Session 2: Community ecology and ecological networks - Earthworm together and with the others
(Tuesday, July 12 – 9:00 a.m. – 12:45 a.m.)
Orals
How network analysis can help us understanding the processes of community assembly and the functional role of earthworms and soil organisms
Jérome Mathieu
Sorbonne Université, Institute of Ecology and Environmental Sciences, Paris, France
Understanding the patterns of diversity and composition of earthworm communities across space and time is a long-standing challenge. How interactions shape community structure, and how the structure of interaction networks constrain community dynamics and ecological function arecentral questions to make progress on this topic. Although graph theory precisely allows the study of ecological communities and trophic networks from this angle, and can help us understanding earthworm community assembly processes, it has been seldomly apply to these organisms. Here we will explore how this approach can help us understanding the patterns of earthworms’ community and their potential role in energy fluxes withinfood-webs.
Graph theory can for instance be used to make inference about the impact of a species loss or gain on the others, and subsequently, identify the species with the highest potential impact on others. This can be useful to explore the potential impact of global change on earthworm communities, such as land use change, climate change, or biological invasions, and also to guide management recommendations. Network analysis can also be useful to identify communities of species,based on the typology of their pairwise interactions, putting aside their potentially correlated response to the environment. Indeed, recent techniques now allows to circumvent the main weakness of traditional approaches based on co-occurrence, which is the impossibility to disentangle common ecological preferences from true species association. It is also now possible to identify interactions involving more than two species, extending the analysis beyond pairwise interactions. In such approach, interacting clusters of species can be identified, allowing the definition of multilevel and hierarchal networks.
Finally, the wide field of theoretical analysis of models of dynamic networks provides – debated - predictions about the link between network structure and community stability that can be tested and used as a framework to study the potential dynamics of earthworm communities in response to disturbances.
Through a series of examples on earthworm communities macroecology, we will see what we need and how to apply graph theory to earthworm ecology and discuss the benefits and limitations of this approach.
keywords: interactions; competition; complementarity; predation; community ecology
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Earthworm diet shifts in response to root-derived resources in species-specific ways – Insights from bulk and compound-specific isotope analyses
Linlin Zhong1, Stefan Scheu1,2,Melanie M. Pollierer1
1 Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, University of Goettingen, UntereKarspuele 2,37073Goettingen, Germany
2 Centre of Biodiversity and Sustainable Land Use, University of Goettingen, Buesgenweg 1, 37077 Goettingen, Germany
Root-derived resources are crucial for soil animalfood webs. However, it remainsunclear how root-derived resourcesaffect the diet of earthworms.To fill this gap, we established a mesocosm experiment witha full factorial design of two treatments: plant(four levels: without plant, Trifolium pratense, Lolium perenne, and their mixtures) and earthworm (five levels: Eisenia fetida, Lumbricusterrestris, Aporrectodea rosea, A. caliginosa and Allolobophorachlorotica). We combined compound-specific stable isotope analysis of carbon and nitrogen in amino acids and bulk stable isotope analysis to quantify the dietary contribution of root-derived resources to earthworms across plant communities of different nutritional quality. Plant affected bulk 13C values of earthwormstronger than on bulk 15N values. Earthworms were lower in 13C values in planted treatments suggesting the incorporation of recent photosynthetic carbon, whereas 15N values were only depleted in a few species. Further, earthworm species varied in their diet responding to plant communities. Trophic position of A. roseagenerally increased in presence of plants, indicating more pronounced feeding on microbial resources. The trophic position of E. fetidaincreased in monoculture L. perenne treatment, butdecreased in treatments with T. pratense, potentially due to the consumption of high-quality plant resources.We also found that the majority of energy was channeled to earthworms via fungal resources as suggested by 13C fingerprinting and Bayesian mixing models, and that energy fluxes to earthworms were not directly related to the microbial community composition in the bulk soil as indicated by phospholipid fatty acid analyses. Overall, our findings indicated that trophic position and basal resources of earthworms shift in species-specific ways in response to root-derived resources of different quality plants.
keywords: Amino acid CSIA; Trophic interaction; Energy channel; Plant quality; PLFA
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A core microbiota of the plant-earthworm interaction conserved across soils
Samuel Jacquioda1, Ruben Puga-Freitas2, AyméSpor1, Arnaud Mounier1, Cécile Monard3,
Christophe Mougel4, Laurent Philippot1, Manuel Blouin1
1 Agroécologie, InstitutAgroDijon, INRAE, Université deUniversité Bourgogne, Franche-Comté, Dijon, France
2 UMR, 7618 IEES-Paris (CNRS, INRAE, UPMC, IRD, UPEC), France
3 UMR, 6553 ECOBIO (CNRS, Université de Rennes 1), France
4 UMR, 1349 IGEPP (INRAE - Agrocampus Ouest - Université Rennes 1), France
The core microbiota defines the fraction of microorganisms common to all individuals from the same host species, regardless of the environmental context. Such core microbiota has been observed in the gut or feces of animals, or in plant rhizosphere. These observations support the idea that the holobiont, defined as a macroorganism and its associated microbiota, can be a unit of selection. While the core microbiota of many host species have been documented in different abiotic environments, no study attempted to decipher how these core microbiota could be altered when their host is interacting with a host from another species. This question could be particularly relevant in soils, due to the proximity of plant’s rhizospheres and earthworm’s drilospheres. We thus tested the existence of a core microbiota of the plant-earthworm interaction, by determining if microbiota from rhizosphere was influenced by earthworms, and, reciprocally, microbiota from drilosphere by plants. We sequenced bacterial communities from rhizospheres, casts and bulk in three contrasting soils, in which a plant, earthworm, both or none were present. A “source-sink” model evidenced the presence of a core microbiota of bacterial OTUs resulting from plant-earthworm interaction common to all soils, either in the drilosphere or in the rhizosphere. Earthworms increased the relative abundances of bacterial taxa stimulated by the plant in the rhizosphere and reduced those which were inhibited. Reciprocally, the plant strengthened the stimulation or inhibition of taxa by earthworms in the casts. Co-occurrence patterns indicative of soils were observed in interaction networks. qPCR abundance estimates revealed that not only bacteria, but also fungi and archeae, were affected by plant-earthworm interactions. Furthermore, the influence of plant, earthworm and their interaction on microbiota extended beyond the rhizosphere and drilosphere, in the surrounding bulk which is often taken as a control... Beyond the classical core microbiota, two macroorganisms can be faithfully associated with a core microbiota. The reinforcement of each macroorganism effect by the other suggests convergent ecological mechanisms behind the effect of earthworms and plants. This and the specificity of the core microbiota emerging from plant-earthworm interaction can be regarded as a co-evolution between plants, earthworms and soil microbiota.
keywords: Core microbiota; drilosphere; plant-earthworm interaction; rhizosphere; soils
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Earthworm contribution to pest control in cereal fields.
