Abstract
This study uses mensuration data to characterize old-growth stands. The biogeoclimatic ecosystem classification (BEC) sampling program provided data for almost 400 plots greater than 140 years old in the Nelson Forest Region (NFR). Summary statistics for this data set were limited because there were no plots in the Ponderosa Pine (PP) zone, and a few site series from other zones either lacked data or only had a few plots. In general, the data set provided good coverage for most of the ecological units; useful old-growth criteria could be developed to the site series level for many variants, and where site specific criteria were not possible, general zone level criteria could be suggested. Zonal criteria based on the density of trees >50 cm dbh for the PP and Interior Douglas-fir (IDF) zones would be 25 and 17 stems/ha, respectively. For the Interior Cedar-Hemlock (ICH) zone, the density for trees of the same minimal diameter would yield a zonal criterion of 36 stems/ha for the drier variants and 60 stems/ha for the wetter variants. Zonal criteria based on the density of trees >30 cm dbh for the Engelmann Spruce-Subalpine Fir (ESSF) zone, and for the Montane Spruce (MS) zone with stands dominated by lodgepole pine, would be 41 and 75 stems/ha, respectively. Density of trees >40 cm dbh also yield zonal criterion for the IDF zone, and for the MS zone with stands not dominated by lodgepole pine, of 58 and 39 stems/ha, respectively. Summaries of the BEC plot data also provide baseline information on tree class and tree species composition.
Twenty-six stands were sampled in detail for BEC units identified by a geographical information system (GIS) as having limited areas of forests >140 years old. Twenty-two of these stands were rated as rare old-growth stands. The criteria used included age and density of larger living or dead trees. Four additional stands had detailed sampling but did not meet the minimal screening criteria. Thirty-eight stands were examined but not sampled because the reconnaissance indicated a lack of old-growth attributes, the BEC unit was not identified as rare by the GIS project, limited access or time prevented detailed sampling, or only helicopter viewing was possible. Notes and summary information were compiled for both the stands with detailed sampling and other stands examined for rare old-growth.
Management application of the old-growth criteria developed in this study is briefly discussed. Summary statistics for the BEC data sets can be used as standards for evaluating and mapping potential old-growth stands. These standards could also be used for setting management targets where old-growth recruitment is required.
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Updated April 12, 2007
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