Earthworm Species Richness Research Articles

Permaculture enhances carbon stocks, soil quality and biodiversity in Central Europe

Permaculture is proposed as a tool to design and manage agroecological systems in response to the pressing environmental challenges of soil degradation, climate change and biodiversity loss. However, scientific evidence on the effects of permaculture is still scarce. In this comprehensive study on a wide range of soil and biodiversity indicators, we examined nine farms utilizing permaculture and paired control fields with locally predominant agriculture in Central Europe. We found 27% higher soil carbon stocks on permaculture sites than on control fields, while soil bulk density was 20% lower and earthworm abundance was 201% higher. Moreover, concentrations of various soil macro- and micronutrients were higher on permaculture sites indicating better conditions for crop production. Species richness of vascular plants, earthworms and birds was 457%, 77% and 197% higher on permaculture sites, respectively. Our results suggest permaculture as effective tool for the redesign of farming systems towards environmental sustainability.

A complex relationship between cropping systems and soil macrofauna: Influence of practice intensity, taxa and traits

Larger soil organisms have often been reported as the most sensitive to disturbances caused by cropping practices. However, soil macrofauna comprises groups with a wide diversity of morphological and ecological features, which may respond differently to applied practices. In order to further assess the effect of cropping systems on soil macrofauna, macrofauna organisms were extracted from soil blocks over 21 fields (each comprising three plots) located in the Paris basin, in autumns 2020 and 2021. Fields belonged to conventional, conservation or organic systems, either long-established (≥ 7 years) or in transition (≤ 3 years). Tillage, pesticide treatment and organic matter input intensity were assessed in each field using composite indexes of practice intensity. Macrofauna density and diversity, earthworm ecological categories, species richness and functional traits were investigated. Our results showed that the density and diversity of macrofauna demonstrated few differences regarding different cropping systems, with highly variable effects across groups and years. Specific macroarthropod groups responded differently to tillage, pesticide treatment and organic input intensity, but not over the two years of the study. Regarding earthworms, high tillage intensity had a negative effect on the density and biomass of epi-anecic juveniles and on species with a small body size. Higher organic matter inputs had a negative effect on the density and biomass of endogeic earthworms, and could be related to several earthworm functional traits (body length, mass/length ratio, carbon preferences). Effects of pesticide treatments were less clear, although they could have impacted some earthworm species. More generally, taxonomic and functional trait approaches of earthworm community led to similar conclusions. Overall, our results support the need to account for (i) the actual intensity of practices in cropping systems and (ii) the different taxonomic, trophic and ecological groups of macrofauna, in order to assess the effects of cropping systems on soil biodiversity.

Soil and Vegetation Characteristics of Grassland have a Greater Influence on the Abundance and Diversity of Earthworms than the Mowing Intensity in a Managed Nature Reserve

Effects of mowing on vegetation parameters have been well studied. However, less is known about mowing effects on soil fauna and if soil properties alter this. We investigated earthworm communities in a long-term experiment 14 years after its establishment in 5 dry, fresh and moist grassland plots located in the Natura 2000 site Lainzer Tiergarten near Vienna, Austria (238–402 m a.s.l., 48°10′ N, 16°12′ E). The grasslands were either mowed once a year or every second year, or not mowed since being established. Earthworms were assessed using the non-destructive octet electro-shocking method. Additionally, vegetation composition, soil conductivity, temperature and moisture were assessed. We found 13 earthworm species across all treatments, although their abundance was generally low with 6.1 ± 4.7 worms m−2. The total earthworm abundance and species diversity was higher in dry compared to fresh and moist grasslands but was not affected by mowing frequency. Endogeic earthworms (Aporrectodea caliginosa, Aporrectodea rosea) and epigeics (Lumbricus rubellus) were more tolerant to mowing than anecics (Lumbricus terrestris, Allolobophora longa). Since plant species richness was highest in annually mown grasslands and earthworm species richness was positively related to plant species numbers, we recommend regular, low-input management to promote above- and belowground biodiversity in these grasslands.

