Hedgerows are more multifunctional in preserved bocage landscapes

Abstract

Hedgerows are key wildlife habitats in agricultural landscapes, with presumably high multifunctionality – that is the capacity to provide multiple ecological, agronomic or cultural functions. However, knowledge gaps remain regarding the drivers of hedgerow multifunctionality and potential synergies and trade-offs between functions. In particular, it is unknown in which landscapes hedgerows best support a range of taxa and associated functions. We assessed the effects of hedgerow features, adjoining farming systems, landscape context, and their interactions on hedgerow multifunctionality based on four ecological functions – biodiversity conservation, potential pollination, potential predation, and pest colonization. We estimated these functions by the abundance and diversity of plant and arthropod taxa in 40 hedgerows, in Brittany (France). Results support previous studies showing the beneficial effects of flower cover, margin width, adjacent organic farming, and other variables related to hedgerow structural complexity on individual taxa or proxies of functions. Most importantly, our study reveals that hedgerows are more multifunctional in landscapes with dense hedgerow networks (so-called ‘bocage’ landscapes), which is likely the result of greater habitat amount, connectivity, and environmental heterogeneity. In addition, we find weak correlations between proxies of functions, and more synergies than trade-offs in response to the explanatory variables, indicating that there is considerable scope for improving the ecological value of hedgerows. We draw attention to the fact that ongoing destruction of hedgerow networks, including wide and structurally complex hedgerows, might lead to long-term or irretrievable loss of associated species and ecological functions, jeopardizing restoration and replanting efforts.