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A biophysical model for estimating site index for the major commercial tree species in British Columbia

Author(s) or contact(s): G. Nigh
Source: Forests, Lands, and NR Operations
Subject: Growth and Yield
Series: Technical Report
Other details:  Published 2012. Hardcopy is available.


A site index geographic information system (GIS) layer is being developed for British Columbia so that estimated site indices are available for the major commercial tree species across their ranges. The Site Index - Biogeoclimatic Ecosystem Classification (SIBEC)/predictive ecosystem map (PEM)/terrestrial ecosystem map (TEM) method will be used to populate the layer with site index by species. However, there will be gaps in the layer where there are no PEM/TEM or SIBEC data. The biophysical models resulting from this project will be used to fill these gaps. They predict, by species, site index from biogeoclimatic zone, slope, aspect, elevation, and climate variables. Data for these models come from the SIBEC project and various Site Index Adjustment projects. The climate variables are predicted from the ClimateWNA model. A biophysical model was fit separately for the following species: trembling aspen (Populus tremuloides), amabilis fir (Abies amabilis), subalpine fir (Abies lasiocarpa), western redcedar (Thuja plicata, coastal and interior), paper birch (Betula papyrifera), Douglas-fir (Pseudotsuga menziesii, coastal and interior), western hemlock (Tsuga heterophylla, coastal and interior), western larch (Larix occidentalis), lodgepole pine (Pinus contorta), ponderosa pine (Pinus ponderosa), black spruce (Picea mariana), Engelmann spruce (Picea engelmannii), Sitka spruce (Picea sitchensis), white spruce (Picea glauca), and interior spruce (white spruce, Engelmann spruce, or their cross). When compared to benchmark models, the biophysical models performed about as well as the benchmark except for the models for coastal western redcedar, coastal Douglas-fir, coastal western hemlock, Sitka spruce, and paper birch.

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Updated January 15, 2013