The effects of flower-rich fields on biodiversity-based ecosystem services in the agricultural landscape.

Abstract

The rising demand of agricultural products has led to agricultural intensification based on external inputs. Therefore, biodiversity and semi-natural habitats in agricultural landscapes have decreased in the last decades. Biodiversity-dependent ecosystem services like pollination and natural pest control are negatively affected by this development. Pollination provided by animals is of major importance to a wide variety of crops as well as the majority of wild plants. Furthermore, natural pest control gains importance due to increasingly frequent pesticide resistances. In Germany, Agri-environmental schemes (AES) aim to restore biodiversity in the agricultural landscape and to compensate at least partly for the lack of perennial semi-natural habitats by providing key resources for wild animals. For example, sown flower-rich fields are implemented to provide nectar, pollen and nesting sites to insects. The optimal management, composition and distribution of these flowering fields are still matters of ongoing discussion, especially concerning their interaction with the surrounding landscape in terms of maximizing ecosystem services. In addition, knowledge gaps exist about trade-offs and synergies among pollination and pest control services in response to AES and landscape context. Experiments were carried out in Lower Franconia, Germany in 2016 to address these questions. A total of 31 oilseed rape fields with adjacent flowering fields differing in age/continuity, size and management or with adjacent oilseed rape controls located in 1km radius landscapes along a semi-natural habitat gradient were selected for this study. In the oilseed rape fields, transects leading away from the flowering fields were established to examine distance decay effects of the AES by conducting pollinator observations, pest density and yield measurements. We present results on pollinator visitation rates, pollinator richness, pest control efficiency and crop yields. In doing so, we consider interactive effects of landscape context, different types of AES and within field distance-decay functions.