Key message Rut depth in fine-grained boreal soils induced by an 8-wheeled forwarder is best predicted with soil moisture content, cumulative mass of machine passes, bulk density and thickness of the humus layer. Context Forest machines are today very heavy and will cause serious damage to soil and prevent future growth if forest operations are carried out at the wrong time of the year. Forest operations performed during the wettest season should therefore be directed at coarse-grained soils that are not as prone to soil damage. Aims The study aimed at investigating the significance of the most important soil characteristics on rutting and developing models that can be utilized in predicting rutting prior to forest operations. Methods A set of wheeling tests on two fine-grained mineral soil stands in Southern Finland were performed. The wheeling experiments were conducted in three different periods of autumn in order to get the largest possible variation in moisture content. The test drives were carried out with an 8-wheeled forwarder. Results Soil moisture content is the most important factor affecting rut depth. Rut depth of an 8-wheeled forwarder in fine-grained boreal soil is best predicted with soil moisture content, cumulative mass of machine passes, bulk density and thickness of the humus layer. Conclusion The results emphasize the importance of moisture content on the risk of rutting in fine-grained mineral soils, especially with high moisture content values when soil saturation reaches 80%. The results indicate that it is of high importance that soil type and soil wetness can be predicted prior to forest operations.

中文翻译：

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预测细粒北方森林土壤中由 8 轮运输车诱发的车辙深度

关键信息 由 8 轮运输机引起的细粒北方土壤中的车辙深度最好通过土壤水分含量、机器通过的累积质量、堆积密度和腐殖质层的厚度来预测。背景 今天的森林机器非常重，如果在一年中的错误时间进行森林作业，将对土壤造成严重破坏并阻碍未来的生长。因此，在最潮湿的季节进行的森林作业应针对不易损坏土壤的粗粒土壤。目的 本研究旨在调查最重要的土壤特征对车辙的重要性，并开发可用于在森林作业前预测车辙的模型。方法 在芬兰南部的两个细粒矿质土壤林分上进行了一组轮转试验。轮式试验在秋季的三个不同时期进行，以获得最大可能的水分含量变化。使用 8 轮货运代理进行了试驾。结果土壤含水量是影响车辙深度的最重要因素。8 轮运输车在细粒北方土壤中的车辙深度最好通过土壤含水量、机器通过的累积质量、堆积密度和腐殖质层厚度来预测。结论 结果强调了含水量对细粒矿质土壤车辙风险的重要性，尤其是当土壤饱和度达到 80% 时含水量较高的土壤。结果表明，在森林作业之前预测土壤类型和土壤湿度非常重要。