STUDIES IN TREE PHYSIOLOGY: IV. FURTHER INVESTIGATIONS OF SEASONAL CHANGES IN MOISTURE CONTENT OF CERTAIN CANADIAN FOREST TREES

Abstract

Complete seasonal patterns of moisture content of the wood and bark of Betula lutea (which resembles other species of birch) and of Tsuga canadensis are given, along with those for sapwood and heartwood of Abies balsamea and Picea rubens. Incomplete seasonal data are also presented on the moisture content of the wood of Picea glauca and Thuja occidentalis.Minor variations in the water content pattern of yellow birch due to precipitation, evapotranspiration, and winter insolation are described. These variations, examined in the light of climatic data, lend little support to the view that birch dieback is due to an increase in temperature or to drought, except possibly through their effects on some unknown biotic factor.The practical aspects of tree water content studies are discussed with particular reference to the questions of flotation and sinkage of logs.