Understanding how plant communities assemble after restoration is a critical for establishing a diverse plant community with more ecosystem services. Often restoration assessments focus on taxonomic diversity, revealing little about shifts in plant functional traits. We present results of two studies in Northeast Ohio, USA: a shorter term, before and after restoration, and a longer-term perspective on restorations regionally. In the first study, following a pre-restoration survey, two commonly used seeding methods, broadcast and drill seeding, were applied. We hypothesized that seeding would increase native and functional diversity, and that there would be a difference in germination rates between the two seeding methods. The second study examined five different restoration sites in the region, restored between 2 and 20 years ago, each paired with an adjacent unrestored site. We expected that restoration would improve native and functional diversity, and that these effects would be strongest in sites with longer time since restoration. Analyses focus on the functional diversity of plant traits before and after restoration or between restored and unrestored areas.
Results/Conclusions
In the short-term study, broadcast seeding established significantly more species, at greater abundances. The resulting plant community also had a higher coefficient of conservatism, an indicator of conservation value. In contrast, drill seeding led to a higher diversity of native species overall. Meadow restoration shifted some individual functional traits (community weighted means of leaf dry matter content, height, and seed mass and the functional dispersion of height seed mass and rooting depth), but multi-trait functional diversity of evenness and dispersion were not significantly different between methods. In the regional survey, restored and unrestored sites had similar native species richness and diversity overall, contrary to our expectations, but native species abundance increased with time since restoration. There was no difference between functional trait means and diversity in restored and unrestored meadows; however, there were significant differences in the coefficient of conservatism. Phenology patterns also revealed that seed mixes might benefit from additions of spring and fall flowering plants. For this reason, using functional diversity to assess restorations and plant communities can be important for future planning of natural areas. Overall, it seems that meadow restoration may not shift functional diversity, but native diversity shows improvement over longer time-periods.