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

[RWG#2] [Copyright] [Title Page] [Next Page] [Last Page]

3.8 GROWTH AND INCREMENT

Growth is increase in size over time, and increment is the increase in size which occurs in a specified time interval due to growth. To ensure the reliability and utility of growth and increment data for forest stands, it is imperative that the measurement, estimation and sampling procedures used to derive the information be standardised both within and between organisations and over time.

The two conventional expressions of increment are current annual increment (CAI) and mean annual increment (MAI).

Current annual increment is the increment over a period of one year at any stage in the history of the tree or stand. The period to which the CAI refers and the age and/or size of trees at that time must be defined (e.g. CAI 1969/70, age 25-26 years). The CAI varies from year to year being affected by seasonal conditions and treatment. For this reason, it is common practice to express the increment as a mean over a period of years, termed the periodic mean annual increment (PMAI or PAI). It is important to maintain the distinction between CAI and PAI. The PAI is a more realistic indicator of the capacity of a tree or stand of a certain age or size to grow.

Mean Annual Increment is the mean annual increment over the whole period from origin to a specific age. The specific age must be given when quoting MAI figures. The interrelationships of the CAI and MAI curves of a tree (more particularly of a stand), their relative shape, and the position of their point of intersection, are of particular interest to management. Conventionally, CAI and PAI data are plotted against the middle of the period to which they refer whereas MAI data are plotted against the specific year.

  

[RWG#2] [Copyright] [Go to Top of Page]
WWW maintenance: Cris.Brack@anu.edu.au
January, 1999.