Ambre Sacco--Martret de Préville1, Karin Staudacher2, Michael Traugott2, Manuel Plantegenest3, Elsa Canard1
1 IGEPP, INRAE, Institut Agro, Univ Rennes, 35653, Le Rheu, France
2 Mountain Agriculture Research Unit, Institute of Ecology, University of Innsbruck, Technikerstraße25, 6020 Innsbruck, Austria
3 IGEPP, INRAE, Institut Agro, Univ Rennes, 35000, Rennes, France
Earthworms are ecosystem service providers that influence organic matter dynamics and soil structure, and they are considered soil quality indicators. However, one ecosystem service in which the involvement of earthwormshas never been considered is the service of pest regulation. Carabids are generalist predators and recognized biocontrol agents. Their year-round presence in fields suggests that they consume alternative prey when pests are absent. Considering that earthworms are active all year round, they could be one of the alternative preys sustaining carabids and hence indirectly supporting the service of pest regulation they provide. In this study, we applied diagnostic PCR to analyse the gut content of carabids to assess the contribution of earthworms to their diet. In addition, a diachronic study was performed to evaluate the possibility of shift in diet from earthworms to prey pests (aphids and slugs) allowing the persistence of carabid populations when pest populations are scarce.
For this study, adult carabids were pitfall trapped in winter wheat fields, in 5 French counties, from November 2018 until June 2019 and the presence of aphid, slug and earthworm DNA in their gut was detected using multiplex PCR diagnostic. Prey DNA was successfully detected in 47.2% of sampled carabids. Global detection rate for earthworm DNA was 37.9% and reached 15.9% for pests’ DNA (8.1% and 9.6% for slug and aphid DNA, respectively). At carabid community scale, detection rates of prey DNA were not constant over wheat season and a prey switching was observed: pest consumption increased over time in accordance to their availability, while earthworm consumption decreased. Moreover, diet variations were not completely consistent between carabid taxa: earthworm contribution to carabid diet varied greatly, suggesting different level of preference between taxa.
Molecular gut content analysis revealed a high consumption of earthworms, emphasizing the importance of alternative prey in sustaining populations of natural enemies of pests in agroecosystems and their indirect effect on pest regulation.
keywords: Pest regulation; Alternative prey; Carabid; Trophic interactions; DNA detection
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Earthworm communities and biotic associations with other soil taxa across an altitudinal gradient in north eastern Spain
Juan J. Jiménez1, M.V. López2, D. Moret2, J.M. Igual3, S. Sánchez4, C. Castellano1, M. García1
1Biodiversity Conservation and Ecosystem Restoration Department, Pyrenean Institute of Ecology (IPE-CSIC), Jaca, 22700, Huesca, Spain
2Soil and Water Conservation Department, EEAD-CSIC, Zaragoza, Spain
3IRNASA-CSIC, C/ Cordel de Merinas 40-52, 37008 Salamanca, Spain
4Department of the Environment and Agronomy, INIA-CSIC, Crta. Coruña km 7.5 28040 Madrid, Spain
Holisticapproaches are needed in the study of the relationships (interactions) between soil organic matter, soil fauna and soil microorganisms (bacteria and fungi) contributing to prediction models of soil carbon and nutrient cycling. In this study we analysed the structure of the earthworm community along an altitudinal gradientand its biotic association with other soil organism communities such as nematodes, bacteria and fungi. Nematodes were collected and kept cold until extraction in Baermann funnels and PLFA determinations were used to identify the community of microorganisms. Soil environmental variables (soil pH, texture, soil aggregate stability, bulk density, root length and biomass, C fractions and available P) and functions (N mineralization, sorptivity and hydraulic conductivity) were determined. Coarse and fine particulate organic matter fractions (cPOM, >250 µm, and fPOM, 250–53 µm), mineral-associated organic matter fraction occluded within microaggregates (µagg-Min, <53 µm) and easily dispersed mineral-associated fraction (d-Min, <53 µm) were quantified in each site.
In the semiarid region of the gradient one community was only represented by one species, Prosellodrilus psammophilus Qiu & Bouché 1998, while at least 3-4 earthworm species were found in the rest of sites, such as Lumbricus friendCognetti, 1904, Octolasion lacteum (Örley, 1881), O. cyaneum(Savigny, 1826), Aporrectodea rosea(Savigny, 1826), A. caliginosa(Savigny, 1826), Allolobophora chlorotica (Savigny, 1826), and Prosellodrilus pyrenaicus (Cognetti, 1904) following ISO 23611-5:2011.
