Nature will have its way: local vegetation trumps restoration treatments in semi‐natural grassland

Abstract

Questions: How do various grassland restoration methods (hay transfer from local or distant donors, seed sowing or natural regeneration) perform in restoration of species-rich, semi-natural grasslands? Are any of the donors particularly well suited as reference vegetation? Do bare soil treatments give better results than treatments where the soil is covered? What are the probabilities of steering vegetation development towards donor vegetation under the various restoration treatments?Location: Sunnfjord open-air museum in rural, Western Norway.Methods: In a replicated field trial we tested four restoration methods: transferring fresh hay from a local or a distant donor (hay transfer), seeding with a regional species mix, and allowing natural regeneration. We evaluated outcomes by comparing species richness, transfer rates and vegetation dynamics in donor and trial vegetation over four successive years.Results: Our study revealed considerable changes in species composition under all restoration treatments, which decreased over time, indicating decelerating succession rates. Many non-trial grassland species became established, especially after seeding and natural regeneration (bare soil treatments). All trajectories became synchronized from the second year, and by trial end, the restoration treatments converged with respect to species richness and species composition.

Near‐natural methods promote restoration of species‐rich grassland vegetation—revisiting a road verge trial after 9 years

“…Although this process is most distinct in studies employing small plots, it has also been observed in in situ restoration experiments using larger plots (Lepš et al ; Baasch et al ). Colonization by natural dispersal is actually regarded as an inherent (and beneficial) property of natural regeneration (Conrad & Tischew ), given sufficient seed sources and connectivity between restoration areas and grasslands in the surrounding landscape (Auestad et al ). Our results indicate that natural regeneration may be regarded as a successful and economically favorable restoration method.…”

“…Plant material may be transferred as hay from local sources (Kiehl et al ; Rydgren et al ) or as site‐specific seed mixtures of local origin. Using the latter makes it possible to tailor vegetation to include particular target species or to meet aesthetic requirements (Rydgren et al ; Auestad et al ). The species in local seed mixtures also serve as target species for the restoration as they are deliberately selected to increase species richness and support local seminatural grassland vegetation.…”

Initial soil amendments still affect plant community composition after nine years in succession on a heavy metal contaminated mountainside

“…Other researchers working on similar timescales have documented that different seed sources can generate differences in plant communities (Baasch et al 2012;Auestad et al 2015), and that soil amendments like those used here can jump-start improvements in soil quality (Tandy et al 2009;Oldfield et al 2014;Emam 2015) and affect plant community composition (Paschke et al 2005). However, few, if any, have connected multiple soil amendment types to plant communities on this timescale.…”

Long Term Positive Effect of Grassland Restoration on Plant Diversity - Success or Not?

“…Regardless of restoration measure, it is important to evaluate restoration outcomes, especially in long-term follow-up studies. Short-term studies may reveal temporary trends, but the results might not be stable over time [ 18 , 87 ]. In this study, the species richness and density in the restored grasslands did not resemble reference conditions even after 12–20 years, while composition including all species as well as grassland specialists was similar.…”