Lesson 4 spacer BEC Method
Lessons
Lesson 1
Lesson 2
Lesson 3
Lesson 4
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Lesson Objectives

BEC Method

Old Vancouver Forest Region Format

Old Prince Rupert Forest Region Format

Old Nelson Forest Region Format

New Provincial Format for the BEC Method

SIBEC Guide Tables

Relationships Between SI and Soil Moisture, Soil Nutrients, and Biogeoclimatic Subzone

SIBEC Guide Accuracy and Limitations

Accuracy for Site Index of Single Stand

Accuracy for Mean Site Index of Population of Stands

The SIBEC Program

Local SIBEC Tables


Lesson 5
Lesson 6
Lesson 7
Lesson 8
Lesson 9
Lesson 10
Lesson 11
Lesson 12
Appendices
Appendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
Appendix 6
Appendix 7
Appendix 8
Appendix 9
Course Homepage
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Relationships Between SI and Soil Moisture, Soil Nutrients, and Biogeoclimatic Subzone

Plant growth is greatest on moist sites. On wetter and drier sites, growth is reduced. Consequently, average SI for a species within a subzone follows a predictable pattern over soil moisture regime (Figure 4.8). The SIBEC guide SI estimates for Fd in the CWHdm reflect the expected relationship (Figure 4.9).

Plant growth increases with soil fertility. Consequently, average SI for a species within a subzone follows a predictable pattern over soil nutrient regime (Figure 4.10). The SIBEC guide SI estimates for Fd in the CWHdm reflect the expected relationship (Figure 4.9).

Average site index for Pl stands

Figure 4.8. Average site index for Pl stands sampled in the SBS by soil moisture regime.

SIBEC guide SI estimates for FD on the CWHdm edatopic grid

Figure 4.9. SIBEC guide SI estimates for Fd on the CWHdm (Vancouver Forest Region) edatopic grid. Site index values are circled.

Average site index for Pl stands

Figure 4.10. Average site index for Pl stands sampled in the SBS by soil nutrient regime.

Plant growth is partially determined by regional climate. BEC subzones are areas of distinct regional climates. So, we might expect SI to vary in a predictable manner across subzones. However, this is not the case. Regional climate is a complex mix of numerous important elements such as average summer temperature, length of growing season, timing of precipitation, and so on. These factors often offset one another and, as a result, the average SI for a species on zonal sites generally does not follow a predictable pattern over BEC subzones (Figure 4.11).

Mean Pl site index and five climate variables

Figure 4.11. Mean Pl site index and five climate variables on zonal sites across SBS subzones expressed as a percent of their value in the SBSdk.

Most tree species display the same general pattern of SI over soil moisture and nutrient regimes that is illustrated by Pl in the SBS (Figures 4.8 and 4.10). However, species do differ in the actual SI level on a given site as illustrated by a comparison of Sx and Pl SI over soil moisture regime in the SBS on nutrient poor and medium sites (Figure 4.12).

Figure 4.12. Average SI of Sx and Pl over soil moisture regime in the SBS on nutrient poor and medium sites.

 

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