Nematode taxa were assigned to functional groups (herbivores, fungivores, bacterivores, omnivores and predators). In the study area, 51 nematode taxa have been identified, of which 19 were bacterivores, 4 are fungivores, 15 were herbivores, 5 were omnivores and 8 were predators. The abundances of bacterivores and herbivores variedalong the gradient, being lower and higher respectively in the semiarid area Monegros area than in the two Pyrenean areas. Earthworm abundance and biomass data will be provided together with a complete analysis of their interactions with different soil taxa and soil environmental variability across the gradient. The results will certainly be used in forthcoming models of soil ecosystem functioning linked to earthworm communities
keywords: Earthworms; Soil biota; water infiltration; soil carbon; PLFAs
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Positive correlation between soil phyto hormone-like molecules and growth of two Coffea species influenced by Pontoscolex corethrurus
M. Álvarez-Jiménez1, C.R Cerdán1, G. Sánchez-Viveros1, J.L. Monribot-Villanueva3, E. Hernández-Hernández1,I. Barois2, J.A. Guerrero-Analco3
1 Facultad de Ciencias Agrícolas, Universidad Veracruzana, Xalapa, Veracruz, Mexico
2 Red de Ecología Funcional, Instituto de Ecología A.C., Xalapa, Veracruz, Mexico
3 Red de Estudios Moleculares Avanzados, Instituto de Ecología A.C., Xalapa, Veracruz, Mexico
Earthworms are associated with promotion of plant growth by the action of associated bacteria and phytohormone-like molecules found in their casts. However, there are no studies that correlate these aspects. Our objective was to determine if an over-accumulation of phytohormone-like compounds was linked to the earthworm Pontoscolex corethrurus activity and associated with growth of two coffee species (Coffea arabica and C. canephora). It has been hypothesized that presence of P. corethrurus increases the concentration of plant growth promoters in soil, and plants exposed to these elements would havegreater height or stem thickness. Thus, a randomized experiment was established under semi-controlled conditions with three factors: coffee species, earthworm presence and soil from different sites (worms’ gut content, casts, bulk and rhizosphere soil). The height and stem thickness of each plant from each treatment was determined after six-month experiment. The presence and abundance of phytohormone-like compounds were estimated by untargeted metabolomics analysis based on accurate mass spectrometry (UPLC-MS-QTOF) ofsoil samples from the four sites. Statistical analysis and hierarchical ordering heat-maps were performed in MetaboAnalyst 4.0. Subsequently, Shapiro Wilk tests and Pearson or Spearman correlations were made with RStudio®. Results suggest a positive correlation between the tentatively identified compounds as dioxindole-3-acetic acid (r2= 0.96, p = 0.17) 5-hydroxyindole-3-acetic acid (r2= 0.96, p = 0.16), (E)-ribosylzeatin 5 '' - phosphate (r2= 0.96, p = 0.17) and dihydrojasmonic acid (r2= 0.94, p = 0.11) found in the gut content of P. corethrurus with the height of C. canephora. The differences were not statistically significant, but general trends were identified where the presence of earthworms probably increases phytohormone-like molecules in soil and these compounds positively correlated with growth of coffee plants. It is suggested to carry out targeted metabolomic studies to corroborate the molecules identities with greater number of replicates and longer experiments.
keywords: Chemical diversity; Rhizosphere, Microbial community; Signal molecules;Plant growth.
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Annelids of spring fens and adjacent grasslands along a mineral-richness and pH gradient in the Western Carpathians
Jiří Schlaghamerský1, Martina Bílková1, Michal Horsák1, Jana Schenková1, Vendula Polášková1,Andrea Tóthová, Václav Pižl2
1 Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno, Czech Republic
2 Institute of Soil Biology, Biology Centre of the Czech Academy of Sciences, Na Sádkách 7, 370 05 České Budějovice, Czech Republic
Wetlands have received substantial attention by researchers, but the knowledge on invertebrates of the transition zone between aquatic sediments and terrestrial soils remains poor. We studied assemblages of annelids (represented by several families andof ecological importance in both habitat types) in spring fens and adjacent grasslands located in the Western Carpathians (Central Europe). The sites represented a mineral richness and pHgradient. We sampled 27 fen-grassland pairs in spring and again in autumn of either 2015 or 2016 (some additional samples were taken at selected sites in 2017 and 2022, in particular, to confirm some species identities by molecular barcoding). Soil (or Fen sediment) was sampled by cylindrical corers (microannelids: 17 cm2 working area to 10-15 cm depth, taking five cores per habitat type and site; earthworms: 625 cm2 working area to 20 cm depth, two cores in the fen, two in the grassland and two at their transition; in the drier parts, earthworms were additionally expelled from underlying soil using diluted formaldehyde). Microannelids were obtained by wet funnel extraction and identified alive to allow for enchytraeid identification to species. Earthworms were extracted in a Kempson apparatus, fixed in formaldehyde and identified subsequently. About 20000 microannelids were obtained, belonging to Enchytraeidae (73 spp.),Naididae (11 spp., incl. former Tubificidae), Aeolosomatidae (5 spp.), Lumbriculidae (3 spp.), Hrabeillidae (1 sp.) and Parergodrilidae (1 sp.). The large cores yielded 3154 earthworms (Lumbricidae) of 18taxa. Annelid assemblages differed markedly both between fens and grasslands and between individual sites, with a clear effect of the above gradient. Microannelid densities were much higher in the grasslands than in the fens due to high enchytraeid densities. Of the earthworms, Eiseniella tetraedra and Dendrobaena octaedra were dominant, the prior in particular in the fens, the latter in the fens, grasslands and in the transition zone. The hygrophilous Fitzingeria platyura depressa, Octodrilus transpadanus and Octolasion tyrtaeum occurred almost exclusively in the transition zone. Aporrectodea rosea, A. caliginosa and Octolasion lacteum dominated the grassland soils. Our work was funded by the Czech Science Foundation (grant 15-15548S) and the Czech Ministry of Education, Youth and Sports (grant LTC20040).
