Effects of Crown Decline on Increment in Norway Spruce (Picea abies (L.) Karst) in Southern Sweden

1989

S. 19-36

9 Abb., 2 Tab., 18 Lit. Ang.

Unselbständiges Werk

200037847

A monitoring programme has been executed in Sweden by the National Forest Survey since 1984 in order to study the condition of forests with regard to forest decline. The basis for the classification of trees and stand has been the morphological character of the tree crown i.e. amount of needle loss in relation to "undamaged" trees. Few attempts have been made earlier in Sweden to study the relationship between needle loss and current tree increment. Material from six different Norway spruce stands in South and Southwestern Sweden have been analysed with regard to needle loss and current volume or basal area increment. Increment functions for single spruce have been designed. The following parameters are included in the growth model; stand characters (tree height, basal area, tree age, sapwood area); weather parameters (mean temperature and precipitation for different months); observations of the ground water table level; figures derived for water deficiency during different months according to Bergstroem's HBV-model; dry weight of needles from a sample of whorls iin the top section; fresh weight of needles and branches from a top sectin of the tree; needle percent in a specified part in the top section; needle decline class. Logical relationships between tree increment and the above mentioned factors are demonstrated. An observation period between 1950 and 1984 was divided into sub-periods. The results show that the effect on increment of needle loss can be traced back in time but with weakening strength. The effects of needle loss in the increment vary from locality to locality. The reasons for this inconsistency in increment pattern of needle loss is discussed.