Japanese beech (Fagus crenata) plantations established from seedlings of non-native genetic lineages

In order to examine whether seedlings of non-native genetic lineages had been planted, we compared chloroplast DNA haplotypes in plantations and neighboring natural populations of Fagus crenata in Nagano Prefecture, Japan. This region was chosen for study because there are abundant natural F. crenata populations with different haplotypes, and because the species is also frequently used for afforestation in the area. We sampled 159 trees from 30 populations of the species across most of its natural range in the region, and 136 trees from 20 plantations of the species, ranging in age from 3 to 17 years. Six single nucleotide polymorphisms and four insertions/deletions in two chloroplast DNA regions (trnL–trnF and trnK) were analyzed in each of the sampled individuals in order to determine their haplotypes. Four haplotypes (B, D, E and F) were detected in the natural populations, and these exhibited a clear geographical structure; in contrast, only two haplotypes (A and B) were found in the plantations. We found that 15 out of the 20 plantations—located in central and southern areas on the Pacific side of Honshu, where the natural populations contain haplotypes D, E, and F, and where the climate is characterized by dry, cold winters—had been established using seedlings with haplotypes A and B derived from the Sea of Japan side of the Japanese Islands, where it snows heavily. The risks associated with planting seedlings of inappropriate lineages are discussed.