Natural revegetation on forest topsoil and subsoil along roadsides in boreal forest

Questions: Does natural revegetation from indigenous soil improve the restoration success of roadside areas? What are the effects of topsoil, subsoil and fertilization on natural revegetation? Location: Akershus county, SE Norway (10 degrees 25' E. 59 degrees 44' N). Methods: We used a recently constructed road through a boreal coniferous forest for a three year (2000-2002), fully replicated revegetation experiment (six replications). Treatments were soil type (two levels: one topsoil and one subsoil type) and fertilization (two levels: NPK and unfertilized control). Ordination methods, constrained ordination methods as well as univariate statistical methods. Such as Wilcoxon's signed-rank test and correlation analvsis, were used to assess the relative importance and significance of treatments on the plant species composition. Results: There was no fertilization effect on species composition. The species composition on both soil types was stabilised by the second year. The species dominating the topsoil were more in accordance with the indigenous vegetation than was the case on the subsoil. The significant difference in species composition among blocks, persisting for the entire study period. indicated that local factors are important determinants of the outcome of revegetation. Conclusion: Unfertilized topsoil provides a revegetation result in better accordance with the indigenous vegetation than does subsoil.