Plant and bee communities and their interactions are differently influenced by extensive grazing by horses or sheep in the South of France (Causse Méjean)

Pollinators, especially bees, are vital for ecosystem resilience through their role in pollination, yet they are increasingly threatened by the current biodiversity crisis. Large herbivores, by maintaining open ecosystems and facilitating plant dispersal, can contribute positively to increase floral resources with moderate carrying capacity, but the effect of grazing pressure and type on biodiversity remains under investigations, especially in protected areas. In the Cévennes National Park (southern France), the Causses are dry limestone grasslands traditionally grazed by sheep and more recently by horses, whose distinct grazing behaviours may differentially shape plant communities. By identifying plant and bee abundance and diversity, this study investigates how different extensive grazing regimes, by semi-wild Przewalski horses (takhi), domestic horses and sheep compared to a control without regular grazing, affect floral resources, wild bee communities, and bee-plant interaction networks. Results show that takhi-grazed plots host richer plant and wild bee communities, likely due to more heterogeneous grazing. However, the structure of bee-plant networks (in terms of specialization metrics and Shannon diversity) remain unchanged across all grazing conditions, suggesting that extensive grazing has limited impact on network architecture. These findings highlight the value of diverse, extensive grazing practices, particularly involving semi-wild grazers like takhi, in supporting pollinator and plant diversities without disrupting ecological interactions. Long-term monitoring will be essential to understand the lasting effects of grazing on plant-pollinator dynamics and to guide adaptive management of protected agroecosystems. This approach can contribute to more resilient agroecosystems capable of withstanding environmental changes.