Temporal variation in the roles of exotic and native plant species in plant–pollinator networks

Abstract

The role of individual plant species, including those that are rare or invasive, in the structure of plant–pollinator networks will depend on how connected the plants are to pollinator species and when they flower. Plant species visited by a high diversity of pollinators that visit few other species during a particular time period are thought to provide high value to the insect community. Here, we examined the role of plant species in a plant–pollinator network across the entire flowering season and across dune and adjacent woodland habitats in Wisconsin, USA. We found strong turnover of plants, pollinators, and their interactions in time and space. Both native and exotic species play important structural roles in plant–pollinator networks. Simulations reveal that the loss of the early‐flowering rare plant, Cirsium pitcheri, would result in a disproportionate loss of pollinator species. Furthermore, the critical role that this species plays in the network is not replaced by its exotic relative, Centaurea stoebe. Our research demonstrates that consideration of temporal and spatial variability in networks allows for critical plant species to be identified within a plant–pollinator network that might otherwise be overlooked.

Asclepiasdynamics on US rangelands: implications for conservation of monarch butterflies and other insects

“…Twenty-one milkweed species have been listed as endangered, threatened, vulnerable, or of special concern (USDA-NRCS 2020). For many pollinating insects, both native and exotic introduced plant species have important roles in plant-pollinator networks (Vitt et al 2020). Brummitt et al (2008) estimate that "one of every five plant species are threatened by extinction … and preventing the loss of these species, and the services they provide are global conservation priorities.…”

Pollinator individual‐based networks reveal the specialized plant–pollinator mutualism in two biodiverse communities

“…For example, species can appear as specialists in networks that are combined over narrow time scales, such as 1 day or week. In contrast, they can appear as generalists in networks that are combined over broad time scales, such as a survey season or year if they change interaction partners throughout the season (Chávez‐González et al, 2020; Olesen et al, 2008; Vitt et al, 2020). Therefore, further research is required to examine the structure of pollinator individual‐based pollination networks across a variety of time scales and to fully understand the implications of the pollination network structure.…”

Impacts of the introduced European honeybee on Australian bee‐flower network properties in urban bushland remnants and residential gardens

“…2019; Vitt et al . 2020), differences in the duration (Nov–Feb in 2016/17 and Oct–March in 2017/18), and thus phenology of plants and bees, analyses were conducted separately for each year.…”

“…In the light of these considerations, we conducted analyses from pollination networks conducted during a standardised 100 9 100 m survey over three hours, which also meant there was an adequate sample size so as to conduct statistical analyses. To account for interannual variability, like bees and flowers can exhibit substantial variation in visitation associations (Nakano & Washitani 2003;Cirtwill et al 2018;Rabeling et al 2019;Vitt et al 2020), differences in the duration (Nov-Feb in 2016/17 and Oct-March in 2017/18), and thus phenology of plants and bees, analyses were conducted separately for each year.…”