Limited honeybee hive placement balances the trade-off between biodiversity conservation and crop yield of buckwheat cultivation

An increasing number of farmland initiatives aim to aid biodiversity conservation through alternative farming practices such as nature-inclusive farming. However, these approaches frequently lead to trade-offs between biodiversity conservation and crop yield. For example, buckwheat (Fagopyrum esculentum) is a melliferous crop that flowers for a long period in the summer when nectar in agricultural areas is generally scarce, and buckwheat cultivation could therefore contribute to wild pollinator conservation. However, honeybees (Apis mellifera) are placed to ensure sufficient crop pollination, which potentially increases resource competition with wild pollinators in and around the crop. Here, we have studied this trade-off by surveying pollinators in and around 16 small-scale (∼1 ha) flowering buckwheat fields and we determined the contribution of pollinator density to crop yield in a nature-inclusive farming project. We found that the buckwheat pollinator community was diverse, albeit dominated by honeybees. We found no clear indications of resource competition between honeybees and wild pollinators within the buckwheat fields. Honeybee density in the surroundings was generally low, and increased minimally during honeybee-hive placement. While densities of honeybees decreased non-linearly over the day in buckwheat fields, they did not (temporarily) move into the surroundings of the field, suggesting limited competition for resources with wild pollinators. Crop yield was largely dependent on crop pollinator density, notably of honeybees, and to a lesser extent crop biomass (as a proxy for agricultural management). Our results show that buckwheat cultivation fits well within nature-inclusive farming if some simple precautionary measures are being taken, such as limiting the honeybee-hive densities and placing hives only during the main flowering period. The introduction of buckwheat cultivation into crop rotation could then contribute to fill an important nectar gap in the summer, which potentially boosts wild pollinator populations in the long term.