Converting cropping systems into seasonal habitat functionality reveals the hump-shaped responses of carabid beetles to agricultural management

Abstract

O_LIUnderstanding effects on 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 promising to decipher the relationship between cropping systems and biodiversity but has never been implemented for arthropods. C_LIO_LITo 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. C_LIO_LIWe found that the 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 spring preceding the spring-summer period to determine carabid variations. C_LIO_LIMoreover, we identified thresholds above which resource and disturbance gradients start being beneficial or detrimental for carabids. For example, a Treatment Frequency Index above 2.07 in spring decreased the total activity density of carabids during the spring-summer period. C_LIO_LISynthesis and application. 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. The identification of such thresholds can guide the provision of recommendations for policy, stakeholders and farmers about how to reduce cropping systems impact on arthropods. C_LI