Restoration of grasslands using commercially produced seed mixtures: genetic variation within and among natural and restored populations of three common grassland species

The use of commercially produced seed material is a common practice in restoration. However, the impact of sowing on genetic variation of natural populations is still unclear. Aim of this study was, therefore, to test if genetic variation within and among populations restored with local seed material corresponds to the genetic variation of neighboring natural populations. We investigated each ten natural and restored populations of three common grassland species (Knautia arvensis, Silene vulgaris and Plantago lanceolata), situated in five study regions in southeastern Germany. Our study revealed significant genetic differentiation between natural and restored populations of the insect-pollinated K. arvensis and S. vulgaris although differentiation was much stronger for K. arvensis since most restored populations contained another ploidy level than natural populations. For the wind-pollinated P. lanceolata, genetic differentiation between natural and restored populations was comparable to the genetic differentiation between its natural populations. Genetic diversity within restored populations of each species was equivalent or even higher than within natural populations. Our study provides evidence that the local genetic structure especially of common insect-pollinated grassland species may be affected by the application of regional seed mixtures in restoration. Regional admixed provenancing in seed production is an important approach to preserve regional patterns and to provide seeds for the reestablishment of genetically variable populations. The method would however be an even more powerful tool in restoration when ploidy levels would be checked before seed production and seed transfer zones would be smaller