The aim of the study was to find out what are the causes of damage in different parts of the trees and the frequency of different kinds of injuries. Sample plots were studied in over 80-year old forests in mineral soil sites and peatlands. All the trees over 1.5 m high were felled in the sample plots and the stem injuries were studied. The structure of the stand and the crown classes were recorded. The proportion of undamaged trees was largest in in dominant and codominant trees and increased towards the better forest site types. The typical injuries are listed for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L). H. Karst.) and Betula sp. stands. The injuries were divided in inner and outer form defects and injuries, and defined in more detail by the part of the stem and tree species. Defects caused by decay were analyzed separately.
Healing over of injuries was faster in the better sites. Form defects and other injuries were more common in birch stands than in Scots pine and Norway spruce stands. Decay was most common in birch stands. The pine stands were the healthiest, followed by spruce stands. Fire wound were most usual in pine, butt rot for spruce, and crooks and general decay for birch.
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