Species Interactions in Spruce-Fir Mixed Stands and Implications for Enrichment Planting in the Changbai Mountains, China

To identify the sapling species that can be planted in spruce-fir forest in the Changbai Mountains, China, we analyzed the associations among saplings and between saplings and adult trees of 4 tree species (spruce [Picea koraiensis Nakai], fir [Abies nephrolepis (Trautv.) Maxim.], Korean pine [Pinus koraiensis Sieb. et Zucc.], and lime [Tilia amurensis Rupr.]), and the spatial distribution of saplings under the adult trees. We observed positive associations between the saplings and adult trees of spruce, fir, Korean pine, and lime. In addition, the numbers of saplings of spruce, fir, Korean pine, and lime with distance from adult trees exhibited a positively skewed distribution. We conclude that saplings of any one or several of these 4 species can be planted in the mixed forests and the optimum distance between saplings and adults trees of the coniferous species is 2-3 m, whereas the corresponding optimal distance from the broadleaved lime is 4-5 m. Our results provide new insights into the development of reforestation techniques in spruce-fir forests in the Changbai Mountains.