Units of measurement, symbols, significant digits and rounding off
1.1 Units of measurement and symbols
1.2 Significant digits
1.3 Rounding off
1.4 Bias, accuracy and precision
Individual Trees and Logs
2.1 Bole characteristics
2.1.1 Diameter
2.1.2 Height
2.1.3 Bark thickness
2.1.4 Volume
2.1.5 Stem form and taper
2.2 Log characteristics
2.2.1 Diameter
2.2.2 Length
2.2.3 Volume
2.2.4 Weight
2.2.5 Allowance for defect
2.3 Crown characteristics
2.3.1 Width
2.3.2 Depth
2.3.3 Surface area
2.3.4 Volume
2.3.5 Biomass
2.4 Stem analysis
Groups of Trees (Stands)
3.1 Number of trees
3.2 Diameter
3.3 Basal area
3.3.1 Fixed-area plots
3.3.2 Angle count sampling
3.3.3 Advantages and disadvantages of angle count sampling
3.4 Height
3.4.1 Mean height
3.4.2 Predominant height, top height, dominant height
3.4.3 Stand height curve
3.5 Volume
3.6 Crown closure
3.7 Crown biomass
3.8 Growth and increment
References
Appendix 1: Checklist of equipment and materials

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3.2 DIAMETER

The mean diameter of a group or stand of trees can be expressed by either the arithmetic or quadratic mean. The latter is the more useful and more widely applied measure because it is directly related to volume. It is the diameter of the tree of mean basal area, i.e. the quadratic mean diameter (dg) of all the trees in the stand. dg is preferable to the arithmetic mean, d - , as a size parameter of trees in a stand because of the additional weight it gives to the larger diameters. The mean diameter calculations usually excludes any dead trees, but if these are included it should be stated clearly. In larger stands, derivation of the mean diameter may be based on a representative sample of trees drawn from the population. 		 

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January, 1999.