Earthworm community characteristics during afforestation of abandoned chalk grasslands (Upper Normandy, France)

La biomasse, la densité et la composition spécifique des vers de terre a été évaluée dans différents stades d'une succession secondaire après l'abandon d'une pelouse calcicole pâturée. La biomasse et la densité des populations de vers de terre sont très élevées (51,2 à 130,2 g/m2 et 175,8 à 522,6 ind/m2 en moyenne) dans toutes les parcelles échantillonnées. L'abandon du pâturage conduit à un rapide développement des communautés de vers. La biomase et la densité atteignent leur maximum dans une pelouse récemment mise en exclos, puis diminue dans une pelouse abandonnée depuis 50 ans. La densité croit ensuite, alors que la biomasse diminue légèrement pendant l'installation du bois de feuillus. La densité et la biomasse sont minimales sous pinède. La richesse taxonomique (nombre d'unités taxonomiques) ne change pas pendant la succession, mais la composition spécifique varie de façon nette. La dynamique des communautés de vers de terre semblent être sous l'influence de deux facteurs environnementaux prépondérants, eux-même étroitement liés à deux paramètres de la végétation : la structure verticale de la végétation (importance de la couverture du sol par la végétation herbacée, la litière, les mousses, présence d'arbres) et la qualité des litières restituées, liées à la nature de la végétation (herbacée, conifères ou feuillus). (Résumé d'auteur

Factors influencing soil macrofaunal communities in post-pastoral successions of western France

The soil macrofaunal communities (Lumbricidae, Formicidae, Coleoptera, Chilopoda, Diplopoda, Isopoda, Arachnida, Gastropoda) were studied in six plots representing different stages in theoretical post-pastoral succession chalk grassland. Macrofaunal biomass was high in all the plots (70.2-140.3 g/m2). The macroinvertebrate communities along successional gradients respond to two major environmental factors : the structure of the vegetation, which determines the diversity of microhabitats and life conditions for macroinvertebrates ; and the quality of above-ground litter production, which depends on the nature of vegetation and the presence of domestic herbivores. (Résumé d'auteur

Population dynamics and adaptative strategies of Martiodrilus carimaguensis (Oligochaeta, Glossoscolecidae), a native species from the well-drained savannas of Colombia

#Martiodrilus carimaguensis (Oligochaeta, Glossoscolecidae) is a large, anecic native earthworm species which was found in natural and disturbed savannas in the Oxisols of the Colombian Llanos. Its population dynamics were studied in a native savanna, and in a 17 year old grazed grass-legume pasture where density and biomass were higher. Monthly cast deposition on the soil surface in the improved pasture was 38.4 x 10(exp 3) fresh casts/ha, eleven times more than in the native savanna. A strong relationship was found between numbers of #M. carimaguensis and numbers of fresh surface casts. Different patterns of adaptation to the dry season were observed for adults and juveniles. Adults are active for eight months whereas juveniles enter diapause 3-4 months earlier. The vertical distribution pattern of the earthworm population also shows marked seasonal changes. (Résumé d'auteur

Things turned upside down

Aim: Soils and their biological communities face increasing pressure from multiple global drivers, including land management and climate change. In soils, earthworms play key roles in ecosystem functioning, but the environmental controls on their global communities are not fully understood. Here, an earthworm dataset was compiled to investigate the effects of environmental controls and land management on global earthworm communities. Location: 40 ° S – 65 ° N. Time period: 1962 to 2016. Major taxa studied: Earthworms Methods: A dataset of 899 earthworm community observations, together with environmental variables, was compiled across 169 globally distributed sites. Sites included natural forests and grasslands or managed arable, pasture or plantation ecosystems. Total, anecic, endogeic and epigeic abundances were compared in natural and managed ecosystems to quantify the effects of land management across climates. A hierarchical model was used to test interactions between earthworm communities with environmental controls and management across eighteen ecosystem types. Results: Land management prompted little change in total earthworm abundance at the global scale, but reduced species richness and shifted community composition. Endogeic earthworms were more abundant in managed ecosystems, while anecic and epigeic earthworms show variable responses across ecosystem types. Global relationships between total earthworm species richness and abundance were explained by climate, soil pH and land management. Main conclusions: Land management modulates the effects of environmental controls on global earthworm communities, through direct disturbance and indirect changes in edaphic conditions