9 days, the laminas were collected, and an organic matter degradation score was calculated based on the number of empty holes on each lamina. Earthworm biomass was measured using one mustard flour extraction by plot followed by hand sorting a 30x30x30 cm soil volume to recover residual individuals (Lawrence and Bowers, 2002). ...
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Terrestrial enhanced rock weathering (ERW) is a promising carbon dioxide removal technology that consists in applying ground silicate rock such as basalt on agricultural soils. On top of carbon sequestration, ERW has the potential to raise the soil pH and release nutrients, thereby improving soil fertility. Despite these possible co-benefits, concerns such as heavy metal pollution or soil structure damage have also been raised. To our knowledge, these contrasted potential effects of ERW on soil fertility have not yet been simultaneously investigated. This field trial aimed at assessing the impact of ERW on biological, physical, and chemical soil properties in a temperate agricultural context. To do so, three vineyard fields in Switzerland were selected for their distinct geochemical properties and were amended with basaltic rock powder at a dose of 20 tons per hectare (2 kg.m−2). On each field, basaltic rock powder was either applied one year before the sampling campaign, one month before the sampling campaign, or not applied (control) for a total of 27 plots with 9 repetitions of each level. Overall, basaltic rock powder addition had a predominantly positive to neutral effect on soil fertility. Most soil properties showed no significant change either 1 month or 1 year post application. Nevertheless, our study highlighted a significant increase in earthworm abundance (+71 % on average), soil respiration (+50 %) and extractable sodium concentration (+23 %) as early as 1 month post application. The higher soil respiration raises the question of CO2 losses from organic matter mineralization that could limit ERW's efficiency. The increase in sodium raises concerns about a sodification risk potentially damaging soil fertility. These elements now require further investigation before enhanced rock weathering can be considered a viable and secure carbon dioxide removal technology.
... In late October 2019, earthworms were extracted from the soil in each plot by searching and clearing the surface leaf litter and pouring 3 L of mustard solution (10 g mustard powder [Bulk Barn Food Limited, Aurora, Ontario, Canada] per litre water) on the plot over 12 min to extract earthworms (Lawrence and Bowers 2002;Hale 2013). To rapidly collect gut contents, all earthworms were immediately placed in portable, aerated, plastic containers (14 cm × 9 cm × 5 cm; Dollar Tree Canada, Mississauga, Ontario, Canada) lined with moistened viscose cloth ( Figure 1). ...
... Although we did find that L. terrestris egested more seeds per individual than smaller earthworms, the latter occurred at higher densities overall and egested just as many seeds in total. The influence of mineral soil-dwelling endogeic earthworms may be even greater than observed because of the tendency of mustard extraction to marginally under-sample these taxa (Lawrence and Bowers 2002). Given the predominantly belowground feeding behaviour of many of the earthworms that egested seeds, these findings also reinforce the relatively unique ability of earthworms to access seeds both below and above ground (Thompson 1987). ...
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Although awareness of the influence of earthworms on soil seed banks in Canadian forests is growing, there have been few direct field measurements. We used a novel pairing of field-collected earthworms from a central Great Lakes forest in Ontario with a laboratory seed egestion assay to obtain a snapshot of the number of seeds passing through earthworms compared with seeds found in the surrounding soil. We identified a pool of seeds egested by earthworms that accounted for 2.4% of all seeds found in the earthworms and the top 0–10 cm of soil. Individual earthworms contained 0–5 seeds. The large-bodied adult anecic non-native Dew Worm or Common Nightcrawler (Lumbricus terrestris) egested a disproportionate number of seeds for its abundance (50% of egested seeds from 17% of earthworms), but smaller earthworms were also an important source of egested seeds (the other 50%). This small-scale proof-of-concept study demonstrates a method of directly measuring earthworm–seed interactions in the field. It can also detect seeds egested by earthworms below ground that would otherwise be missed by other seed accounting methods and it highlights the importance of granivory by non-surface casting earthworms.
... The most used method by scientists is the Tropical Soil Biology and Fertility -TSBF (Anderson and Ingram, 1993), which consists of sampling soil monoliths (generally 25 cm length x 25 cm width x 25 cm height) followed by a manual screening of earthworm individuals (Azevedo et al., 2010). The advantages of this method are based on precision, which allows sampling earthworms: live, in a latent state and also cocoons (Lawrence and Bowers, 2002). As disadvantages can be pointed: the escape of some species to deeper layers (Baretta et al., 2007), the low efficiency in extracting of anecic (Lawrence and Bowers, 2002) and small size species (< 2 mm body length) (Baker et al., 1996). ...
... The advantages of this method are based on precision, which allows sampling earthworms: live, in a latent state and also cocoons (Lawrence and Bowers, 2002). As disadvantages can be pointed: the escape of some species to deeper layers (Baretta et al., 2007), the low efficiency in extracting of anecic (Lawrence and Bowers, 2002) and small size species (< 2 mm body length) (Baker et al., 1996). ...
... The earthworms were then placed in a solution of 75% ethanol for storage. Commercial mustard, as used by Pelosi et al. (2009) and Lawrence and Bowers (2002), was preferred to the formalin solution commonly used, as formaldehyde is known to be carcinogenic and harmful to the environment (Eichinger et al., 2007). Moreover formalin solution is a chemical synthesis-derived product, so it was prohibited from being used in the 4 organic-certified plots. ...
... They also need a sophisticated logistic. Recently, innovative and no harmful extracting substance as mustard was used (Chan and Munro, 2001), with positive results (Lawrence and Bowers, 2002;Pelosi et al., 2009). Mustard suspension shows no phytotoxic effects contrary to formalin and is safe for men and environment (Valckx et al., 2011). ...
Thesis
Le sol, composante du Terroir doit être considéré comme une ressource non renouvelable essentielle au fonctionnement des agro‐écosystèmes. Or, les sols viticoles sont particulièrement vulnérables aux dégradations. L’objectif central de ma thèse est donc d’évaluer comment les pratiques viticoles affectent la qualité des sols dans le Languedoc‐Roussillon. Pour ce faire, j’ai d’abord évalué la qualité des sols sur 164 parcelles présentant une grande variabilité de pratiques culturales et réparties sur 9 zones pédologiques très diversifiées. Puis, j’ai évalué la vitesse de changement de la qualité des sols par l’analyse de 23 parcelles d’une zone homogène converties progressivement en viticulture biologique depuis un maximum de 17 ans. Plusieurs indicateurs physiques (densité apparente, porosité totale, stabilité structurale et humidité à la capacité au champ), chimiques (teneur en carbone et azote, C/N, disponibilité des éléments P, K, et Cu, capacité d’échange cationique) et biologiques (biomasse microbienne, respirométrie, nématodes, vers de terre) ont été mesurés afin de fournir une vision holistique de la qualité des sols. Mes résultats montrent une diversité de qualité des sols viticoles au regard des perturbations subies par les différentes pratiques. J’ai également démontré que la majorité des indicateurs étudiés sont sensibles aux pratiques viticoles indépendamment des types de sol étudiés. Concernant la dynamique de changement, la qualité des sols viticoles se stabilise après 7‐11 de pratiques biologiques. Toutefois, malgré une augmentation significative des activités biologiques du sol (micro‐organismes et nématodes libres), la conversion depuis 17 ans n’a pas mis en évidence une amélioration nette de la qualité du sol. En conclusion, nous avons confirmé la vulnérabilité des sols viticoles languedociens aux pratiques en cours. Mes travaux mettent en lumière l’importance du transfert des connaissances acquises lors de ce travail pour améliorer la perception de la qualité des sols par les viticulteurs et les professionnels de la filière viticole.
... We visited islands from June to July 2016 and Apr 2017 to sample for exotic earthworms using a minimally-invasive, standard protocol for estimating presence and relative abundance of anecic and epigeic earthworms (Gunn 1992;Lawrence and Bowers 2002). Islands were selected based on access, published and local knowledge of their histories, and inclusion in prior surveys. ...
... All plots were located in sites with [ 20 cm of soil and plant cover typical of more or less invaded meadow habitat. Earthworms were sampled using a 0.33 m 2 quadrat and mustard extraction method (Gunn 1992;Lawrence and Bowers 2002) known to be effective in dry soils (Eisenhauer et al. 2007). To do so, a solution of 4 L freshwater mixed with 50 g of ground mustard seed was slowly distributed over the quadrat and observed for 10 min. ...
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Non-native earthworms can drive ecosystem change, simplify native plant communities, and promote invasion by non-native plants, but we know little about their pathways into island archipelagos, which currently support about 40% of the worlds threatened species. We studied links among non-native earthworms, human settlement, deer, and plant communities on 26 islands in the San Juan and Southern Gulf Island archipelagos of the Georgia Basin Ecoregion of western North America. We evaluated the (1) invasion pathways and occurrence of non-native earthworms on islands, (2) influence of non-native earthworms on herbaceous and woody plant cover, and (3) potential for synergistic interactions among deer, earthworms and non-native plants. Human settlement was a pre-condition to detecting non-native earthworms on islands. Non-native earthworm abundance was related positively to the cover of non-native herbaceous and woody plants, effects which may be exacerbated by high deer density. Our findings suggest that the absence of non-native earthworms on many small islands makes their protection crucial to the conservation of intact examples of native ecosystems, including critically endangered Garry oak and maritime meadows in Canada.
... On each of these dates, two of our students visited each plot where they first collected epigeic earthworm species that could be found under woody debris, rocks and other coarse fragments, over a period of 15 min. They then proceeded to collect endogeic and anecic earthworm species at eight random sampling locations within each plot, using the hot mustard extraction method (Lawrence and Bowers, 2002). More precisely, they removed the forest floor at each sampling location over a 30 × 30 cm 2 area and dug the underlying surface mineral soil down to a depth of 30 cm. ...
... We sampled earthworms in 10 0.5 m 2 quadrats along two diagonal transects within each plot in September 2011 (before fence installation) and again in September 2012, 2013 and 2015. We used liquid mustard extraction (3 g powdered mustard in 3.79 L tap water), poured over sampling quadrats with leaf litter removed (Lawrence & Bowers, 2002). We collected all surfacing earthworms and preserved them in 10% formalin for 48 h before transferring them into 70% ethanol for storage. ...
