Changbai Mountain, September 18th (Xinhua) (Lv Shengnan, Zhang Mohan) "This is a sample plot we have in the original broad-leaved Korean pine forest, with around 200 to 300 trees over 200 years old per hectare. All trees in the sample plot have been listed, and we will conduct surveys such as measuring breast diameter and marking positions, and retest every 5 years to record the development and changes of the forest...