keywords: Earthworms; Enchytraeids; Oligochaetes; wetlands; grasslands
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Interactions of the invasive plant spec ies Gunnera tinctoria with earthworms
Olaf Schmidt1,2, Maurício Cruz Mantoani2,3, Fawzah Talal Alhakami1, Hannah Fearon1,Margherita Gioria4, Bruce Arthur Osborne2,3
1 UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland
2 UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
3 UCD School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
4 Czech Academy of Sciences, Institute of Botany, Department of Invasion Ecology, Zamek 1,CZ-252 43 Průhonice, Czech Republic
Invasive plants often modify soil properties through changes in soil physico-chemical properties or litter inputs. We assessed the impacts of Gunnera tinctoria(Giant rhubarb) invasions on soil and the earthworm community, on Achill Island, Co. Mayo, Ireland. We compared replicated Gunnera invaded areas (GUN) with uninvaded semi-natural grasslands (GRASS), as well as with areas subjected to mechanical removal (MER) or herbicide treatment (HER). Modifications in soil properties included lower soil temperatures and higher soil pH during the summer in invaded areas, yet little effect on C and N stocks, or soil moisture were detected. Marked differences in litter was observed, however, with GUN having c. 20-fold higher (above-ground) litter input than GRASS, as well as lower C:N ratio (17 vs. 29), likelydue to symbiotic N2 fixation by the cyanobacterium Nostoc associated with Gunnera. This was reflected by a significantly larger overall abundance and biomass of earthworms in GUN invaded plots (375 individuals/m2, 115 g biomass/m2), compared to the uninvaded control GRASS (130 individuals/m2, 45 g biomass/m2), with removal treatments having intermediate values. Earthworm communities comprised 10 species, typical for Irish grasslands, dominated by the common endogeic species. Stable isotope ratio measurements (13C/12C) showed that both soil and litter feeding earthworm species rely on Gunnera-derived carbon. Preliminary tests suggested that earthworms readily ingest Gunnera seeds and that these seeds remain viable after earthworm ingestion. Based on this new information, we conclude that plant invaders may increase the abundance and diversity of earthworms, in this case due to much larger litter inputs, and that positive feedbacks such as seed dispersal may occur.
keywords: invasive plants; soil food webs; stable isotope techniques
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Aporrectodea caliginosa (Savigny, 1826)
Maxim Shashkov
Institute of Mathematical Problems of Biology, Laboratory of Computational Ecology, Pushchino, Russia
In this study, the population structure of widespread in Europe earthworm Aporrectodea caliginosa was considered based on the combination of ontogenetic stages with individual biomass.
This investigation used data on field hand sorting collections carried out in the protected areas of the Kaluga Region (European Russia). Twelve biotopes were studied during six field seasons between 2000 and 2012. Some biotopes were sampled once, others repeatedly within one or different seasons. The sites represented old-growth broad-leaved forests, young birches on abandoned agricultural lands and forest floodplain habitat. In total, during 38 surveys, 2296 specimens of A. caliginosa were collected. Cocoons had not being collected within the field works.
Three commonly accepted ontogenetic stages were distinguished: juvenile, subadult and adult (mature) earthworms. Based on individual biomass distribution, considering all collected worms together, the juvenile stage was divided into five size groups (classes), subadult into two, and adult into three ones. Population spectra for each survey were drawn. A graph representing the life cycle of an individual of A. caliginosa was compiled.
The direct complete cycle of an individual worm, including the cocoon stage, takes from five to eight steps. The indirect cycle is possible since mature worms can become visually indistinguishable from subadult ones. So, the ontogeny multivariance is realised. Some juvenile worms can be much larger than adult ones by individual biomass in a distinct population, indicating asynchronous dynamics. It seems that worms have fewer ontogenetic steps in harsh conditions, and the population tends to be asynchronous in a favourable environment.
Cocoons production by adult worms were evaluated according to literature data.
The eigenvalue (lambda) of the matrix was found to be about 1.163. It means sustainable population growth in the long term projection. However, when real population spectra were taken for the initial step of the model run, the model showed that the population could go extinct in some cases. It was population spectra from biotopes with extremely low earthworm density where most size-ontogenetic groups were absent.
keywords: ontogenetic stage, multivariate ontogeny, population projection, eigenvalue, life cycle graph
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The protecting effects of earthworm on Fusarium wilt of strawberry
Yan-Meng Bi1,3, Gei-Lin Tian2, Chong Wang1, Yi Zhang1, Dan-Ni Wang2, Fang-Fang Zhang2, Lu-Sheng Zhang2, Zhen-Jun Sun1
1 College of Resources and Environmental Science, China Agricultural University, Beijing 100193, PR China
2 College of Horticulture, China Agricultural University, Beijing 100193, PR China
3 School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin, 300384, PR China
Earthworms can reduce soil-borne diseases via diverse mechanisms. The differential effects of different earthworm species on soil-borne diseases, and the mechanisms that account for the differences, however, have been largely ignored. To assess the effects of different earthworm species on Fusarium wilt in replanted strawberry and the underlying mechanisms involves, a greenhouse experiment in which plants were placed in soil with earthworms (either Metaphire guillemi (M) or Eisenia fetida (E)) or without earthworms (CK) was carried out. The disease index and biomass of each strawberry plant, along with soil microbial biomass, soil basal respiration, and the Shannon-Wiener diversity index (H′) for soil bacteria based on T-RFLP profiles and residual phenolic acids were determined. Both M. guillemi and E. fetida reduced the disease index, from 50.9 to 11.8 and 27.7 (or from 72.2 to 16.0 and 31.3 in repeated experiment) respectively, at harvest. In addition, both earthworm species increased soil microbial biomass, altered the structure of bacterial community and decreased the content of pcoumaric acid (PA), which may result in reducing the disease index. Earthworm E. fetida reduced PA from 53.22 to 30.98 (μgg−1), and M. guillemi reduced PA even more than E. fetida (from 53.22 to 13.15 (μgg−1)). Different earthworm species showed different capacities in reducing PA, a potential promoter to the growth of Fusarium oxysporum, which may lead to the different effects of the two earthworm species on the disease index.
keywords: Earthworm; Fusarium oxysporum; Continuous cropping; Phenolic acids Microorganisms
Posters
Seasonal fluctuation of the earthworm populations in vineyard soils
Christina Chalkia1, Evangelia Vavoulidou2, Dionyssios Perdikis1, Csaba Csuzdi3, Nikolaos Emmanuel1
1 Agricultural University of Athens, Laboratory of Agricultural Zoology & Entomology, 75 Iera Odos, 11855 Athens, Greece
2 Hellenic Agricultural Organization DEMETER, Institute of Soil & Water Resources – Department of Soil Science of Athens, 1 S. Venizelou str., 14123 Lykovryssi, Attiki, Greece
3 Eszterházy Károly University, Department of Zoology, Leányka u. 6, H-3300 Eger, Hungary
The activity of earthworms depends on the moisture levels in the soil, so, in temperate regions characterized by an alteration of dry and moist period, their population density displays clear seasonal variations and is tightly connected with local environmental conditions. Factors, such as land use and its management by man, are also responsible for the formation of earthworm populations.
