SPIRAL GRAIN IN EUROPEAN ASPEN (POPULUS TREMULA L.): VARIATIONS WITHIN AND BETWEEN THE TREES

摘要

The consequences of spiral grain are encountered in the form of twist in dry timber, distortion in veneer and plywood sheets, short-grained failure of timber under stress, and surfacing problems during machining. In this study grain angle measurements were made on wood disc samples from six 50 – 70 year old trees of European aspen (Populus tremula L.) from two different sites in southern Sweden. The grain angle was measured every 15mm pith to bark at three fixed heights using a disc “scribing method”. The aim of the study was to examine variation in the spiral grain in vertical (bottom to top) and radial (pith to bark) direction within and between aspen trees.The results proved that aspen tree belong to the group of "straight grained" trees. The highest values and deviations of grain angle were registered in the butt log and lowest in the middle. With regard to absolute values, the values of grain angle and deviations were highest in the top log and lowest in the middle.