Earthworms as soil health indicators in no-tillage agroecosystems

No-tillage (NT) and no-tillage systems (NTS) are widely used conservation agriculture practices in Brazil, and in the state of Paraná, nearly 80% of annual crops are cultivated using these methods. Compared with NT, NTS sites permanently include: minimum soil disturbance, soil cover (straw and living vegetation) and crop rotation and diversification with cover crops. These practices often increase earthworm populations, that can be used to indicate soil health. Herein, we review soil health classification of NT sites, and the species found in Paraná state. We compiled information from 130 sites with NT or NTS, located in 29 counties, of which 93 had biomass and 91 had species richness data, aiming to compare NT with NTS sites, and the effect of the age of these practices on earthworm populations. Overall, 29 earthworm species were recorded, of which 17 were native, including many new to science. Mean abundance and biomass in NT + NTS were 104 ind m−2 and 2.5 g m−2, respectively, and richness 2.5 species per site. Abundance was significantly higher in NT than NTS in the initial phase of adoption, and both abundance and biomass decreased with increasing age of NT. Earthworm abundance and species richness were positively correlated with clayey soils and phosphorus content, while higher biomass was associated with soil carbon content and pH. A new classification system was proposed, with the categories poor (<50 ind. m−2, 1 species), moderate (≥50 to <100 ind m−2, 2 species), good (≥100 to <150 ind m−2, 3 species), very good (≥150 to 200 ind m−2, 4 species) and excellent (≥200 ind m−2, ≥5 species) soil health, using earthworm abundance and species richness, respectively. Most of the sites sampled showed poor or moderate soil health, with few displaying very good or excellent health, indicating the need for improved management practices, in order to promote earthworm populations and their potential benefits to soil fertility and plant production.

Influence of agroforestry systems on earthworm diversity and soil properties in a Sudano-Sahelian landscape

Agroforestry systems promote a range of ecological base management to support sustainable agriculture. However, the influence of agroforestry management on soil biodiversity is still poorly investigated in Sudano-Sahelian landscapes. This study aims to guide sustainable management for soil biodiversity conservation in agroforestry systems by determining the drivers of earthworm diversity with their abundance and corresponding soil properties. Nested sampling following three management systems (agroforestry fallow, agroforestry intercropping, agroforestry grazing) and the protected area as a baseline, were designed for data collection in a Sudano-Sahelian landscape. Earthworm inventory and soil sampling (0–10 cm), coupled with a survey focusing on the cropping and fallowing duration with other agricultural practices (herbicide use, soil tillage), were conducted on the farm. The soil analysis included soil texture, bulk density and a suite of chemical analyses (pHKCl, C and N, available macro and micronutrients). The data were analyzed using generalized linear models (GLMs) and ANCOVA to determine the effects of agroforestry systems on earthworm abundance and soil properties. A Principal Component Analysis (PCA) was performed to determine the relationship between the species richness of earthworms, agroforestry systems and soil properties. The results showed a diversity of five species belonging to the endogeic and epigeic ecological groups numbered at 7 ± 3 to 22 ± 10 individuals m−2 (mean ± standard deviation). In agroforestry fallow systems, earthworm diversity and abundance were both highest, and the abundance increased with the fallow duration. The prolongation of cropping duration coupled with herbicide use in agroforestry intercropping systems decreased significantly the abundance of earthworms. Agroforestry grazing systems increased significantly soil C, N and available nutrients, but the abundance of earthworms and species richness were the lowest likely due to soil destructuration by trampling. Overall, soil texture controlled the species richness of earthworms. Fallow management and agricultural practices with fewer herbicide use and soil destructuration, are essential to improve earthworm abundance and diversity.

