Functional redundancy of weed seed predation is reduced by intensified agriculture.
Résumé
Intensified agriculture is recognised as a key driver of biodiversity loss, which in turn, can impede ecosystem functions and their stability. Although biodiversity is expected to enhance functional redundancy and stabilize ecosystem functions, few studies have explored how agricultural intensity, affects functional redundancy and its link with ecosystem function stability. Within a large-scale study of 60 fields across Europe, we investigated how agricultural intensity affected the functional redundancy of seed predation. By combining metabolic theory with molecular gut content analysis, we quantified functional redundancy in seed predation for 65 weed genera. In addition, to test if functional redundancy enhanced the stability of functioning, we related it to independent field estimates of weed seed predation. We found that across the weed genera, functional redundancy of seed predation is reduced in homogenous landscapes with high field management intensity and simplified crop rotations. As expected, functional redundancy increased the spatial stability of field estimates of weed seed predation. Our results confirm the importance of biodiversity for stable ecosystem functioning across space and suggest that ecosystem functions are vulnerable to disturbances in intensively managed agroecosystems.