Table 2. The class distributions for different cohors.

Cohors	Diameter at breast height
Class I	1 cm ≦ DBH < 10 cm
Class II	10 cm ≦ DBH < 20 cm
Class III	20 cm ≦ DBH < 30 cm
Class IV	30 cm ≦ DBH < 40 cm
Class V	40 cm ≧ DBH