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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3.4 HEIGHT

The height of forest crops in Australia is described in terms of mean height or of predominant height, top height, or dominant height.

3.4.1 MEAN HEIGHT

Mean height is meaningless as a stand characteristic in uneven-aged stands but it is of considerable value in even-aged stands. It is defined as the arithmetic mean height of all the trees, N, in a stand (international symbol, h- ).



where hi = height of tree i.

With the exception of experimental plots and small but valuable stands, this measure of stand height is rarely used in Australia owing to the cost of measuring all trees. More usually, an approximation is used, viz. h- is accepted as being the average height of a defined number, n, of trees (e.g. 60/ha) having a dbhob most closely approximating the arithmetic mean basal area (= quadratic mean d (international symbol dg)) of the stand. Defined this way, stand mean height can be derived either directly by enumerating the stand for d and measuring, and averaging, the heights of the n trees most closely approximating dg, or indirectly by compiling a stand height curve (d vs. h) and reading off the curve the height equivalent to dg. Alternatively, h- can be estimated by sampling, e.g. by measuring the height of, say, 10 trees per hectare selected systematically from the whole of the main crop, and averaging the result. Whatever method is used, it should be applied consistently over time.



 

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January, 1999.