Article
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Forests in northeastern North America have undergone dramatic transformations due to losses and gains of species, changes in land use and pollution. Historic stressors combined with new threats of white‐tailed deer and non‐native earthworms are threatening native plant diversity. We developed a transplant approach to gauge the importance of deer and earthworms in allowing understorey species recovery. This approach, instead of censusing existing individuals, avoids problems imposed by past land use, dispersal limitation or climate change. We selected 20 native species in different taxonomic and functional groups, with different palatability to herbivores, different life‐history strategies and a range of plant traits (%N, specific leaf area [SLA]) and our selection included species indicative of primary or secondary forests. Using a 2 × 2 full factorial design, we planted species into fenced and unfenced plots with and without existing earthworm invasions in five secondary hardwood forests. We measured survival, plant growth and reproduction over 4–6 years. Earthworm biomass was associated with increased survival of 13 and decreased survival of five species. Surviving transplants grew taller (eight of 12 species measured) and wider (seven of nine species measured) in earthworm plots but were more likely to be attacked by insects. Excluding deer benefitted most species' survival and growth. Taxonomic class, SLA or foliar N did not affect species sensitivity to deer or earthworms. Synthesis . Secondary forests in our region continue to provide suitable habitat for native species. Earthworms and deer are major structuring forces affecting survival and growth of our transplant species, but their impacts are species‐specific and change over time. We observed poorly recognized indirect negative impacts of deer on many unpalatable species. Taxonomic class and differences in plant traits offered no important insights regarding vulnerability to deer or earthworms. Transplanting native species into secondary forests can succeed in restoring understorey communities, but will require fencing or substantial deer population reductions to be successful long term.
... To bring up anecic earthworms (which can live several metres beneath the soil) a solution of hot mustard powder was then poured into the hole. This combination of hand-sorting soil and chemical expellant is a standard method for earthworm surveys and provides a consistent index of earthworm abundance across soil and land-use types [38,39]. Although shallower than some soil invertebrate sampling protocols e.g. ...
Article
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The distribution of earthworm ecological groups in urban areas is not well-known, despite their crucial role in delivering soil ecosystem services such as nutrient cycling and water drainage. Citizen science engages public audiences in the scientific research process and is an excellent tool for collecting biodiversity data in urban areas, where most of the UK population resides. However, a disadvantage is that differing levels of skill and engagement among participants can create statistical challenges. The Earthworm Watch citizen science project used 668 matched-pair surveys to estimate how the abundance and ecological diversity of earthworms respond to land management practices, and soil properties in UK urban habitats. A total of 5170 earthworms were counted during the project with a mean of 8 earthworms per soil pit-equivalent to a density of 198 earthworms per m 2. Soil moisture and texture were the largest drivers of total earthworm abundance, with habitat borderline statistically insignificant. Endogeic earthworms were found in 71 % of soil pits, epigeic in 62 % and anecic in 33 %. Fertiliser use also had a significant effect on total abundance, but only when organic fertiliser was used. Earthworm ecological groups demonstrated varied responses to habitat, with endogeic earthworms consistently the most abundant group, showing slight preferences for grasslands and vegetable beds. Anecic earthworms had the lowest abundance across all habitats but were more prevalent in grasslands and vegetable beds. Epigeic earthworms were most abundant beneath shrubs and hedges. These findings align with expected patterns of earthworm ecology, underscoring the potential of well-designed citizen science projects to yield valuable insights into urban earthworms and soil health.
... At each sampling date, two technicians collected epigeic earthworm species found under woody debris, rocks and other coarse fragments, over a period of 15 min. They then sampled endogeic and anecic species at eight random locations around the perimeter of each plot, using the hot mustard extraction method (Lawrence and Bowers 2002). This was accomplished by removing the forest floor and excavating the mineral soil over a (30 × 30) cm 2 area, down to 30 cm depth. ...
Article
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Non-native earthworms found in Eastern Canada substantially affect soil properties and plant diversity, but less is known about their impacts on higher faunal species. We investigated the effects of non-native earthworms on populations of Plethodon cinereus, a common woodland salamander. We hypothesized that earthworms could adversely affect P. cinereus by consuming the forest floor, thereby decreasing soil moisture and the abundance of native preys. Conversely, earthworms could positively affect P. cinereus by providing refuge in their abandoned burrows and by being a novel prey. We installed 25 coverboards in 38 mature sugar maple (Acer saccharum) forests, 24 of which were earthworm-free. Over the next two years, we monitored earthworm and salamander populations using hot mustard extractions and visible implant elastomers, respectively. At a subset of four sites, two with and two without earthworms, we determined salamander diets in the spring (May–June), summer (July–August) and fall (September–October) seasons, using gastric lavage techniques. Forest floor depth decreased, whereas population density, body size and total prey volume of P. cinereus increased, with earthworm abundance. Earthworms, which are soft-bodied and nutritious prey, composed most of the salamander diet at sites with earthworms, volumetrically accounting for > 50% of total prey volume. Despite this, we found fewer prey items in the stomach of salamanders at earthworm-invaded sites, indicating that salamanders are getting a higher caloric intake per feeding while expending less energy. We conclude that non-native earthworms have a net beneficial effect on P. cinereus populations in Eastern Canada, mainly by improving diet quality. Supplementary Information The online version contains supplementary material available at 10.1007/s10530-023-03168-3.
... The presence of earthworms was determined in 2018 by hand-sorting of the litter and hot-mustard extraction from the mineral soil surface (Lawrence and Bowers, 2002) and from clear signs of earthworm activity such as the presence of surface casts or extensive bioturbation. Within each site, it was possible to identify earthworm-invaded and earthworm-free patches. ...
Article
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Earthworm invasion in North American forests has the potential to greatly impact soil microbial communities by altering soil physicochemical properties, including structure, pH, nutrient availability, and soil organic matter (SOM) dynamics. While most research on the topic has been carried out in northern temperate forests, little is known about the impact of invasive earthworms on soil microbial communities in hemiboreal and boreal forests, characterized by a slower decay of organic matter (OM). Earthworm activities can increase OM mineralization, altering nutrient cycling and biological activity in a biome where low carbon (C) and nitrogen (N) availability typically limits microbial and plant growth. Here, we characterized and compared microbial communities of earthworm-invaded and non-invaded soils in previously described sites across three major soil types found in the Canadian (hemi)boreal forest using a space-for-time approach. Microbial communities of forest floors and surface mineral soils were characterized using phospholipid fatty acid (PLFA) analysis and metabarcoding of the 16S rRNA gene for bacteria and archaea and of the internal-transcriber-spacer-2 (ITS2) region for fungi. In forest floors, the effects of earthworm invasion were minor. In mineral soil horizons, earthworm invasion was associated with higher fungal biomass and greater relative abundance of ectomycorrhizal fungi. Oligotrophic bacteria (Acidobacteriota and Chloroflexi) were less abundant in invaded mineral soils, where Gram(+) : Gram(-) ratios were also lower, while the opposite was observed for the copiotrophic Bacteroidota. Additionally, earthworm-invaded mineral soils harboured higher fungal and bacterial species diversity and richness. Considering the important role of soil microbial communities for ecosystem functioning, such earthworm-induced shifts in their community composition are likely to impact nutrient cycling, as well as vegetation development and forest productivity at a large scale, as the invasion progresses in these (hemi)boreal systems.
... We placed a 0.5 × 0.5 m metal frame on the ground, removed leaf litter within the frame, and collected any earthworms found in the leaf litter. We then slowly poured 3.8 L of a mustard solution (15 g/L) evenly across the area within the frame (Lawrence & Bowers, 2002) and collected all earthworms that emerged from the soil within a 10-min period. We stored earthworms in 2% formalin in the field and then transferred earthworms to 75% ethyl-ethanol 7-10 days later. ...
Article
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Land managers spend substantial resources managing invasive species to mitigate their negative ecological and economic impacts. However, invasive species management is seldom coupled with empirical assessments of management outcomes or the ecological impacts of the target species. Additionally, the study of invasive species has, until recently, neglected to acknowledge co‐stressors on native communities, which often are the drivers of ecological degradation. We assessed the effects of the invasive plant Vincetoxicum rossicum and its removal on understory plant communities, as well as whether these effects were mediated by deer and invasive earthworms. We used paired fenced and open plots with V. rossicum and an open plot without V. rossicum at each of the three forested sites in New York State Parks from 2017 to 2020. Following a nested design, we located paired sets of open and fenced plots in areas where V. rossicum was experimentally removed and in areas where it was unmanaged. After three years of V. rossicum removal, V. rossicum significantly declined. However, the ultimate goal of management was native plant recovery. Contrary to this aim, native plant diversity and cover increased if V. rossicum was left unmanaged but did not change with V. rossicum removal. Thus, we provide strong evidence that reducing target species abundance does not always translate into native plant recovery. This disparity may be because deer and invasive earthworms are stronger drivers of understory plant communities than V. rossicum, as native plant cover and diversity were lower the more earthworms were in a plot and invasive plant species declined after fencing to exclude deer. Management that prioritizes reducing deer and earthworm impacts over invasive plant removal is therefore worth exploring, especially when coupled with continued monitoring to assess if these actions result in the desired management outcomes. Overall, our findings underscore the need to collect data to test management assumptions: reducing the abundance of an invader may not always result in native plant recovery, especially if other stressors are the ultimate drivers of change in invaded communities.
... material 1). This combined approach has been shown to be the most accurate for obtaining a representative sample of earthworm communities at a site (Lawrence and Bowers 2002), whilst handsorting is also suitable for sampling a wide-range of soil macrofauna (ISO 2018). For each sample, the total abundance and fresh biomass of each soil fauna group (e.g. ...