In this study, the earthworm populations in soils of vineyards cultivated under different production systems (natural-abandoned, organic or conventional) located in two areas in Greece, were monthly recorded by the combined extraction method for a period of 2.5 years approximately. Spata and Nemea were the two areas selected because, apart from their importance as traditional cradles of good quality vine products, they differ in some climatic factors very important for earthworm ecology. Nemea is a wetter place than Spata receiving 618mm of precipitations annually, compared to 516mm at Spata and has a shorter dry period too.
The size of the earthworm populations in the same field showed a clear differentiation between years. In the wetter area (Nemea) earthworms developed much higher populations and had longer active period than the drier one (Spata). Their activity was restricted at the period of the water deficit in both areas. Although the structure of the earthworm communities differed between area and cropping system, the dominant species was the anecic Octodrilus complanatus (Dugès, 1828) in all fields. The system of production affected the size of their populations which, within the same area, ranked as follows: natural-abandoned > organic ≥ conventional. The cropping parameters responsible for the qualitative and quantitative results were irrigation levels, weed management, soil mechanical cultivation and use of agrochemicals.
keywords: earthworm active period, climatic conditions, seasonal fluctuations
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Abundance, biomass and species richness of earthworm at the Gorongosa National Park in Mozambique
Marie Luise Carolina Bartz1,2; María de JesúsIglesisas Briones3; Sérgio Timóteo1; Henrique Azevedo Pereira1; Sara Mendes1; Artur Serrano4; Mário Rui Canelas Boieiro4; António Alves da Silva1; Joana Alves1; José Paulo Filipe Afonso de Sousa1; Pedro Guilherme Pereira Martins da Silva1
1 Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
2 Organic Farming - Agriculture and Organic Production Partnership, Idanha-a-Nova, Portugal
3 Department of Ecology and Animal Biology, Faculty of Biology, University of Vigo, Vigo, Spain
4 Center for Ecology, Evolution and Environmental Change,Faculty of Sciences, University of Lisbon, Lisbon, Portugal
Mozambique is still an unexplored country considering the soil invertebrate fauna, especially the earthworms, which are considered important ecosystem engineers and play a significant role providing ecosystem services. So far, only eight earthworm species were recorded in Mozambique and no study has evaluated their abundance, biomass and species richness. The Gorongosa National Park is one of the most successful examples of ecosystem restoration in the world. For more than 20 years they are making a huge effort to restore populations of emblematic megafauna and to preserve the natural vegetation, working together with the local community. Yet, studies on the inventory and ecology of key soil functional groups, namely the earthworms, are still lacking. The aim of this work was to assess the earthworm communities at the Gorongosa National Park in Mozambique, as part of the project EcoAssess – A biodiversity and ECOlogicalASSESSment of soil fauna of Gorongosa National Park (Mozambique). Samplings were performed in four main vegetation formations of the park: grasslands, transitional forests, mixed forests and miombo. Field campaigns were carried out in the end of the dry season and after the first two rainfall events (around 70 mm and 110 mm, respectively, with one week apart), in the period of middle October to the end of November of 2019, using the TSBF method (25 x 25 cm width to 20 cm depth). The total abundance of earthworms in the end of the dry season was: 0 in grasslands and miombo and 0,5 and 7,1 ind m-2 in transitional and mixed forests, respectively. On the other hand, after rainfall the abundance raised to 3,0 and 7,3 ind m-2 in grasslands and transitional forests, 29,3 ind m-2 in the miombo and 65,2 ind m-2 in mixed forests. Considering the biomass, transitional and mixed forests had 0,09 and 0,21 g m-2 in the dry samples and in the beginning of the wet period 0,42 g m-2 in grasslands, 0,77 g m-2 in transitional forests, 1,45 gm-2 in the miombo and 2,14 g m-2 in mixed forests. Total richness was low in the dry sampling period (0 to 2 species) and after the two rains, it reached four species in the miombo and seven species in the mixed forest.
keywords: East Africa; Afro-tropical region; natural vegetation; soil biodiversity; ecosystem engineers
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DNA barcoding provides new insights into the drivers of earthworm species diversity in old Swedish grasslands
Kaisa Torppa, Karina Engelbrecht Clemmensen, Anders Glimskär, Helle Skånes, Tomas Roslin, Maria Viketoft, Astrid Taylor, Nadia Maaroufi
Swedish University of Agricultural Sciences
A good understanding on the distribution and prevalence patterns of earthworm species, and the drivers of earthworm diversity and community composition, is needed for conservation purposes and to support the functional diversity of earthworms for enhanced ecosystem service provision.
Traditional methods for earthworm species determination make use of morphological characteristics and therefore fail to determine juveniles that still lack certain morphological features and cryptic species that are morphologically similar. Consequently, our present knowledge of earthworm ecology and distribution patterns is incomplete as juveniles commonly stand for the majority of earthworm individuals in a community and cryptic species may occupy different ecological niches and thus affect soil functions differently.
In this study, we describe the earthworm species composition and densities, determined by species barcoding, in 28 old semi-natural grasslands in Uppland, Sweden. We also characterize the drivers of earthworm community composition in these grasslands, by linking environmental variables to species densities using joint species distribution modelling. The environmental variables determined for each grassland include vegetation (species diversity, coverages of plant functional groups, vegetation height), soil properties (texture, SOC, total N, total P, pH), management (fertilization, grazing intensity) and landscape structure (proportion and diversity of earthworm suitable habitat types within 100 and 500 m radius from sampling locations).
