Urban areas within the United States have rapidly expanded over the past 50 years, increasing the extent of suburban development. Such change in land use has been proposed as a dominant factor in the decline of native bee pollinators, raising concern over the integrity of pollination services in suburban areas. However, many factors likely determine how suburbanization affects bees and the plants that depend on them for pollination. The goal of this study is to determine how suburbanization changes interactions between plants, their bee pollinators, and other insects that consume flowers. Previous research has documented that suburban forests actually harbor more bees than natural forests, but that plants growing in suburban forests are also more likely to have flowers damaged by floral herbivores, which could make plants less attractive to bee pollinators. This research will determine 1) how damage to flowers affects pollination of native plants, and 2) how this relationship varies between suburban and natural forests. This research is novel because few studies have addressed how suburbanization affects pollination indirectly through changes in interactions between beneficial bees and detrimental flower feeding insects.
Pollination is of great ecological and economic importance ? pollinators are essential for the reproduction of most flowering plants, and the value of pollination for global food production is estimated to exceed $200 billion annually. In addition, growing concern over declines in native pollinators and the sustainability of their pollination services underscores the need for research on factors driving changes in plant-pollinator interactions. The results of this study will provide ecological insight into how human development affects pollination and could produce recommendations for the conservation of pollination services in developing and developed areas. In addition, this research fosters public interest in and awareness of the importance of pollination through interactions with public and private land owners, cooperation with suburban home owners associations, and communication with individual homeowners. As public interest and involvement are integral to the dissemination of scientific research, an informational pamphlet, including the findings from this and previous research, will be developed and distributed to all cooperating landowners, homeowners, and public agencies.
Land-use change is a dominant factor driving species distributions, abundances, and biodiversity. While much attention has been given to the effects of land-use change on the loss of species diversity, fewer studies have addressed the ecological or evolutionary implications of land-use change for species persisting in human-dominated systems. The goal of this study was to determine how suburbanization affected native plants via changes in plant-animal interactions. Gelsemium sempervirens is a flowering vine endemic to the southeastern United States that occurs in natural forests and forests persisting within suburban development. Prior research indicated that Gelsemium growing in suburban forests received higher rates of floral herbivory relative to those in natural forests. The specific goals of this research were to determine how floral herbivory affected Gelsemium reproduction in suburban vs. natural forests, and the degree to which floral herbivores had direct consumptive effects on plant reproduction vs. indirect effects mediated through changes in pollinator behavior. We accomplished this through the experimental manipulation of both floral herbivory and pollination and measured subsequent effects on plant reproduction. Overall, floral damage reduced the number of pollinator visits to plants. However, floral damage increased the time pollinators spent per flower. Thus, on a per-flower basis, damage actually increase pollen movement from flowers, but on a per-plant basis, the costs of damage reducing pollinator visitation outweighed any benefits of increased time spent per flower. Moreover, floral damage reduced the number of fruits and seeds produced per flower, and providing supplemental pollen to flowers to simulate increased pollinator visitation did not rescue flowers from the direct consumptive effects of floral tissue damage. Taken together, these results suggest that floral herbivores can have negative effects on plant reproduction, and that suburban plants may be at increased risk for fitness loss due to the activity of insects interacting with and consuming their flowers, an unexpected consequence of suburbanization. Broader Impacts – Land-use change is anticipated to be the single greatest factor affecting biodiversity in the future. Studies within human-dominated systems are integral to understand how anthropogenic change will alter ecological patterns and species interactions in native communities persisting in remnant wildlands. Working in suburban environments and public lands enabled us to interact with the general public through research happening in their favorite natural areas and own back yards, fostering positive relationships between scientists and the public. This research provided valuable field and training experience to a graduate student, and the research makes up a final chapter of his PhD dissertation. The graduate student successfully defended his dissertation and now is a post-doctoral associate. Through this award, the graduate student also had the opportunity to provide field experience to one participant who is now back in school to receive her masters degree, and to seven undergraduate students through part-time laboratory research experiences during the academic year. Participation in research can be a critical learning experience in the education of many students, and this award provide the opportunity for significant human-resource development.
