The functioning of plant-pollinator mutualistic networks is crucial for ecosystem service provisioning and biodiversity maintenance. These communities are, however, heavily affected by both global and local scale environmental and human-induced changes, as shown by the alarming rate at which wild pollinators' abundance and richness are declining worldwide. We propose an ecological, process-based mathematical model describing the dynamics of pollinators and plants, properly mediated by reward resources. Our model explicitly accounts for the main interactions of both facilitative and competitive nature that occur both within and between the two guilds. In this study, we focus on fragmented landscapes, akin to those that can be observed in urban and peri-urban environments. We contrast the outcomes from a novel ecological model with empirical evidence to investigate how the degree of specialization (and the resulting niche width) can determine a species’ temporal persistence and abundance at the community level, and its rarity at landscape level. Our results suggest that few generalist pollinators form a core of abundant, persistent and widely distributed species, while increasing specialization is generally associated with low abundance, low persistence and high turnover between patches. Specialists, however, are crucial to maintaining high levels of biodiversity within the community. This finding highlights the importance of ecological connectivity, through which local extinctions can be counter-balanced by recolonizations. Our analysis shows how a mechanistic model accounting for the interplay between the species traits and the structure of plant-pollinator networks can serve as a tool to investigate important ecological mechanisms driving community composition, dynamics and the resulting biodiversity patterns.