The Restoration of Serpentine Plant-Pollinator Mutualisms

Abstract

Abstract Plant-pollinator mutualisms contribute to biodiversity and ecosystem function. Invasive species, however, can alter the structure and function of plant-pollinator mutualisms. Illuminating how restoration affects plant-pollinator mutualisms can provide insights into how mutualistic communities assemble and can inform management. We investigated how removing invasive barbed goatgrass (Aegilops triuncialis) influenced the diversity, abundance, and structure of plant-pollinator interactions in a California serpentine meadow. Goatgrass removal treatments resulted in decreased goatgrass cover and increased native forb cover compared to the control treatment. Restored plots had increased pollinator morphospecies richness, Shannon diversity, and pollinator abundance across all years. The restored network had a less nested structure than the control network. Plant-pollinator networks for the restored treatments had higher mean numbers of shared plant partners among pollinators and higher pollinator niche overlap relative to the control. The native forb goldfields (Lasthenia californica) acted as a generalist hub for pollinators within the networks, contributing more strongly to network nestedness in the restored treatment relative to the control. Overall, we found that removing invasive goatgrass increased pollinator diversity and abundance, resulting in higher niche overlap among pollinators visiting a generalist wildflower species. Network-based approaches can inform the restoration of plant-pollinator mutualisms, while providing insights into how mutualistic communities respond to invasive species.