We specifically ask the following questions: 1) Does DNA barcoding reveal patterns that are undetectable with traditional determination methods, such as higher species richness or differing patterns in adult and juvenile densities within a species? 2) Which environmental parameters best explain earthworm species richness and diversity in old grasslands? 3) Do earthworm species and ecological groups respond differently to environmental parameters?
keywords: Lumbricidae; soil biodiversity; pasture
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Effect of soil properties on the distribution of earthworms in Zagros Mountains
Masoumeh Malek1, AtabakRoohi aminjan2, Maria J. I. Briones3, Robabeh Latif4, Mansoureh Sadat Hosseini1, Behnam Youneszadeh1
1 School of Biology and Centre of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran, Iran
2 Department of Biology, Faculty of Science, Bu-Ali Sina University, Hamedan, Iran
3 Departamento de Ecología y Biología Animal, Universidad de Vigo, Spain
4 Farzanegan Campus, Semnan University, Semnan, Iran
Earthworms are very responsive to changes in soil physico-chemical properties, which also directly or indirectly influence the availability of resources for their survival. Soil properties, such as soil organic matter and moisture contents, pH, and texture, have a profound effect on the diversity and abundance of earthworm communities. In this study,soil and earthworm samples were taken from four habitats (grasslands, farmlands, mixed forests, and highlands) and35 different locations in Zagros Mountains. At each sampling site, earthworms were collected from quadrats (25 x 25 x 30 cm) and hand-sorted in the field. Thereafter, the preserved biological samples were studied morphologically and dissected for further taxonomic identification. Soil samples from the same sites were analyzed for texture, pH, electrical conductivity (EC), and moisture content. Overall, 18 species of earthworms were identified, with Simpson's diversity index reaching values of 0.067, 0.071, 0.081, and 0.091 for mixed forests, farmlands, highlands, and grasslands, respectively. In addition, the Jacquard similarity index, based on the presence and absence of species, showed the highest similarity between grassland and mixed forest habitats (0.714) and the lowest similarity between farmland and highland habitats (0.438). Finally, the results of statistical analysis showed that three abiotic factors (pH, moisture, and EC) had a significant effect on their distribution and species richness, with earthworm diversity increasing with increasing EC and moisture, but decreasing with increasing pH values.
Diversity; Species richness;Moisture;pH; Electrical conductivity
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Pheretimoid species assemblages and soil responses to jumping worm invasion in northern North America
Timothy S. McCay, Sophie G. Pedzich, and Caroline M. Barnhart
Department of Biology, Colgate University, Hamilton, New York 13346 USA
Three pheretimoid earthworms, originally from Asia, are becoming widespread in the northern United States: Amynthastokioensis, A. agrestis, and Metaphirehilgendorfi. This represents the second wave of earthworm invasion, following the colonization of this region by European species. This process has been described as a co-invasion because these three species are often found together.We aimed to better understand the pattern of syntopy among these three species and their effects on nutrient loss from soils. We analyzed syntopy based on species co-occurrence at field sites in the northeastern and midwestern United States. Loss of nutrients was examined based on a microcosm study. We found positive associations between A. tokioensis and M. hilgendorfiand between A. tokioensis and A. agrestis. However, we detected no dependence in the occurrence of A. agrestis and M. hilgendorfi, the two species most similar in size. In microcosms, pheretimoids caused the increased percolation of nitrate and fluoride in soil leachate and the decreased percolation of potassium, magnesium, and calcium ions. These differences did not vary among species assemblages in the microcosm. Metaphirehilgendorfi had a much higher survival rate than either Amynthas spp. in our trials, suggesting potentially important differences in physiology among these species. The percolation of potassium, magnesium, and calcium increased as biomass mortality in our microcosms increased, reflecting a pulsed return of these nutrients into the soilpercolate.Pheretimoid assemblages in northern North America typically include at least two species that differ markedly in size, and this may magnify their impact on ecosystems. Invasion by pheretimoids into areas previously unoccupied by earthworms has the potential to change nutrient availability for plants and increase nitrate loss from soils. Pheretimoids may extract cations from soils temporarily during the growing season, then return them during the end of the growing season when earthworms perish. More research is needed into species-level differences in ecology, physiology, and behavior among the three common pheretimoids invading North America.
keywords: Pheretimoids; invasion; community; nutrients
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Run and hide at your nearest refuge: the bromeliad invasion of earthworm Perionyx excavatus in trees of Mexican coffee plantations.
Carlos Fragoso1, Luis Quijano-Cuervo2, Dionicio Juárez3, Antonio Ángeles1and Simoneta Negrete-Yankelevich2
1 Instituto de Ecología A.C. Red de Biodiversidad y Sistemática, Xalapa, Ver. México
2 Instituto de Ecología A.C. Red de Ecología Funcional, Xalapa, Ver. México
3 CenAgro, ICUAP, Benemérita Universidad Autónoma de Puebla, Puebla, México
Perionyx excavatus is an Asiatic epigeic earthworm that is currently found in several tropical countries. Outside its original distribution range, this earthworm has been successfully used in the vermicomposting of different organic residues. In Mexico this species has been found only in a small geographic region of central Veracruz, at 1080 -1250 m.a.s.l. Most of the records for this region are associated to coffee pulp residues,derived from the wet coffee processing system, that were abandoned close to streams or coffee plantations.
In this study we recorded the presence of P. excavates in two surveys carried out in soils (1998) and epiphytic plants (2018) of coffee plantations and adjacent pastures. In the first study, 12 different coffee plantations were surveyed for earthworms by using the standard TSBF macrofauna sampling method (5 monoliths of 25 x 25 cm and 30 cm depth/ plantation). In the second study the epiphyte plant community was sampled in 24 trees of five different species (Inga vera,Inga inicuil, Inga oerstediana andJacaranda mimosifolia),12 outside (in pasture isolated trees) and 12 inside the coffee plantation.
Our results show that this species was extremely rare in coffee plantation soils, being found in 3 out of the 12 studied plantations (presence in 9% of monoliths and with abundances of 0.18 ind/monolith) and always limited to litter (78% of individuals) or the first 5 cm of soil depth (22%). It represented 1% of the total amount of earthworms found.
Conversely, this species was found in 58% of sampled trees (14 worms/tree), being only found within tank bromeliads. However the presence in trees was highly different between those found outside plantations (92% of trees with worms; 28 worms/tree) and those located within it (25%; 0.25 worms/tree).
We suspect that P. excavates arrived to these plantations in the coffee pulp waste that used to be piled in the margins of plantations and that, after the compost process ended, was currently used to fertilize soils of plantations. Accordingly, we discuss that once all coffee pulp was decomposed, this species left the compost pile and looked for the nearest suitable habitat: the bromeliad plants of the nearest trees- i.e. the isolated trees outside plantations.
