Sowing of regionally specific seed mixtures on former arable land is increasingly used to restore species-rich grasslands, but it often faces important obstacles in environmental conditions and colonisation from preserved surrounding grasslands. Long-term landscape scale studies, which explore the processes governing plant establishment from seed mixtures and later colonisation from the surrounding landscape are scarce. We studied the species and functional trait composition of 32 grasslands restored 1–11 years before the first sampling by sowing regional seed mixtures in the White Carpathian Mts (SE Czech Republic). We compared them with 23 well-preserved permanent grasslands in their surroundings. In each grassland we estimated plant species cover in three plots of 25 m², in restored grasslands in 2009, 2014 and 2019, in permanent grasslands in 2009. The species composition of the restored grasslands converged towards the permanent grasslands due to expansion of dry grassland species and retreat of mesic grassland and weed species. The majority (60–71%) of the vegetation cover of restored grasslands was formed by sown species, while the species number was mainly determined by colonising unsown species (61–63%). The species number of restored grasslands remained lower than that in permanent grasslands. Functional trait composition (Community Weighted Mean) of the sown seed mixtures, permanent grasslands and restored grasslands overlapped in all three samplings. With increasing grassland age, species with resource-retaining traits of low specific leaf area and high leaf dry matter content, lower stature, higher seed mass, and lower capacity for clonal reproduction expanded. Functional trait diversity of the plots was mostly lower than expected by null model randomisations of community, which indicates strong environmental filtering. Comparison of newly colonising species and extinct species indicated that mainly species with traits similar to the rest of the community are able to colonise the grasslands successfully. Synthesis and applications. Sowing of regionally specific seed mixtures was successful and demonstrated to be a fast way of grassland restoration, particularly in terms of functional trait composition. The resulting species diversity depended on the colonisation processes, which are controlled by the functional composition of the local communities.

We repeatedly sampled (2009, 2014, and 2019) 32 grasslands restored on former arable land and compared them with 23 well preserved reference of permanent grasslands (sampled in 2009). Grasslands (localities) were restored 1–11 years (age) before the first sampling by sowing regional seed mixtures in the White Carpathian Mts (SE Czech Republic). We analyzed species composition of grassland communities, and the sown seed mixture by ordinations and we classified them into following groups:

Sown dry grassland species, Sown mesic grassland species, Unsown dry grassland species, Unsown mesic grassland species, Weedy species, Other species.

We analyzed cover and number of species within those groups.

We further analyzed functional trait composition by computing community weighted means of traits (CWM). The used traits were:

Canopy height – height of the highest photosynthetic tissue in m.

Seed mass – weight of one seed in mg.

SLA – specific leaf area in m²/kg

LDMC – leaf dry matter content in g/mg

Connection persistence – persistence of connection between clonal ramets of plants in years

Multiplication rate – number of offspring ramets produced by mother ramet per year     

Lateral spread – distance to which plant can spread clonally in cm

Terminal velocity – speed of the diaspore in the still air in m/s.

Based on those traits and we further analyzed functional diversity of the communities, which was standardized by null model randomization of the communities (resulting in SES index). We used two types of null models. One restricted by species pool of each grassland (SES_local) and with unrestricted species pool allowing all species of the dataset appear in the community (SES_global).

We also analyzed to which above described group newly colonizing and extinct species (species appearing or disappearing on individual grasslands in periods 2009-2014 and 2014-2019) belonged to and we analyzed the similarity of new colonizers and extinct species to the rest of the community in terms of their functional traits (MPD_CE).  We further related the traits of colonizing and extinct species to the rest of the community and compared the differences between them in the index Standardized mean difference (CWM_CE).

First cell of each sheet contains brief data description as comment. Variable names are kept as described in the manuscript (Mudrák et al., DOI: 10.1111/1365-2664.14456).

Missing data are marked as "NA".