Use of direct seeding and seedling planting to restore Korean pine (Pinus koraiensis Sieb. Et Zucc.) in secondary forests of Northeast China

•82.4% of seeds was eaten by rodents, and only 9.9% of seeds germinated and survived by direct seeding.•Rodent exclusion was more effective in protecting seeds from predation than microsites.•The survival and growth proportions of planted seedlings were the highest in large gaps.•Planted seedlings achieved a much higher (43.7%) survival rate compared with direct seeding (9.9%).•Planting 3-yr old Korean pine seedlings in large gaps is recommended to restore secondary forests.