2017 ASHS Annual Conference

Human activities are responsible for changes in climate and biogeochemical cycles at unprecedented rates, with uncertain consequences for biodiversity and ecosystem function. Globally, air pollution, industry, and transportation drive increased temperature, carbon dioxide (CO₂) concentration, and nitrogen (N) deposition. Understanding the ecological effects of these simultaneous changes on plants in urban settings is an essential foundation for managing diversity and ecosystem function on local and global scales. Our research addresses this issue, using two annual species of plants typically found in urban gardens and three species commonly planted to enhance urban pollinator habitat in the United States. Pollination services, provided primarily by managed honey bees (Apis mellifera L.), bumble bees (Bombus spp.), and some wild bees (Order Hymenoptera) are threatened by declines in the health and abundance of these insect pollinators, and the changes in urban landscapes. It is highly likely that climate and atmospheric changes will impact nectar and pollen quantity, as well as growth of urban plants which, in turn, can impact bee health. The overall goal of this controlled-environment study was to understand the combined effects of three critical climate change variables (temperature, CO₂, and N) on floral traits and pollination services on pumpkin (Cucurbita pepo), sunflower (Helianthus annuus), California poppy (Eschscholzia californica Cham.), gaillardia (Gaillardia pulchella Foug.), and partridge pea [Chamaecrista fasciculate (Michx.) Greene]. Initial results show that temperature, CO₂ level, and N level (in the form of liquid fertilizer) all affected some measure of pollen production, be it pollen quantity or quality. For example, treatment affected pollen counts per flower in pumpkin, but not in sunflower. This poster will share the detailed results from our study, as well as how these findings could impact how environment and habitat composition influence urban bee populations and inform horticultural planting selections in “bee-friendly” urban gardens.