An Old Growth Index for Douglas-fir Stands in Portions of the Interior Douglas-fir Zone Central British Columbia

This report introduces a quantitative old-growth index specifically designed for Douglas-fir forests in central British Columbia's Interior Douglas-fir zone, particularly in the IDF_dk_3 and IDF_dk_4 biogeoclimatic variants. Recognizing that traditional age-based definitions of old growth are insufficient for forests frequently impacted by disturbances, the authors developed an index based on measurable structural attributes like tree size, canopy complexity, and the presence of dead trees. This index aims to provide forest managers with a consistent tool to identify and classify old-growth stands into four seral stages, helping guide management practices for biodiversity conservation and the enhancement of old-growth characteristics. The study emphasizes that this index relies on expert professional judgment to quantify what constitutes old-growth attributes in these specific forest types.