Salvage logging management affects species' roles in connecting plant-pollinator interaction networks across post-wildfire landscapes.
Abstract
Spatial connections between habitats are important to allow movement of organisms across heterogeneous landscapes with diverse disturbances and management. Similarly, species providing functional connections between subnetworks of species interactions (modules) are important for ecosystem services across these landscapes. These functional connectors have received less study. In post-wildfire landscapes, we investigated the influence of salvage logging, a common management technique, on plant-pollinator network modularity. We measured the composition, strength and characteristics of forb and bee connector species across spatial and temporal scales. Salvage logging influenced the structure of plant-pollinator interaction networks. Network modularity was higher in salvage-logged areas compared to unlogged areas, indicating that logging functionally fragmented these species interactions. There were compositional differences in connectors, especially of plants, between logged and unlogged areas. Plant species, but not bee species, had weaker connections across modules in salvage-logged areas, suggesting that although some plant species were serving as connectors after salvage logging, they were performing worse in this role. While some suites of species formed spatial connections, others formed temporal connections (linking interactions across the growing season), indicating that disparate groups of species are likely needed to provide these critical functions across space and time. Synthesis and applications. Investigating species' roles as connectors can provide a more complete understanding of the implications of management and provide insight into how best to conserve or restore the structure and function of species interactions across landscape mosaics. Bees may be more capable of readily responding to changes in their plant partner's spatial or temporal distributions due to salvage logging. As a result, bees may be better poised to maintain stable connections across modules compared to plants, and management actions supporting highly mobile connector species (like bees) may help offset detrimental effects of salvage logging or other disturbances. This work also indicates that minimizing the spatial extent of salvage logging relative to the proximity of other habitat types will likely aid species in forming spatial connections. Applying this framework of species as network connectors may help maintain the spatial and temporal continuity of floral resources and pollination services, even when management reduces biodiversity.