Development of flower strips near agricultural fields with minimal weed management

Perennial field margin plantings are known to contribute to both biodiversity and ecosystem services in agricultural landscapes, but the duration of their functionality is not clear, especially in the northeastern region of the United States. A four-year study was conducted near Ithaca, New York, USA, from 2022 through 2025 to investigate the effects of seeding density and seed mix composition on the establishment and development of perennial field margin plantings established in 2022 under weedy conditions. Our results indicate that weed pressure negatively affected plant establishment during the first two years; however, planted strips ultimately enhanced biodiversity despite these initial inhibitory effects. To assess longer-term impacts, vegetation density, diversity, and biomass measurements were collected in 2024 and 2025. Four years after establishment, we found that, as in the first two years, the highest densities of seeded species still occurred in flower strips with high seeding rates. Flower strips planted with native grass species at a high seeding rate tended to have less weed biomass than strips planted with a seed mix containing only wildflowers, especially at higher seeding rates. Contrary to expectations, the establishment of native species did not increase alpha-diversity metrics, including the Shannon diversity index. Despite no significant differences in total species richness among treatments, margins established with native grasses and wildflowers contained more seeded species. Our results suggest that realizing the biodiversity benefits of field-margin plantings may require active weed management, despite the modest suppression of weeds observed in high-density plantings containing native grass species. However, seeded dicot species were consistently found even under weedy conditions, suggesting that the presence of weeds in flower strips does not prevent them from enhancing the floral resources available to pollinators within field margins.