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Conservation and organic agriculture are two alternative crop management strategies associated with environmental impact reduction, leading theoretically to more biodiversity and higher ecological functioning, underpinning better ecosystem service delivery. The combination of these two farming strategies is increasingly seen as an opportunity to mitigate shortcomings of each of them taken individually. However, combining organic and conservation agriculture is undeniably challenging, since it leaves nocurativeoption (neither synthetic pesticides nor soil plowing) for pest control (phytophagous, pathogens, and weeds). Hence, the latter must be ensured by effective restoration of predatory communities. The present research investigated the potential of combining organic and conservation agriculture to support two major ground-dwelling natural enemy communities: carabids and spiders. We used pitfall traps to sample these two communities in paired adjacent cereal fields conducted under organic-conservation (OC) and conventional (CV) agriculture in Belgium. Community assemblages were significantly different across system types, both in terms of species diversity and functional trait diversity. OC parcels showed higher alpha and beta species diversities for both carabids and spiders and species composition differed between OC and CV parcels. OC systems were associated with higher variation of species assemblages among parcels than CV systems Functional traits also differed across system types for both groups. We found more herbivorous and granivore carabids in OC parcels, and more predator species in CV parcels. We found larger spiders, more hunting spiders and more wetland spiders in OC parcels, whereas we found more web weavers and more forest spiders in CV ones. Functional diversity was higher in OC parcels for carabids, but not for spiders. In brief, OC parcels supported more diverse communities, both taxonomically and functionally. These outcomes show that OC systems are promising systems to support these natural enemy communities. Further studies should assess whether combining organic and conservation agricultural enables sufficient pest control levels to achieve high levels of food production and farmers income.

La Vipère péliade (Vipera berus) étant une espèce en forte régression en Europe, ses populations relictuelles font l’objet d’efforts de conservation importants dans de nombreux pays. La population des Hautes Fagnes (Belgique), découverte récemment, paraît, quant à elle, en pleine expansion. Son étude constitue une opportunité unique d’appréhender la dynamique d’une population introduite sur une vaste zone. Pour établir la répartition de cette espèce discrète sur ce vaste site tourbeux, nous avons utilisé une technique de modélisation de l’occupation de sites afin de déterminer la probabilité d’utilisation de 52 stations réparties sur près de 5 000 ha. L’effectif a quant à lui été estimé au sein de six zones échantillons étudiées par capture-recapture. Il a ensuite été extrapolé en quantifiant la surface d’habitats favorables sur le périmètre actuellement occupé. Les résultats indiquent que la zone d’occupation principale couvre actuellement un peu plus de 800 ha dont environ 450 sont favorables à la reproduction de l’espèce. Les densités sont élevées, atteignant entre six et 14 individus par hectare selon les stations. L’effectif est estimé entre 3 000 et 6 000 individus. Nos résultats suggèrent que moins de 10% des zones potentiellement favorables à l’espèce au sein de la réserve naturelle sont actuellement occupées. La population pourrait donc abriter à terme plusieurs dizaines de milliers d’individus. Nos résultats montrent également que la probabilité d’utilisation des stations est négativement influencée par la couverture arborée, et ce même lorsque cette dernière est peu présente, démontrant ainsi l’importance du maintien du caractère non arboré des landes pour la reproduction de la Vipère péliade. De plus, la probabilité d’utilisation des stations est positivement corrélée à l’abondance d’éricacées (Calluna vulgaris, Erica tetralix, Vaccinium myrtillus et V. uliginosum), de sphaignes (Sphagnum sp.) et de polytrics (Polytrichum sp.) et négativement corrélée au recouvrement en molinie (Molinia caerulea). De ce fait, la Vipère péliade peut être considérée comme un bon indicateur de l’état de conservation des landes.

We are currently facing a large decline in bee populations worldwide. Who are the winners and losers? Generalist bee species, notably those able to shift their diet to new or alternative floral resources, are expected to be among the least vulnerable to environmental change. However, studies of interactions between bees and plants over large temporal and geographical scales are limited by a lack of historical records. Here, we used a unique opportunistic century-old countrywide database of bee specimens collected on plants to track changes in the plant-bee interaction network over time. In each historical period considered, and using a network-based modularity analysis, we identified some major groups of species interacting more with each other than with other species (i.e. modules). These modules were related to coherent functional groups thanks to an a posteriory trait-based analysis. We then compared over time the ecological specialization of bees in the network by computing their degree of interaction within and between modules. "True" specialist species (or peripheral species) are involved in few interactions both inside and between modules. We found a global loss of specialist species and specialist strategies. This means that bee species observed in each period tended to use more diverse floral resources from different ecological groups over time, highly specialist species tending to enter/leave the network. Considering the role and functional traits of species in the network, combined with a long-term time series, provides a new perspective for the study of species specialization.

An increasing number of agricultural transition initiatives are taking place, seeking more autonomy and resilience on the farms. This undeniably reshapes the landscape and the delivery of ecosystem services (ES). To date, little research includes the knowledge and perceptions of local communities on rural landscapes in agricultural transition. Yet, farmers shape the landscape and ES delivery, and local inhabitants are directly impacted. The present work aims at assessing the extent to which locals (local inhabitants and farmers) appreciate and view landscapes undergoing agricultural transitions. To do so, questionnaires were submitted to locals enquiring about appreciation and ES perceptions of transitioning landscapes. These landscapes were shown in manipulated photographs simulating an agroecological landscape, a conventional agriculture landscape, and landscapes including each isolated agroecological practice (resulting in six &lsquo, scenarios&rsquo, ). In order to put locals&rsquo, perceptions in perspective, the same questionnaire was submitted to &lsquo, ES experts&rsquo, and ES perceptions were compared to field-based ES measurements in agroecological and conventional parcels of the same study region. The results show that locals and ES experts appreciate and perceive these scenarios similarly. The agroecological scenario was seen as the most appreciated and the one delivering the most ES, while the conventional one was the least appreciated and seen as the one delivering the least ES. These perceptions of ES delivery partially correspond to the ES field measurements, which showed a similar productivity within agroecological and conventional parcels and more regulating ES in agroecological parcels. We discuss how our results call for the assessment of the multi-performance of agricultural systems in terms of ES rather than focusing on yield only, and how future research addressing agroecological transition should rely on integrated valuations and mixed methods to better embrace the complexity of such transitioning systems.