Earthworm diversity and community assemblage: influencing factors at plot-scale in urban areas

Soil fauna including earthworms play a crucial role in various ecosystem functions, thereby contributing to human well-being. The relationships between earthworm populations and environmental factors have frequently been established at regional scales, particularly in urban soils. However, the diversity and community assemblage of earthworms, as well as their influencing mechanism at plot scale, have rarely been studied. Based on the earthworm assemblage from 29 sites in 12 residential communities, the average earthworm abundance, biomass, and species richness were 59.0 individuals/m2, 21.7 ​g/m2, and 1.59 species, respectively. Based on a generalized linear mixed model, vegetation distribution pattern, vegetative cover type, and surrounding built environment all affected earthworm biomass. However, none of these residential variables significantly affected its community assemblage. Variation partitioning in canonical ordination revealed that edaphic properties, rather than landscapes, played a significant role in explaining the variation in its community assemblage, with an approximate contribution of 23%. The abundance and biomass of earthworms at the plot-scale in this study were consistent with previous studies at regional scales. However, the species richness at plot scale was lower than those at regional scale, suggesting that earthworm biodiversity may not accurately represent that at a larger scale, species-area relationship. The results indicate a shift in the driving factors of earthworm community assemblage from edaphic property variation at the plot scale to edaphic, historical, and biogeographical heterogeneities at the regional scale. Certain species that are sensitive to key edaphic/landscape parameters are potential candidates for monitoring soil ecological health.

Effects of climate on the distribution and conservation of commonly observed European earthworms.

Belowground biodiversity distribution does not necessarily reflect aboveground biodiversity patterns, but maps of soil biodiversity remain scarce because of limited data availability. Earthworms belong to the most thoroughly studied soil organisms and-in their role as ecosystem engineers-have a significant impact on ecosystem functioning. We used species distribution modeling (SDMs) and available data sets to map the spatial distribution of commonly observed (i.e., frequently recorded) earthworm species (Annelida, Oligochaeta) across Europe under current and future climate conditions. First, we predicted potential species distributions with commonly used models (i.e., MaxEnt and Biomod) and estimated total species richness (i.e., number of species in a 5 × 5km grid cell). Second, we determined how much the different types of protected areas covered predicted earthworm richness and species ranges (i.e., distributions) by estimating the respective proportion of the range area. Earthworm species richness was high in central western Europe and low in northeastern Europe. This pattern was mainly associated with annual mean temperature and precipitation seasonality, but the importance of predictor variables to species occurrences varied among species. The geographical ranges of the majority of the earthworm species were predicted to shift to eastern Europe and partly decrease under future climate scenarios. Predicted current and future ranges were only poorly covered by protected areas, such as national parks. More than 80% of future earthworm ranges were on average not protected at all (mean [SD] = 82.6% [0.04]). Overall, our results emphasize the urgency of considering especially vulnerable earthworm species, as well as other soil organisms, in the design of nature conservation measures.

Seasonal dynamics of agricultural land use impacts on earthworm communities: Insights into diversity, abundance, and functional composition

Earthworms play a key role as soil bioengineers, but livestock farming and croplands can impact on the composition, structure, and functioning of earthworm communities. This study aimed to quantify the effects of replacing natural grasslands with crop rotations on the seasonal dynamics of key attributes of earthworm communities and explore soil physicochemical properties as mechanisms behind these effects. We conducted paired samplings on seven sites across Uruguay, comparing earthworm communities in soils under grazed natural grasslands and adjacent croplands, considering earthworm species composition, richness, diversity, and evenness, biomass, density, and mean body weight, over five consecutive seasons. Results revealed a clear negative impact of croplands on earthworm communities, showing substantial reductions in all considered attributes. Observed changes were attributed to environmental filters limiting the occurrence of larger exotic earthworm species in croplands, and variations in soil physicochemical properties were identified as potentially mediating some of these effects, including soil water regime (particularly affecting juvenile individuals) and soil organic matter content. These impacts resulted in a shift to dominance of r strategists (smaller, surface-feeding species such as Microscolex spp. in croplands compared to larger deeper-burrowing species in grasslands) and reduced functional composition of earthworm communities. Furthermore, seasonal dynamics revealed that differences between land uses were more pronounced during wetter periods, underscoring the relevance of seasonal variations when evaluating land use impacts on earthworm communities. Earthworms mean body weight resulted a useful attribute to be included in earthworm's assessments, allowing to identify impacts in community functional composition and suggesting size dependent mechanisms. Additional research is required to comprehensively understand the mechanisms behind these patterns and to develop more sustainable agricultural practices by considering soil fauna.

