Eccentricity and Fluting in Young–Growth Western Hemlock in Oregon

Stem irregularities can influence estimates of tree and stand attributes, efficiency of manufacturing processes, and quality of wood products. Eccentricity and fluting were characterized in young, managed western hemlock stands in the Oregon Coast Range. Sixty-one trees were selected from pure western hemlock stands across a range of age, site, and densities. The trees were felled and disks were removed from breast height, base of live crown, and various percentage-of-height locations along the bole. Indices of out-of roundness (OOR), pith-off-center (POC), and fluting severity (fluting index) were computed, flutes were counted, and depth of deepest flute was measured on each disk. These variables were related to relative tree height, tree diameter, and several standand tree-level attributes. The lower portions of stems tended to be more out-of-round and have a higher degree of off-centered piths than upper stem heights. Basal and breast-height disks had a higher number of flutes, deeper flutes, and higher fluting severity compared to disks from upper stem positions. Tree size (diameter at 4.5 ft) was only weakly correlated with OOR and uncorrelated with POC, but strongly correlated with more flutes, deeper flutes, and higher fluting severity. OOR and POC were not significantly correlated with any other tree or stand attributes. The fluting variables were positively correlated with stand age and overall tree growth rate and negatively correlated with trees/ac. Thus, silvicultural practices that result in more rapid growth, wider spacing, and longer rotations are likely to result in more extensive fluting but will have little or no effect on stem eccentricity. West. J. Appl. For.18(4):221–228.