Article
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Soil is often described as a ‘black box’, as surprisingly little is known about the high levels of biodiversity that reside there. For aboveground organisms, we have good knowledge of the distribution of the species and how they might change under future human impacts. Yet despite the fact that soil organisms provide a wide variety of ecosystem functions, we have very limited knowledge of their distribution and how their diversity might change in the future. In order to create accurate and generalisable models of biodiversity, the underlying data need to be representative of the entire globe. Yet even with our recently compiled global earthworm dataset of over 11000 sites, there are gaps across large regions. These gaps are consistent across many other datasets of both above- and belowground diversity. In order to fill the gaps we propose a sampling network (SoilFaUNa), to create a comprehensive database of soil macrofauna diversity and soil functions (e.g. decomposition rates). Building on the existing dataset of earthworm diversity and early data from the SoilFaUNa project, we will investigate changes in earthworm diversity. From our current work, we know that both climate and land use are main drivers in predicting earthworm diversity, but both will change under future scenarios and may alter ecosystem functions. We will, using space-for-time substitution models, estimate how earthworm diversity and their functions might change in the future, modelling earthworm diversity as a function of climate, land use and soil properties and predicting based on future scenarios. Previous studies of aboveground diversity changes over time using time-series analysis have found no-net-loss in richness, but analyses have criticisms. We aim to use time-series data on earthworms to move this debate forward, by using data and statistical methods that would address the criticisms, whilst increasing our knowledge on this understudied soil group. Field experiments and micro-/mesocosm experiments have been used to investigate the link between a number of soil organisms and ecosystem functions under few environmental conditions. Meta-analyses, which can produce generalisable results can only answer questions for which there are data. Thus, we have been lacking on information on the link between the entire community of soil fauna and ecosystem functions and impact of changes to the soil fauna community across environmental contexts. Using data collected from the SoilFaUNa project, we will, for the first time, synthesise globally distributed specifically-sampled data to model how changes in the community composition of soil macrofauna (due to changes in land use, climate or soil properties) impact the ecosystem functions in the soil.
... We collected local earthworm communities (EWL) from wet grasslands in the agricultural areas located within 1 km to the east of the study site (Fig. 1). We identified these three source sites after an initial characterization of the surrounding grasslands earthworm density using the mustard extraction method (Lawrence and Bowers, 2002).We only selected wet meadows presenting an earthworm density equal or higher to 80 individuals per square meter. Earthworms were collected by hand without any sizing or sorting of species. ...
Thesis
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Les friches industrielles représentent de réelles opportunités pour la création d’espaces naturels mais les méthodes de restauration et d’évaluation des bénéfices environnementaux de ces opérations sont très lacunaires. L’objectif de cette thèse a été, au travers d’un cas d’étude, de palier à ce manque. Les résultats obtenus mettent en évidence que la restauration des technosols de friches industrielles nécessite une approche pluri-compartimentale (végétation et sol) et que les méthodes utilisées actuellement en restauration des sols sont moins efficaces dans des milieux aussi dégradés. Une approche pluridisciplinaire alliant outils d’évaluation économique et indicateurs écologiques a été ajustée permettant l’évaluation des bénéfices environnementaux de tels projets. Des adaptations sont cependant encore nécessaires dans la récolte de données, la sélection des indicateurs et la conception de la méthode pour garantir une meilleure prise en compte du compartiment sol, optimiser l’intégration des objectifs du projet de restauration et des potentiels impacts de la restauration sur les populations locales.
... To include deeper-dwelling worms, earthworms were sampled from the mineral soil within two, randomly selected areas (50 × 50 cm) per plot using the mustard extraction method (Lawrence & Bowers, 2002). After litter removal, 5 L of 0.33% mustard solution was poured onto the soil surface in two steps after a 10-min interval (Gunn, 1992). ...
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Summer droughts strongly affect soil organic carbon (SOC) cycling, but net effects on SOC storage are unclear as drought affects both C inputs and outputs from soils. Here, we explored the overlooked role of soil fauna on SOC storage in forests, hypothesizing that soil faunal activity is particularly drought‐sensitive, thereby reducing litter incorporation into the mineral soil and, eventually, long‐term SOC storage. In a drought‐prone pine forest (Switzerland), we performed a large‐scale irrigation experiment for 17 years and assessed its impact on vertical SOC distribution and composition. We also examined litter mass loss of dominant tree species using different mesh‐size litterbags and determined soil fauna abundance and community composition. The 17‐year‐long irrigation resulted in a C loss in the organic layers (−1.0 kg C m ⁻² ) and a comparable C gain in the mineral soil (+0.8 kg C m ⁻² ) and thus did not affect total SOC stocks. Irrigation increased the mass loss of Quercus pubescens and Viburnum lantana leaf litter, with greater effect sizes when meso‐ and macrofauna were included (+215%) than when excluded (+44%). The enhanced faunal‐mediated litter mass loss was paralleled by a many‐fold increase in the abundance of meso‐ and macrofauna during irrigation. Moreover, Acari and Collembola community composition shifted, with a higher presence of drought‐sensitive species in irrigated soils. In comparison, microbial SOC mineralization was less sensitive to soil moisture. Our results suggest that the vertical redistribution of SOC with irrigation was mainly driven by faunal‐mediated litter incorporation, together with increased root C inputs. Our study shows that soil fauna is highly sensitive to natural drought, which leads to a reduced C transfer from organic layers to the mineral soil. In the longer term, this potentially affects SOC storage and, therefore, soil fauna plays a key but so far largely overlooked role in shaping SOC responses to drought.
... At each site, earthworms were collected from one 20 × 20 cm plot using a mustard liquid extraction technique (Lawrence and Bowers 2002). Plot boundaries were marked with a plastic frame. ...
Article
Introduced earthworms alter the trajectory and composition of plant communities, for example, through their feeding, burrowing behaviour, and interactions with seeds. High densities of several earthworm species may decrease native biodiversity and disrupt restoration efforts in tallgrass prairies. This affects efforts to conserve and restore such habitat, which is of high conservation and restoration priority in eastern North America and typically restored through seeding events. To date, Lumbricus terrestris (Lumbricidae) and other species have remained largely undocumented in tallgrass prairies. We surveyed 22 tallgrass prairie sites in southern Ontario, Canada, to document earthworm density and species. Lumbricus terrestris was found at all sites. The average density was 66 ± 91 (SD) earthworms/m2 across our sampling plots, mostly juveniles (~94%). The number of all earthworms per plot significantly increased with the number of earthworm middens in each plot (χ21 = 4.50, P = 0.034). Prairies with a large number of middens had high earthworm density, but middens alone appear to explain little variation in our data (linear mixed-effects model, marginal R2 = 0.12) meaning there are other biologically important factors that affect their density. However, we found no effects of soil pH, organic matter content, or texture on the number earthworms per plot suggesting that earthworms can invade a range of tallgrass prairie soils with pH values between 5.27 and 7.67.
... Ten publications did not specify the species ratios of constituent plants in mixtures; thus, we assumed that the plant species in these studies were evenly distributed. For earthworm studies that used the mustard extraction method, the soil depth of extraction was assumed to be 25 cm (Lawrence and Bowers, 2002). Stand age was recorded as the number of years between stand establishment or the experiment initiation and the sampling of soil fauna. ...
Article
Soil fauna communities are an important component of soil biodiversity, which is key to myriad terrestrial ecosystem processes. However, despite the current alarming loss of plant diversity, it remains unclear how plant diversity affects soil fauna communities. By synthesizing 623 paired observations of plant mixtures and corresponding monocultures from 40 studies, we examined the effects of plant mixtures on soil fauna abundance and diversity. Further, we investigated the dependence of mixture effects on species richness, stand age, climate conditions, and ecosystem types. We found that, on average, the diversity of soil fauna was 10% higher in plant mixtures than the average of corresponding monocultures, while the abundance of fauna did not differ significantly between the mixtures and the average of monocultures. The mixture effects on both soil fauna abundance and diversity increased with plant species richness in mixtures, which resulted in higher abundance and diversity of soil fauna in species-rich plant mixtures than the averages of their corresponding monocultures. Moreover, the effects of plant mixtures on soil fauna abundance increased over time in diverse species mixtures. After accounting for the effects of species richness in mixtures and stand age, the effects of plant mixtures on the abundance and diversity of soil fauna were consistent across soil depths, ecosystem types, and climate conditions. Our analysis highlights the potential importance of plant diversity conservation for the maintenance of soil fauna communities.
... The soil from the 25 cm × 25 cm × 20 cm hole was sorted for earthworms. A hot mustard powder solution (50 g L -1 ) was poured in the excavated hole to extract deeper earthworms (Lawrence and Bowers 2002). The number of adult and juvenile earthworms was tallied for each excavation, and reported as individuals m -3 . ...
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Soil quality assessments are needed to improve a professional’s ability to manage urban soils and trees. This research was conducted to identify which soil properties are most useful for relating information on urban tree performance. In total, 48 soil properties were measured at 84 sites from five urban landscapes in the western suburbs of Chicago, Illinois, U.S. Key physical, chemical, and biological properties to be included in a minimum data set (MDS) for assessing urban soil quality were identified using statistical approaches and practical considerations. The MDS included: texture, bulk density, wet-aggregate stability, pH, electrical conductivity, soil organic matter (SOM), and particulate organic matter. The MDS was used to establish an urban soil quality index (USQI). The MDS and USQI were highly correlated with tree size attributes of height, trunk diameter, crown area, and age. Correlations between the MDS and USQI with trunk diameter growth rate, height growth rate, foliar N, and chlorophyll content were often significant, but less strong. Among the MDS parameters, SOM, pH, and texture appear to be the most informative measures for soil quality relating to urban tree performance. Soil quality and tree performance increased logarithmically following site disturbance, with a plateau after 50 years.
... Earthworm specimens were obtained by hand-sorting of the litter and hot mustard application to the mineral soil surface (0.0625 m 2 ) within two meters of the pit used for soil description (Lawrence and Bowers, 2002). Each mature specimen was identified to the species level according to Reynolds (1977) and functional groups of earthworms were determined following Bouché (1977). ...
