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TIPSY Error Bulletin 5 - Interpolating fertilization response between site indices

Summary

The species-specific fertilization response information in TIPSY is based on 5m steps of site index. With a site index of 5, 10, 15, 20, 25, 30 or 35, TIPSY gave the correct results. If your pine stand has a site index of 18 and is 10m in height, TIPSY should interpolate between the response for site index 15 (28% increase) and the response for site index 20 (24% increase). For most species and site indices, there was no interpolation. As soon as TIPSY exceeded site index 15, the 24% increase kicked in.

Response is measured as % increase in the total volume increment in a 10-year period. Typically, the percent gain in volume decreases as the site index increases, so users were getting a lower response than we intended in version 3.2, though the difference was small – around 1% in many tests.

Problems with site index conversions between species in BatchTIPSY version 3.2 could have exacerbated problems with volume projections for fertilized stands.

Affected Software Version

All versions of TIPSY and BatchTIPSY 3.2.

Corrected Software Version

TIPSY 4.1.

More information and support

Shelley Grout at 250 387-6718

Acknowledgements

Craig Mistal of J. S. Thrower, and Mel Scott, consultant with Forest Practices Branch reported this problem.

About this notice

This bulletin was created November, 2006.

Last Modified: 2007 MAR 20. Ministry Contact: Mario di Lucca
Webmaster: For.Prodres@gov.bc.ca