Height growth of young Pacific silver fir and noble fir established on clearcuts in the Pacific silver fir zone of western Washington

Abstract

Stem analyses were done on young (20–30 years at breast height) Pacific silver fir (Abiesamabilis (Dougl.) Forbes) and noble fir (Abiesprocera Rehd.) trees established after clear-cut harvesting of old stands in the Pacific silver fir zone of western Washington. Early height-growth patterns and heights attained at 20 years breast-height age were compared with existing data and curves derived from old stands, and among plant associations and elevations. Early growth of Pacific silver fir and noble fir on recent clearcuts was more rapid than would be expected on the basis of existing data derived from old trees. We hypothesize that the more rapid growth of recently established stands represents the combined result of several factors, including less competition, possible climatic change, exclusion of poorer sites from the new sample, and bias associated with past shifts in competitive status of the old trees used to construct height-growth curves from stem analyses. Early height growth (to a breast-height age of 20) is strongly associated with elevation and with plant association groupings.