Structure and diversity of earthworm communities in long-term irrigated soils with raw effluent and treated wastewater

Abstract This study was conducted in two natural meadows: first, soils were irrigated with raw wastewater (SIRWW) and in the second, soils were irrigated with treated wastewater (SITWW). Earthworms were sampled in eight soil blocks spaced 10 m apart at each site. Earthworm community was characterized and compared using density, biomass, composition, structure, species richness, and diversity parameters. At both meadows, 459 earthworm individuals from two families and seven species were collected. The highest earthworm density and species richness were recorded at SIRWW. Nicodrilus caligenus was the most abundant species. Most of earthworm community parameters decreased significantly at SITWW. Only two species (N. caligenus and Octodrilus complanatus) were common between the two grasslands. Among the seven species identified at both meadows, four (Allolobophora longa, Eisenia foetida, Allolobophora rosea, Allolobophora chlorotica) were exclusively present in SIRWW, whereas a single species (Amynthas sp.) was characterized in SITWW. Three ecological earthworm groups (epigeic, endogeic, and anectic) were represented in SIRWW, with the dominance of endogeics. Further studies are needed to quantify pollution in this soils and the accumulation of pollutant load in earthworms. It is also important to highlight the relationship between the abundance and diversity of earthworms in these two ecosystems with soil biological activity.

Earthworms in natural grasslands and agropastoral systems in the Brazilian Pampa.

In this study, we sampled grazed natural grassland and agropastoral systems in two regions (Alegrete and Aceguá) in the highly diverse Brazilian Pampa region which is undergoing significant change in land use cover. By hand sorting the soil, a total of five species were found, belonging to the families Glossoscolecidae (Glossoscolex sp.50 and Glossoscolex sp.51), Ocnerodrilidae (Kerriona sp.6 and Eukerria sp.3), and Lumbricidae (Aporrectodea trapezoides). The former four were identified as native-new to science-and the latter as exotic. Differences were observed in both earthworm species richness and abundance between regions and land-use systems, likely due to environmental conditions and agricultural practices, respectively. Agropastoral systems had higher abundance and species richness than natural grasslands, though these differences varied by location. This suggests that conversion from natural grassland to agropastoral systems can maintain native earthworms and, possibly, enhance ecosystem services. However, an exotic species was found in high abundance at one agropastoral site. These results highlight the need for additional biodiversity studies on earthworms in the Brazilian Pampa and for research on the impacts of land use changes in this region.

Earthworms in various agricultural and forest ecosystems in São Carlos—SP, Brazil

Integrated agricultural systems have been greatly expanding in Brazil and currently cover over 30 million hectares. Although these land use systems help soil and environmental quality, little is known of their impacts on earthworm communities. In the present study we evaluated earthworm abundance, biomass and species richness in various integrated and conventional agricultural production systems (pasture, crops), as well as native forest and Eucalyptus plantations. The research was carried out at Fazenda Canchim (Embrapa Livestock Southeast) and at the neighboring campus of the University de São Carlos (UFSCar), in São Carlos municipality in São Paulo state, Brazil. Two earthworm sampling methods, i.e., quantitative (25 x 25 x 20 cm deep monoliths) and qualitative (holes of similar size and niche sampling), were used in three integrated production systems, three conventional systems and two forest systems, totaling 232 quantitative samples and over 160 qualitative samples. Earthworms were counted and identified using available keys. Eight earthworm species of five families (Rhinodrilidae, Ocnerodrilidae, Megascolecidae, Benhamiidae and Glossoscolecidae) were found, with most of the 2,145 individuals being exotic or peregrine species, particularly Pontoscolex corethrurus (88% of total) and various Dichogaster spp. (8% of total). Two native species were encountered in low abundance (55 individuals), both of which are new to science (Fimoscolex n.sp.7 and Glossoscolex n.sp.9) and must still be formally described. The new species were found in the agricultural systems, but not in the native forest and the Eucalyptus plantation, where P. corethrurus and Megascolecids predominated. One unidentified Ocnerodrilid sp. was found only in the intensive pasture. Species richness was highest in the intensive pasture (7 spp.), followed by the agrosilvopastoral and agropastoral systems, highlighting the importance of integrated and pastoral systems in preserving earthworm richness and native species.

