This Web guide provides background
information for the second approximation of site index estimates for tree species
according to site units of the Biogeoclimatic Ecosystem Classification system of British
Columbia. The estimates themselves are presented in tabular form in two downloadable
reports.
The background information consists of seven sections and two appendices. Following
this introduction, Section 2 explains the basics of
site index. In Section 3, the general relationships
between site index and site factors are discussed. Section
4 provides a summary of the methods used to generate the site index estimates
presented in the two reports. Section 5 outlines the
content and format of the report tables. Section 6
explains how to use the tabular information presented in each report to estimate site
index in the field. References to literature cited in this guide are provided in Section 7. Appendix
1 contains a site index species conversion table for mixed species stands. Appendix 2 provides a listing of additional
references, resources, and important contacts.
Two reports are available in PDF format and as downloadable Microsoft Excel files. The
first report, "Site Index-Site Unit Report by Region" (PDF/Excel), provides a compilation of
site index estimates by biogeoclimatic unit for each forest region. The second report,
"Site Index-Site Unit Report by Biogeoclimatic Unit" (PDF/Excel), displays site index estimates
by site series for each biogeoclimatic subzone/variant.
The site index estimates provided in these reports are second approximations as they
report mean plot site index and its standard error for each BEC site series/species
combination that have a minimum sample size of 7. This new estimate replaces the first
approximation (1997) site index class estimate only if the minimum sample size criterion
is met. As more data become available, subsequent approximations will be produced and
named by year, e.g., 2006 approximation.
A companion report,
"SIBEC comparison report",
provides an at-a-glance view of the
changes in the latest release of the SIBEC estimates to the 1997 Approximation.
Site index estimates for some hardwood species are also included in this edition.
To contribute
data to the provincial SIBEC (Site Index-Biogeoclimatic Ecosystem Classification) data
warehouse, please contact the SIBEC Administrator ,
B.C. Ministry of Forests.
For SIBEC data collection standards, see the Site Productivity Working Groups SIBEC Sampling and Data Standards
(Version 5.3).
For timber supply analysis, SIBEC estimates are usually applied using ecosystem mapping,
either predictive (PEM) or terrestrial (TEM), but may also be applied by sampling the
landbase to determine the proportion of each BEC site series. The Technical Report
"SIBEC Site Index Estimates in Support of Forest Management in British Columbia"
by Mah and Nigh (2003) evaluates the accuracy of the SIBEC estimates for use in
supporting allowable annual cut (AAC) determinations.