1st Place: D3129: The early flower gets the pollinator: Investigating the influences of seasonality and nutrient additions on floral resources and pollinators in a long-term ecological experiment

Pollinators are vital for the reproduction of wild and cultivated plants, with clear connections to both ecosystem functioning and human well-being. Over the course of a growing season, however, the available floral resources may change, with potential consequences for pollinator activity and plant fitness. In this study, we complement previous work investigating plant-pollinator interactions in a diverse, old-field ecosystem by extending floral and pollinator surveys throughout the growing season. Twelve 25 m² field plots were randomly assigned control or nutrient addition (NPK) treatments, with fertilizers applied yearly each spring. We hypothesized that nutrient additions would increase floral abundance, that this effect would be evident across years, and that floral visits by pollinators would be greater in plots with more flowers. Standardized pollinator observations (number of flower visitations in twenty-minute intervals) and floral abundance surveys were completed in 2019 (pre-treatment) and 2021 (post-treatment) in June and July, with an early-season survey added in 2022. Across three years and five surveys, we recorded 50400 flowers and nearly 2000 pollinator visits. In early-season surveys, we found no significant differences in flower abundance, flowering plant species richness, or pollinator visits when comparing fertilized and control plots, indicating no strong carry-over effects of previous nutrient enrichment on early-season flowering. Despite this, we discovered a diverse set of early-flowering plants and a consistent positive correlation between floral abundance and pollinator visits. Further characterizing how seasonality influences plant-pollinator interactions will be a key to understanding and mitigating pollinator declines.