Seed sourcing for climate-resilient grasslands: the role of seed source diversity during early restoration establishment

Restoration often advocates for the use of local seed in restoration, however increasingly new strategies have been proposed to incorporate diverse sources to maintain evolutionary potential within seed mixes. Increasing seed sources per species within a seed mix should increase genetic variation, however, few empirical studies have evaluated how seed source diversity impacts plant community composition following restoration. Thus, the goal of this research was to compare the use of single or multi-source seed mix treatments to plant community diversity following restoration. Using 14 species commonly applied in grassland restoration, we examined plant community diversity following restoration comparing seed mixes with either one or five sources per species across two restoration sites in Minnesota and South Dakota, United States. Following seeding, species establishment and abundance were recorded to calculate plant diversity for each seed mix treatment. There were no major effects of seed mix treatment on community emergence and diversity observed, with the majority of plant establishment reflecting non-seeded species. However, site-specific differences were observed. Heterogeneous land-use history associated with the Minnesota site likely contributed to differences across the restoration treatments. In contrast, community diversity at the South Dakota site was homogeneous across seed mix treatments with changes in plant community influenced solely by early season species establishment. This suggests land-use history irrespective of seed mix treatment influences establishment and persistence, particularly in the first year following restoration. Future monitoring across seasons will be needed to evaluate if community diversity changes in response to seed mix treatment.