Carabid beetles have hump-shaped responses to disturbance and resource gradients (...)
Muneret, L., Ricci, B., Vialatte, A., Aviron, S., Ducourtieux, C., Biju-Duval, L. and Petit, S. (2023), Carabid beetles have hump-shaped responses to disturbance and resource gradients within agricultural landscapes. J Appl Ecol. Accepted Author Manuscript. https://doi.org/10.1111/1365-2664.14357
Abstract
Understanding the effects of the huge diversity of cropping systems on local biodiversity is challenging but necessary to implement agroecological systems. Through a functional approach, the translation of cropping systems into resource and disturbance gradients is a promising way to decipher the relationship between cropping systems and biodiversity but has never been implemented for arthropods.
To investigate contributions of resource and disturbance gradients arising from cropping systems vs environmental context (regional effect, meteorological conditions and landscape characteristics) on beneficial arthropod communities, we used a dataset collected in 60 crop fields from three French areas over a five-years period. It includes all farmers interventions, crop sequences, meteorological data, landscape composition and carabid samplings.
We found that environmental context contributed to about 75% of explained carabid variations on average, while resource and disturbance gradients contributed to about 25% of explained carabid variations. The resource and disturbance gradients were particularly important in winter and in the spring preceding the spring-summer period to determine carabid variations.
Moreover, we identified thresholds above which resource and disturbance gradients start being beneficial or detrimental for carabids. For example, increased treatment index in spring decreased the total activity density of carabids during the spring-summer period.
Synthesis and applications. While implementing for the first time a functional approach to understand the effects of different facets of cropping systems on arthropods, our study also allows us to identify periods and thresholds above which specific practices affect carabids. Finally, avoiding bare soils all along the year, keeping pesticide use intensity below the identified thresholds and adopting a wide diversity of tillage strategies at the landscape scale should all contribute to enhance in-field carabid occurrences and richness.
Pour comprendre les effets des différentes facettes des systèmes de culture sur les carabes, nous avons développé et mis en œuvre une approche fonctionnelle originale pour représenter la disponibilité des ressources pour ces arthropodes auxiliaires des cultures. Cette étude identifie les périodes et les seuils à partir desquels des pratiques agricoles spécifiques affectent les carabes. Eviter les sols nus, maintenir l'intensité d'utilisation des pesticides en dessous des seuils identifiés et adopter une grande diversité de stratégies de travail du sol à l'échelle du paysage contribue à améliorer diversité des carabes dans les champs.
Merci à Jérôme Willm, Jérôme Molina et Laurent Raison de DYNAFOR pour les enquêtes, les acquisition de données écologiques et l’identification des insectes ayant largement contribué à cette étude
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