Article
Non-native earthworms have been invading North America since European settlement. Compared to temperate forests, their presence in the boreal forest is much more recent and thus remains understudied, despite the potential threat they represent for soil carbon (C) stocks. Here we compared earthworm-invaded and earthworm-free zones in soil types representative of the boreal forest, including Luvisols, Podzols, and Brunisols (Cambisols). We observed that the forest floor (surface organic layer, or LFH) decreased in thickness after invasion in most cases and developed into a Vermimull, with the loss of the most humified layer (humic or H horizon). Simultaneously, the surface mineral horizon was reworked by earthworms into a novel Ahu horizon, characterized by higher organic matter and enriched in earthworm casts. Forest floor C stocks decreased by 94% and 59% for Luvisols and Brunisols respectively, while those of Podzols remained apparently unaffected. Mineral soil C stocks in Brunisols increased after invasion, while no changes were observed in Luvisols and Podzols. Our results demonstrated the substantial impact that invading earthworms are having on soil morphological features and C stocks in boreal forests. Effects were similar to what has been reported for temperate forests, although the degree of impact depended on soil type. While C stocks were less affected in the mineral soil compared to the forest floor, the development of a novel surface horizon reworked by earthworms could alter microbial dynamics and impact mineral C persistence. Further research is needed to quantify long-term implications of earthworm presence for boreal soil C stocks.
... castings and burrows), soil depth (using a graduated metal rod) and location using a handheld GPS (accuracy: ± 8 m ,Garmin eTrex® 20x). We used 50 g of mustard powder mixed into 1 gallon of water, poured slowly over each quadrat to extract earthworms following Gunn (1992), Lawrence and Bowers (2002) and Arcese and Rodewald (2019) and identified all adults to species and juveniles to genus before returning them to an area adjacent to the sample quadrat. ...
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Biological invasions by cryptic ecosystem engineers can alter the ecological and socio‐economic values of ecosystems in ways that may take decades to detect. The invasion of North American glacial refuges by non‐native earthworms offers a prominent but understudied example of a cryptic invasion. Non‐native earthworms are known to alter carbon sequestration, disrupt mycorrhizal networks and homogenize plant communities, but natural resource managers still lack robust protocols to identify and safeguard high conservation value communities (HCVCs) from such invasions. In the absence of such protocols, or reliable methods to eradicate non‐native earthworm populations once established, there is an urgent need for methods to identify HCVCs at risk of or potentially shielded from earthworm invasion by the existence of abiotic barriers to their dispersal or persistence in such sites. We developed species distribution models (SDMs) using in situ field surveys and remotely sensed data to (1) identify factors limiting the occurrence of non‐native Lumbricus earthworms in imperilled coastal Douglas‐fir (Pseudotsuga menziesii) forest and Garry oak (Quercus garryana) and maritime meadow ecosystems endemic to glacial refugia of the Pacific Northwest of North America and to (2) evaluate their influence on plant species diversity and identify abiotic factors capable of preventing their dispersal or persistence at a site. As predicted, shallow, drier soils and steeper terrain limited earthworm occurrence and abundance in our highly heterogeneous study area, and earthworm presence appeared to reduce plant species richness. Our results indicated that HCVCs endemic to shallow‐soil (< 12 ± 3 cm) sites that experience regular summer drought appear to act as refuges from invasion by non‐native earthworms. Our results also elevate concerns for the conservation of deep‐soil habitats not isolated from earthworm invasions by shallow soil, saltwater or other barriers to earthworm dispersal. The SDMs developed here offer guidance to the identification of potential refuges for the conservation of imperilled native species and communities from the detrimental effects non‐native earthworms in glacial refugia of western North America and should thereby facilitate proactive planning by conservation practitioners.
... Two earthworm species were used in this experiment, namely the anecic Nicodrilus nocturnus (Nn), also known as Aporrectodea nocturna (according to Sims and Gerard (1999)) and the endogeic Allolobophora icterica (Ai) species, which are both commonly present in Swiss meadows. The earthworms were collected in different meadows using the mustard technique, rapidly rinsed in tap water (Lawrence and Bowers, 2002) and identified using the identification keys of Bouché (1972). ...
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Earthworms are known to play an important role in soil processes, especially in the regeneration of soil structure. However, quantitative studies about their role on soil physical properties are still scarce. In this study the effects of two earthworm species (Nicodrilus nocturnus as anecic, Allolobophora icterica as endogeic) following three treatments (N. nocturnus only, A. icterica only and both species with 80% weight of N. nocturnus and 20% of A. icterica) on soil specific volumes and pore properties are evaluated in mesocosms (30 cm height and 15 cm diameter) for a loamy Anthrosol and a silt loam Luvisol. The soils were repacked to bulk density observed in the field (1,15 and 1,25 g cm⁻³ respectively) and to compacted bulk density (1,4 and 1,5 g cm⁻³ respectively). Except earthworm-free controls, introduced earthworm biomass was close to 500 g.m⁻². The experiment lasted 23 weeks, under constant temperature and soil matrix potential, and earthworms were fed with hay. The impact of earthworms on soil porosities and specific volumes was assessed using (i) computed tomography on mesocosm and (ii) shrinkage analysis on undisturbed cubic samples (150 cm³). Anecic surface cast bulk density was determined after wax coating. At mesocosm scale, the specific volume of compacted soils increased significantly with the anecic and mixed earthworm treatments (+1.9% for the Anthrosol and +2.6% for the Luvisol), while no change was observed with endogeics regardless of the initial level of compaction or the soil type. After subtracting the burrow volumes, the remaining soil matrix specific volume showed significant decrease with earthworms in case of loose soils, particularly with endogeics with 5.6% decrease of the specific soil matrix volume, while the compacted soil matrix was not decompacted. At undisturbed cubic sample scale, shrinkage analysis confirmed these observations with earthworms decreasing the larger structural pores and promoting a more rigid plasma. Anecic surface casts showed intermediate bulk density (0.82 cm³ g⁻¹ for the Anthrosol and 0.73 cm³ g⁻¹ for the Luvisol) between compacted (0.73 cm³ g⁻¹ for the Anthrosol and 0.67 cm³ g⁻¹ for the Luvisol) and loose (0.88 cm³ g⁻¹ for the Anthrosol and 0.81 cm³ g⁻¹ for the Luvisol) soil matrices. We concluded that the decompaction effect of earthworms was due to the opening of burrows at mesocosm soil scale, while the matrix volume was i) either compacted in case of loose soil especially with endogeics at the expense of the >150 µm equivalent radius structural pores or ii) unchanged in case of compacted soil. Our results support the conclusion that earthworms alone cannot regenerate the matrix of compacted soils and even compact the soil matrix in case of loose soils.
... Four pits were excavated in each plot within 5 m distance from the labeled litter quadrats. Earthworms were extracted in each plot using the "hot mustard" method (Lawrence and Bowers 2002) on three or four 0.25 m 2 quadrats positioned within 3 m of the litter addition quadrats in May 2008, October 2008 and October 2009. Earthworms were returned to the laboratory, sorted by species and processed to determine ash-free dry weight. ...
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AimsWe conducted a suite of tracer studies using the stable isotope 13C to follow and quantify the flow of carbon from leaf litter and roots into soil components including aggregates and biota with and without invasive earthworms.Methods Ten-year-old saplings of sugar maple growing in the understory of a thinned northern hardwood forest were labeled with 13CO2. The 13C labeled leaf litter was applied to forest plots with and without invasive earthworms (Lumbricidae) and traced for three years. We also traced the label from the trees through the roots and into soil components in the labeling chambers. Labeled fine roots and stem wood were incubated in a forest and the label was quantified over six years of decomposition.ResultsWe were able to detect the litter tracer to 10 cm soil depth in plots without earthworms and to 20 cm with earthworms present, and earthworms promoted C incorporation into soil aggregates. The soil food web was much more enriched in the label from roots than from aboveground plant litter.. Rapid fine root decay was observed (k = 0.9 yr−1), and although labelled wood was almost completely decayed, little 13C was recovered in soil (0.33%).Conclusion The approach was successful for quantifying transport and fate of tree carbon in forest soils and could be enhanced with careful quantification of gross assimilation.
... Across the EcoUnits where earthworms were added, the density of earthworms extracted was around 18.3 ± 4.9 ind.m 2 (mean ± sd), and their total biomass was around 50.1 ± 9.9 g.m 2 (mean ± sd). However, the density of earthworms in the mesocosms is probably underestimated, as the mustard extraction method is not comprehensive and also less efficient for endogeic species (Chan and Munro, 2001;Lawrence and Bowers, 2002;Gutiérrez-López et al., 2016). Indeed, extracted earthworms mainly belonged to the anecic species L. terrestris (17.8 ± 4.8 ind.m 2 ; 50 ± 9.7 g.m 2 ), while few were from the endogeic species A. rosea (0.4 ± 1.0 ind.m 2 ; 0.1 ± 0.3 g.m 2 ). ...
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As ecosystem engineers, invasive earthworms are one of the main drivers of plant community changes in North American forests previously devoid of earthworms. One explanation for these community changes is the effects of earthworms on the reproduction, recruitment, and development of plant species. However, few studies have investigated functional trait responses of native plants to earthworm invasion to explain the mechanisms underlying community changes. In a mesocosm (Ecotron) experiment, we set up a plant community composed of two herb and two grass species commonly found in northern North American forests under two earthworm treatments (presence vs. absence). We measured earthworm effects on above- and belowground plant biomass and functional traits after 3 months of experiment. Our results showed that earthworm presence did not significantly affect plant community biomass and cover. Furthermore, only four out of the fifteen above- and belowground traits measured were affected by earthworm presence. While some traits, such as the production of ramets, the carbon and nitrogen content of leaves, responded similarly between and within functional groups in the presence or absence of earthworms, we observed opposite responses for other traits, such as height, specific leaf area, and root length within some functional groups in the presence of earthworms. Plant trait responses were thus species-specific, although the two grass species showed a more pronounced response to earthworm presence with changes in their leaf traits than herb species. Overall, earthworms affected some functional traits related to resource uptake abilities of plants and thus could change plant competition outcomes over time, which could be an explanation of plant community changes observed in invaded ecosystems.
... For example, in a residential yard, participants would walk through the space for approximately 10 minutes, brushing aside leaf litter and checking underneath planters or landscaping cloth (where the species are anecdotally known to congregate) for live earthworms, and examining garden soil for structural characteristics. Next, earthworms were surveyed at three haphazard locations using a 30 cm × 30 cm quadrat and a standard mustard extraction (Lawrence and Bowers 2002). This simple, fast, and nondestructive procedure involves pouring a mixture of mustard powder and water over a designated area of soil (figure 3). ...
