Clarifying the process of northward expansion for Fagus crenata Blume forests at their natural northern range front

为了澄清准确的位置和分布的孤立的天然山毛榉（水青冈）森林在其范围的最北边界，航空摄影和地面实况进行。结果发现，孤立的山毛榉林的数量至少有9个，它们之间的最大距离为4公里。这些孤立的森林被认为可能是由鸟类散布的山毛榉种子建立的。遗传分析表明，孤立的山毛榉林有较高的分化和较低的遗传多样性，但树轮分析表明，山毛榉树的年龄大多在120岁以下，这表明山毛榉林正在逐步扩大其范围，偶尔发生的森林冠层干扰。

To clarify accurate locations and distributions of isolated natural beech(Fagus crenata Blume) forests at the northernmost boundary of their range, aerial photograph and ground truth were performed. It was found that the number of isolated beech forests were at least nine, and they were the maximum of 4 km apart with each other. These isolated forests were thought to have possibly been established from bird-dispersed beech seeds. Genetic analysis showed that isolated beech forests had higher differentiation and lower genetic diversity ; however, tree ring analyses showed that the beech tree's ages were mostly under 120 years old, suggesting that the beech forests are gradually expanding their range, after occasional events of forest canopy disturbances.