Linear transport infrastructure as a relay for soil biodiversity

Aim: Several studies have highlighted the impact of linear transportation infrastructures on the flows of certain animal populations. These infrastructures have important ecological impacts on the environment, as they contribute to the parcelling out of habitats of organisms. However, they can also represent refuges in uniform landscapes, particularly for the soil fauna. This study is particularly interested in the infrastructure of energy transport via the electric pylons.Method: Three management modalities under pylons were studied: conventional agriculture, grazed meadows and unmanaged. Five pylons distributed on 2 sites in the north of France, Rhuminghem and Bailleul, were monitored. This monitoring focused on the meso (springtails) and macrofaunal (woodlice, ground beetles and earthworms) communities of the soil. The sampling was done under the pylon and at 5 and 15 m from the pylon.Results: No significant refuge effect is visible for carabid beetles, which prefer open environments, adapted to their way of life. The distribution of carabid beetles is little affected and seems to be homogeneous on the cultivated plots. Similarly, the vegetation under the pylons does not seem to influence their presence either. The only evidence in favor of this refuge effect is the greater abundance of woolouse and worms under pylons in fallow areas compared to adjacent cultivated plots.Conclusion: The pylons monitored did not show an overall positive effect on the abundance and composition of edaphic communities. The effects are punctual and limited to 1 or 2 taxa (collembola, woodlouse). No influence on the most mobile taxa was observed

Isolation and characterization of eight polymorphic microsatellites markers for the earthworm Lumbricus terrestris

International audienc

Comparison of the interest of four types of organic mulches to reclaim degraded areas: a field study based on their relative attractiveness for soil macrofauna

ACLThe study focused on the attractiveness of mulches (consisting of the addition of a layer material to the soil surface) and their efficiency to promote recolonization by pedofauna of isolated and degraded areas. The experimental study was set up in the former coal mining area of Northern France. This area is particularly disturbed and fragmented by land-use change, urbanization, industry, intensive agriculture and metal pollution. To examine the movements of pedofauna, four kinds of mulches were applied: (i) Ramial Chipped Wood (RCW), (ii) chopped Miscanthus, (iii) dead leaves and (iv) wheat straw as well as plastic sheeting, a material often used in green spaces. A negative control consisted in soil without mulch addition. The experimental set-up consisted of a set of 18 bands of mulch (6 m long x 0.5 m width x 8 cm thick, i.e. a volume of 0.04 m3 per band) installed on three adjacent plots on a surface area which stretch on 4400 m2: (i) plot F1, a mixed plantation, (ii) plot M consisted of three rows of maples (both considered to be the reservoir of biodiversity) and (iii) plot BF, an ash plantation (with lower biodiversity). Faunistic communities of soil present within the mulches were monitoring using pitfall traps for four months (April to July), at a rate of eight surveys for each of the 90 traps installed, i.e. 720 samples. Different life traits and indices of diversity were studied, more specifically on carabid beetles. The main objective of the study was first to check whether mulches could or not reconnect different planted plots in a peri-urban landscape highly modified by human activities. The second aim was to find which type of mulch had the best efficiency in the recovery of the connectivity between plots. The last questions were which type of zoological groups could be favoured by the use of mulches and which benefits for ecosystem functioning. The main hypotheses of this study were: (i) Organic mulches would act as dispersal corridors and refuge zones to the soil organisms; (ii) organic mulches would be attractive to many organisms with various ecological needs. This study highlighted the potential benefits of using the mulching technique to support ecological connectivity in disturbed environment since this method highlighted the presence of individuals with different diets (saprophagous, predators, phytophagous and so forth), small and large size species which do not have the same dispersal capacities as well as species that are more dependent on forest environments and others that depend on more open environments. The study concluded that organic mulches are more favourable to pedofauna than soil without mulch or plastic sheeting. With regard to organic mulches, no difference was noted, either in terms of cumulative abundance or monthly monitoring. However, for carabids, it should be noted that dead leaves and wheat straw have higher specific richness than Miscanthus and RCW

Isopod physiological and behavioral responses to drier conditions: An experiment with four species in the context of global warming