It remains to clarify the effect of this species over tank bromeliads and the phytotelmata associated community.
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Soil fauna distribution in microhabitats around a watercourse
Irene de Sosa, Mónica Gutiérrez, Adrián Marcos, Sergio Jiménez-Pinadero,Dolores Trigo, Darío Díaz Cosín
Biodiversity, Ecology and Evolution Department, Faculty of Biology, Complutense University of Madrid, C/José Antonio Nováis 12, 28040, Madrid, Spain.
This study investigates the microhabitat preferences of earthworms and edaphic microarthropods in the well of the Hondillas, an area crossed by a small stream in the Guadarrama Mountains of Madrid. We also want to verify whether lineages of Eiseniellatetraedra, one of the earthworm species inhabiting this zone, select different microhabitats and whether their population composition changes over time. Three different habitats were selected: at the edge of the stream (A), under stones (B), and in the surrounding soil (C). Soil samples were collected for analysis of soil properties. The earthworm community was identified to species level and the COI gene was sequenced. The edaphic microarthropods were extracted and identified at the suborder or family level, and the QBS index was calculated.
In terms of soil properties, we found significant differences between microhabitats only for moisture, which was higher in the wetter areas (A and B). The earthworm community showed a different distribution between microhabitats. E. tetraedra was associated with the wetter microhabitats (A and B), while the other earthworm species found (Dendroaenaalvaradoi, Eisenionacarpetana and Aporrectodeatrapezoides) were more abundant in the surrounding soils (C). In E. tetraedra, we found three distinct lineages that did not show a clear preference for any of the microhabitats. These lineages did not change over time, but only in the proportion in which they occurred. The community of microarthropods also showed a different distribution with greater richness and QBS index in the surrounding soil (C) associated with Gamasida, Actinedida and Acaridida mites and with Arthropleona springtails. However, Oribatida mites and Simphipleona springtails were more abundant in the wetter microhabitats (A and B). In addition, the family Passalozetidae was found only in the surrounding soil (C), while the family Galumnidae was found only in wetter microhabitats (A and B).
keywords: Earthworms; microhabitat; microarthropods; river
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Virginie Roy1, Mathis Ventura1, Yoan Fourcade1, Jean-Lou Justine2, Agnès Gigon1, Lise Dupont1
1 Université Paris Est Créteil, Sorbonne Université, CNRS, INRAE, IRD, Institut d'Ecologie et des Sciences de l'Environnement de Paris, 94010 Créteil Cedex, France
2 Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, EPHE, Institut Systématique, Évolution, Biodiversité, 75005 Paris, France
The invasion by terrestrial flatworms (Platyhelminthes: Geoplanidae) isof great concern since they aretop predators of soil fauna, some species inducing a severe reduction of native earthworm populations and major changes in community structure. One of the species recently reported in private gardens, garden centers and urban parks in metropolitan France, Obama nungara, hasalready invaded 75% of the territory. Because its preferred habitats are the underside of flowerpots, pieces of wood or objects stored on the ground, we hypothesized that not all species and ecological categories (i.e. epigeic, anecic, endogeic) of earthworms are equally available as prey for Obama nungara. Such differential predation may have drastic implication for soil functioning and indigenous earthworm-feeding wildlife. Here we present a preliminary analysis of the gut contents of Obama nungaraspecimens, all obtained thanks to a participatory citizen project. Using a metabarcoding approach, we showed that 16s rDNA of earthworms can be amplified and sequenced from these digestive extracts. All ecological categories of earthworms were identified as being consumed, suggesting that Obama nungara is unexpectedly able to predate on species living in deep soil environments such as endogeic species.
keywords: invasive flatworm, predation, metabarcoding, earthworm community structure
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The influence of selected chemical methods for Lumbricidae-flushing in the natural environment on selected features of Eisenia fetida (Sav.) earthworms under laboratory culture conditions
Anna Mazur-Pączka1, Grzegorz Pączka1, Mariola Garczyńska1, Joanna Kostecka1, Kevin R. Butt2
1 Department of the Basis of Agriculture and Waste Management, Institute of Agricultural Sciences, Land Management and Environmental Protection, College of Natural Sciences, University of Rzeszow, Cwiklinskiej 1a, 35-601 Rzeszow, Poland; mgar@ur.edu.pl
2 University of Central Lancashire, Natural Sciences, Preston PR 1 2HE, UK
A standard method of chemically flushing Lumbricidae from the soil uses a 0.4% formaldehyde solution. Attempts are being made to develop effective and environmentally safe chemical methods of flushing earthworms, with the use of plant extracts potentially safe for soil ecosystems. There is no information of their influence on the further life cycle of earthworms, e.g., in the case of in vivo field studies on Lumbricidae. Therefore, the research aimed to determine the effects of selected chemical methods used to flush Lumbricidae in field studies on selected features of Eisenia fetida under laboratory conditions. The experiment was carried out in containers with a capacity of 2 dm3 with adequately balanced organic kitchen waste as food. The whole container was filled with organic soil. Each container was provided with ten mature E. fetida with a mean m,ass of 0.4 ± 0.02 g. Four treatment groups were used (OE - onion extract, GE - garlic extract, TE - tobacco extract, FS - formalin solution) and a control group (CG). Earthworms were individually immersed for 10 seconds in the appropriate concentration of the stressor. The dynamics of the number and biomass of earthworms and cocoons as well as the amount of processed food were then analyzed. The cocoons were removed from the rearing containers and incubated in Petri dishes.
