Crown condition and growth relationships within stands of Picea abies

Relationships within stands between growth and crown condition are presente d. The data set contained about 25 000 trees on 500 plots. Growth of single trees was determined by diameter measurements in 1991 and 1996. Diameter i ncrements were recalculated to relative values in two steps; firstly relati ve to their stem diameter, and secondly relative to reference values for tr ees in the same plot, having no defoliation or no discoloration. These rela tive increment values. or growth indices, were distributed on a scale commo n for all plots, rendering them influenced neither by site and stand proper ties, nor by social status of each tree. The correlation between crown cond ition and growth, although of moderate strength, did validate crown conditi on assessments as a meaningful, but rough measure of forest health or vigou r. The relationships were concave, and considerable growth depressions were already found at slight levels of defoliation and discoloration. Growth ap proached zero as defoliation and discoloration increased towards 100%. Thes e relationships applied for all plots, regardless of their site productivit y, development stage or regeneration method.