ACLIn the context of global warming, an increase in soil drought is suspected by the IPCC predictions and litter breakdown activity could be affected. An experiment was conducted using microcosms (controlled conditions) and woodlice which are recognized as shredders of litter and bioindicators of global warming. The impact of relative air humidity (90 and 50% RH) on litter breakdown by woodlice was studied through the monitoring of one behavioral (distribution of individuals on microcosms), one morphological (Absolute Growth Rate) and four physiological traits (Survival rate, Relative Consumption Rate, Relative Growth Rate, Feeding rate). Four species of isopods known to have different microclimatic sensitivities (Armadillidium vulgare, Porcellio scaber, Oniscus asellus, Philoscia muscorum) were used simultaneously. Sensitivities of males and females have also been tested. Main results showed that the seven studied parameters under the two relative humidity conditions were not affected in the same way according to the species nor genders. A. vulgare is the most affected species followed by O. asellus. The least affected species are P. scaber and P. muscorum. Their morphological and physiological differences allow to the most evolved species to be more resistant to drier conditions but in return they are no longer active, which can affect soil functionality. With global warming, it could be envisaged that woodlice spend less time foraging and more time seeking refuge to reduce the risk of mortality from desiccation stress. Modifying the feeding behavior of terrestrial isopods could slow down litter degradation with consequences on the process of organic matter recycling

Does adding fly ash to metal-contaminated soils play a role in soil functionality regarding metal availability, litter quality, microbial activity and the community structure of Diptera larvae?

ACLThis study aimed at evaluating the impact of the use of fly ash-aided phytostabilisation as a method to manage highly metal-contaminated soils on soil functionality taking into account the soil and the litter qualities, the Diptera larvae communities and the microbial activity. To reach this goal, 70 parameters were studied. The main results showed that the two studied fly ashes Soproline® and Sodeline® had a positive influence on soil characteristics especially the availability of metals, nearly 14 years after amendment. Regarding biological parameters, no positive or negative effects were found by adding fly ashes to the soil concerning soil basal respiration and urease activity. The fungal activity was even enhanced. In the same way, the fly ashes had no negative effect on the Diptera larvae community and a greater richness of larvae was even found in amended soils. Thus, this study confirmed that aided-phytostabilisation using these fly ashes should be an advantageous technique to manage metal-polluted soils and to recycle industrial wastes

Comparison of the interest of four types of organic mulches to reclaim degraded areas (Part 2): Microbial activities and abiotic factors

International audienc

Litter breakdown as a tool for assessment of the efficiency of afforestation and ash-aided phytostabilization on metal-contaminated soils functioning in Northern France

ACLThe main objective of the study was to assess the efficiency of phytoremediation methods implemented for 14 years on highly metal contaminated soils. The different experimental strategies were plots planted with a tree mix or with a single tree species coupled or not with the use of fly-ashes as an amendment to limit metals mobility in soil. The breakdown of poplar litter on the four plots was monitored during 10 months. In parallel, colonization of litter bags by functional groups of mesofauna (Collembola and Acari) was followed. Two mesh sized litter-bags were used to allow distinguishing microbial and mesofaunal actions on the litter breakdown. We observed the breakdown of litter in four studied plots. Litter breakdown occurred faster in 3 mm litter bags than 250 µm ones during summer demonstrating the importance of mesofauna. Mixed plantation allowed faster litter breakdown than mono-specific plantation. A higher abundance of mesofauna and/or better abiotic conditions (moisture, shading…) could explain this result. Regarding litter breakdown and mesofauna, no significant difference was observed between the amended plots and those subjected to soil phytomanagement. However, communities of the studied area are disturbed since a low abundance of detritivores was observed. This could explain also the slower litter breakdown than expected in our study. To conclude, among the phytomanagement methods tested, mixed plantations could provide a benefit for the restoration of degraded soils. By contrast, the use of fly-ashes does not seem to have any effect on the functionality of ecosystem neither on the litter breakdown process nor on the abundance of mesofauna

Soil invertebrate functional traits as indicators for metal contamination

International audienc

Vers une meilleure utilisation des traits fonctionnels des invertébrés du sol

National audienc

Vers une meilleure utilisation des traits fonctionnels des invertébrés du sol

National audienc