RING WIDTH PATTERNS OF DOUGLAS-FIR IN RELATION TO CROWN VITALITY AND AGE

Ring width patterns of ten different stands, five vitality classes and three age-classes are used to explore the effect of the decline in vi tality on radial growth of Douglas fir in the Netherlands and to deter mine the onset of this decline. A relationship between growth performa nce and crown vitality is found in most stands, although the variation within and between stands is large. Severe needle loss leads to serio us decline in ring width. The onset of the decline varies from c. 1959 to 1976. The present data set does not enable a choice between the va rious causal scenarios of forest decline that have been proposed in th e literature.