Transplantation of native species to existing vegetated slopes: Importance of optimal habitat and initial nutrient reserves

Although ecosystem degradation is often caused by existing slopes vegetated with commercial species, limited data are available for implementing practical approaches for nature restoration by transplanting native species to those vegetated slopes. Existing vegetated slopes are characterized by spatial heterogeneity in the habitat environment and competition with existing vegetation, which affect the behaviors of transplanted native species. In this study, we examined the factors affecting the survival, growth, verticillation, and flowering of Lilium pensylvanicum, a native coastal-meadow species transplanted to a vegetated road slope in Hokkaido, Japan. In the fourth year after transplantation, the number of surviving plantlets was 364 (57% of 640 transplanted plantlets) and the number of plantlets that shifted to verticillate leaves was 181 (50% of the survivors). The flowering plantlets accounted for 9% (n = 34) of the survivors. The generalized linear model showed that plantlet survival is strongly promoted by a larger bulb scale, that is, nutrient reserves. Furthermore, the survival ratio was greatly improved in the drought-prone, stressful habitats with low vegetation coverage, even for plantlets with relatively smaller bulb scales. However, in the moist habitat with high coverage, the survival ratio was greatly decreased regardless of the bulb scale size. Growth, verticillation, and flowering were facilitated by higher soil nutrient availability, such as a lower C/N ratio and thicker soil layer. Therefore, transplanting of native species to vegetated slopes requires the selection of stress-tolerant species with large nutrient reserves and identification of optimal habitats for transplanting, namely stressful environments with reduced vegetation coverage. •The transplantation of native species on slopes for nature restoration was examined.•Plantlet survival was most strongly affected by nutrient reserves.•Survival negatively correlated with vegetation cover and soil water content.•Plantlet growth and flowering were facilitated by higher nutrient availability.