Stem analysis of mature Abiesamabilis (Dougl.) Forbes (Pacific silver fir) trees was used to analyze patterns of radial growth in areas of southwestern Washington where this species is experiencing a severe crown decline associated with heavy tephra deposition from the 1980 eruption of Mount St. Helens. Reductions in stem growth after 1980 appeared to be related to the severity of crown damage. The largest reductions in cross-sectional area increment exceeded 50% and extended along most of the stem. An increase in stem growth in the upper crown was common among declining trees. This zone coincided with a portion of the crown that has experienced vigorous and rapid growth since 1980. The role of this recovery zone on subsequent tree recovery is discussed. Decline or recovery of trees appeared independent of crown class per se. Reductions in radial growth of declining trees tended to be more pronounced at breast height, suggesting that estimations of whole-stem growth based on breast height measurements would overestimate growth losses.
