Kishi, Y., & Asari, M. 2003 [Mortality factors of Pinus thunbergii planted beyond the northern limits of its natural distribution.]. Eurasian Journal of Forest Research 6-2: 131-135.
Notes: In autumn throughout spring of 1999, Pinus thunbergii, which had been planted beyond the northern limit of its natural distribution, changed colour in plots near the cities of Dalian in Liaoning, China and Hakodate in Japan. In Dalian area, dieback shoots of 40 trees near the coast, 40 trees with needle discoloration on tree tops and/or branches at windy sites and 80 trees with total discoloration in the hill forests were surveyed in June 1999. In Hakodate area, dieback shoots of 11 trees near the coast, 17 trees with needle discoloration at windy sites and 9 trees with total discoloration were surveyed in November 1999. In both areas, harmful insects such as Matsucoccus matsumurae and diseases were not found, and Bursaphelenchus xylophilus, the causal agent of pine wilt disease, was not detected. Since the size of winter buds on damaged trees was normal, the trees would be damaged during winter, just before the investigation time. The weather data suggested that P.thunbergii trees suffered from winter desiccation injury in both areas. In Dalian area, a minimal precipitation would seriously weaken P. thunbergii to cause enormous death of pine trees, while in Hakodate area a milder injury due to low precipitation would cause death in pine trees that had been stressed by some other factors.