Influence of individual tree and stand attributes in stem straightness in Pinus pinaster Ait. stands

The potential relationships between stem straightness and site, and both individual and stand attributes were studied in Pinus pinaster Ait. stands. To thin; effect, 32 plots encompassing different densities and sites of varying quality were laid out in mature stands. In a young stand, a completely randomised design with 9 plots was set up in order to compare three regeneration densities. During the study numerous saplings were bent down by heavy snowfalls. Data analysis using multinomial logistic regression failed to show any relationship between stem straightness and the attributes under study in mature stands. In young stands, however, stem straightness appeared to be influenced by the height/diameter ratio as well as by the total height and the density of the stand at the time of the snowfalls. High density plots were severely affected by snow and consistently contained the least satisfactory instances in terms of stem straightness.