• Energy Research

Earthworms play a major role in the biogeochemical cycling of carbon and nitrogen through their bioturbation activity and cast production. Thus, they affect soil greenhouse gas emissions mainly, N2O and CO2 as well as carbon sequestration through their influence on soil organic matter protection processes. However, earthworm casts exhibit differents physical, chemical and biological characteristics, even when the species belong to the same ecological category. Animal functional traits were recently used in ecology approach to study invertebrates’ effect on ecosystem function. These traits drive the response of organisms at individual level to environmental changes and their effects on ecological processes. The objective of this work was to investigate the role of earthworm functional traits in organic matter dynamics. We performed a laboratory experiment to assess the effect of morphological, anatomical, physiological, and behavioral traits of 9 temperate earthworm species on the nature, protection, and molecular chemical composition of organic matter from earthworm casts. We characterized the particular organic matter (POM) and mineral-associated organic matter (MAO)M through physical fractionation. The nature and molecular chemical composition of organic matter in casts was determined from elementary, isotopic and mid-infrared spectra analyses. results showed a strong correlation between physical and chemical parameters (i.e., dissolved organic carbon, particulate organic matter, total carbon, C/N ratio and nitrogen contents) and the size of the earthworm, gizzard, pharynx, pigmentation, low dissepiment and selection of organic matter. We conclude that earthworm traits can be used to predict their effect on organic matter dynamic.

Numerous pesticide applications are required for orchard protection, regardless of the guidelines.Organic fruit production (OFP) mainly relies on the use of mineral fungicides and microbiological ornaturally-occurring insecticides. The environmental impact of this type of production does notsignificantly differ from that of conventional production when assessed in terms of synthetic indicators.However, the abundance of earthworms, as well as the abundance and specific richness of arthropodpests and beneficials in the orchards and surrounding hedges, is greater in OFP than in conventionalorchards. Generalist predators are usually less affected by OFP compounds than by the chemicalpesticides applied in conventional orchards. OFP also benefits avian communities, and above all,insectivorous birds, for which organic orchards offer a suitable habitat similar to that of undisturbednatural areas.In addition to this general trend, discrepancies may be observed in the protection responses of differentinsect groups. The abundance of hymenopteran parasitoids is the lowest in organic orchards in whichoutbreaks of phytophagous mites are also recorded in relation to the intensive use of sulphur for scabprotection. Biological insecticides often act in ways that are similar to those of chemical ones, and therestricted choice of available compounds is likely to induce resistance selection in insect pests.Although maintaining biodiversity is not a direct result of the implementation of OFP guidelines, it seemsto be widely considered as an option by organic growers, both alone and as a complementary tool forpest regulation. La protection des vergers nécessite de nombreux traitements antiparasitaires, quel que soit le cahierdes charges. L’agriculture biologique (AB) utilise des fongicides minéraux et des insecticides d’originevégétale, microbiologiques ou dérivés ; l’arboriculture conventionnelle a essentiellement recours à lachimie de synthèse. Evalués au moyen d’indicateurs synthétiques, ces différents programmes deprotection ne se distinguent pas fondamentalement en termes d’impacts environnementaux. Lesobservations biologiques directes dans le verger et dans son environnement immédiat indiquentcependant un effet de l’AB moindre que celui du conventionnel sur les lombrics, les communautésaviaires, et sur l’abondance globale des arthropodes. Des réponses opposées sont enregistrées pourles hyménoptères parasitoïdes et les acariens prédateurs, sensibles aux applications répétées defongicides minéraux contre la tavelure. Peu diversifiés, les insecticides biologiques dont les modesd’action s’apparentent souvent à ceux des molécules de synthèse sont fréquemment répétés, doncsujets à l’acquisition de résistances par les ravageurs cibles. Si la préservation de la biodiversité n’estpas acquise par le simple respect du cahier des charges AB, elle semble bien prise en compte par lesarboriculteurs biologiques, conscients de son utilité pour la limitation des infestations parasitaires

