Abstract The heavy machines used in forest operations not only cause reduction of the total amount of soil pores but also drastically modify their size distribution. The effects in these terms of repeated passages of a tracked skidder and a wheeled one of quite similar size were evaluated in a forest of central Italy. In particular, we focused on macro-aggregates, i.e. the ones of centimetric size, which are crucial for soil functioning and fertility. Empty machines, i.e., without dragging or loading logs, were driven along trails for five round trips (back and forth) with two soil water contents: 11–13%, after a relatively dry period, and 24–25% right after a rain. Soil cores were sampled in the travelled trails and, for comparison, a couple of meters away from them. Bulk density and total porosity were substantially affected by both machines only in the moister soil, while the pore-size distribution changed because of compaction also in the drier soil. The main change the pore system experienced concerned the “coarse storage” pores (the ones from 7 to 50 µm equivalent pore size diameter), which decreased up to more of the 30% in the moist soil. Focusing on just such class of pores, which is the most important for soil water holding capacity, the wheeled machine was slightly more impactful than the tracked one. Overall, the findings of this study highlight the importance of basing on soil moisture for deciding when to perform forest operations and, possibly, with which machine.

中文翻译：

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机械对森林土壤孔隙度的影响

摘要 林业作业中使用的重型机械不仅减少了土壤孔隙的总量，而且极大地改变了它们的大小分布。在意大利中部的森林中评估了履带式集材机和尺寸非常相似的轮式集材机重复通过的影响。我们特别关注宏观聚集体，即厘米大小的聚集体，它们对土壤功能和肥力至关重要。空机器，即不拖曳或装载原木，沿着小径行驶五次往返（来回），土壤含水量有两种：11-13%，在相对干燥的时期后，24-25% 刚下雨后. 在行驶的小径中对土壤核心进行采样，作为比较，距离它们几米。两种机器仅在潮湿土壤中对体积密度和总孔隙度产生显着影响，而在干燥土壤中，由于压实，孔径分布也发生了变化。孔隙系统经历的主要变化与“粗存储”孔隙（等效孔径直径为 7 至 50 µm 的孔隙）有关，在潮湿土壤中减少到 30% 以上。专注于对土壤保水能力最重要的一类孔隙，轮式机器比履带式机器更具影响力。总的来说，这项研究的结果强调了基于土壤湿度来决定何时进行森林作业以及可能使用哪种机器的重要性。孔隙系统经历的主要变化与“粗存储”孔隙（等效孔径直径为 7 至 50 µm 的孔隙）有关，在潮湿土壤中减少到 30% 以上。专注于对土壤保水能力最重要的一类孔隙，轮式机器比履带式机器更具影响力。总的来说，这项研究的结果强调了基于土壤湿度来决定何时进行森林作业以及可能使用哪种机器的重要性。孔隙系统经历的主要变化与“粗存储”孔隙（等效孔径直径为 7 至 50 µm 的孔隙）有关，在潮湿土壤中减少至 30% 以上。专注于对土壤保水能力最重要的一类孔隙，轮式机器比履带式机器更具影响力。总的来说，这项研究的结果强调了基于土壤湿度来决定何时进行森林作业以及可能使用哪种机器的重要性。轮式机器比履带式机器更具影响力。总的来说，这项研究的结果强调了基于土壤湿度来决定何时进行森林作业以及可能使用哪种机器的重要性。轮式机器比履带式机器更具影响力。总的来说，这项研究的结果强调了基于土壤湿度来决定何时进行森林作业以及可能使用哪种机器的重要性。