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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2.3.5 BIOMASS

The traditional approach to estimating crown biomass or weight has been to fell selected sample trees, sever the branches (or a sample of them), strip the leaves, weigh both components fresh, dry a sub-sample and reweigh, determine the individual tree component dry weights, and then derive prediction equations relating these weights to diameter breast height, d, and total height, h. Once developed, the equations are applied to the population at large to estimate the crown biomass of any tree. Procedures for doing this are well documented in the forestry literature but they are not necessarily unbiased (Cunia 1979, De Gier and Kaboré 1993, Gregoire et al. 1994).

A new, unbiased and more efficient technique for estimating biomass (also volume, mineral content, number of cones, and many other characteristics) of the above-ground components of sample trees was published by Valentine et al. (1984). It comprises two steps, randomised branch sampling (Jessen 1955, Valentine and Hilton 1977) and importance sampling (Gregoire et al. 1986), both of which invoke variable probability sampling. The technique is quick to apply particularly to trees and shrubs with multiple stems (mallee type habit) because measurement of weight is confined to a single disc cut from the tree. The procedure has been applied successfully to estimate woody fuel biomass in natural woodlands and shrublands (De Gier 1989, De Gier and Kaboré, 1993) and biomass in loblolly pine (Williams 1989; Valentine et al. 1994). Readers interested in the technique should refer to these papers and the excellent review paper of Gregoire et al. (1994) 		 

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