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Asian pheretimoid earthworms of the genera Amynthas and Metaphire (jumping worms) are leading a new wave of coinvasion into Northeastern and Midwestern states, with potential consequences for native organisms and ecosystem processes. However, little is known about their distribution, abundance, and habitat preferences in urban landscapes—areas that will likely influence their range expansion via human-driven spread. We led a participatory field campaign to assess jumping worm distribution and abundance in Madison, Wisconsin, in the United States. By compressing 250 person-hours of sampling effort into a single day, we quantified the presence and abundance of three jumping worm species across different land-cover types (forest, grassland, open space, and residential lawns and gardens), finding that urban green spaces differed in invasibility. We show that community science can be powerful for researching invasive species while engaging the public in conservation. This approach was particularly effective in the present study, where broad spatial sampling was required within a short temporal window.
... The plots were sampled for earthworms three weeks after ash amendment (early October for pre-litterfall plots, early November for post-litterfall plots) and then again one year later. Earthworms were collected by clearing two 25 cm × 25 cm quadrats in corners of the plot (total area = 0.125 m 2 ) of litter and ash and driving earthworms to the surface by applying 2.5 L of mustard solution (10 g dry mustard powder to 1 L tap water) over 15-minutes (Lawrence and Bowers, 2002;Singh et al., 2016). The earthworms were euthanized in isopropyl, transferred to a 10% formalin solution for 24-48 h for fixation, and transferred back to isopropyl for storage (Hale, 2013). ...
Article
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.
... For soil fauna such as earthworms, ants and termites, it is possible to use hand-sorting method in all soils, however it is very labor intensive and time consuming (Schmidt, 2001a). Additionally, this method requires some destructive extraction technique like excavation, washing and sieving (Raw, 1960) or behavioral extraction (heat, electrical, chemical) (Raw, 1959;Tisdall and McKenzie, 1999;Schmidt, 2001b;Lawrence and Bowers, 2002), which inevitably lead to underestimation of the real abundance of animals due to the fact that animals may move into deeper soil instead of crawling to the soil surface. Moreover, destructive extraction means that the habitat is destroyed, so such methods cannot be considered as environmental friendly. ...
Article
Soil biota is the living component of soil organic matter (SOM), and plays a key role in the decomposition of SOM. Both soil biota and SOM are indicators of soil fertility and soil quality. However, they both are sensitive to soil disturbance. Although researchers developed various technologies to detect soil biota and SOM, they are mostly destructive and cause disturbance to soil, which may not reflect the actual situation of soil biota and SOM. Therefore, here we mostly focused on the non-destructive physical methods for estimating soil biota and SOM and discussed their advantages and disadvantages. These methods include but not limited to acoustic detection, radio frequency identification, radioactive tagging, hyperspectral sensing and electron energy loss spectroscopy. In addition, we pointed out the current research problems and the potential research directions for applications of physical methods in estimation of soil biota and SOM.
... These methods present logistical difficulties and several of them can be toxic for the operators (Eichinger et al., 2007). Innovative and harmless earthworm extracting substances, such as mustard, have been used (Chan and Munro, 2001) with encouraging and positive results (Lawrence and Bowers, 2002;Pelosi et al., 2009). Mustard suspension has no phytotoxic effects on plants, as shown by potassium permanganate and formalin, it is not prohibited by organic practices and it is safe for human beings and the environment (Valckx et al., 2009). ...
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Non-invasive geophysical methods, such as EMI (Electromagnetic Induction), are innovative tools to study soil biological parameters. This work was carried out to assess correlations between soil earthworm abundance and biomass and soil apparent electrical conductivity (ECa) measured by means of a Profiler GSSI EMP-400. The trial was performed in a 1-hectare commercial peach orchard characterized by a clay loam soil. Mustard method combined with hand-sorting technique were used to sample earthworms in areas (1 x 1 m) falling in cover cropped (CC) and chemically weeded (CW) strips. Statistically significant linear relationships were found between ECa, measured at 13 kHz, and earthworm biomasses in both CC and CW strips (R-2 > 0.72). Instead, abundance earthworm showed relations only in CW strips (R-2 > 0.50). EMI technique seems to be a very efficient tool to locate representative soil sampling areas and spatialize earthworm parameters at field level.
... Studying earthworm populations is difficult due to seasonal variations, identification issues (not least its ethics [38], and imperfect methods of extraction. This study employed the non-toxic "hot" mustard extraction method, which has been shown to provide a consistent index of earthworm abundance across a range of soil and land use types [39]. This widely used standard technique is less destructive than hand sorting or methods involving more toxic chemicals. ...
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The reclamation of surface (opencast) coal mines is not always successful; there remains a legacy of degraded land that burdens local communities. This article evaluates a community-oriented, low-cost means of geoecological regeneration, the “Cradle for Nature” strategy, which uses mosaic tree planting to foster positive natural ecological processes. Results show that, while the autocompaction of minestones quickly raises soil densities to levels hostile to plant growth, forestation helps moderate soil densities. Weathering concentrates metals in minestones, but 14 years of forestation reduced the loadings of five metals by 35–52%. Twenty years of forestation doubled soil organic carbon to >7%; increased bacilli from 7% to 46%; actinomycetes from 10% to 26%; and soil microbe counts 12–15 times, especially in tree plantings treated with fertiliser. Soils under trees also supported a significantly greater earthworm biomass than under grass but, while open-canopy plantings had increased ground flora biodiversity, closed-canopy plantings had lower diversity and biomass. Following closure to grazing, ground biomass increased sevenfold. Young trees act as bird perches and significantly increase seed fall. Small mammal biomass and biodiversity increases after tree planting and higher predators appear. Varteg’s constructed forest provides an effective “cradle” for an emergent geoecological system and its habitat mosaic maximises biodiversity.
... The sediment was collected from a recent alluvial deposit from a Calcaric Fluvisol (IUSS Working Group WRB, 2015) in the Sarine River floodplain near Grandvillard (7 04 0 E, 46 32 0 N). Earthworm sampling was performed using hot mustard (Lawrence & Bowers, 2002) and three species were selected relative to their ecological behaviour: the epigeic Lumbricus rubellus (R), the endogeic Allolobophora chlorotica (C) and the anecic Lumbricus terrestris (T), all of which are encountered in floodplains (Fournier, Samaritani, Shrestha, Mitchell, & Le Bayon, 2012;Salomé, Guenat, Bullinger-Weber, Gobat, & Le Bayon, 2011). All mesocosms were prepared similarly and randomly allocated to four treatments with earthworms (L. ...
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Soil structure is closely linked to biological activities. However, identifying, describing and quantifying soil aggregates remain challenging. X‐ray micro computed tomography (X‐ray μCT) provides a detailed view of the physical structure at a spatial resolution of a few microns. It could be a useful tool to discriminate soil aggregates, their origin and their formation processes for a better comprehension of soil structure properties and genesis. Our study aims to (a) determine different X‐ray μCT‐based aggregate parameters for differentiating earthworm casts belowground (earthworm aggregates) from aggregates that are not formed by earthworms (non‐earthworm aggregates), and (b) to evaluate if these parameters can also serve as specific “tomographic signatures” for the studied earthworm species. For this purpose, we set up a microcosm experiment under controlled conditions during 8 weeks, including three species of earthworms tested separately: the epigeic Lumbricus rubellus, the anecic Lumbricus terrestris and the endogeic Allolobophora chlorotica. Our results show that X‐ray μCT analysis helps distinguish earthworm aggregates from non‐earthworm ones using (a) the relative volume of the components within aggregates and (b) the volumetric mass of aggregates and their global volume. In particular, the volume ratio of mineral grains within the aggregates is significantly different according to earthworm species. So, X‐ray μCT is a powerful and promising tool for studying the composition of earthworm casts and their formation. However, future research is needed to take into account the shapes and spatial distribution of the aggregates' components, in particular the different states of organic matter decomposition. Highlights • Can earthworm belowground casts be differentiated from other soil aggregates using X‐ray μCT? • The use of X‐ray μCT for characterizing soil aggregates at a spatial resolution of a few microns. • A combination of X‐ray μCT variables discriminates earthworm casts from non‐earthworm aggregates. • X‐ray μCT, used alone, is relevant for defining species‐specific signatures of earthworm casts.
... Earthworms were sampled concurrently with vegetation sampling, using the hot mustard extraction method (Lawrence and Bowers 2002). At each site, a quadrat was selected from the 5.64 m radius circular plot, but within about 20 m from the circular plot. ...
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The Kenai National Wildlife Refuge has been given a broad conservation mandate to conserve natural diversity. A prerequisite for fulfilling this purpose is to be able to identify the species and communities that make up that biodiversity. We tested a set of varied methods for inventory and monitoring of plants, birds and terrestrial invertebrates on a grid of 40 sites in a 938 ha study area in the Slikok Creek watershed, Kenai Peninsula, Alaska. We sampled plants and lichens through observation and specimen-based methods. We surveyed birds using bird call surveys on variable circular plots. We sampled terrestrial arthropods by sweep net sampling, processing samples with High Throughput Sequencing methods. We surveyed for earthworms, using the hot mustard extraction method and identified worm specimens by morphology and DNA barcoding. We examined community membership using clustering methods and Nonmetric Multidimensional Scaling. We documented a total of 4,764 occurrences of 984 species and molecular operational taxonomic units: 87 vascular plants, 51 mosses, 12 liverworts, 111 lichens, 43 vertebrates, 663 arthropods, 9 molluscs and 8 annelid worms. Amongst these records, 102 of the arthropod species appeared to be new records for Alaska. We found three non-native species: Deroceras agreste (Linnaeus, 1758) (Stylommatophora: Agriolimacidae), Dendrobaena octaedra (Savigny, 1826) (Crassiclitellata: Lumbricidae) and Heterarthrus nemoratus (Fallén, 1808) (Hymenoptera: Tenthredinidae). Both D. octaedra and H. nemoratus were found at sites distant from obvious human disturbance. The 40 sites were grouped into five community groups: upland mixed forest, black spruce forest, open deciduous forest, shrub-sedge bog and willow. We demonstrated that, at least for a subset of species that could be detected using these methods, we were able to document current species distributions and assemblages in a way that could be efficiently repeated for the purposes of biomonitoring. While our methods could be improved and additional methods and groups could be added, our combination of techniques yielded a substantial portion of the data necessary for fulfilling Kenai National Wildlife Refuge's broad conservation purposes.
