Taper equations for Eucalyptus pilularis and Eucalyptus grandis for the north coast in New South Wales, Australia

Abstract Function which predict tree taper are tools that can be used by forest managers to provide accurate and timely information on current growing stock. State Forests of New South Wales has embarked on a program of collection and analysis of data for volume and taper information. Taper models for blackbutt ( Eucalyptus pilularis Smith) and flooded gum ( E. grandis W. Hill ex Maiden) were fitted using historical data from the northern coastal areas of New South Wales, as part of the program. Two taper models were developed for each species, one using total tree height in addition to diameter at breast height over bark and sectional height and the other using only diameter at breast height over bark and sectional height. The two taper models were compared with well tested taper models by Max and Burkhart (1976) , Kozak (1988) , and Gordon (1983) taper form. The taper model developed using total height in addition to dbh and sectional height (model 1a) performed best for describing the stem profile and predicting stem volume for blackbutt and flooded gum. The modified Gordon (1983) taper model (model 5b) was the most precise model for flooded gum even though it was biased. Model 1a is recommended for use for blackbutt and model 5b for flooded gum for the north coast of NSW.