Effect of Rainfall and Elevation on Specific Gravity of Coast Douglas-Fir

Abstract

Analysis is made of the effects of five ranges of summer precipitation and three ranges of elevation on variation in specific gravity of Coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). The average specific gravity of Coast Douglas fir wood formed during single growing seasons varied from 0.52 for dry summers to 0.45 for wet summers. The negative linear trend held for three elevational levels. Wood produced under a combination of dry summers at low elevations averaged 0.55 specific gravity, whereas wood produced during wet summers at high elevations averaged only 0.44 specific gravity. Both percentage of latewood and thickness of latewood tracheid wall followed trends that were similar to those of specific gravity with summer rainfall and elevation