... Earthworms were sampled in late-May to early-June of 2016 and 2017 (results reported in Mahon and Crist 2019). We sampled earthworms using mustard extraction (Lawrence and Bowers 2002) from 0.25 m 2 quadrats located 1 m from paired litter boxes ( Figure S1). Earthworms were immediately placed in 70% ethanol and brought to the laboratory for identification and mass determination. ...
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Herbivore overabundance and species invasions could alter decomposition rates in temperate forests, with consequent effects on carbon sequestration, nutrient retention, and other ecosystem processes. At local scales, herbivores, invasive plants, and soil macroinvertebrates can be important drivers of decomposition, but interactive effects among these different groups are unknown. We tested for the effects of white-tailed deer, Amur honeysuckle, and earthworm activity (manipulated via mesh exclusion) on litter decomposition rates and loss of litter nitrogen (N) in five hardwood forest sites in southwestern Ohio. Each site consisted of a 20 × 20-m deer exclosure paired with a deer access plot; honeysuckle was removed from half of each plot. Effects of earthworm activity were tested using paired litter boxes of fine mesh (0.25 mm; earthworms excluded) or coarse mesh (10 mm; earthworm access). Restriction of earthworm activity in fine mesh treatments slowed litter decomposition and increased retention of N in the litter layer compared to coarse mesh. Deer access interacted with mesh treatments, with faster decomposition occurring in deer access, coarse mesh treatments relative to others. Greater earthworm biomass in deer access plots relative to deer exclosure plots corresponded with more rapid litter decomposition. Honeysuckle presence did not affect litter decomposition, but did increase litter N retention. The interactions between deer and earthworm activity indicate that reductions in deer populations may slow litter decomposition rates, increasing complexity of habitat structure at the soil surface, which relates to habitat for plants and animals.
... Within each plot, we marked 20 transects (each 2 m wide by 10 m long) divided into 20 planting cells (1 9 1 m). We repeatedly checked presence and abundance of earthworms (N = 10 sampling areas per plot) using the mustard extraction method (Lawrence and Bowers 2002). Earthworms were always present in the invaded areas although their abundance fluctuated from year to year, while earthworm free areas continue to remain earthworm free (Dobson and Bowe, unpublished data). ...
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Forest understory plants in eastern North America experience heavy white-tailed deer browse and impacts associated with invasive species, including of non-native earthworms. Deer and earthworms are well-recognized ecosystem engineers due to their ability to alter understory plant dynamics. We examined interactive effects of earthworms and deer on four woodland ferns (Adiantum pedatum, Polystichum acrostichoides, Dryopteris marginalis, and Dennstaedtia punctilobula) using field and common garden experiments. In the field we planted ferns into fenced and deer-accessible plots in areas with and without earthworms. In a common garden, we assessed both fern responses to different earthworms and fern effects on earthworm survival and biomass. Venue was important in determining experimental outcomes. In the field, A. pedatum and P. acrostichoides showed higher survival and P. acrostichoides grew taller or produced more fronds in worm-invaded areas. Deer presence/absence was not a significant explanatory variable. In the common garden, earthworms had no discernible effect on ferns, but fern species identity varied in its effect on earthworm survival and leaf litter decomposition. Our findings indicate that, contrary to many other understory species, common ferns benefit or are unaffected by earthworms. That we obtained different and even contradictory results in different venues should encourage investigators to validate common garden findings in the field.
... For each sampling point, average carbon content (%) of forest floor and litterfall was used to work out fractional annual loss of carbon on a per m 2 basis.To capture the effect of environmental drivers on functional marker performance, we measured two additional predictors of decomposition important in urban systems: earthworm density and climate. In late October, earthworm density was estimated from three 25 cm × 25 cm quadrats at each plot using a mustard solution; this method, in which a solution of dry mustard is poured onto the soil, causing earthworms to emerge, is at least as precise as manual extraction(Lawrence & Bowers, 2002). Mean annual precipitation and mean summer temperature were obtained for each woodland from spatially continuous climate model estimates for the 1980-2010 period(McKenney et al., 2011). ...
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Questions With increasing focus on urban sustainability, new tools are needed to manage urban woodlands for resilience and ecosystem service provision. Functional traits can provide quantitative and testable links between urban plant communities and specific ecosystem properties (functional markers). We ask whether commonly described multivariate patterns of trait association with urbanization (trait syndromes) capture changes in ecosystem properties associated with urbanization. Given that environmental heterogeneity can generate weak or non‐linear trait–ecosystem property relationships, we ask whether linear methods can yield functional markers with significant power for different ecosystem properties. Location Montreal metropolitan area (Canada). Methods We documented the functional composition of 43 woodlands along an urbanization gradient and measured proxies of three ecosystem properties: plant colonization, soil water infiltration and organic matter decomposition. We use redundancy analysis to identify traits associated with urbanization, and multiple linear regression and model selection to identify response and effect traits that best predict actual differences in ecosystem properties. We compare the resulting linear model with a non‐linear equivalent. Results Traits associated with urbanization (urban syndrome) were inconsistently selected as best predictors of ecosystems properties (functional markers). Although predictive power varied between ecosystem properties, all three could be significantly predicted from community‐weighted traits (functional markers), with both response and effect traits contributing to the final model. When we fitted equivalent non‐linear models, we found that traits had largely non‐linear relationships with ecosystem properties. Conclusions Our results demonstrate that community‐weighted traits of urban woodlands can yield functional markers that capture ecosystem properties, but these are inconsistently identified by “trait syndrome” approaches. In linear combinations, such functional markers provide a testable and generalizable way to quantify ecosystem properties in urban woodlands. Capturing such properties is one important step toward management of woodlands for their continued ability to provide ecosystem services into the future.
... Non-destructive or "environmental friendly"; more effective on anecic species; expensive(Chan and Munro, 2001)(Lawrence and Bowers, 2002) Formalin A standard method for the expulsion of earthworms; highly toxic to soil organism. Allyl isothiocyanate (AITC) Environmental friendly; effective on deep-burrowing anecic species. ...
Article
Vermiremediation is an expanding technology that uses earthworms to remediate organically contaminated soils and has been attracting attention from researchers gradually. This review outlines general aspects of vermiremediation, including its concepts, processing of organics-polluted soils, its advantages and limitations, the methods for enhancing vermiremediation, and other peripheral issues. Processes involved in vermiremediation of soils contaminated by organic chemicals mainly include vermiaccumulation and vermiextraction, vermitransformation, and drilodegradation. Vermiaccumulation plays an important role in vermiremediation and should be highlighted. Vermiremediation technology can be characterised as environmentally friendly, effective, sustainable. Strategies for enhancing vermiremediation might include the use of surfactants, nutrient amendments, management strategies, or combinations with other remediation technologies. Unlike previous reviews, peripheral issues such as the inoculation and colonising of earthworms in contaminated field and methods for harvest and disposal of earthworms used in vermiremediation are also discussed. However, there are many issues need to be clarified, including i) the capacity, contribution, and mechanisms of different vermiremediation processes; ii) the behaviour of organic pollutants in the drilosphere, iii) enhancement measures for vermiremediation and their side effects, and iv) earthworm collection methods in polluted soil and their post-harvest disposal. This review gives a general outline of vermiremediation, which is expected to promote further studies and practical application of vermiremediation in organically contaminated soils.
... Also during the vegetation periods, P. arundinacea shoots cut from outside of the experimental plots were applied in equal amounts to all plots without vegetation every two months and after each major flood, in order to provide a nutrient resource for earthworms and to minise differences in evaporation from plots with and without vegetation. The abundance of earthworms was reduced by using the hot-mustard extraction method, described in Lawrence and Bowers (2002), in May and October 2015. After pre-moistening the soil by extensive sprinkling with river water, two 24 L portions of a suspension of 6% pre-soaked mustard seeds in river water were applied with a watering can. ...
... Prior to earthworm extraction, we collected leaf litter and woody detritus leaving a bare soil surface. We then poured 3.1 L of mustard solution (10 g/L concentration) onto the bare soil to extract earthworms (Lawrence and Bowers 2002). Mustard extraction is a non-destructive method of collection that is sensitive to both soil moisture and earthworm activity (Eisenhauer et al. 2008). ...
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Recent studies have shown that complex species interactions can regulate above‐ and belowground processes in terrestrial systems. Ungulate herbivory and invasive species are known to have strong effects on plant communities in some systems, but their impacts on soil biota and belowground processes are lesser known. Growing evidence suggests white‐tailed deer (Odocoileus virginianus) and invasive plants facilitate increased abundance of exotic earthworms in temperate forests of the eastern United States. We conducted an experimental study that manipulated deer access and the presence of an invasive understory shrub in an eastern deciduous forest of southwestern Ohio, USA, from 2013 to 2017. Earthworm density and biomass, and standing litter biomass were measured in five paired deer access and exclosure plots, each with a split‐plot removal of Amur honeysuckle (Lonicera maackii). Earthworm density declined in response to the experimental exclusion of deer, with earthworm density decreasing over time in the deer exclosure plots relative to deer access plots. Deer exclusion produced greater variation in earthworm species composition relative to access plots. Multivariate analyses indicated that larger earthworms in the genus Lumbricus were associated with deer exclosure plots, while smaller endogeic species were ubiquitous in both treatments. Standing litter biomass decreased over time in the deer‐access plots. In contrast, honeysuckle removal had little effect on earthworm density and standing litter biomass. There was an interaction between deer and honeysuckle treatments on earthworm biomass, with honeysuckle removal reducing earthworm biomass when deer were excluded. Our results demonstrate strong effects of herbivores on invasive earthworms and ecosystem processes, but indicate a weaker influence of invasive shrubs. Further, our findings suggest that the effects of deer overabundance in forest ecosystems are potentially reversible with long‐term intervention.