Impact of No-Tillage on Soil Invertebrate Communities in the Southern Forest Steppe of West Siberia: Preliminary Research

The aim of our study is to assess changes in soil macroinvertebrate biodiversity when conventional tillage (CT) is replaced by no-tillage (NT) in agroecosystems of the southern part of the West Siberian forest steppe. The research was conducted in the Novosibirsk region at the end of May 2017, May 2018, and in June 2018. The agricultural plots with CT and NT were located close to each other on identical soils, at a distance of about 200 m from the nearest forest shelterbelts. NT technology has been applied on the experimental plot since 2007. Sampling of invertebrates was conducted in two ways, namely soil sampling and pitfall trapping. The majority of basic physicochemical properties of soil were the same or similar between the CT and NT plots. However, depending on the type of tillage, different soil invertebrate communities had already developed in the control (CT) and experimental (NT) plots during this time. The community of the CT plot includes a large number of flying predatory Carabidae species typical of early successional stages (such as Bembidion properans and B. quadrimaculatum, Poecilus spp.) and phytophages, i.e., larvae of Elateridae. The NT plot has significantly higher density and species richness of earthworms (Eisenia nordenskioldi and synanthropic E. fetida in the NT plot versus one individual of E. nordenskioldi in the CT plot). The NT plot has a significantly richer and more abundant assemblage of spiders (especially in spring) and a poor assemblage of insect predators (except for the superdominant ground beetle Poecilus cupreus and the subdominant P. versicolor in summer 2018). Large numbers of larvae of some carabids (e.g., Amara consularis) were found in the NT soil, suggesting that they complete a full life cycle in this habitat.

Two decades of monitoring earthworms in translocated grasslands at Manchester Airport

Construction of a second runway at Manchester Airport included a mitigation package of habitat restoration with relocation of earthworms as prey items for protected vertebrates. Translocation of turf in blocks was the standard method used for four of five monitored sites with loose soil moved at the other. To assess earthworm communities at these translocated grassland sites, monitoring was undertaken each October (1998–2019) by digging and hand sorting of soil, followed by vermifuge application. Fourteen earthworm species were recorded, representing all ecological groups, but the majority were endogeic species, dominated by Aporrectodea caliginosa. Total earthworm numbers fluctuated during the monitoring period, with lowest density at 4 m−2 and highest more than a hundred times larger. The overall mean from all sites across the monitoring period was 151 ind. m−2. The differences between sites such as total earthworm numbers and species richness were clearly influenced by the translocation method and specific site topography. Created Hummocks to 3 m for hibernating amphibians proved successful with grassland soil establishing well. Lumbricus terrestris failed to establish due to translocation technique. Using non-metric multidimensional scaling, integration of environmental data with earthworm records showed effects of soil moisture content, pH and rainfall on abundance of ecological groupings and particular species. In general, earthworm community composition was dynamic over the monitoring period suggesting that this and population size needs to be appraised over realistic timescales, which may be best monitored in decades.

