Floral offer and seasonality shape plant–pollinator networks in tropical gardens

Abstract

Urban expansion is accelerating global pressure on pollinators and their interactions with plants. Urban green spaces may nevertheless act as key refuges, provided they offer a suitable floral environment. Here, we investigated how pollinator assemblages and plant–insect pollinator networks responded to spatial and temporal floral offer (i.e., floral abundance and composition) across private and communal gardens in a tropical urbanized landscape (Martinique, Lesser Antilles). Using a motif‐based approach, we found that both floral abundance and composition shaped plant–insect interaction networks. Specifically, floral abundance enhanced insect pollinator species richness and interaction occurrences, but this effect was modulated by human‐driven patterns in floral composition characteristics (i.e., human use, life form, and origin status). A phenological mismatch occurred between floral resources and wild insect pollinators: garden floral resources were at their lowest in the wet season when wild insect pollinators' occurrence peaked, leading to greater insect pollinator specialism and plant generalism. The western honey bee Apis mellifera —a super‐generalist exotic pollinator—hugely dominated interactions, producing networks characterized by higher insect generalism, especially in the dry season when wild insect pollinator abundance and diversity were lowest. Insects contributed more to species turnover in communal gardens, whereas plants contributed more in private gardens, with overall plant contribution to species turnover far exceeding that of insects. Private gardens, especially those proportionally richer in ornamental, arborescent, and exotic plants, tended to be less attractive to wild insect pollinators but more so to bird pollinators. Together, these patterns underscore the role of human floral management in structuring plant and pollinator assemblages as well as their interactions. As urbanization expands, fostering diverse and seasonally reliable floral resources through inclusive gardening practices may be key to conserving pollinators and sustaining their ecological roles.