... Gastropod identification followed (Hausser, 2005), whereas isopods were identified by specialists (see acknowledgements). Earthworms were collected between mid-September and the end of October 2015 using a standardised method combining hand sorting (Bartlett et al., 2010) and mustard solution (0.6%) extraction (Lawrence and Bowers, 2002). The sampling sites were 0.3 m × 0.3 m with a depth of 0.3 m. ...
Article
In the face of growing urban densification, green spaces in cities, such as gardens, are increasingly important for biodiversity and ecosystem services. However, the influences of urban green space management on biodiversity and ecosystem functioning (BEF) relationships is poorly understood. We investigated the relationship between soil fauna and litter decomposition in 170 urban garden sites along a gradient of urbanisation intensity in the city of Zurich, CH. We used litter bags of 1 and 4 mm mesh size to evaluate the contribution of soil meso- and macrofauna on litter decomposition. By using multilevel structural equation models (SEM), we investigated direct and indirect environmental effects and management practices on litter decomposition and litter residue quality. We evaluated the role of taxonomic, functional and phylogenetic diversity of soil fauna species on litter decomposition, based on a sample of 120 species (81,007 individuals; 39 collembola, 18 earthworm, 16 isopod, 47 gastropod species). We found highest litter decomposition rates using 4 mm mesh size litter bags, highlighting the importance of soil macrofauna. Urban warming, a proxy for urbanisation intensity, covaried positively, whereas soil disturbances, such as intensive soil and crop management, were negatively correlated with decomposition rates. Interestingly, soil fauna species richness decreased, with the exception of gastropods, and soil fauna abundance increased with urban warming. Our data also show that plant species richness positively affected litter decomposition by increasing soil fauna species richness and microbial activity. A multivariate analysis of organic compounds in litter residues confirmed the importance of soil fauna species richness and garden management on litter decomposition processes. Overall, we showed, that also in intensively managed urban green spaces, such as gardens, biodiversity of plants and soil fauna drives key ecosystem processes. Urban planning strategies that integrate soil protecting management practices may help to maintain important ecosystem services in this heavily used urban environment.
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Earthworm invasion in North American forests has the potential to greatly impact soil microbial communities by altering soil physicochemical properties, including structure, pH, nutrient availability, and soil organic matter (SOM) dynamics. While most research on the topic has been carried out in northern temperate forests, little is known on the impact of invasive earthworms on soil microbial communities in the boreal forest, a region characterized by a slower decay of organic matter (OM). Earthworm activities can increase OM mineralization, altering nutrient cycling and biological activity in a biome where low carbon (C) and nitrogen (N) availability is typically limiting microbial and plant growth. Here, we characterized and compared microbial communities of earthworm-invaded and non-invaded soils in previously described sites across three major soil types found in the Canadian boreal forest using a space-for-time approach. Microbial communities of forest floors and surface mineral soils were characterized using phospholipid fatty acid (PLFA) analysis and metabarcoding of the 16S rRNA gene, for bacteria and archaea, and ITS2 region for fungi. In forest floors, the effects of earthworm invasion were minor. In mineral soil horizons, earthworm invasion was associated with higher fungal biomass and greater relative abundance of ectomycorrhizal fungi. Oligotrophic bacteria (Acidobacteriota and Chloroflexi) were less abundant in invaded mineral soils, where Gram(+) : Gram(−) ratios were also lower, while the opposite was observed for the copiotrophic Bacteroidota. Additionally, earthworm-invaded mineral soils harboured higher fungal and bacterial species diversity and richness. Considering the important role of soil microbial communities for ecosystem functioning, such earthworm-induced shifts in their community composition are likely to impact nutrient cycling, as well as vegetation development and forest productivity at a large scale as the invasion progresses in these boreal systems.
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Fly ash (FA) is an inevitable byproduct of coal-fired thermal power plants that need timely, effective, and safe disposal in many developing countries. It is an amorphous Ferro-alumino silicate material similar to soil having practically all the elements except organic carbon, nitrogen, and phosphorous. Although in many developed countries, its use has reached saturation but technologically-starved poor countries are still lagging far behind in its resourceful use. Its use in cement-concrete, and land and mine filling have been widely accepted but in agriculture, this chemically heterogeneous material deserves cautious consideration. At low concentrations, FA alters soil physicochemical properties and thus, acts as a soil ameliorant or conditioner. However, its use at a higher rate is restricted due to the presence of heavy metals that affect the soil biosphere and limit plant growth. Hence, remediation of toxic metal ions for sustainable agricultural intervention is a prerequisite in FA-contaminated soils or dumpsites. Like phytoremediation, earthworms with unique accumulation, extraction, transformation, conversion, degradation, and stimulation properties could also be engaged in the remediation of FA. In this chapter, attempts have been made to elucidate various mechanisms and processes involved in vermiremediation, and the advantages, disadvantages, and future prospects of this innovative technology.
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Brownfield technosol restoration represents a real opportunity to minimize land consumption, but it often requires intensive intervention and reconstruction, leading to soil donor site destruction and potential pollution. Using a former oil refinery brownfield site, this research compares the short-term (one year) impact of localized restoration methods, including soil surface scarification, organic matter addition, earthworm inoculation (locally and commercially sourced), on the soil fauna and vegetation properties. Vegetation rapidly covered the bare soil, but few significant impacts were observed in terms of the soil or vegetation structure. The initial positive impact of soil scarification on surface compaction quickly faded and earthworm inoculations did not seem to impact soil characteristics. Natural soil colonization by vegetation or fauna was the major driver in soil modification. The analysis of an intermediate reference showed a delay of multiple decades between vegetation, fauna density, and soil structure improvement, as well as the achievement of a soil of “good biological quality”. We conclude that the use of engineer species on brownfield soil in its actual form is not an early restoration step but should be tested in later steps (e.g., when organic matter content is sufficient). However, additional research is needed in engineer species selection and multi-compartment approaches. A better understanding of the impacts of natural colonization in the early stages of technosol restoration is also essential for restoration techniques’ improvement.
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For several decades resilience thinking has served as a major theoretical lens for social‐ecological research, with geographers playing important roles in both advancing the theory and offering meaningful critique. In recent years resilience thinking has also emerged as a promising tool for the assessment of food systems, yet there is significant disagreement among scholars as to the best way to apply resilience thinking to food systems. At the heart of these disagreements lie a set of conceptual tensions that have long existed in the resilience community regarding best practices for operationalizing resilience and the extent to which resilience thinking can (or should) engage with issues of social justice and power dynamics. Geographers, particularly those working in the fields of political ecology and critical physical geography, are well positioned to navigate these tensions and contribute to the growing scholarship on food system resilience through what I call an instrumental‐reflexive approach to resilience thinking. Drawing on scholarship on the role of environmental science in political ecology and critical physical geography, I develop an approach to resilience that deploys empirical assessments to provide instrumental knowledge of food systems, but also engages reflexively with empirical findings to consider how they interact with entrenched power relations across multiple scales—practices that have a long tradition in geographic scholarship. In so doing, I chart an approach to resilience that, provides significant utility for farmers and food system workers, and gives support (though not the ultimate justification) for dismantling unjust and exploitative structures in our current food systems.
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A comprehensive and quantitative knowledge of ecological factors affecting crop production is needed in purpose to meet the challenge of growing world population with minimal environmental impact. Earthworms are target organisms both for scientists studying the biological component of soils and for farmers concerned with monitoring the quality of their soils. For the growing social interest to quantify the role of earthworms in ecosystems, a precise and accurate estimation of their diversity, abundance and biomass is needed. Earthworm ecologists tend to use methods of extraction with less use of chemicals, with this purpose we want to test some new environmental friendly methods like chili powder, mustard powder, mustard-vinegar suspension, in comparison with formalin 0.1% (10 ml in 8 l water) and 0.2% (15 ml in 8 l water). Efficiency of methods is compared in terms of earthworm species composition, numbers, biomass, ecological groups (epigeic, anecic, endogeic), development stages (adults + subadults vs. juveniles) and the mortality rates in the first week after sampling.
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For developing efficient sampling method for earthworm in Japanese agricultural lands, we investigated mustard extraction technique in efficiency of earthworm sampling and the sampling time. Test was conducted at nine agricultural lands in volcanic and non-volcanic ash soil three times during the year, early summer, summer, and fall. Firstly earthworms were collected by using mustard method, and then the rest of earthworms being from 5 to 30cm were collected by hand sorting. Around 80% of earthworms were collected by mustard method. The efficiency was affected by soil moisture and soil type. The efficiency was higher in volcanic ash soil than non-volcanic, and the efficiency decreased in less than 25% volumetric water content. Surface dwelling earthworms were collected 100% and soil dwelling species were collected about 70%. Mustard extraction technique was able to save sampling time 24.4 minutes in 0.125m^2 compared with hand sorting. Although sampling efficiency varies in ecological groups based on their habitat, mustard method under suitable soil condition, moist and from 15 to 25℃ provide saving time and labor. This investigation showed mustard method is useful earthworm sampling technique in Japanese agricultural land.
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Studies of interactions among earthworms as prey for visually foraging predators required a field method that measures earthworm availability (i.e., the density of surfacing earthworms). We present such a method by counting surfacing earthworms at night by an observer lying prone on a cart propelled by an observer across measured distances at constant low speed. The method was applied in dairy farmland grasslands in The Netherlands during October and November 2011. We quantified the numbers of surfacing earthworms as well as those measured during standard hand‐sorting sampling (i.e., total abundance based on soil counts), distinguishing clay or peat soils and grasslands with either monocultures or species‐rich vegetation. Managed grasslands with different soil types showed opposing correlations between surface availability and total abundance of earthworms. This emphasizes the importance of direct measurements of earthworm availability if the goal of the study is to explain the behavior of either visual earthworm predators or earthworms themselves. © 2019 The Wildlife Society. We developed and field‐tested a quantitative research tool to measure the availability of earthworms in grasslands for visually hunting predators, a method that is easy to perform and replicable. We have shown that only a small fraction of the total earthworms come to the surface at night and soil counts of earthworms do not predict densities of surfacing earthworms.