Gunnera tinctoria invasions increase, not decrease, earthworm abundance and diversity

Invasive plants often modify soil biotic communities through changes in soil physicochemical characteristics or the amount and/or quality of litter inputs. We assessed the impacts of Gunnera tinctoria invasions on soil and the earthworm community, on Achill Island, Co. Mayo, Ireland. We compared replicated (n = 5) areas invaded by G. tinctoria with uninvaded semi-natural grasslands, as well as with areas subjected to mechanical removal or herbicide treatment. Modifications in physiochemical 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. Marked differences in litter were observed, however, with invaded areas having c. 20-fold higher (above-ground) litter input than uninvaded ones, as well as lower C:N ratio (17 vs. 29). This was associated with a significantly higher overall abundance and biomass of earthworms in invaded plots (375 individuals m–2, 115 g biomass m–2), compared to the uninvaded control (130 individuals m–2, 45 g biomass m–2), with removal treatments having intermediate values. Earthworm communities comprised 10 species, typical for Irish grasslands, dominated by the common endogeic species Allolobophora chlorotica, Aporrectodea caliginosa and Aporrectodea rosea. Both earthworm species richness and Shannon diversity were significantly higher in invaded areas, but only in spring samples. Based on this new information, plant invaders may increase the abundance and diversity of earthworms, mainly due to much larger litter inputs, increased soil pH and possibly lower soil temperatures in the summer.

Species richness and community structure of earthworms (Oligochaeta: Lumbricidae) in natural and agricultural ecosystems

Species richness and community structure of earthworms (Oligochaeta: Lumbricidae) in natural and agricultural ecosystems

Aboveground and belowground biodiversity responses to seed mixtures and mowing in a long-term set-aside experiment

Set-asides sown to wildflowers are introduced to promote agrobiodiversity. Often, sown seed mixtures have been used to enhance aboveground biodiversity while belowground biodiversity has received less attention. We studied in a 15-year-old set-aside experiment, the impact of seed mixtures (grass vs. meadow) and mowing (mown vs. unmown) on the abundance and diversity of plants, two aboveground invertebrate groups (pollinators and natural enemies of pest species) and one key belowground group, earthworms. We also studied the treatment effects on selected soil chemical properties. In general, a sown meadow seed mixture mostly benefitted aboveground biodiversity, whereas the impacts of late-season mowing were most discernible for earthworms. Plant species richness or coverage did not differ between seed mixtures, but plant coverage showed a positive response to mowing, while the impact on species richness was minor. The meadow seed mixture was dominated by Centaurea jacea. A non-mown meadow treatment supported the highest earthworm density and species richness, while the values were lowest in the mown meadow, where earthworm total mass was also at its lowest. In a grass seed mixture of intermediate density and richness, the mowing had no measurable effect on the earthworm community. Topsoil carbon, nitrogen and soluble phosphorus concentrations showed a typical gradient for non-inverted soils, with the highest concentrations in the 0–2.5 cm layer. The two uppermost soil layers (to 5 cm depth) had higher soluble phosphorus content under grass than under meadow seed mixture. Abundance of natural enemies of pests was not significantly different between the treatments, but for carabids there was a marginally significant positive response to mowing. Bumblebee species richness and the abundance of bumblebees and honeybees were highest in the mown meadow seed mixture plots. Butterfly species richness was marginally significantly higher in mown than in non-mown treatments in both seed mixtures. The results showed the potential of set-asides to promote both aboveground and belowground biodiversity through increased plant diversity.

Earthworm species occurrence in agroecosystems in the Midlands, KwaZulu-Natal, South Africa

Little is known about the species composition of earthworms in agroecosystems in South Africa even though earthworms provide soil ecosystem services and are useful biological indicators of changes in the habitats. Given the land use and management impact biodiversity, the aim of this study was to document earthworm species that occur under cultivated land in the KwaZulu-Natal Midlands. A survey of nine farms that practise conservation agriculture was carried out between 2018 and 2020. Twelve earthworm species belonging to four introduced families: Acanthodrilidae (Dichogaster bolaui), Rhinodrilidae (Pontoscolex corenthrurus), Lumbricidae (Aporrectodea caliginosa,Aporrectodea rosea,Aporrectodea trapezoides,Lumbricus rubellus,Octolasion cyaneum,Octolasion lacteum), Megascolecidae (Amynthas aeruginosus,Amynthas corticis,Amynthas gracilis,Amynthas rodericensis) and juveniles from an indigenous family Tritogeniidae were recorded from cultivated fields. The type of crop (habitat) affected both species richness and abundance of earthworms significantly. However, post hoc results showed differences in species richness between the soya and the maize only, with greater species richness in the maize. Our results demonstrate that habitat type has a major influence on communities of earthworms in agroecosystems.

