Genetic differentiation and regional adaptation among seed origins used for grassland restoration: lessons from a multispecies transplant experiment

One of the key questions in ecosystem restoration is the choice of seed material for restoring plant communities. More and more scientists and practitioners are currently advocating the use of regional seed sources, based on the argument that plants are often adapted to local or regional environmental conditions, and thus, regional seed sources should provide the best restoration success. However, there is still substantial debate about this approach, partly because of a lack of solid empirical data.
We conducted a multispecies transplant experiment in which we compared the performance of eight seed origins of seven plant species frequently used in grassland restoration in four common gardens across Germany.
We found that, on average, plants of regional origins produced 10% more inflorescences and 7% more biomass than those of foreign origins. There were substantial differences among species in the strength of these effects, but in the majority of the study species fitness decreased w...