Short-term physicochemical and biological impacts on soil after forest logging in Mediterranean broadleaf forests: 15 years of field studies summarized by a data synthesis under the meta-analytic framework

Abstract Sustainable Forest Management (SFM) is a key objective of the European Forest Strategy. One of the most important aspects to be considered to achieve this fundamental goal is the implementation of Sustainable Forest Operations (SFOs). This study aims to investigate how and to what extent forest logging and silvicultural treatments affect soil physicochemical properties in the context of Mediterranean forestry by summarizing the results of 55 field studies, performed within the development of Master’s and PhD theses, carried out in Italy over the last 15 years. In order to define reliable and scalable conclusions, and going beyond the typical case-study approach, we applied a data synthesis under the meta-analytic framework summarizing the results of the studies analyzed. The results show that disturbance triggered by the silvicultural treatments (meant as an alteration of canopy cover as a consequence of the removal of some trees) is much lower than that caused by forest logging, in particular passage of forest vehicles and woody loads. Furthermore, as expected, a clear relationship was observed between the impacts on soil physicochemical properties and biological impacts. Based on our results we recommend that ground-based extraction on slopes steeper than 20 per cent should be limited, extending the applications of skyline systems or winch-assisted extraction. Interestingly, different conditions of terrain roughness showed variable effects on the magnitude of impacts, suggesting the need for future dedicated studies on this topic. The application of machineries specifically developed for the forestry sector showed better performance than lower levels of mechanizations, confirming what was reported in previous literature on the topic. However, the major finding from this study clearly shows that the way in which extraction is carried out is the major factor causing soil disturbance.