Response of boreal clay soil properties and erosion to ten years of no-till management

We compared soil physical, chemical and biological properties, erosion rate and carbon allocation to soil physical fractions between conventional tillage (CT) and no-till (NT) management at a clay soil site under spring cereal monoculture in southwestern Finland. Subsurface drain discharge, surface runoff and soil erosion were continuously monitored in 2008 − 2018. At the end of the 10-year monitoring period in 2018, various soil properties and earthworm total density, mass and species richness were determined. Total soil erosion was 56 % less in NT than in CT although surface water discharge was higher in NT. NT had a clear effect on the topsoil physical structure by decreasing the pore size and increasing soil aggregate size. The total soil carbon stock in the 700 kg m−2 mineral topsoil layer (approx. 0−60 cm layer) was slightly lower in NT (108 ± 12 Mg C ha-1) than in CT (118 ± 9.0 Mg C ha-1) due to lower carbon content of the 10−30 cm layer in NT. In NT the proportion of large macroaggregates was higher and more organic carbon was bound to large macroaggregates in the 0−10 cm layer which may be related to the higher abundance of earthworms in NT. The results showed that NT is an effective method to reduce erosion rates but other means to increase carbon input especially below the topsoil layer are likely required to achieve a significant increase in the carbon stock of boreal clay soils. For both tillage managements, the rate of erosion through subsurface drains depended clearly on annual precipitation and winter temperature, posing a challenge in the future climate with mild winters and more extreme discharges.

Earthworms of the World

For decades, scientists have known where the highest numbers of species that live aboveground are found. So, they made maps of the world showing these patterns. For most of the aboveground groups, the highest numbers of species occur in the tropics and numbers decrease toward the poles. However, until recently, we did not understand such global patterns for many organisms living in the soil. We decided to create global maps of earthworm species richness. Earthworms provide humans with many useful services, such as moving the soils and improving their quality, which can increase the amount of food that is grown. If we want to protect earthworms and the services they provide, these global maps of earthworms are important because we need to understand where they are and why they live there.

Soil properties, grassland management, and landscape diversity drive the assembly of earthworm communities in temperate grasslands

Earthworms are widespread soil organisms that contribute to a wide range of ecosystem services. As such, it is important to improve our knowledge, still scanty, of the factors that drive the assembly of earthworm communities. The aim of the present study was to conjointly evaluate the effects on the assembly of earthworm communities of i) soil properties (texture, organic matter content, and pH), ii) grassland management (grassland age, livestock unit, and type of fertilization), iii) landscape diversity (richness, diversity of surrounding habitats, and grassland plant diversity), and iv) presence of hedgerows. The study was conducted in temperate grasslands of Brittany, France. Earthworms were sampled in 24 grasslands and, in three of these grasslands, they were sampled near a hedgerow or near a ditch (control without a hedgerow). Soil properties explained the larger portion of the variation in the earthworm community parameters compared to grassland management or landscape diversity. The increase in soil organic matter content and pH were the most favorable factors for earthworm abundance and biomass, in particular for endogeic species. Regarding grassland management, the increase in the livestock unit was the most damaging factor for earthworm communities, in particular for the anecic earthworm biomass and endogeic species richness. Surprisingly, landscape diversity negatively affected the total earthworm abundance and epigeic earthworm biomass, but it was related to an increase in the epi-anecic species. At a finer scale, we also demonstrated that the presence of hedgerows surrounding grasslands enhanced earthworm species richness, especially within the epigeic and anecic ecological categories. This study highlights that the earthworm ecological categories respond specifically to environmental filters; further studies need to be conducted to elucidate the factors that drive the assembly of earthworm communities at this ecological category level. We recommend that policymakers should act on landscape management to favor earthworm diversity in order to improve the ecosystem services they drive.