Estimated decrease in productivity for pacific silver fir as elevation increases

• Main Author: Klinka, Karel
• Format: Report
• Language: English
• Published: Forest Sciences Department, University of British Columbia 1998
• Subjects: West coast hemlock; Western hemlock; Forest productivity; Mountain hemlock; Pacific silver fir; Abies amabilis; Elevation; Site index; Pacific; Forbes; Tundra
• Online Access: http://hdl.handle.net/2429/667

When making decisions on which areas to harvest in a sustained yield, even-flow manner in mountainous areas such those in coastal British Columbia, it is important to know how timber productivity changes with elevation. This information allows foresters to decide at what elevation to start increasing the rotation age and to decide at what elevation sustainable harvesting becomes infeasible due to low productivity. Since Pacific silver fir (Abies amabilis Dougl. ex Forbes) has an elevation range that extends from sea level nearly to the tree line (0 m to approximately 1,650 m; from the Coastal Western Hemlock zone, through the Mountain Hemlock zone; to the lower limits of the Alpine Tundra zone), productivity-elevation relationships are especially important. To acquire quantitative measures of productivity decrease with increasing elevation a regression equation relating site index (the height of the dominant trees at a base age of breast height age of 50 years) to elevation in southern coastal BC was developed. In turn, we used this regression as an input into the height driven yield model named the Variable Density Yield Prediction model (VDYP). The use of the VDYP model allows the site index values to be translated into actual productivity measures (e.g., volume per hectare, mean annual increment at culmination age). Forestry, Faculty of Forest Sciences, Department of Reviewed Faculty