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The process to recycle lignin-rich coconut leaves, produced in abundance from coconut gardens, to vermicompost, using a local isolate of Eudrilus sp. is an important value-addition technology from ICAR-Central Plantation Crops Research Institute helping coconut farmers and entrepreneurs to enhance their economic returns. Vermicompost is produced in cement tanks and at the end of the composting period, earthworms are hand-sorted from the mature and partially composted materials by employed workers. The scarcity of labour for earthworm sorting and nonavailability of earthworms at the required time for further vermicomposting had become an impediment in sustained production of vermicompost leading to abandonment of the technology by many adopters. To overcome this situation, a simple push–pull/pull–pull strategy was developed for harvesting the earthworms, wherein freshly ground mustard solution was used as repellant (push agent) and cow dung (with or without bagasse/banana wastes) was used as an attractant (‘pull’ agent). The strategy is simple, efficient and saves on labour, eliminates drudgery, reduces production cost and time. It will pave way for sustained adoption of vermicomposting technology by coconut farmers and entrepreneurs.
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Above and belowground interactions between animals can influence species abundances, biological invasions, and ecosystem processes. A deeper understanding of above and belowground interactions among animals might benefit from considering functional groups or functional traits, yet most studies have focused on plant functional traits. Here, we consider the possible role of functional group and body size for interactions between invasive earthworms and deer. White-tailed deer are overabundant and are often times considered ecosystem engineers within many forest communities, while invasive earthworms have become an emerging threat to forest communities. We therefore asked a series of questions determine if there were any connections between these two species, with the first being: Do white-tailed deer influence invasive earthworm populations? Because invasive earthworms are divided into different functional groups based on their placement in the soil column and feeding mode, we asked if each of the earthworm functional groups would respond differently to the presence of deer. Finally, we asked if earthworm body size might correlate with the effects of white-tailed deer. We sampled earthworms across 44 paired deer exclosure and control sub-plots across four spatial regions in Ohio, USA. Our analysis controlled for phylogenetic relationships among invasive earthworms, to ensure that confounding effects of evolutionary history did not obscure our ability to detect trait correlations. We found that control sub-plots had more than twice as many endogeic, or soil-dwelling earthworms (e.g. Octolasion tyrtaeum) than paired deer exclosure sub-plots, in the three regions in which they were found. Smaller earthworms were more likely to have higher abundance in the presence of deer, including in phylogenetically corrected tests. If deer overpopulation has a positive effect on some functional groups of invasive earthworms, this suggests that managing deer is important, not only for their aboveground effects on plant communities, but also for their belowground effects on invasive earthworms. More generally, studies of above and belowground interactions might benefit from considering animal functional traits, such as body size, which correlates with functional feeding group.
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Most Dutch dairy farmland today is fertilized with slurry, a mixture of cattle dung and urine. As a food source for earthworms, this type of organic fertilizer is of lower quality than the traditionally used farmyard manure consisting of dung with some urine and mixed with bedding material such as straw. Earthworms living in dairy farmland belong to two distinct ecotypes, the detritivores and the geophages. Detritivores rely on farmyard manure as a food source more than geophages and therefore the type of organic fertilizer is expected to determine their relative abundances. In turn, this would affect higher trophic levels, as detritivores, when they come to the surface to collect food, are particularly important as prey for birds and mammals. Here we tested the hypothesis that dairy farmland fertilized with slurry will contain fewer detritivorous earthworms (thereby becoming less attractive for earthworm predators) by quantifying the abundance of the two earthworm ecotypes in 45 grasslands fertilized with either slurry, farmyard manure, or both. To determine the availability of detritivores for earthworm predators, we quantified earthworm surface availability by counting surfacing earthworms in the field and compared these numbers with densities belowground. To study the direct effects of different organic fertilizer types on earthworms, we measured their growth rates under controlled constant conditions using either slurry or farmyard manure, with hay as a control. We found that detritivores occurred in the highest densities in grasslands only fertilized with farmyard manure and that they also grew better on farmyard manure than on slurry. These differences were not found in geophages. Detritivores made up 25% of the total earthworm abundance in the soil, but contributed 83% to the surfacing earthworms at night; detritivore earthworms will thus be the main prey for visually hunting earthworm predators. The few dairy farmers using farmyard manure to fertilize their grasslands today will thus encourage the presence and availability of an earthworm ecotype which benefits higher trophic levels such as the endangered meadow birds.
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Information on bioavailability of two antibiotic TOrCs, ciprofloxacin (CIP) and azithromycin (AZ), to terrestrial organisms is severely limited, especially in the biosolids context. Responses of two terrestrial organisms, earthworms and microbes, to a range of environmentally relevant concentrations of biosolids-borne CIP and AZ were assessed in laboratory incubation studies involving 3H-labeled compounds. Earthworm assessments were based on the Earthworm Sub-chronic Toxicity Test (OCSPP 850.3100). Microbial impacts were assessed using respiration and reverse transcriptase-quantitative PCR (mRNA) analyses of nutrient (N and P) cycling genes as toxicity markers. Antibiotic extractability and stability during incubations were assessed using sequential extractions with CaCl2, methanol:water, and accelerated solvent extraction and analyses using thin layer chromatography. Subsample combustion, in addition to sequential extraction, recovered nearly 100% of the added antibiotic. The two compounds persisted (estimated half-lives ≥ 3 y), but extractable fractions (especially of CIP) decreased over time. Neither biosolids-borne antibiotic significantly impacted overall respiration or N and P cycling. Microbial toxicity responses were minimal; complementary DNA (cDNA) concentrations of ammonia oxidizing bacterial genes were affected, but only initially. Similarly, earthworms showed no apparent response related to toxicity to environmentally relevant (and much greater) concentrations of biosolids-borne CIP and AZ. Earthworms, however, accumulated both compounds, and the bioaccumulation factor (BAF) values (dry weight basis) were ~4 (CIP) and ~7 (AZ) in depurated worms and ~20 (CIP and AZ) in un-depurated worms. The microbial and earthworm responses strongly to moderately correlated with "bioaccessible" fractions of the target TOrCs. The results suggest that biosolids-borne CIP and AZ toxicity to terrestrial microbes and earthworms is minimal, but there is a potential for target TOrC entry into ecological food web.
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Comparison of 3 earthworm sampling techniques. Provides an assessment of biases versus species, season, stages of development, activity level.-from Authors
Article
SVENDSEN1 showed that the estimate of an earthworm population obtained by hand sorting soil samples was much greater than that by the prevalent method of bringing worms to the soil surface with potassium permanganate solution, and so emphasized that, although laborious, hand sorting was more accurate for population studies. The accuracy of estimates by hand sorting has not been studied but is likely to depend on soil type and conditions, as well as on the time and care taken to examine the sample. One way to estimate accuracy is to see how many worms can be recovered when samples, already hand sorted, are examined again by a different method.
Article
The efficiency of mustard as a vermifuge for estimating earthworm populations or collecting earthworms for laboratory studies was compared with that of formalin, potassium permanganate and household detergent. Mustard was as efficient as potassium permanganate and both these substances were better than formalin. Household detergent was an extremely poor vermifuge. Mustard does not kill earthworms as does potassium permanganate, and unlike formalin it is not carcinogenic and does not have phytotoxic effects on clover. -from Author
Article
Fifteen species of earthworm were collected from a reclaimed fen peat soil used for rough hay in County Offaly, Ireland. The most common species were Aporrectodea tuberculata, Allolobophora chlorotica, Eisenia rosea and Octolasion tyrtaeum. A. tuberculata, A. chlorotica and E. rosea formed a significant association. The total numbers of earthworms collected by hand-sorting reached a maximum of 197.1 m−2. Compared with hand-sorting, formalin-expulsion was an inefficient sampling method for most species. Soil moisture varied within the study area. Total densities and biomasses of the earthworms were greater where the soil was drier. A. tuberculata, A. turgida, Satchellius mammale and the pink form of A. chlorotica were more common in the dry soils whilst O. tyrtaeum, Lumbricus rubellus and the green form of A. chlorotica were more common in the wet soils.
Article
Soil-inhabiting invertebrates are extremely diverse in form, differ greatly in size and numbers, and are often aggregated in horizontal and vertical distribution. Methods available for assessing populations are all based on representative samples. They include field counting, use of attractant traps or pitfall traps, and assessing numbers of invertebrates in soil samples. Invertebrates can be separated from soil either by wet or dry methods based on physical principles, or by dynamic methods which use stimuli to make them leave the samples.Physical methods of separation include hand sorting of soil, soil washing and flotation, elutriation in an upward flow of water, use of a technique which involves passing soil over plates covered with a grease film in which the invertebrates become embedded, and centrifuging soil samples in water or dense solutions so that invertebrates come to the surface. Dynamic methods suitable for most arthropods include the use of dry funnels with, high controlled temperature and moisture gradients, and wet-funnel methods which are used mainly for nematodes and echytraeid worms.Dry funnels which are easy to use are the most popular technique, but have the drawback that they do not extract eggs or resting stages. Wet funnels, which are more laborious, recover these stages, but also dead individuals. Flotation methods are best for sandy soils, whereas dry funnels are more efficient for peat or clay soils. For most soils, dry funnels are most efficient for the extraction of micro- and mesoarthropods, but flotation is usually preferable for macroarthropods.
Article
SVENDSEN1 showed that the estimate of an earthworm population obtained by hand sorting soil samples was much greater than that by the prevalent method of bringing worms to the soil surface with potassium permanganate solution, and so emphasized that, although laborious, hand sorting was more accurate for population studies. The accuracy of estimates by hand sorting has not been studied but is likely to depend on soil type and conditions, as well as on the time and care taken to examine the sample. One way to estimate accuracy is to see how many worms can be recovered when samples, already hand sorted, are examined again by a different method.
Distribution, abundance, and species associations of earthworms (Lumbricidae) in a reclaimed peat soil in Ireland Comparison critique de methodes d'evaluation des populations de Lumbricides Earthworm functions VIII. Popula-tion estimation techniques
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The use of mustard to estimate earthworm populations Earthworms: Their Ecology and Relationship With Soils and Land Use Earthworm population studies: a comparison of sampling methods
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Extracting earthworms from the soil
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Fox, C.A., 1999. Extracting earthworms from the soil. At: http://res.agr.ca/ lond/pmrc/faq/wormsoil.html.
Oligochaeta: Lumbricidae
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