STUDIES IN FOREST PATHOLOGY: X. DECAY OF WHITE PINE IN THE TIMAGAMI LAKE AND OTTAWA VALLEY AREAS

Abstract

The study of decay and decay relationships of white pine was undertaken to provide forest authorities in Ontario with information essential to the management of even-aged stands. Of 1012 white pine trees examined in 10 1-acre plots, located in even-aged white pine stands, 52% contained decay. A well-defined relationship existed between age and decay. The proportion of trees with decay increased gradually with age from 40% in the 60-year age class to 100% in the 220-year age class. The loss in merchantable volume increased from 4% at 60 years to 40% at 200 years. No consistent relationship between percentage of decay and diameter was found. The incidence of decay in vigorous and non-vigorous trees was about the same but the percentage of volume lost through decay was considerably higher in slow-growing, less vigorous trees. The pathological rotation, as indicated by the maximum periodic increment, was 160 to 170 years. A number of methods of estimating the volume of decay in logs are compared. Regression lines, which define the percentage of cull allowances at all ages, are presented. Thirteen wood-destroying fungi were found to be associated with the decay of living white pine in Ontario. Fomes pini (Thore) Lloyd was responsible for 90% of all loss in trunks and butts of living trees. External signs of decay were rare, except in cases of advanced white pocket rot caused by F. pini.