Freezing rain is a frequently occurring, but relatively rarely studied disturbance in Europe, although ice accumulation may occasionally cause severe damage for forestry. We aimed to characterize ice-accumulation damage to overstory trees in spruce stands, assess the probability of damage based on the stand and individual tree parameters, and define the most significant parameters that affect the probability of individual tree damage in all stands and in recently thinned stands. Among the studied stands, the proportion of damaged overstory spruce ranged from 1.8% to 60.9% and was higher (p < 0.001) in recently thinned stands (27.8% ± 1.9%) than in the other stands (20.4% ± 1.6%). Stem breakage was the prevalent (98.5% ± 1.1%) damage type. At the stand level, the probability of damage decreased for older, less dense stands with a larger mean diameter. Within stands, overstory trees were more damaged (23.5% ± 1.2%; p < 0.001) than those in the lower stand layers, but, within overstory, trees with larger dimensions and a higher social position (high relative diameter and low slenderness ratio) and a higher proportion of crown were less damaged. The probability of breakage to overstory trees was most accurately predicted using almost the same variables for all stands and recently thinned stands. The site type, tree height, relative diameter, and crown ratio were common for both, with the addition of mean diameter at breast height for all stands and the stand density for recently thinned stands. Our results indicate the importance of the tree and stand characteristics on the resistance of individual tree to ice accumulation and the need for management practices that balance increased growth and the stability of trees throughout the rotation.

中文翻译：

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挪威云杉（Picea abies（L.）Karst。）积雪造成的树木损害

在欧洲，冻雨是经常发生的，但研究相对较少，尽管冰积聚有时可能会对林业造成严重破坏。我们的目标是表征云杉林分中过高乔木的积冰损害，根据林分和单个树木参数评估损害的可能性，并定义影响所有林分和最近减薄的单个树木损害可能性的最重要参数站立。在所研究的林分中，受损云杉的比例在1.8％至60.9％之间，并且更高（p最近变薄的林分（27.8％±1.9％）小于其他林分（20.4％±1.6％）<0.001）。茎破裂是普遍的（98.5％±1.1％）损伤类型。在林分水平上，损坏的可能性对于较大，平均直径较大的较旧，密度较小的林分降低。在林分内，过高的树木受损程度更大（23.5％±1.2％；p<0.001）的树木比低立木层的树木少，但在树皮内，尺寸较大，社会地位较高的树木（相对直径大，细长比低）和树冠比例较高的树木受到的损害较小。对于所有林分和最近减薄的林分，使用几乎相同的变量可以最准确地预测树木倒塌的可能性。立地类型，树高，相对直径和树冠比率在这两种情况下都是相同的，除了所有林分的胸高平均直径和最近减薄林分的林分密度外。我们的结果表明，树木和林分特性对单个树木抵抗冰积聚的重要性以及需要在轮作期间平衡生长和树木稳定性的管理实践的需求。