Some Phenomena Associated with Pruning

Drastic early pruning on young Norway spruce (Picea abies Karst.)on poor soils in Central Jutland resulted in an improvementin the colour of the needles and an increase in their nutrientcontent lasting, however, only a few months. Thereafter therewas a decrease in N and a return to the previous bad colourof the needles. The author offers an explanation for these changesand considers its bearing on any attempt to assess the contributionmade to stem increment by different branch whorls. He pointsout that the results of pruning may vary considerably accordingto whether single trees are pruned or all the trees in the plotare pruned.