Characterization of wetwood from four balsam fir trees

Balsam fir wetwood had lower longitudinal permeability to both water and air than sapwood, but higher than heartwood. Based upon the average initial flow rate of water in sapwood, wetwood, and heartwood, a ratio of 45:6:2 was calculated. The ratio of average air permeability of sapwood to wetwood to heartwood was 50:9:1 calculated at an average mean pressure of 0.5 atmosphere (38 cm Hg). The low permeability of wetwood and heartwood results from pit aspiration and incrustation of bordered-pit membranes. Scanning electron microscopy suggested that deposits on wetwood-bordered pit membranes facilitated greater flow through wetwood than heartwood. Sapwood and wetwood moisture contents were comparable and were higher than heartwood. Extractive content values of green wetwood were between those for sapwood and heartwood.