Lesson 2 spacer Introduction to Site Index
Lesson 1
Lesson 2

Lesson Objectives

What is Site Index

Where is SI Used?

Site Index in Forest Cover Labels

Problems with Incorrect Site Index Determinations

When/Where is SI Recorded?

FPC and SI

SI Source Codes

Biased Site Index and Stands Growing Below Potential

Site Index and Yield

Tree Growth Response to Improved Site Quality

Lesson 3
Lesson 4
Lesson 5
Lesson 6
Lesson 7
Lesson 8
Lesson 9
Lesson 10
Lesson 11
Lesson 12
Appendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
Appendix 6
Appendix 7
Appendix 8
Appendix 9
Course Homepage


Site Index in Forest Cover Labels

SI is now used on forest cover maps and replaces the site class labels (G, M, P, L).

Figure 2.6 shows the former map labels and the ones currently used.

Format of old and new forest cover map labels

Figure 2.6. Format of old and new forest cover map labels. (Click on image to see enlarged comparison view)

Consider these two labels for a polygon (Figure 2.7):

Inventory and silviculture labels for a polygon

Figure 2.7. Inventory and silviculture labels for a polygon.

Note the following:

  1. Site index is only reported for one species in the label—the leading species (Hw in the inventory label and Fd in the silviculture label).
  2. If the silviculture and inventory labels have the same leading species,they must have the same site index. If they differ, site index may differ.
  3. Age is total age—not breast height age.
  4. Height is average height—not top height.
  5. The trees sampled for height and age may not be unsuppressed and undamaged.
  6. Height and age may be estimated—not accurately measured.
  7. In a multi-layered stand, all layers with the same leading species must have the same SI.


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