Effect of population reinforcement method, site, and plant characteristics on early establishment of the rare endemic plant species <i>Minuartia smejkalii</i>

Many habitat‐specialist plant species have been endangered by fragmentation or destruction of their habitats. Minuartia smejkalii is a serpentinophyte endemic to the Czech Republic. It is highly threatened by recent habitat destruction and fragmentation, calling for effective conservation measures. We evaluated two conservation methods to reinforce M. smejkalii populations: sowing seeds collected from natural populations and transplanting pre‐grown individuals in three consecutive years to sites currently or recently occupied by the species. We checked for seed emergence (recruitment) and followed the survival and performance of the transplants and recruits to identify factors responsible for the establishment success for up to three years after transplantation. Recruitment from sown seeds was unsuccessful, but overall, 83% of transplants survived the first year and 49% until the third year. Survival depended on the year of transplantation, size of the transplanted individual and mother plant characteristics. Mother plant characteristics were important for growth and flowering in the first year, but not for survival. Across years, initial size and age were more important for size and number of flowers than mother plant identity. Population differences had a larger effect on size and number of flowers in the first year than across years. Seedlings established from seeds of the transplants in four of the five populations. This led, despite mortality of transplants, to a four to six times larger population size after three years in two populations, compared to the number of transplanted individuals. Overall, our findings emphasize that for long‐lived perennials with poor seedling establishment, repeated transplantations across years and sites are key for population reinforcement.