Balsam fir death and deterioration in eastern Canada following girdling

Abstract

Balsam fir (Abiesbalsamea (L.) Mill.) trees lived from 2 to 30 months following girdling in five regions of eastern Canada. Girdled trees died fastest in the eastern Ontario plot (2 to 16 months), whereas in Newfoundland all of the 22 girdled trees were still alive 1 year after girdling; these regional variations were related to precipitation during the growing season, the length and mean temperature of the growing season, and to the level of bark beetle populations. Once dead, the sapwood of balsam fir in the three easternmost provinces developed sap stain more extensively than in western and eastern Ontario; however, the sapwood of trees in the latter areas was affected by sap rot far more rapidly than those in New Brunswick, Quebec, and Newfoundland. The principal cause of these observed differences appears to be regional differences in intensity of attack by the three major insects that invade weakened and dead balsam fir, which in turn may at least partly be due to regional climatic differences. The results of this study can be used as an aid in predicting the rate and pattern of deterioration of killed balsam fir in connection with salvage operations in eastern Canada.