High heterogeneity of grassland communities supports a high diversity of species and represents a key point forthe retention of pollinators in agricultural landscapes. In the present study, we explored whether the co-oc-currence of different grassland communities has any effect on the stability of the network of pollination inter-actions. We monitored pollination interactions in two co-occurring grassland communities, differing in dis-turbance history and water and nutrient supply. The monitoring was carried out during the summer season (7surveys). For each survey we compared the role in the pollination networks (i.e., keystone vs. peripheral species)of habitat-specialist and habitat-generalist plant and pollinator species. We found that plant and pollinatorspecies of the two different grassland communities were highly interconnected, revealing that pollination in-teractions occur at a level of organization above that of the single community. The co-occurrence of the twograssland communities increased the type, number and frequency of contacts, thereby contributing to networksstability. The role of habitat-specialist and habitat-generalist plant and pollinator species in pollination networkswas asymmetric, with habitat-specialist plants and habitat-generalist pollinators being keystone species, whilehabitat-generalist plants and habitat-specialist pollinators being peripheral in the pollination networks. Ourresults showed that the stability of the network does stem from the co-occurrence of different species poolshaving different but complementary roles in the pollination networks. From a conservation perspective, themaintenance of different grassland communities is important not only because they allow the conservation ofhabitat-specialist species, but specifically because plant species specialized in either grassland community arealso keystone for the maintenance of the stability of the pollination networks.
