Table 9. Duncan test grouping for environmental variables affecting site index.

Survey order	Mean site index	Significant grouping	Climate zone	Mean site index	Significant grouping	Altitude (m)	Mean site index	Significant grouping
7th	15.5	A	NT	13.5	A	201-300 m	13.8	A
6th	12.6	B	CT	13.2	A	101-200 m	13.1	AB
5th	10.9	C	WT	12.4	B	301-400 m	12.5	B
-	-	-	ST	12.4	B	>100 m	12.1	B

(note) NT: northern temperate zone, CT: central temperate zone, ST: southern temperate zone, WT: warm temperate zone.