Professor University of California Davis, California
Wildflower seed mixes and the resulting plantings are an effective and widely implemented tool for mitigating floral resource scarcity, one of the major factors contributing to global pollinator declines. The design of seed mixes for native bee habitat plantings depends on conservation goals. Mixes can target ecosystem service provision and/or the conservation of biodiversity with a likely focus on rare or threatened species. Seed mix design can address the different goals with a focus on floral diversity, floral abundance and continuity or long term performance. Moreover, management related aspects such as weed control, resowing and cost effectiveness are of interest for stakeholders. In the presented study we tested California native wildflower mixes in a 3-years field experiment. The mixes differed in floral composition, diversity, seeding density and inclusion of grasses. All mixes contained annual as well as perennial plant species. Generalized-linear mixed model analysis analysis revealed benefits of slightly higher seeded diversity and exclusion of grasses for floral coverage and number of established plant species. Whereas, seeding density did not significantly affect mix performance. Dominant floral species changed over the subsequent seasons.