As a result, the most significant (p < 0.05) effect of three concentrations of formalin solution FS was on the decrease in the number of E. fetida individuals with a simultaneous increase in their average weight and the number of cocoons produced. Individuals in the control group CG and treatments OE, GE, TE were characterized by similar values of the analyzed traits. On the other hand, significant (p < 0.05) differences were found in the mean number of hatched earthworms (individual/cocoon) between the CG control group and the other treatments (CG > OE > TE > GE > FS).
keywords: earthworms; stressors; A. cepa; A. sativum; N. tabacum; formaldehyde
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Characteristics of Lumbricidae communities in agroecosystem soils grown with plants intended for energy purposes
Anna Mazur-Pączka1, Grzegorz Pączka1, Mariola Garczyńska1, Joanna Kostecka1, Kevin R. Butt2
1 Department of the Basis of Agriculture and Waste Management, , College of Natural Sciences, University of Rzeszow, Cwiklinskiej 1a, 35-601 Rzeszow, Poland
2 University of Central Lancashire, Natural Sciences, Preston PR 1 2HE, UK
One of the most significant and common renewable energy sources in agricultural countries is biomass. Despite the many benefits of biomass energy processing, doubts are raised by large-area plantations of energy monocultures, which may lead to soil sterilization and a decline in soil biodiversity. An analysis of the structure of Lumbricidae communities may indicate any negative changes taking place in the environment. Hence, this study aimed to determine the qualitative and quantitative differentiation of Lumbricidae population in areas used for the cultivation of plants intended for energy purposes. The research was carried out in south-eastern Poland at experimental sites: SV - the cultivation of Salix viminalis without the addition of sewage sludge in the soil, and SVSS + sewage sludge; PT - the cultivation of Prunus tomentosa without the addition of sewage sludge in the soil and PTSS + sewage sludge, RP - Robiniapseudoacacia cultivation without the addition of sewage sludge in the soil and RPSS + sewage sludge. At each stand, there were five randomly distributed sampling areas (10 × 10 m in size). According to ISO [23611-1: 2006], the mixed method was adopted to extract earthworms. Soil samples (n=3) were collected from each area to determine physical properties and the content of selected macro-elememts, micro-elements, and heavy metals. The earthworms found at the research sites belonged to 5 species: Lumbricuscastaneus (Sav.), Dendrodrilusrubidus (Eis.), Allolobophoracaliginosa (Sav.), Allolobophorarosea (Sav.) and Lumbricusterrestris (L.). In the cultivation of SVSS, a higher earthworm density was found compared to the SV plots. In the research area, a higher density and biomass of earthworms were found in the PT cultivation than with PTSS sewage sludge. A similar tendency was observed in the black locust plantation.
keywords: earthworms; biodiversity; plantations of energy crops; sewage sludge
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Would Carpetania. matritensisand Carpetania elisae cohabite under a climate change scenario
Navarro Zurro, R.1, Trigo, D.1, Fernández Marchán2, D., Martínez Navarro, A1., Gutiérrez López, M1
1 Biodiversity, Ecology and Evolution Department, Faculty of Biology, Complutense University of Madrid, C/José Antonio Nováis 12, 28040, Madrid, Spain.
2 CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
Carpetania elisae and C. matritensis are two cryptic species that live in different areas and usually coexist with A. trapezoides. C. elisae lives in the area of El Tomillar at the foot of the Sierra Norte de Madrid at an altitude of 1125 m, while C. matritensis lives in El Molar at 833 m. The climate of El Tomillar is colder and wetter than that of El Molar. Due to climate change, it is possible that C. matritensis could colonise the area where C. elisae lives. If so, would there be competition between the two species? In this work, laboratory microcosms were set up to study the interspecific relationships between the two species and with A. trapezoides, a species that coexists with both species. It was found that C. elisae was not affected when cohabiting with the other two species, while C. matritensis was negatively affected in its growth, although it benefits when cohabiting with A. trapezoides, which also increased its weight when cohabiting with C. matritensis. It is concluded that C. elisae would not be affected by the presence of C. matritensis in its soil, but that C. matritensis would be negatively affected, so it would be unlikely that C. matritensis would coloniseEl Tomillar area. However, C. matritensis increases its weight when in the presence of A. trapezoides, which can be explained by two causes.The first is that each speciesfeed on different food sources and the second is that C. matritensis can take advantage of the faeces of A. trapezoides by activating the microbiota that is ingested with the soil.
keywords: Carpetania; Aporrectodea trapezoides; competition; crypticspecies
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Reasons to move far away: studying the drivers of Carpetaniamatritensis (Hormogastridae: Crassiclitelatta) dispersal behaviour.
Martínez Navarro1, S. Jimenez Pinadero1, D. Fernández Marchán2, D. Trigo Aza1
1 Biodiversity, Ecology and Evolution Department, Faculty of Biology, Complutense University of Madrid, C/José Antonio Nováis 12, 28040, Madrid, Spain.
2 CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
Dispersal is a crucial process for animal populations as it allows the colonisation of new habitats and the maintenance of genetic diversity. However, it is still poorly known for soil fauna, which is the basis for a wide variety of ecosystem services. Therefore, the study of their dispersal and the factors that trigger this behaviour is a relevant area of knowledge for the maintenance of the services they provide. For this work, Carpetania matritensis, an endogeic earthworm species endemic to the central Iberian Peninsula, has been used as a model to study the effect of habitat quality and conspecific density on dispersive potential. The experiment was carried out in horizontal mesocosms divided into three sectors of the same dimensions: an inoculation section (left), a crossing section (centre) and a target sector (right), occupied by soil, a favourable habitat for earthworms, or by sand, which represents an unsuitable habitat for earthworms and a physical barrier for their dispersal. Earthworms were inoculated at two different densities (2 and 6 worms) and at two experimental durations (4 and 8 days) for each of the three different experimental treatments. These treatments were: unsuitable-unsuitable-suitable (U-U-S), suitable-unsuitable-suitable (S-U-S) and suitable-suitable-suitable (S-S-S), depending on the habitat type (soil or sand) filling the inoculation, crossing and target section respectively. The results showed a large effect of treatment on the dispersal rate, being higher when earthworms were inoculated in an adverse environment, establishing habitat quality as a driver of the species’ dispersal behaviour. No significant effects of conspecific density or experimental duration were found. These results suggest that C. matritensis may follow a negative density dispersal pattern, opting for aggregation under unfavourable conditions. Further studies are needed to clarify the species dispersal behaviour with a view to its conservation.
keywords: Dispersive potential; dispersal rate; habitat quality; conspecific density
