European beech (Fagus sylvatica L.) forests in Central and Southern Italy are managed applying the shelterwood system. Prior to the regeneration cut, it is common to apply 2–3 thinning interventions, aiming to obtain mostly firewood, considering the low dimension and poor quality of the stems. These interventions are usually carried out by local forest enterprises relying on a low or medium level of mechanization (small-scale forestry). In particular, the short wood system is applied, thus processing the logs to 1 m length and extracting them with forestry-fitted farm tractors equipped with forwarding bins. Despite the large application of this harvesting system in the Mediterranean forestry, no information is available in the literature about its possible disturbance to the forest soil. To fulfill this knowledge gap, we developed the first assessment of soil physicochemical (bulk density, penetration resistance, shear resistance, organic matter content) and biological (soil microarthropods biodiversity evaluated with the QBS-ar index, that is, an index based on the idea that high-quality soils have more groups of microarthropods that are morphologically better adapted to the soil than low-quality soils) properties for this kind of logging operation. In three case study areas in Central Italy, we applied an experimental design to evaluate separately the impacts related to the passage of the machine and that of the silvicultural treatment itself. We further applied linear mixed-effect models to investigate the relationship between changes in soil physicochemical and biological properties. We found the effect of the silvicultural treatment to be negligible, but there was a significant alteration of the investigated parameters in the soil affected by the passage of the machine. Soil penetration and shear resistance doubled in the forwarding trails (0.25 MPa and 4.02 t m⁻², respectively) in comparison with the other two experimental treatments (control area and soil not affected by the machine passage; about 0.12 MPa and 2.10 t m⁻², respectively). Soil organic matter and soil microarthropod biodiversity (QBS-ar index) were reduced by 25% in the forwarding trails (about 30% and 92 respectively) in comparison with the soil not affected by the machine passage (about 39% and about 130, respectively). Such significant disturbance, which occurred even if the applied machinery had lower weight in comparison to other alternatives (forwarders), is related to the high number of machine passes needed to extract the woody material with forwarding bins applying the short wood system. We found a significant relationship between soil compaction and soil organic matter removal and microarthropod biodiversity, with the latter which resulted significantly lower in more compacted and organic matter-poor soils. We demonstrated that this small-scale extraction system can have a negative effect on soil features in the short term. We therefore recommend the application of best management practices, for instance placing brush mats and logging residues, on the forwarding trails to limit the soil disturbance within the framework of small-scale forestry. We further recommend a wider application of aerial harvesting systems, which generally have lower impacts to the soil. However, this could happen only after an extensive training program aimed to increase the knowledge and skills of local loggers about aerial harvesting systems.

中文翻译：

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评估地中海山毛榉高林森林土壤的小规模采伐干扰


意大利中部和南部的欧洲山毛榉（ Fagus sylvatica L.）森林采用防护林系统进行管理。考虑到茎的尺寸小且质量差，在再生切割之前，通常会进行 2-3 次间伐干预，旨在获得大部分木柴。这些干预措施通常由当地林业企业依靠中低机械化水平（小型林业）进行。特别是，采用了短木系统，将原木加工至 1 m 长，并使用配备有转运箱的林业配套农用拖拉机进行提取。尽管这种采伐系统在地中海林业中得到广泛应用，但文献中没有关于其可能对森林土壤造成干扰的信息。为了填补这一知识空白，我们开发了第一个土壤理化（容重、渗透阻力、剪切阻力、有机质含量）和生物（土壤微节肢动物生物多样性）评估，采用 QBS-ar 指数进行评估，即基于优质土壤有更多的微型节肢动物群，这些微节肢动物在形态上比低质量土壤更适应土壤），适合这种伐木作业。在意大利中部的三个案例研究区域，我们应用了实验设计来分别评估与机器通过和造林处理本身相关的影响。我们进一步应用线性混合效应模型来研究土壤理化和生物特性变化之间的关系。 我们发现造林处理的影响可以忽略不计，但受机器通过影响的土壤中所研究的参数发生了显着变化。与其他两个实验处理（控制区域和不受机器通道影响^{的土壤；约0.12 MPa和2.10 tm -2 ，}分别）。与未受机器通道影响的土壤（分别约39%和约130）相比，转发路径中的土壤有机质和土壤微节肢动物生物多样性（QBS-ar指数）减少了25%（分别约为30%和92） ）。即使所应用的机械与其他替代方案（集运机）相比重量较轻，也会发生这种严重的干扰，这与使用短木材系统的集运箱提取木质材料所需的大量机器通过有关。我们发现土壤压实与土壤有机质去除和微节肢动物生物多样性之间存在显着关系，后者在压实程度更高和有机质贫乏的土壤中显着降低。我们证明，这种小规模提取系统可能在短期内对土壤特征产生负面影响。因此，我们建议采用最佳管理实践，例如在运输路径上放置刷垫和伐木残留物，以限制小规模林业框架内的土壤扰动。我们进一步建议更广泛地应用空中收割系统，该系统通常对土壤的影响较小。 然而，这只有在开展旨在提高当地伐木工人有关空中采伐系统的知识和技能的广泛培训计划之后才能实现。