To determine the role of earthworms in regenerating compacted zones, it is essential to consider their capacity to colonise these zones. This study aimed to determine the short-term (3-4 years) response of earthworm populations to heavy traffic in two forest soils, at Azerailles (AZ) and Clermont-en-Argonne (CA) in north-eastern France. Earthworm populations were recorded immediately and for 3-4 years after heavy traffic by a 8-wheel drive forwarder with a load of about 23 Mg at AZ and 17 Mg at CA. To test the capacity of earthworms to recolonise traffic plot from the edges, an extra sampling was performed at the border of the traffic plots at AZ. Heavy traffic had a detrimental impact on the density and biomass of three earthworm functional groups. At AZ, earthworm populations, dominated by endogeic species, followed by anecic and epigeic species, had not fully recovered four years after compaction. The absence of statistically significant colonisation by the three functional groups from control to traffic plots indicated that the soil habitat was not yet favourable. At CA, earthworm populations, represented exclusively by epigeic species, had fully recovered three years after compaction, suggesting that the soil habitat was already suitable for them. This strong dependence on soil habitat quality is discussed and may be one reason for variation in the recovery rate of earthworms after compaction reported in the literature. In conclusion, this study did not support the hypothesis that earthworms play a role in regenerating soil structure the first few years following forest-soil compaction.

Earthworms have a prominent role in supporting soil functioning and thus in providing key services to humanity. Their beneficial role relates to effects on soil structure, carbon and nutrient cycling as well as the soil microbial community. Optimizing the role of earthworms in agricultural systems is therefore crucial for maintaining or improving soil quality and supporting a more sustainable, circular agriculture. Here, we summarize established knowledge on the role of earthworms in agronomy; present novel insights from the past decades; and identify key knowledge gaps to be addressed in the future to fully benefit from earthworms in our agricultural soils. We start by discussing how earthworms affect basic soil processes through their effects on soil structure, microbial communities and biogeochemical cycles. Further, we show how as a result of these changes, earthworms indirectly affect plant growth, the soil greenhouse gas balance and play a role in remediation of contaminated arable soils. We further address one of the paradoxes of earthworm ecology: that they are often not present in the soils where they are most needed. We subsequently discuss potential solutions to this paradox. Finally, we identify 10 key questions that need to be addressed in the near future. In our view, recognizing that earthworms are not a stand-alone solution to improving the sustainability of cropping systems, but an essential piece of the puzzle is crucial for optimizing the benefits they offer in agronomic systems. By managing our earthworm populations well, we manage our soils well.

In Southeastern France, viticulture is of great social, cultural, and economic importance. This sector is threatened by climate change particularly in the Mediterranean (longer droughts and more frequent heat waves) where soils are poor in organic matter and weakly developed. Since organic amendment can strongly modify soil properties and consequently the final products (grapes and wine), the effects of sustainable practices on soil characteristics have to be carefully assessed. This seasonal field survey focuses on the effects green waste amendment (GWA), i.e. semi-composted green wastes, have on vineyard soil functionality. The effects of GWA were compared with those of grass cover (GC), known as a sustainable practice. Soils were collected in vineyards under organic practices (Bouches-du-Rhône and Var, France) over four seasons and physico-chemical (Total C and N, pHwater, pHKCL, EC, WHC, copper content and soil organic carbon SOC) and biological (microbial respiration and biomass, microbial catabolic structure, earthworm abundance and biomass) properties were characterized. Both practices were beneficial to soil physicochemical properties. For example, under both practices, higher (2 fold) Total N and SOC on late spring were observed. Both GWA and GC favored soil microbial communities, with microbial respiration having doubled and tripled on late spring. Similar results were observed for microbial biomass and both bacterial and fungal catabolic diversities (increased approximately by half) over summer. These benefits were particularly prominent during drought season (June and August), and probably linked to a shift in microbial communities as revealed by catabolic profiles. GWA also favored abundance and biomass of earthworm during winter. These findings reveal the potential GWA to counteract the effect of tillage, to mitigate the stress from drought and to improve overall soil functionality in vineyards.

AbstractEarthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.